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Aquatic Mammals, Volume 33, Number 4, 2007 ISSN 0167-5427

Marine Mammal Noise Exposure Criteria: Initial Scientific Recommendations

Brandon L. Southall, Ann E. Bowles, William T. Ellison, James J. Finneran, Roger L. Gentry, Charles R. Greene Jr., David Kastak, Darlene R. Ketten, James H. Miller, Paul E. Nachtigall,

W. John Richardson, Jeanette A. Thomas, & Peter L. Tyack

Contents

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411

Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415Historical Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416Acoustic Measures and Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417Sound Production and Use in Marine Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419Responses to Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420

Chapter 2. Structure of the Noise Exposure Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427Sound Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427Marine Mammal Functional Hearing Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430Exposure Criteria Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434Levels of Noise Effect: Injury and Behavioral Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

Chapter 3. Criteria for Injury: TTS and PTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437Effects of Noise on Hearing in Marine Mammals: TTS Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437Injury from Noise Exposure: PTS-Onset Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441Criteria for Injury from a Single Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442Criteria for Injury from Multiple Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444Criteria for Injury from Nonpulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444

Chapter 4. Criteria for Behavioral Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446Behavioral Response Data Analysis Procedures: Disturbance Criteria and Severity Scaling . . . . . . . . . . . . . 448Criteria for Behavioral Disturbance: Single Pulse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451Behavioral Response Severity Scaling: Multiple Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452Behavioral Response Severity Scaling: Nonpulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456

Chapter 5. Research Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474Measurements of Anthropogenic Sound Sources and Ambient Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474Marine Mammal Auditory Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474Behavioral Responses of Marine Mammals to Sound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477Effects of Noise Exposure on Marine Mammal Hearing and Other Systems . . . . . . . . . . . . . . . . . . . . . . . . . 478Particularly Sensitive Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480Necessary Progressions of Marine Mammal Noise Exposure Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482

Appendix A. Acoustic Measures and Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498

Appendix B. Studies Involving Marine Mammal Behavioral Responses to Multiple Pulses . . . . . . . . . . . . . . . . . 502

Appendix C. Studies Involving Marine Mammal Behavioral Responses to Nonpulses . . . . . . . . . . . . . . . . . . . . . 509

Aquatic MammalsPapers dealing with all aspects of the care,

conservation, medicine, and science of aquatic mammals

Editor and Copyright: Jeanette A. Thomas

Department of Biological Sciences, Western Illinois University–Quad Cities, Moline, IL 61265, USA

Co-Editor: Kathleen Dudzinski Dolphin Communication Project, Stonington, Connecticut 06378, USA

Prepared and published by Document and Publication Services, Western Illinois University, Macomb, IL 61455, USA


Supported through Joint Sponsorship by the European Association for Aquatic Mammals, the Alliance of Marine Mammal Parks and Aquariums,

and the International Marine Animal Trainer’s Association

Founded by EAAM in 1974

Established by the EAAM in 1974

AQUATIC MAMMALSThe European Association for Aquatic Mammals (EAAM), the Alliance of Marine

Mammal Parks and Aquariums (AMMPA), and the International Marine Animal Trainer’s Association jointly sponsor Aquatic Mammals (ISSN 0167-5427), printed four times per year.

Managing EditorJeanette A. Thomas, Ph.D., Professor

Department of Biological Sciences, Western Illinois University–Quad Cities, 3561 60th Street, Moline, Illinois 61265, USA

E-mail: [email protected], Tel: (309) 762-9481, ext. 311, Fax: (309) 762-6989

Co-EditorKathleen M. Dudzinski, Ph.D., Director

Dolphin Communication Project, 222 Wolf Neck Road, Stonington, Connecticut 06378, USA E-mail: [email protected], Tel: (860) 514-4704, Manual Fax: (860) 536-1740

Book Review EditorJustin Gregg

School of Psychology, Áras an Phiarsaigh, Trinity College, Dublin 2, Ireland E-mail: [email protected], Tel: +31 (0)475-330006 (Netherlands),

Fax: +1-860-572-5973 (USA)

Graduate Assistants to the EditorsEmily M. Walter and Sara Crowell

Western Illinois University–Quad Cities, 3561 60th Street, Moline, Illinois 61265, USAE-mail: [email protected] and [email protected]

Tel: (309) 762-9481, ext. 289, Fax: (309) 762-6989

Editors EmeritiWillem H. Dudok van Heel, Victor J. A. Manton, and Paul E. Nachtigall

Editorial BoardArne Bjørge, Institute of Marine Research, Gaustadalleen 21, 03439 Oslo, NorwayManuel E. dos Santos, Instituto Superior de Psicologia Aplicada, Lisboa, Portugal

Manuel García Hartmann, Duisburg Zoo, Duisburg, GermanyPhilip Hammond, Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife, UK

Heidi Harley, Division of Social Sciences, New College of Florida, Sarasota, Florida, USAA. Rus Hoelzel, School of Biological and Biomedical Sciences, University of Durham, Durham, UK

Christina Lockyer, North Atlantic Marine Mammal Commission, Polar Environmental Centre, Tromsø, NorwayLee A. Miller, Institute of Biology, University of Southern Denmark, Odense, Denmark

Paul E. Nachtigall, Hawaii Institute of Marine Biology, Kailua, Hawaii, USAGiuseppe Notarbartolo di Sciara, Tethys Research Institute, Milano, ItalyDan Odell, Hubbs-Sea World Research Institute, Orlando, Florida, USA

Grey Stafford, Wildlife World Zoo, Litchfield Park, Arizona, USA

Publication and Administrative Services Document and Publication Services (DPS), Western Illinois University, Macomb, Illinois 61455, USA

To obtain hard copies, back issues, or CD versions, contact Gina Colley, DPS, Western Illinois University, Macomb, Illinois 61455, USA; E-mail: [email protected]

Cover Photo Credits C. Richter, Sperm Whale Seismic Study, Gulf of Mexico, U.S. Minerals Management Service (2002);

J. Thomas, Antarctica (YEAR); J. Thomas, Antarctica (YEAR); J. Anderson, Patagonia (1999); J. Anderson, Southern Ocean (2002); J. Anderson, Patagonia (1999); A. S. Friedlaender, Bay of Fundy (2002); J. Anderson,

San Simeon, CA (1999); P. Scheifele, St. Lawrence Seaway (mid-1990s)

AQUATIC MAMMALSEuropean Association for Aquatic Mammals

Board of the European Association for Aquatic MammalsPresident: Niels van Elk, Dolfinarium Harderwijk, Strandboulevard Post 1,

3841 AB, Harderwijk, The Netherlands; E-mail: [email protected] Elect: Birgitta Mercera, Parc Asterix, BP 8, 60128 Plailly, France;

E-mail: [email protected] President (2004-2006): Pedro Roberto Lavia, Mundo Aquatico, Zoomarine, Estrada Nacional

125 KM 65, Guia, 8200 Albufeira, Portugal; E-mail: [email protected]/Treasurer: Sabrina Brando, Animal Concepts, Sea Mammal Research Unit, Gatty Marine Laboratory,

University of St. Andrews, St. Andrews, Fife, UK; E-mail: [email protected] Committee: Emily M. Walter, Western Illinois University–Quad Cities,

Moline, Illinois 61265, USA; E-mail: [email protected]

Alliance of Marine Mammal Parks and AquariumsExecutive Director: Marilee Menard

418 North Pitt Street, Alexandria, Virginia 22314, USA; E-mail: [email protected] Board of Directors

President: Dave Merritt, Indianapolis ZooImmediate Past President: Jeff Jouett, Dolphin QuestVice President: Clint Wright, Vancouver Aquarium

Treasurer: Bill Hughes, SeaWorld OrlandoSecretary: John Rupp, Point Defiance Zoo and Aquarium

Director-at-Large: Mark Swingle, Virginia Aquarium & Marine Science CenterDirector-at-Large: Dave Blasko, Six Flags Marine World

International Marine Animal Trainers’ Associationc/o John G. Shedd Aquarium, 1200 S. Lake Shore Drive, Chicago, Illinois, 60605, USA

2007 Board of DirectorsPresident: Billy Hurley

President Elect: Shelly BallmanPast President: Al Kordowski

Secretary: Michael HuntTreasurer: Traci Belting

First Vice President: Dave RobertsSecond Vice President: Andrew Scullion

Third Vice President: Mike Osborne

For instructions to authors, abstracts of previous issues, and publication fees, see the journal website:www.aquaticmammalsjournal.org

For information on EAAM, see website:http://eaam.org

For information on the Alliance of Marine Mammal Parks and Aquariums, see website:www.ammpa.org

For information on IMATA, see website:www.imata.org

For details about the online version of Aquatic Mammals, see the Ingenta website:www.ingentaconnect.com

MarineMammalNoiseExposureCriteria �


Brandon L. Southall,1, 2 Ann E. Bowles,3 W�ll�am T. Ell�son,4 James J. F�nneran,5 Roger L. Gentry,6 Charles R. Greene Jr.,7 Dav�d Kastak,2 Darlene R. Ketten,8, 9

James H. M�ller,10 Paul E. Nacht�gall,11 W. John R�chardson,12 Jeanette A. Thomas,13 and Peter L. Tyack8

1NationalOceanicandAtmosphericAdministration(NOAA),NationalMarineFisheriesService,OfficeofScienceandTechnology,MarineEcosystemsDivision,NOAA’sOceanAcousticsProgram,1315East-WestHighway#12539,

SilverSpring,MD20910-6233,USA;E-mail:[email protected],UniversityofCaliforniaatSantaCruz,100ShafferRoad,SantaCruz,CA95060,USA

3Hubbs-SeaWorldResearchInstitute,2595IngrahamStreet,SanDiego,CA92109,USA4MarineAcoustics,Inc.,809AquidneckAvenue,Middletown,RI02842,USA

5U.S.NavyMarineMammalProgram,SpaceandNavalWarfareSystemsCenter–SanDiego,53560HullStreet,SanDiego,CA92152-5000,USA

6ProScienceConsulting,LLC,P.O.Box177,Dickerson,MD20842-0177,USA7GreeneridgeSciences,Inc.,4512ViaHuerto,SantaBarbara,CA93110,USA

8WoodsHoleOceanographicInstitution,WoodsHole,MA02543,USA9HarvardMedicalSchool,DepartmentofOtologyandLaryngology,Boston,MA02114,USA

10UniversityofRhodeIsland,DepartmentofOceanEngineering,SouthFerryRoad,Narragansett,RI02882,USA11Hawai’iInstituteofMarineBiology,P.O.Box1346,Kane’ohe,HI96744,USA

12LGLLtd.,environmentalresearchassociates,P.O.Box280,22FisherStreet,KingCity,ONL7B1A6,Canada13WesternIllinoisUniversity–QuadCities,DepartmentofBiologicalSciences,356160thStreet,Moline,IL61265,USA

ContentsOverv�ew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411

Chapter 1. Introduct�on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415Object�ves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415H�stor�cal Perspect�ve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416Acoust�c Measures and Term�nology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417Sound Product�on and Use �n Mar�ne Mammals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419Responses to Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420

Chapter 2. Structure of the No�se Exposure Cr�ter�a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427Sound Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427Mar�ne Mammal Funct�onal Hear�ng Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430Exposure Cr�ter�a Metr�cs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434Levels of No�se Effect: Injury and Behav�oral D�sturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

Chapter 3. Cr�ter�a for Injury: TTS and PTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437Effects of No�se on Hear�ng �n Mar�ne Mammals: TTS Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437Injury from No�se Exposure: PTS-Onset Calculat�on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441Cr�ter�a for Injury from a S�ngle Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442Cr�ter�a for Injury from Mult�ple Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444Cr�ter�a for Injury from Nonpulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444

Chapter 4. Cr�ter�a for Behav�oral D�sturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446Behav�oral Response Data Analys�s Procedures: D�sturbance Cr�ter�a and Sever�ty Scal�ng. . . . . . 448Cr�ter�a for Behav�oral D�sturbance: S�ngle Pulse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451Behav�oral Response Sever�ty Scal�ng: Mult�ple Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452Behav�oral Response Sever�ty Scal�ng: Nonpulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456

�� Southalletal.

Chapter 5. Research Recommendat�ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474Measurements of Anthropogen�c Sound Sources and Amb�ent No�se . . . . . . . . . . . . . . . . . . . . . . . 474Mar�ne Mammal Aud�tory Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474Behav�oral Responses of Mar�ne Mammals to Sound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477Effects of No�se Exposure on Mar�ne Mammal Hear�ng and Other Systems . . . . . . . . . . . . . . . . . . 478Part�cularly Sens�t�ve Spec�es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480Necessary Progress�ons of Mar�ne Mammal No�se Exposure Cr�ter�a . . . . . . . . . . . . . . . . . . . . . . . 481

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482

L�terature C�ted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482

Append�x A. Acoust�c Measures and Term�nology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498

Append�x B. Stud�es Involv�ng Mar�ne Mammal Behav�oral Responses to Mult�ple Pulses . . . . . . . . 502

Append�x C. Stud�es Involv�ng Mar�ne Mammal Behav�oral Responses to Nonpulses . . . . . . . . . . . . 509

MarineMammalNoiseExposureCriteria ��

Acronyms

Acronym Def�n�t�on

A-we�ght�ng Frequency-select�ve we�ght�ng for aer�al hear�ng �n humans der�ved from the �nverse of the �deal�zed 40-phon equal loudness hear�ng funct�on across frequenc�es

ABR Aud�tory bra�nstem response

ADD Acoust�c deterrent dev�ce

AEP Aud�tory evoked potent�als

AHD Acoust�c harassment dev�ce

ANSI Amer�can Nat�onal Standards Inst�tute

ASSR Aud�tory steady-state response

ATOC Acoust�c Thermometry of Ocean Cl�mate program

CF Center frequency

C-we�ght�ng Frequency-select�ve we�ght�ng for aer�al hear�ng �n humans der�ved from the �nverse of the �deal�zed 100-phon equal loudness hear�ng funct�on across frequenc�es

EFR Envelope follow�ng response

EPA U.S. Env�ronmental Protect�on Agency

ES Explos�on s�mulator

fh�gh Est�mated upper funct�onal hear�ng l�m�t

flow Est�mated lower funct�onal hear�ng l�m�t

HESS H�gh Energy Se�sm�c Survey

HPA Hypothalam�c-p�tu�tary-adrenal ax�s

IMAPS Integrated Mar�ne Mammal Mon�tor�ng and Protect�on System

ISO Internat�onal Standards Organ�zat�on

JNCC U.K. Jo�nt Nature Conservat�on Comm�ttee

LeqT Equ�valent-cont�nuous sound level over per�od T

LIeqT Impulse equ�valent-cont�nuous sound level over per�od T

LFA Low Frequency Act�ve (sonar)

M-we�ght�ng General�zed frequency we�ght�ngs for var�ous groups of mar�ne mammals, allow�ng for the�r funct�onal bandw�dths and appropr�ate �n character�z�ng aud�tory effects of strong sounds

Mlf Frequency we�ght�ng for low-frequency cetaceans (myst�cetes)

Mmf Frequency we�ght�ng for m�d-frequency cetaceans (most odontocetes)

Mhf Frequency we�ght�ng for h�gh-frequency cetaceans (odontocetes spec�al�zed for use of very h�gh frequenc�es)

Mpw Frequency we�ght�ng for p�nn�peds, l�sten�ng �n water

Mpa Frequency we�ght�ng for p�nn�peds, l�sten�ng �n a�r

MMPA U.S. Mar�ne Mammal Protect�on Act

NIHL No�se-�nduced hear�ng loss

NIPTS No�se-�nduced permanent threshold sh�ft

NIOSH U.S. Nat�onal Inst�tute for Occupat�onal Safety and Health

NMFS U.S. Nat�onal Mar�ne F�sher�es Serv�ce

�v Southalletal.

Acronym Def�n�t�on

NOAA U.S. Nat�onal Ocean�c and Atmospher�c Adm�n�strat�on

NRC U.S. Nat�onal Research Counc�l

NRL U.S. Naval Research Laboratory

Pmax Max�mum sound pressure

OBN Octave-band no�se

PCAD Nat�onal Research Counc�l’s Populat�on Consequences of Acoust�c D�sturbance Model

PICE Porpo�se �nc�dental catch el�m�nat�on

PTS Permanent threshold sh�ft

REFMS A computer program for pred�ct�ng shock-wave propagat�on from underwater explos�ons

RL Rece�ved level

RMS Root-mean-square

SEL Sound exposure level

SL Source level (rece�ved level measured or est�mated 1 m from the source)

SLM Sound level meter

SPL Sound pressure level

TS Threshold sh�ft

TTS Temporary threshold sh�ft

USC Un�ted States Code

VAFB Vandenberg A�r Force Base

Overview

A group of experts �n acoust�c research from behav�oral, phys�olog�cal, and phys�cal d�sc�pl�nes was convened over a several year per�od. The pur-pose of th�s panel was to rev�ew the expand�ng l�t-erature on mar�ne mammal hear�ng and on phys�-olog�cal and behav�oral responses to anthropogen�c sound, and to propose exposure cr�ter�a for certa�n effects. The group employed all ava�lable relevant data to pred�ct no�se exposure levels above wh�ch adverse effects on var�ous groups of mar�ne mam-mals are expected. Recent advances �n these f�elds and the press�ng need for a sc�ence-based para-d�gm to assess the effects of sound exposure were the pr�mary mot�vat�ons for th�s effort. Two cat-egor�es of effects were cons�dered: (1) �njury and (2) behav�oral d�sturbance. The proposed cr�ter�a for the onset of these effects were further segre-gated accord�ng to the funct�onal hear�ng capa-b�l�t�es of d�fferent mar�ne mammal groups, and accord�ng to the d�fferent categor�es and metr�cs of typ�cal anthropogen�c sounds �n the ocean. The group ach�eved many of �ts object�ves but acknowl-edges certa�n l�m�tat�ons �n the proposed cr�ter�a because of scarc�ty or complete absence of �nfor-mat�on about some key top�cs. A major component of these recommendat�ons �s a call for spec�f�c research on cr�t�cal top�cs to reduce uncerta�nty and �mprove future exposure cr�ter�a for mar�ne mammals. Th�s publ�cat�on marks the culm�nat�on of a long and challeng�ng �n�t�al effort, but �t also �n�t�ates a necessary, �terat�ve process to apply and ref�ne no�se exposure cr�ter�a for d�fferent spec�es of mar�ne mammals.

The process of establ�sh�ng pol�cy gu�del�nes or regulat�ons for anthropogen�c sound exposure (�.e., the appl�cat�on of these exposure cr�ter�a) w�ll vary among nat�ons, jur�sd�ct�ons, and legal/pol�cy sett�ngs. Such processes should carefully cons�der the l�m�tat�ons and caveats g�ven w�th these pro-posed cr�ter�a �n dec�d�ng whether suff�c�ent data currently ex�st to establ�sh s�mpl�st�c, broad cr�te-r�a based solely on exposure levels. In many cases, espec�ally for behav�oral d�sturbance, context-spec�f�c analyses cons�der�ng prev�ous stud�es on spec�es and cond�t�ons s�m�lar to those �n quest�on m�ght, at least for the foreseeable future, be more appropr�ate than general gu�del�nes.

StateofCurrentKnowledgeThe ava�lable data on the effects of no�se on mar�ne mammals are qu�te var�able �n quant�ty

and qual�ty. In many respects, data gaps severely restr�ct the der�vat�on of sc�ent�f�cally-based no�se exposure cr�ter�a and, �n some cases, expl�c�t threshold cr�ter�a for certa�n effects are not appro-pr�ate g�ven the amount and type of data ava�lable. Sc�ent�f�c �nqu�ry �nto acoust�c commun�cat�on among mar�ne mammals extends back more than half a century, but most of the spec�f�c data rel-evant to the proposed cr�ter�a have been publ�shed w�th�n the last two decades. Ow�ng to the mount-�ng publ�c, sc�ent�f�c, and regulatory �nterest �n conservat�on �ssues related to acoust�cs, the ava�l-able sc�ence �s progress�ng rap�dly (e.g., see NRC, 2003, 2005).

Th�s paper proposes, for var�ous mar�ne mammal groups and sound types, levels above wh�ch there �s a sc�ent�f�c bas�s for expect�ng that exposure would cause aud�tory �njury to occur. Controlled measurements of hear�ng and of the effects of underwater and aer�al sound �n laboratory sett�ngs have greatly expanded the ab�l�ty to assess aud�-tory effects. Wh�le understand�ng of the hear�ng capac�t�es among all mar�ne mammals rema�ns adm�ttedly rud�mentary, there �s a fa�rly deta�led understand�ng of some key aspects of underwater and aer�al hear�ng �n a few representat�ve spec�es of odontocetes, p�nn�peds, and s�ren�ans, although hear�ng �n myst�cetes rema�ns untested. Ava�lable data, along w�th the compell�ng ev�dence of s�m�lar aud�tory processes among all mammals, enables some reasonable extrapolat�ons across spec�es for est�mat�ng aud�tory effects, �nclud�ng the exposure levels of probable onset of �njury. Recent ev�dence suggests that exposure of beaked whales to under-water no�se may, under certa�n (generally unknown) cond�t�ons, result �n non-aud�tory �njury as well (e.g., Fernández et al., 2005). At present, however, there are �nsuff�c�ent data to allow formulat�on of quant�tat�ve cr�ter�a for non-aud�tory �njur�es.

There are many more publ�shed accounts of behav�oral responses to no�se by mar�ne mammals than of d�rect aud�tory or phys�olog�cal effects. Nevertheless, the ava�lable data on behav�oral responses do not converge on spec�f�c exposure cond�t�ons result�ng �n part�cular react�ons, nor do they po�nt to a common behav�oral mechan�sm. Even data obta�ned w�th substant�al controls, prec�s�on, and standard�zed metr�cs �nd�cate h�gh var�ance both �n behav�oral responses and �n expo-sure cond�t�ons requ�red to el�c�t a g�ven response. It �s clear that behav�oral responses are strongly

AquaticMammals 2007, 33(4), 411-414, DOI 10.1578/AM.33.4.2007.411

412 Southalletal.

affected by the context of exposure and by the an�-mal’s exper�ence, mot�vat�on, and cond�t�on�ng. Th�s real�ty, wh�ch �s generally cons�stent w�th patterns of behav�or �n other mammals (�nclud-�ng humans), hampered our efforts to formulate broadly appl�cable behav�oral response cr�ter�a for mar�ne mammals based on exposure level alone.

Frequency-WeightingFunctionsIn humans, hear�ng processes �n a large number of male and female subjects of d�fferent ages have been tested to determ�ne a bas�c aud�omet-r�c curve, equal-loudness curve, and the levels and exposure durat�ons needed to �nduce e�ther recov-erable hear�ng loss (called temporary threshold sh�ft or TTS) or permanent threshold sh�ft (PTS). In add�t�on, the manner �n wh�ch success�ve expo-sures to no�se contr�bute to TTS growth has been well-documented �n humans (e.g., Kryter, 1994; Ward, 1997). In assess�ng the effects of no�se on humans, e�ther an A- or C-we�ghted curve �s appl�ed to correct the sound-level measure-ment for the frequency-dependent hear�ng func-t�on of humans. Early on, the panel recogn�zed that s�m�lar, frequency-we�ghted hear�ng curves were needed for mar�ne mammals; otherw�se, extremely low- and h�gh-frequency sound sources that are detected poorly, �f at all, m�ght be subject to unreal�st�c cr�ter�a.

One of the major accompl�shments �n th�s effort was the der�vat�on of recommended fre-quency-we�ght�ng funct�ons for use �n assess�ng the effects of relat�vely �ntense sounds on hear�ng �n some mar�ne mammal groups. It �s abundantly clear from measurements of mar�ne mammal hear-�ng �n the laboratory, call character�st�cs, and aud�-tory morphology that there are major d�fferences �n aud�tory capab�l�t�es across mar�ne mammal spec�es (e.g., Wartzok & Ketten, 1999). Most pre-v�ous assessments of acoust�c effects e�ther fa�led to account for d�fferences �n funct�onal hear�ng bandw�dth among mar�ne mammal groups or d�d not recogn�ze that the “nom�nal” aud�ogram m�ght be a relat�vely poor pred�ctor of how the aud�tory system responds to relat�vely strong exposures.

The authors del�neated f�ve groups of mar�ne mammals based on s�m�lar�t�es �n the�r hear�ng, and they developed a general�zed frequency-we�ght-�ng (called “M-we�ght�ng”) funct�on for each. The f�ve groups and the assoc�ated des�gnators are (1) myst�cetes (baleen whales), des�gnated as “low-frequency” cetaceans (Mlf); (2) some odontocetes (toothed whales), des�gnated as “m�d-frequency” cetaceans (Mmf); (3) odontocetes spec�al�zed for us�ng h�gh frequenc�es (�.e., por-po�ses, r�ver dolph�ns, and the genera Kogia and Cephalorhynchus) (Mhf); (4) p�nn�peds (�.e., seals, sea l�ons, and walruses) l�sten�ng �n water (Mpw);

and (5) p�nn�peds l�sten�ng �n a�r (Mpa). These cr�-ter�a do not spec�f�cally address s�ren�ans, the sea otter, or the polar bear, �n part because of the lack of key data �n these spec�es.

The M-we�ght�ng funct�ons were def�ned based on known or est�mated aud�tory sens�t�v�ty at d�f-ferent frequenc�es rather than vocal character�st�cs per se. Ow�ng to the pauc�ty of relevant data, these aud�tory funct�ons are �ntent�onally precaut�on-ary (w�de) and l�kely overest�mate the funct�onal bandw�dth for most or all spec�es. The�r pr�mary appl�cat�on �s �n pred�ct�ng aud�tory damage rather than levels of detect�on or behav�oral response. Consequently, �t �s more appropr�ate to use “flat-ter” funct�ons than would be obta�ned by employ-�ng a s�mple �nverse-aud�ogram funct�on.

ExposureCriteriaMetricsTo further compl�cate the der�vat�on of no�se expo-sure cr�ter�a, sounds can be descr�bed w�th var�ous acoust�c metr�cs, �nclud�ng sound pressure levels and sound exposure levels. The latter �s a measure of rece�ved sound energy. Ava�lable l�terature pro-v�des a m�xture of both measures, but many sound sources have pr�mar�ly been descr�bed �n pressure level un�ts. To accommodate these two measures, and to account for all relevant acoust�c features that may affect mar�ne mammals, we developed dual cr�ter�a for no�se exposures �n each of the f�ve funct�onal hear�ng groups, us�ng both sound pres-sure and sound exposure levels.

ExposureCriteriaforInjuryAnother area �n wh�ch we prov�de substant�ve conclus�ons �s �n the determ�nat�on of sound exposures bel�eved to cause d�rect aud�tory �njury to mar�ne mammals. By all accounts, the �nner ear �s the organ system most d�rectly sens�t�ve to sound exposure and, thus, the most suscept�ble to sound-der�ved damage. We def�ne the m�n�mum exposure cr�ter�on for �njury as the level at wh�ch a s�ngle exposure �s est�mated to cause onset of permanent hear�ng loss (PTS). Data on TTS �n mar�ne mammals, and on patterns of TTS growth and �ts relat�on to PTS �n other mammals, were used to est�mate thresholds for �njury. Ow�ng to the l�m�ted ava�lab�l�ty of relevant data on TTS and PTS, the extrapolat�on procedures underly�ng these est�mat�ons are necessar�ly precaut�onary.

To account for all of the potent�ally �njur�ous aspects of exposure, dual cr�ter�a for �njury were establ�shed for each funct�onal mar�ne mammal hear�ng group based on �nstantaneous peak pres-sure (unwe�ghted) and total energy (M-we�ghted). Exposure cr�ter�a for �njury are g�ven for two types of sounds, pulse and nonpulse, and for s�ngle and mult�ple exposures. The term pulse �s used here to descr�be br�ef, broadband, atonal, trans�ents (ANSI,

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1986; Harr�s, 1998, Chapter 12), wh�ch are charac-ter�zed by a relat�vely rap�d r�se-t�me to max�mum pressure followed by a decay that may �nclude a per�od of d�m�n�sh�ng and osc�llat�ng max�mal and m�n�mal pressures. Examples of pulses are sounds from explos�ons, gunshots, son�c booms, se�sm�c a�rgun pulses, and p�le dr�v�ng str�kes. Nonpulse (�nterm�ttent or cont�nuous) sounds can be tonal, broadband, or both. They may be of short dura-t�on but w�thout the essent�al propert�es of pulses (e.g., rap�d r�se-t�me). Examples of anthropogen�c, ocean�c sources produc�ng such sounds �nclude vessels, a�rcraft, mach�nery operat�ons such as dr�ll�ng or w�nd turb�nes, and many act�ve sonar systems. As a result of propagat�on, sounds w�th the character�st�cs of a pulse at the source may lose pulsat�le character�st�cs at some (var�able) d�stance and can be character�zed as a nonpulse by certa�n rece�vers.

Regardless of the anthropogen�c sound, �f a mar�ne mammal’s rece�ved exposures exceed the relevant (pulse or nonpulse) cr�ter�on, aud�tory �njury (PTS) �s assumed to be l�kely. Chapter 3, “Cr�ter�a for Injury,” prov�des deta�ls regard�ng the exposure levels requ�red to cause TTS-onset and the extrapolat�on of those results to est�mate levels above wh�ch PTS-onset may occur. For all f�ve funct�onal hear�ng groups, we propose dual exposure cr�ter�a above wh�ch aud�tory �njury �s l�kely.

ExposureCriteriaforBehaviorOne challenge �n develop�ng behav�oral cr�ter�a �s to d�st�ngu�sh a s�gn�f�cant behav�oral response from an �ns�gn�f�cant, momentary alterat�on �n behav�or. For example, the startle response to a br�ef, trans�ent event �s unl�kely to pers�st long enough to const�tute s�gn�f�cant d�sturbance. Even strong behav�oral responses to s�ngle pulses, other than those that may secondar�ly result �n �njury or death (e.g., stamped�ng), are expected to d�s-s�pate rap�dly enough as to have l�m�ted long-term consequence. Consequently, upon exposure to a s�ngle pulse, the onset of s�gn�f�cant behav�oral d�sturbance �s proposed to occur at the lowest level of no�se exposure that has a measurable trans�ent effect on hear�ng (�.e., TTS-onset). We recogn�ze that th�s �s not a behav�oral effect per se, but we use th�s aud�tory effect as a de facto behav�oral threshold unt�l better measures are �dent�f�ed. Lesser exposures to a s�ngle pulse are not expected to cause s�gn�f�cant d�sturbance, whereas any comprom�se, even temporar�ly, to hear�ng funct�ons has the potent�al to affect v�tal rates through altered behav�or.

For other anthropogen�c sound types (mult�ple pulses, nonpulses), we conducted an extens�ve rev�ew of the ava�lable l�terature but were unable

to der�ve expl�c�t and broadly appl�cable numer�-cal threshold values for del�neat�ng behav�oral d�sturbance. We d�d develop a quant�tat�ve scor-�ng parad�gm that numer�cally ranks, as a sever�ty scal�ng, behav�oral responses observed �n e�ther f�eld or laboratory cond�t�ons. We appl�ed th�s approach to the appropr�ate behav�oral data for mult�ple pulses and nonpulses. Some of these data suffer from poor stat�st�cal power, l�m�ted �nfor-mat�on on rece�ved sound levels and background no�se, �nsuff�c�ent measurements of all potent�ally �mportant contextual var�ables, and/or �nsuff�c�ent controls. Some such data are analyzed here solely for �llustrat�ve purposes. Most behav�oral stud�es suffered from at least some of these problems. Therefore, we do not �ntend to g�ve un�form sc�-ent�f�c credence to all of the c�ted data, and we expect future stud�es to g�ve greater attent�on and r�gor to these cr�t�cal requ�rements.

Th�s rev�ew and scor�ng process, wh�le not a formal meta-analys�s for normal�z�ng and pool-�ng d�sparate observat�ons, corroborated certa�n �nterest�ng aspects of mar�ne mammal behav�oral responses to sound exposure. Foremost was that a behav�oral response �s determ�ned not only by s�mple acoust�c metr�cs, such as rece�ved level (RL), but also by contextual var�ables (e.g., labo-ratory vs f�eld cond�t�ons, an�mal act�v�ty at the t�me of exposure, hab�tuat�on/sens�t�zat�on to the sound, etc.). Also �mportant �s the presence or absence of acoust�c s�m�lar�t�es between the anthropogen�c sound and b�olog�cally relevant natural s�gnals �n the an�mal’s env�ronment (e.g., calls of conspec�f�cs, predators, prey). W�th�n certa�n s�m�lar cond�t�ons, there appears to be some relat�onsh�p between the exposure RL and the magn�tude of behav�oral response. However, �n many cases, such relat�onsh�ps clearly do not ex�st, at least when response data are pooled across mult�ple spec�es and contexts. Th�s argues for a context-based approach to der�v�ng no�se exposure cr�ter�a for behav�oral responses. That concept, along w�th our rev�ew and scal�ng of the ava�lable observat�onal data, prov�des a founda-t�on for establ�sh�ng dose-response relat�onsh�ps for some spec�f�c c�rcumstances and a start�ng po�nt for future analyses when add�t�onal data are ava�lable.

ConclusionsandResearchRecommendationsTh�s process has resulted �n several s�gn�f�cant advances. These �nclude a rev�ew and �nterpre-tat�on of the ava�lable l�terature on �njury and behav�oral data us�ng precaut�onary extrapola-t�on procedures, der�vat�on of mar�ne mammal frequency-we�ght�ng funct�ons, spec�f�cat�on of quant�tat�ve cr�ter�a for aud�tory �njury, and der�va-t�on of a “sever�ty scale” for behav�oral responses.

414 Southalletal.

The �nab�l�ty to �dent�fy broadly appl�cable, quant�tat�ve cr�ter�a for behav�oral d�sturbance �n response to mult�ple-pulse and nonpulse sounds �s an acknowledged l�m�tat�on.

Our efforts to der�ve mar�ne mammal no�se exposure cr�ter�a clearly �llustrate the fact that, at present, research �n th�s f�eld rema�ns l�m�ted �n many areas. The need for extrapolat�on pro-cedures and precaut�onary assumpt�ons po�nts d�rectly to research needs �n a var�ety of areas on a var�ety of spec�es. In certa�n cond�t�ons, proposed cr�ter�a for an ent�re mar�ne mammal group are based on the most precaut�onary measurement or observat�on for a spec�es w�th�n that group, desp�te the fact that, for other spec�es w�th�n that group, there are emp�r�cal data �nd�cat�ng that h�gher exposures are requ�red to �nduce the same effect. We bel�eve �t �s appropr�ate to use the most precaut�onary data �n propos�ng group-w�de cr�te-r�a appl�cable for spec�es where there are no d�rect measurements. We also feel �t �s appropr�ate on a case-by-case bas�s to apply the most relevant emp�r�cal data (�.e., from the spec�es or genus of concern) �n sett�ng the exposure thresholds spec�-f�ed �n pol�cy gu�del�nes.

F�nally, we emphas�ze that exposure cr�ter�a for s�ngle �nd�v�duals and relat�vely short-term (not chron�c) exposure events, as d�scussed here, are �nsuff�c�ent to descr�be the cumulat�ve and eco-system-level effects l�kely to result from repeated and/or susta�ned human �nput of sound �nto the mar�ne env�ronment and from potent�al �nterac-t�ons w�th other stressors. Also, the �njury cr�ter�a proposed here do not appear to pred�ct what may have been �nd�rect �njury from acoust�c exposure �n several cases where cetaceans of several spe-c�es mass-stranded follow�ng exposure to m�l�tary sonar.

The extens�ve research recommendat�ons g�ven here (see Chapter 5) represent our collect�ve v�ew of the concerted effort that w�ll be requ�red over the com�ng decades. H�gh pr�or�ty catego-r�es of research �nclude (1) cont�nued expans�on of knowledge on bas�c mar�ne mammal hear�ng capab�l�t�es, �nclud�ng sound local�zat�on, the detect�on of real�st�c sound s�gnals, commun�-cat�on mask�ng, and aud�tory “scene analys�s”; (2) cont�nued expans�on of knowledge on basel�ne mar�ne mammal behav�oral patterns; (3) well-controlled, d�rect measurements (us�ng appropr�-ate, standard�zed acoust�c metr�cs) of the effects of sound exposure on mar�ne mammal hear�ng, behav�or, and phys�ology; and (4) r�sk-assessment stud�es of the cumulat�ve and synerg�st�c effects of no�se and other exposure(s) on �nd�v�duals and populat�ons.

Understand�ng and manag�ng the effects of no�se on mar�ne l�fe w�thout unjust�f�ably

constra�n�ng �mportant human act�v�t�es �n the oceans w�ll cont�nue to be challeng�ng for the foreseeable future. W�th susta�ned and focused research �n key areas, future sc�ent�sts w�ll be equ�pped to make �nformed �mprovements to the �n�t�al sc�ent�f�c recommendat�ons presented here. These �mprovements should �deally be �ntegrated �nto sc�ence-based r�sk assessment models that cons�der all aspects of sound exposure and other potent�al stressors on �nd�v�dual mar�ne mammals, populat�ons, and mar�ne ecosystems.

1. Introduction

Objectives

Recent �nterest and concern about the effects of anthropogen�c no�se on mar�ne mammals has tr�ggered cons�derable new research (e.g., Costa et al., 2003; Fr�strup et al., 2003; F�nneran et al., 2005a), summar�es of ava�lable �nformat�on (R�chardson et al., 1995; Wartzok & Ketten, 1999), and recommendat�ons for spec�f�c act�on (NRC, 1994, 2000, 2003, 2005). Systemat�c, object�ve, sc�ence-based �nterpretat�on of the ava�lable data �s cr�t�cally needed to �nform management agenc�es charged w�th m�t�gat�ng adverse effects of anthro-pogen�c no�se on protected spec�es. In response to th�s need, we use here the full body of sc�ent�f�c data on mar�ne mammal hear�ng and the effects of no�se on hear�ng and behav�or, augmented where appropr�ate by �nterpretat�ons of terrestr�al mammal (�nclud�ng human) data, to develop proposed expo-sure cr�ter�a that are as comprehens�ve, defens�ble, and prec�se as �s currently poss�ble. The scope of these cr�ter�a �ncludes �njur�ous and behav�oral effects of a s�ngle no�se exposure event on an �nd�-v�dual cetacean (whales, dolph�ns, and porpo�ses) or p�nn�ped (seals, sea l�ons, and walruses).

The recommended no�se exposure cr�ter�a are sc�ence-based, developed w�thout address�ng the commerc�al, soc�etal, or pract�cal ram�f�cat�ons of �mplement�ng the conclus�ons reached here. We �ntend to m�rror the process used �n the devel-opment of damage r�sk cr�ter�a for humans (see Crocker, 1997). Pol�cy “gu�del�nes” developed for regulatory and soc�etal purposes are based both on sc�ent�f�c ev�dence (as summar�zed �n th�s paper for mar�ne mammals) and on other cons�derat�ons (e.g., econom�c, pract�cal, soc�al, and eth�cal) not dealt w�th here. Thus, on certa�n po�nts, pol�cy gu�del�nes that are developed separately for the purposes of var�ous jur�sd�ct�ons, nat�ons, or users of these cr�ter�a may d�ffer from the sc�ence-based cr�ter�a recommended here.

All forms of anthropogen�c no�se rece�ved by mar�ne mammals were cons�dered, whether pro-duced under water or �n a�r, and we adopted a comparat�ve approach, wh�ch we regard as essen-t�al to any cr�ter�a-sett�ng process for nonhuman an�mals. For most of the ~128 mar�ne mammal spec�es and subspec�es (R�ce, 1998) cons�dered here, no emp�r�cal data were ava�lable on nom�nal hear�ng character�st�cs or on the effects of no�se on hear�ng or behav�or. Pract�cal, eth�cal, and

legal cons�derat�ons l�m�t the level of sc�ent�f�c �nformat�on that �s ava�lable for der�v�ng cr�ter�a appl�cable to e�ther humans or mar�ne mammals. Consequently, certa�n assumpt�ons and cr�ter�a proposed here were based on �nformat�on from other mammal�an groups, where just�f�ed. Where such data present a var�ety of opt�ons, we made �ntent�onally precaut�onary dec�s�ons (�.e., lower proposed exposure levels) to reduce the r�sk of assum�ng no effect when one was actually present. The term “precaut�onary” �s used here w�thout ref-erence to any regulatory or pol�cy �mpl�cat�on of th�s word. Sc�ent�sts would more convent�onally use the term “conservat�ve” �n th�s regard rather than the more bureaucrat�c “precaut�onary,” but �n certa�n complex �nstances here, the term “conser-vat�ve” would be potent�ally amb�guous, depend-�ng on the perspect�ve of the reader. When �nfor-mat�on was l�m�ted, extrapolat�ons were made caut�ously to m�n�m�ze the r�sk of fa�l�ng to recog-n�ze an effect when one actually occurs (Type-II stat�st�cal error) as can occur w�th small sample s�zes or �mprec�se measurements.

Each general�zat�on/extrapolat�on was �dent�-f�ed, all precaut�onary dec�s�ons were noted, and the log�c lead�ng to each proposed cr�ter�on was spec�f�ed. Thus, when new data become ava�lable, appropr�ate mod�f�cat�ons can be made read�ly. Stud�es that are needed to resolve the uncerta�n-t�es encountered �n develop�ng the current cr�ter�a are d�scussed �n deta�l (see Chapter 5, “Research Recommendat�ons”). Real�st�cally, however, the general�zat�on of �nformat�on between related spec�es w�ll rema�n essent�al �n many cases for the foreseeable future.

Our �ntent was to der�ve recommended no�se exposure cr�ter�a us�ng the best �nformat�on cur-rently ava�lable, �dent�fy weaknesses �n the present approach, call for relevant research, and structure the cr�ter�a such that future �mprovements can be �ncorporated eas�ly. Lack of data l�m�ted the pro-posed no�se exposure cr�ter�a to �nd�v�dual mar�ne mammals exposed to acute exposure events (such as the passage of one vessel or a ser�es of act�ve sonar transm�ss�ons). Also, the proposed cr�ter�a are l�m�ted to cetaceans and p�nn�peds. We expect that no�se exposure cr�ter�a for other mar�ne mammals (manatees, dugongs, polar bears, and sea otters), as well as other mar�ne taxa, w�ll be developed as add�t�onal data become ava�lable and are evaluated. In fact, a separate expert panel (S3/


416 Southalletal.

WG92: “Effects of Sound on F�sh and Turtles”) has been establ�shed under the Standards Comm�ttee (S3) of the Acoust�cal Soc�ety of Amer�ca to con-s�der no�se exposure cr�ter�a for f�sh and turtles. Add�t�onally, cr�ter�a are clearly needed for cumu-lat�ve effects and for effects at spec�es or even eco-system levels, but data to support those types of cr�ter�a do not currently ex�st.

The present recommended cr�ter�a represent a major step �n �n�t�at�ng a lengthy, systemat�c pro-cess to pred�ct and �dent�fy acoust�c exposure con-d�t�ons (natural or anthropogen�c) assoc�ated w�th var�ous effects on mar�ne mammals. Th�s paper �s del�berately structured �n a somewhat formula�c and report-l�ke manner so that the log�c underly-�ng certa�n assumpt�ons and extrapolat�ons (as well as the data needed to test and/or strengthen them) �s self-ev�dent. We expect there w�ll be an �terat�ve process of �mprov�ng and expand�ng the complex�ty of the exposure cr�ter�a, s�m�lar to the decades-long development of human no�se expo-sure cr�ter�a (see Crocker, 1997). Because of the matr�x structure of the proposed cr�ter�a, thresh-olds �n spec�f�c cells can be updated �ndependently as new �nformat�on becomes ava�lable.

There �s an extens�ve h�story and d�vers�ty of exposure cr�ter�a for humans w�th var�ous k�nds of acoust�c exposure. A full d�scuss�on of these cr�te-r�a �s beyond the scope of th�s paper, but examples �nclude workplace no�se standards (e.g., NIOSH, 1998), standards for the protect�on of m�l�tary personnel (U.S. DoD, 1997), and nat�onal pol�cy gu�del�nes (e.g., EPA, 1974; BG PPG, 1994). Several add�t�onal examples were also cons�dered, whether rece�ved under water or �n a�r, �n var�ous dec�s�ons underly�ng the mar�ne mammal cr�ter�a proposed here. The process of establ�sh�ng human no�se exposure cr�ter�a has been d�ff�cult and con-tent�ous, but establ�sh�ng no�se exposure cr�ter�a for mar�ne mammals �s cons�derably more daunt-�ng g�ven the d�vers�ty of mar�ne mammal spec�es across three orders, the complex�ty of aer�al and underwater acoust�c exposures, and profound data l�m�tat�ons.

Historical Perspective

Concerns about potent�al adverse effects of anthro-pogen�c no�se on mar�ne l�fe began �n the 1970s (e.g., Payne & Webb, 1971) and expanded �n the 1980s. Exper�ments dur�ng the 1980s w�th se�sm�c a�rguns �nd�cated that bowhead whales (Balaenamysticetus) and gray whales (Eschrichtiusrobus-tus) exh�b�ted clear, susta�ned avo�dance of opera-t�onal areas at d�stances where pulse root-mean-square (RMS) sound pressure levels (SPLs) were 160 to 170 dB re: 1 µPa (Malme et al., 1983, 1984, 1986, 1988; R�chardson et al., 1986; Ljungblad

et al., 1988). In contrast, early observat�ons of bowhead and gray whales exposed to cont�nu-ous �ndustr�al sounds, such as those assoc�ated w�th dr�ll�ng operat�ons, suggested 120 dB re: 1 µPa as the approx�mate threshold for behav�oral d�sturbance of these baleen whales (Malme et al., 1984; R�chardson et al., 1990a, 1995 [pp. 286-287]). S�gn�f�cant �nd�v�dual var�ab�l�ty was noted �n “typ�cal” behav�oral responses, however, w�th some �nd�v�dual whales respond�ng only when very close to sound sources and others react�ng at much longer d�stances (and to lower rece�ved sound levels). Th�s var�ab�l�ty ra�ses quest�ons as to whether behav�oral responses are most appro-pr�ately descr�bed by the exposure rece�ved level (RL) of the st�mulus at the an�mal, the s�gnal-to-amb�ent no�se d�fferent�al, the rate of change of the s�gnal, or s�mply to the presence of the human act�v�ty as �nd�cated by acoust�c cues and/or v�sual st�mul�.

Concern about the effects of acoust�c pulses from se�sm�c explorat�on and cont�nuous sound from other �ndustr�al act�v�t�es resulted �n the �mpos�t�on of m�t�gat�on requ�rements on some �ndustr�al act�v�t�es �n certa�n jur�sd�ct�ons by the early- to m�d-1980s. Subsequent events, such as the Heard Island Feas�b�l�ty Test �n 1991 (Baggeroer & Munk, 1992), the Acoust�c Thermometry of Ocean Cl�mate (ATOC) pro-gram �n the late-1990s (see NRC, 1994, 2000; Au et al., 1997; Costa et al., 2003), and the U.S. Navy’s low-frequency act�ve sonar program (e.g., Croll et al., 2001) resulted �n popular and govern-mental �nterest �n sett�ng cr�ter�a for safe levels of sound for mar�ne mammal exposure (NRC, 1994, 2000, 2003; R�chardson et al., 1995). Th�s �nterest has expanded w�th the f�nd�ng that tact�cal, m�d-frequency, m�l�tary sonar transm�ss�ons are some-t�mes correlated, �n spec�f�c cond�t�ons, w�th mass strand�ng events of (predom�nantly) several beaked whale spec�es, �nclud�ng Cuv�er’s (Ziphiuscaviro-stris), Bla�nv�lle’s (Mesoplodondensirostris), and Gerva�s’ (Mesoplodoneuropaeus) beaked whales (see Evans & England, 2001; Fernández et al., 2005; Cox et al., 2006).

In 1995, the U.S. Nat�onal Mar�ne F�sher�es Serv�ce (NMFS) set underwater “do not exceed” cr�ter�a for exposure of mar�ne mammals to underwater pulses from se�sm�c a�rguns. These cr�ter�a were 190 dB re: 1 µPa for p�nn�peds and most odontocete cetaceans and 180 dB re: 1 µPa for myst�cetes and sperm whales (Physetermac-rocephalus) (and, by �nference, for pygmy and dwarf sperm whales [Kogia spp.]). These exposure l�m�ts were �ntended as precaut�onary est�mates of exposures below wh�ch phys�cal �njury would not occur �n these taxa. There was no emp�r�cal ev�-dence as to whether exposure to h�gher levels of


pulsed sounds would or would not cause aud�tory or other �njur�es. G�ven the l�m�ted data then ava�l-able, however, �t could not be guaranteed that mar�ne mammals exposed to h�gher levels would not be �njured. Further, �t was recogn�zed that behav�oral d�sturbance could, and �n some cases l�kely would, occur at lower RLs.

In June 1997, the H�gh Energy Se�sm�c Survey (HESS) team (1999, Append�x 5) convened a panel of experts to assess no�se exposure cr�ter�a for mar�ne mammals exposed to se�sm�c pulses. The consensus was that, g�ven the best ava�lable data at that t�me, exposure to a�rgun pulses w�th RLs above 180 dB re: 1 µPa (averaged over the pulse durat�on) was “l�kely to have the potent�al to cause ser�ous behav�oral, phys�olog�cal, and hear-�ng effects.” The panel noted the potent�al for ± 10 dB var�ab�l�ty around the 180 dB re: 1 µPa level, depend�ng on spec�es, and that more �nformat�on was needed.

The NMFS has cont�nued to use a “do not exceed” exposure cr�ter�on of 180 dB re: 1 µPa for myst�cetes and (recently) all odontocetes exposed to sequences of pulsed sounds, and a 190 dB re: 1 µPa cr�ter�on for p�nn�peds exposed to such sounds. H�gher thresholds have been used �n the U.S. for s�ngle pulses such as explos�ons used �n naval vessel-shock tr�als. Behav�oral d�sturbance cr�ter�a for pulsed sounds have typ�cally been set at an SPL value of 160 dB re: 1 µPa, based ma�nly on the earl�er observat�ons of myst�cetes react�ng to a�rgun pulses (e.g., Malme et al., 1983, 1984; R�chardson et al., 1986). The relevance of the 160 dB re: 1 µPa d�sturbance cr�ter�on for odontocetes and p�nn�peds exposed to pulsed sounds �s not at all well-establ�shed, however. Although these cr�ter�a have been appl�ed �n var�ous regulatory act�ons (pr�nc�pally �n the U.S.) for more than a decade, they rema�n controvers�al, have not been appl�ed cons�stently �n the U.S., and have not been w�dely accepted elsewhere.

More recently, a cons�derable body of data has accumulated on the levels at wh�ch trans�ent and more prolonged sounds cause the onset of tempo-rary threshold sh�ft (TTS) and var�ous behav�oral react�ons. Some of these data are not cons�stent w�th the aforement�oned defacto cr�ter�a used �n recent years �n the Un�ted States.

One ma�n purpose of th�s paper �s to synthe-s�ze and apply all ava�lable �nformat�on to der�ve proposed object�ve no�se exposure cr�ter�a for a large subset of mar�ne mammals. The effect levels cons�dered (�njury and s�gn�f�cant behav�oral d�sturbance) were generally cons�stent w�th the def�n�t�ons of levels A and B harassment, respec-t�vely, of the U.S. Mar�ne Mammal Protect�on Act (MMPA) of 1972 (16 USC, § 1361); however, many of the behav�ors cons�dered at the lower end

of our sever�ty scal�ng parad�gm would almost certa�nly not const�tute b�olog�cally s�gn�f�cant d�sturbance (or consequently level B harassment under the MMPA). However, our exposure cr�ter�a were der�ved w�thout regard for pol�cy dec�s�ons of the U.S. or any nat�on and should therefore not be assumed to correspond w�th regulatory catego-r�es or def�n�t�ons of effects. S�nce harassment def�n�t�ons under the MMPA are not un�form for all human act�v�t�es and are subject to change, add�t�onal �nterpretat�on of the �nformat�on pre-sented would be requ�red to evaluate effects w�th regard to th�s (or any other) statute.

Acoustic Measures and Terminology

Th�s sect�on br�efly cons�ders those acoust�c mea-sures and term�nology that are d�rectly relevant to these mar�ne mammal exposure cr�ter�a. More deta�led descr�pt�ons of some of the terms g�ven �n th�s and other sect�ons, �nclud�ng equat�ons relevant to many of the def�n�t�ons, are g�ven �n Append�x A. Bas�c acoust�c term�nology �s pre-sented �n numerous other sources (e.g., K�nsler et al., 1982; ANSI, 1986, 1994; R�chardson et al., 1995; Harr�s, 1998; NRC, 2003).

Sound �s appropr�ately descr�bed as hav�ng two components: (1) a pressure component and (2) a part�cle mot�on component. Part�cle mot�on—the osc�llatory d�splacement, veloc�ty, or accelerat�on of the actual “part�cles” of the med�um at a par-t�cular locat�on—�s d�rect�onal and best descr�bed by a 3-d�mens�onal vector. Mar�ne mammal sen-s�t�v�ty to part�cle mot�on �s poorly understood, but �t appears to be funct�onally l�m�ted (F�nneran et al., 2002a) �n contrast to the sensory capab�l�-t�es of most or all f�sh (see Popper et al., 2003). Conversely, as compared to f�sh, mar�ne mammals generally have greater sens�t�v�ty to sound pres-sure (lower detect�on thresholds) and much w�der funct�onal hear�ng bandw�dths (see Fay, 1988; R�chardson et al., 1995; Popper et al., 2003). Consequently, �n cons�der�ng the potent�al effects of sound on mar�ne mammals, part�cle mot�on �s rarely d�scussed. Except for spec�al c�rcumstances (e.g., plane and spher�cal waves), there �s no s�mple relat�onsh�p between pressure and part�cle veloc�ty. The vast major�ty of stud�es of hear�ng �n capt�ve mar�ne mammals have been conducted �n relat�vely small enclosed volumes of water, mak�ng the plane wave assumpt�on (and apriori knowledge of the relat�onsh�p between pressure and veloc�ty) �nval�d.

It �s �mportant to d�st�ngu�sh between the sourcelevel (SL), or level measured 1 m from the source, vs the receivedlevel (RL), wh�ch �s the level mea-sured at the rece�ver (usually a mar�ne mammal here�n).

418 Southalletal.

The term “�ntens�ty” �s often used generally w�th respect to subject�ve acoust�c parameters (�.e., loudness), but �t �s used here �n a str�ct sense. Sound �ntens�ty �s normally def�ned as the t�me-averaged act�ve �ntens�ty (K�nsler et al., 1982; Fahy, 1995); th�s quant�ty corresponds to local net transport of sound energy and �s related to the product of the sound pressure and the part�cle veloc�ty component �n-phase w�th the sound pres-sure. In the major�ty of laboratory stud�es, complex sound f�elds typ�cally create complex, spat�ally vary�ng relat�onsh�ps between pressure and veloc-�ty. In these c�rcumstances, sound �ntens�ty cannot be est�mated from pressure measurements alone (wh�ch assume that pressure and part�cle veloc�ty are �n-phase), and spec�f�c measurements of the sound part�cle veloc�ty (or pressure grad�ent) are requ�red �n order to character�ze �ntens�ty.

We d�st�ngu�shed two bas�c sound types: (1) pulse and (2) nonpulse. Our operat�onal def�-n�t�ons of sound types are g�ven �n Chapter 2, “Structure of the No�se Exposure Cr�ter�a,” and are d�scussed at greater length �n Append�x A. The pulse/nonpulse d�st�nct�on �s �mportant because pulses generally have a d�fferent potent�al to cause phys�cal effects, part�cularly on hear�ng (e.g., Ward, 1997).

Peak sound pressure (Pmax) �s the max�mum absolute value of the �nstantaneous sound pressure dur�ng a spec�f�ed t�me �nterval and �s denoted �n un�ts of Pascals (Pa). It �s �n no sense an averaged pressure. Peak pressure �s a useful metr�c for e�ther pulse or nonpulse sounds, but �t �s part�cularly �mportant for character�z�ng pulses (ANSI, 1986; Harr�s, 1998, Chapter 12). Peak-to-peak sound pressure �s the algebra�c d�fference between the max�mum pos�t�ve and max�mum negat�ve �nstan-taneous peak pressure. The mean-squared pres-sure �s the average of the squared pressure over some durat�on. Sound pressure levels are g�ven as the dec�bel (dB) measures of the pressure metr�cs def�ned above. The RMS SPL �s g�ven as dB re: 1 µPa for underwater sound and dB re: 20 µPa for aer�al sound. Peak sound pressure levels are denoted hereafter as dB re: 1 µPa (peak) �n water and dB re: 20 µPa (peak) �n a�r. Peak-to-peak sound pressure levels are dB re: 1 µPa (peak-to-peak) �n water and dB re: 20 µPa (peak-to-peak) �n a�r.

Duration �s the length of a sound �n seconds. Durat�on �s �mportant because �t affects other sound measures, spec�f�cally mean-square and/or RMS sound pressure (Madsen, 2005). Because of background no�se and reverberat�on, durat�on can be d�ff�cult to spec�fy prec�sely, but a funct�onal def�n�t�on (see Append�x A) �s used here.

Sound exposure level (SEL) �s a measure of energy. Spec�f�cally, �t �s the dB level of the

t�me �ntegral of the squared-�nstantaneous sound pressure normal�zed to a 1-s per�od. It can be an extremely useful metr�c for assess�ng cumulat�ve exposure because �t enables sounds of d�ffer�ng durat�on, somet�mes �nvolv�ng mult�ple expo-sures, to be compared �n terms of total energy. Several methods ex�st for summ�ng energy over mult�ple exposures to generate a s�ngle exposure “equ�valent” value. The relat�vely stra�ghtforward approach used here �s descr�bed �n Append�x A (eq. 5). Th�s summat�on procedure essent�ally generates a s�ngle exposure “equ�valent” value that assumes no recovery of hear�ng between repeated expo-sures. As d�scussed below, recovery funct�ons for mar�ne mammal TTS dur�ng and follow�ng mult�-ple exposures are st�ll unknown; however, cons�d-er�ng nom�nal TTS recovery funct�ons �n terrestr�al mammals when exposures occur m�nutes to hours apart (see Kryter, 1994; Ward, 1997), the above summat�on procedure would l�kely overest�mate the effect of mult�ple exposures �n many cond�-t�ons. Th�s summat�on procedure was �ntent�onally selected as a precaut�onary measure �n the absence of emp�r�cal �nformat�on, although note the tem-poral cond�t�ons g�ven �n the “Sound Types” sec-t�on of Chapter 2. The appropr�ate un�ts are dB re: 1 µPa2-s for underwater SEL and dB re: (20 µPa)2-s for aer�al SEL.

Frequency-selectiveweighting �s often employed to measure (as a s�ngle number) sound pressure or energy �n a spec�f�c frequency band of sound, w�th emphas�s or de-emphas�s on part�cular frequenc�es as a funct�on of the relat�ve sens�t�v�ty of a rece�ver. For aer�al hear�ng �n humans, A-we�ght�ng �s der�ved from the �nverse of the �deal�zed 40-phon equal loudness hear�ng funct�on across frequenc�es, stan-dard�zed to 0 dB at 1 kHz (Harr�s, 1998). Th�s pro-v�des level measures denoted as dB(A). C-we�ght-�ng �s determ�ned from the �nverse of the �deal�zed 100-phon equal loudness hear�ng funct�on (wh�ch d�ffers �n several regards from the 40-phon func-t�on), standard�zed to 0 dB at 1 kHz (Harr�s, 1998). Th�s prov�des level measures denoted as dB(C). In the absence of equal-loudness contours for mar�ne mammals, spec�al frequency-we�ght�ng funct�ons based loosely on human C-we�ght�ng and general knowledge of funct�onal hear�ng bandw�dth were developed here for funct�onal mar�ne mammal hear-�ng groups (see the “Mar�ne Mammal Funct�onal Hear�ng Groups” sect�on of Chapter 2).

Other measures of no�se �nterference w�th cr�t�cal funct�ons �n humans, �nclud�ng the Art�culat�on Index (French & Ste�nberg, 1947) and the more recent Speech Interference Level (see Beranek & Ver, 1992), focused on the percep-t�on of speech and effects of no�se. Consequently, exposure cr�ter�a geared toward speech percep-t�on (e.g., Beranek, 1989) focus on a frequency


bandw�dth narrower than the aud�ble bandw�dth. For a deta�led d�scuss�on of speech �ntell�g�b�l�ty and no�se �mpacts, see Chapter 6 �n Kryter (1994). It �s clear that the percept�on of conspec�f�c vocal s�gnals �n mar�ne mammals �s cr�t�cally �mportant �n var�ous l�fe h�story funct�ons (d�scussed below; see Wartzok & Ketten, 1999) and that �nterference w�th these funct�ons may have part�cularly nega-t�ve consequences.

The hypothes�s that vocal�zat�ons co�nc�de w�th the range of hear�ng �s based on an adapt�ve argument that vocal energy should be selected to l�e w�th�n the range of hear�ng for max�mum eff�-c�ency of commun�cat�on. However, several l�nes of ev�dence suggest that other adapt�ve pressures may shape the vocal range. F�rst, vocal anatomy may produce energy at other frequenc�es as a byproduct of produc�ng sound w�th�n the hear�ng range. If there �s no pressure to el�m�nate these frequenc�es, they can be expected to pers�st. An example �s the ultrason�c components of humm�ng-b�rd song, wh�ch l�e well outs�de the range of b�rd hear�ng (Pytte et al., 2004). Second, to promote long-range transm�ss�on, the vocal range may be adapted to produce greater energy at the low end of the range than would be expected based on the aud�tory threshold funct�on (Larom et al., 1997). Greater relat�ve energy at low frequenc�es �s also seen �n a number of pr�mate spec�es as a byprod-uct of produc�ng the formant structure of the�r calls (F�tch & Hauser, 1995). F�nally, an�mals may pro-duce sounds w�th d�sproport�onate low-frequency �nformat�on to s�gnal greater s�ze, potent�ally tar-get�ng predators rather than conspec�f�cs (F�tch, 1999; Matrosova et al., 2007). Thus, a number of select�ve forces can dr�ve the development of an emphas�s on low-frequency energy �n vocal�zat�ons not matched by the shape of the aud�tory threshold funct�on. Wh�le vocal range can be expected to cor-relate w�th hear�ng range to some degree, g�v�ng a rough �nd�cat�on of the frequency range of hear�ng, �t cannot be used to est�mate e�ther the shape of the aud�tory threshold funct�on or to ass�gn upper and lower frequency l�m�ts.

We lack suff�c�ent emp�r�cal data on whether vocal frequency range suff�c�ently pred�cts all frequenc�es that are b�olog�cally s�gn�f�cant, however.

Certa�n mar�ne mammal responses to anthropo-gen�c sounds, such as the somet�mes strong reac-t�ons by beaked whales to m�d-frequency sonar, would not be expected �f only sounds w�th�n the bandw�dth of vocal output were �mportant �n pre-d�ct�ng a behav�oral response. Hence, our precau-t�onary frequency-we�ght�ng approach assumes that the full aud�ble band �s relevant. As add�t�onal data become ava�lable on both hear�ng capa-b�l�t�es (spec�f�cally, equal-loudness contours)

and behav�oral responses to natural (�nclud�ng conspec�f�c) and anthropogen�c sounds, a more ref�ned means of frequency-we�ght�ng than the �ntent�onally precaut�onary (broad) M-we�ght�ng funct�ons may be recommended.

Kurtosis �s a stat�st�cal measure of a probab�l�ty d�str�but�on often appl�ed to descr�be the shape of the ampl�tude d�str�but�on (Hamern�k & Hsueh, 1991; Le� et al., 1994; Hamern�k et al., 2003). In some regards, �t appears to be a h�ghly relevant metr�c �n that �mpuls�ve sound w�th h�gh nega-t�ve kurtos�s, rap�d onset, and h�gh �nstantaneous peak-pressure may be part�cularly �njur�ous to some mammals (Hamern�k et al., 2003).

Sound Production and Use in Marine Mammals

As a general statement, all stud�ed mar�ne mam-mals can produce sounds �n var�ous �mportant con-texts. They use sound �n soc�al �nteract�ons as well as to forage, to or�ent, and to respond to predators. Interference w�th these funct�ons, through the var-�ous effects of no�se on hear�ng and/or behav�or �dent�f�ed below, thus has the potent�al to �nterfere w�th v�tal rates �dent�f�ed by the NRC (2005) as part�cularly s�gn�f�cant effects of exposure.

The no�se exposure cr�ter�a g�ven here are focused on current knowledge of hear�ng and the effects of no�se on hear�ng and/or behav�or �n mar�ne mammals. Thus, a deta�led d�scuss�on and rev�ew of the expans�ve l�terature on the produc-t�on and the uses of sound �s beyond the scope of th�s paper; �nterested readers are referred to the many rev�ews of mar�ne mammal acoust�c s�gnals (e.g., Schusterman, 1981; Watk�ns & Wartzok, 1985; Au, 1993; R�chardson et al., 1995; Wartzok & Ketten, 1999; Clark & Ell�son, 2004). Because of the extreme �mportance of detect�ng conspec�f�c soc�al s�gnals �n mar�ne mammal l�fe h�story func-t�ons, however, a br�ef and very general d�scus-s�on of sound output character�st�cs �n the major mar�ne mammal groups �s g�ven here.

The large whales (myst�cete cetaceans, as descr�bed below) generally produce low-fre-quency sounds �n the tens of Hz to the several kHz band, w�th a few s�gnals extend�ng above 10 kHz. These sounds appear to serve predom�nantly soc�al funct�ons, �nclud�ng reproduct�on and ma�nta�n�ng contact, but they may also play some role �n spa-t�al or�entat�on.

The dolph�ns and porpo�ses (odontocete ceta-ceans, also descr�bed below) produce sounds across some of the w�dest frequency bands that have been observed �n an�mals. The�r soc�al sounds are generally �n the range aud�ble to humans, from a few hundreds of Hz to several tens of kHz, but spec�al�zed cl�cks used �n b�osonar (echolocat�on)

420 Southalletal.

systems for prey detect�on and nav�gat�on extend well above 100 kHz.

P�nn�peds (seals, sea l�ons, and walruses) also produce a d�vers�ty of sounds, though generally over a lower and more restr�cted bandw�dth (gen-erally from 100 Hz to several tens of kHz). The�r sounds are used pr�mar�ly �n cr�t�cal soc�al and reproduct�ve �nteract�ons. P�nn�peds spend t�me both at sea and on land, however, and thus pro-duce sounds �n both water and a�r.

Because sound product�on �n mar�ne mam-mals �s �ntegral to so many �mportant behav�ors, �nterference w�th these commun�cat�ve funct�ons �s cons�dered to be part�cularly adverse (see sever-�ty scal�ng descr�bed �n Chapter 4, “Cr�ter�a for Behav�oral D�sturbance”). As d�scussed �n Chapter 5, cons�derable add�t�onal research �s needed to �dent�fy cond�t�ons �n wh�ch anthropogen�c no�se exposure �nterferes w�th acoust�c commun�cat�on as well as ways �n wh�ch mar�ne mammals cope w�th mask�ng no�se to overcome �nterference �n detect�ng real-world s�gnals �n complex, 3-d�men-s�onal mar�ne env�ronments.

Responses to Sound

An�mals exposed to e�ther natural or anthropo-gen�c sound may exper�ence phys�cal and psycho-log�cal effects, rang�ng �n magn�tude from none to severe. Th�s br�ef d�scuss�on cons�ders the range of potent�al �mpacts, wh�ch depend on spat�al rela-t�onsh�ps between a sound source and the an�mal rece�ver; sens�t�v�ty of the rece�ver; rece�ved expo-sure level, durat�on, and duty cycle; and many other factors (see also R�chardson et al., 1995).

The same acoust�c source may have rad�cally d�fferent effects depend�ng on operat�onal and env�ronmental var�ables, and on the phys�olog�cal, sensory, and psycholog�cal character�st�cs of exposed an�mals. It �s �mportant to note that these an�mal var�ables may d�ffer (greatly �n some cases) among �nd�v�duals of a spec�es and even w�th�n �nd�v�duals depend�ng on var�ous factors (e.g., sex, age, prev�ous h�story of exposure, season, and an�mal act�v�ty). Responses el�c�ted can depend both on the context (feed�ng, mat�ng, m�grat�ng, etc.) �n wh�ch an �nd�v�dual �s enson�f�ed and on a host of exper�ent�al var�ables (see Wartzok et al., 2004). Consequently, certa�n effects may be poorly descr�bed w�th s�mple measures such as SPL alone, and may only be pred�ctable when add�t�onal var�ables are cons�dered. We cons�d-ered all known factors �n develop�ng the no�se exposure cr�ter�a proposed here, but data l�m�ta-t�ons precluded the der�vat�on of expl�c�t exposure cr�ter�a for all of the effects d�scussed below.

AudibilityWhen a sound can be perce�ved am�dst background no�se, �t �s cons�dered to be aud�ble. Aud�b�l�ty can d�ffer from detectab�l�ty �n that a rece�v�ng system may detect a s�gnal at some level even when �t �s �ncapable of mean�ngful percept�on. Aud�b�l�ty �s determ�ned by the character�st�cs of rece�ved sound, character�st�cs of the rece�v�ng system, and background no�se cond�t�ons (e�ther external or �nternal). Aud�t�on (hear�ng) �s a well-developed and pr�mary sensory modal�ty for most, �f not all, mar�ne vertebrates (Schusterman, 1981; Tyack, 1998; Fay & Popper, 2000). It �nvolves cod�ng, process�ng, �ntegrat�ng, and respond�ng to sound �n a var�ety of ways, some not outwardly ev�dent (Yost, 2000). L�ke other an�mals, mar�ne mam-mals have mult�ple sound-recept�on pathways and rely on s�gnal process�ng at mult�ple levels �nte-grated w�th�n the cochlea and nervous system to opt�m�ze percept�on.

Mar�ne mammal hear�ng capab�l�t�es are quant�f�ed �n l�ve subjects us�ng behav�oral aud�-ometry and/or electrophys�olog�cal techn�ques (e.g., Schusterman, 1981; Au, 1993; Kastak & Schusterman, 1998; Wartzok & Ketten, 1999; Nacht�gall et al., 2000, 2007; F�nneran & Houser, 2006; André & Nacht�gall, 2007; Sup�n & Popov, 2007). For spec�es not stud�ed w�th invivo aud�-ometry, some aud�tory character�st�cs can be est�-mated based on sound product�on frequenc�es; on observat�ons of sound character�st�cs that e�ther do or do not el�c�t behav�oral responses �n untra�ned an�mals (e.g., R�chardson et al., 1995; Erbe, 2002); or on aud�tory morphology, �nclud�ng b�omechan-�cal propert�es of the bas�lar membrane and other character�st�cs (Wartzok & Ketten, 1999).

Behavioralaudiograms are obta�ned from cap-t�ve, tra�ned an�mals us�ng standard psychometr�c test�ng procedures. W�th appropr�ate controls and suff�c�ent tra�n�ng, behav�oral data are presently cons�dered to most accurately represent hear�ng capab�l�t�es of a test subject. Behav�oral aud�o-metr�c stud�es are t�me-consum�ng, however, and the results depend on the tra�n�ng and attent�on of subjects as well as the background no�se cond�-t�ons �n capt�ve sett�ngs. Because mar�ne mam-mals are large and d�ff�cult to ma�nta�n, behav-�oral aud�ograms represent�ng an ent�re spec�es are typ�cally based on a few �nd�v�duals (often one an�mal). Add�t�onally, subjects are generally obta�ned opportun�st�cally (e.g., �nd�v�duals reha-b�l�tated after strand�ng) rather than by random sampl�ng of �nd�v�duals from w�ld populat�ons. Th�s may prov�de a somewhat b�ased representa-t�on of “normal” hear�ng for the spec�es �f reha-b�l�tated an�mals have comprom�sed hear�ng capab�l�t�es (see André et al., 2007). Ind�v�dual d�fferences �n hear�ng sens�t�v�ty among subjects,


and methodolog�cal d�fferences among �nvest�ga-tors, can lead to �mproper conclus�ons when nom-�nal spec�es aud�ograms are based on data from a s�ngle an�mal (e.g., compare Hall & Johnson, 1972, w�th Szymansk� et al., 1999). Hear�ng sen-s�t�v�ty has been measured us�ng behav�oral meth-ods �n fewer than 20 of the ~128 cetacean and p�nn�ped spec�es (based on the taxonomy of R�ce, 1998).

Electrophysiologicalaudiometry �nvolves mea-sur�ng small electr�cal voltages (aud�tory evoked potent�als [AEPs]) produced by neural act�v�ty when the aud�tory system �s st�mulated by sound. W�th th�s techn�que, neural responses are typ�-cally averaged wh�le many relat�vely short dura-t�on s�gnals are presented. Th�s techn�que �s com-parat�vely fast and less sens�t�ve to factors such as subject exper�ence and reproduct�ve, behav�oral, or mot�vat�onal states that affect behav�oral aud�-ometry. Whereas behav�oral aud�ograms can only be made w�th tra�ned, capt�ve an�mals, AEP mea-sures of sound detect�on can also be made w�th untra�ned �nd�v�duals that are stranded, tempo-rar�ly restra�ned, or �n rehab�l�tat�on (see Cook et al., 2006; André et al., 2007; Delory et al., 2007; Taylor et al., 2007).

AEP and behav�oral techn�ques measure d�ffer-ent features of the aud�tory system and may gener-ate somewhat d�fferent measured results. Relevant compar�sons of AEP and behav�oral aud�ograms are l�m�ted and are the subject of ongo�ng sc�en-t�f�c �nvest�gat�on. Bes�des the need to obta�n both types of data on the same �nd�v�duals, there are compl�cat�ons due to d�fferences �n the types of test st�mul� used by d�fferent researchers, prob-lems �n est�mat�ng the true RL at the relevant sensory organ(s), and the d�ff�culty of determ�n-�ng absolute s�gnal ampl�tudes that barely el�c�t neural responses. Even so, Yuen et al. (2005), F�nneran et al. (2007b), and Schlundt et al. (2007) demonstrated that, w�th carefully cal�brated and repeated measurements, the two procedures can produce comparable detect�on thresholds �n at least a few cetacean spec�es.

An aud�tory threshold, est�mated by e�ther behav�oral or electrophys�olog�cal responses, �s the level of the qu�etest sound aud�ble �n a spec�-f�ed percent of tr�als. An aud�tory threshold �s not an �nvar�ant cr�t�cal value above wh�ch a sound �s always heard and below wh�ch �t �s never heard. Instead, �t �s a sound level at wh�ch there �s an expl�c�t s�gnal detect�on probab�l�ty (often 50%; determ�ned a priori). Th�s probab�l�ty depends on a number of �ntr�ns�c factors (Green & Swets, 1974; Egan, 1975; McM�llan & Creelman, 1991). In all spec�es tested thus far, the hear�ng response �n relat�on to frequency �s a generally U-shaped curve w�th a frequency range of best sens�t�v�ty

(lowest hear�ng thresholds) and frequenc�es both below and above th�s range where sens�t�v�ty �s relat�vely poor (h�gher threshold values). Spec�es d�ffer �n absolute sens�t�v�ty and funct�onal fre-quency bandw�dth (see Fay, 1988; R�chardson et al., 1995), such that �dent�cal sounds may be perce�ved rad�cally d�fferently by �nd�v�duals of d�fferent spec�es. Ind�v�dual d�fferences w�th�n spec�es have also been demonstrated �n some ter-restr�al spec�es (see Fay, 1988) and, to a lesser extent, �n mar�ne mammals as well (see Houser & F�nneran, 2006b, for the most def�n�t�ve example of th�s). Sounds whose levels barely exceed back-ground no�se levels may be detectable but may or may not el�c�t changes �n �nd�v�dual behav�or. Ideally, “absolute” or unmasked hear�ng thresh-olds should be measured �n low background no�se cond�t�ons such as anecho�c test�ng enclosures. Wh�le th�s �s standard pract�ce �n human aud�-ometry, very few of the mar�ne mammal hear�ng data obta�ned to date have been measured �n such cond�t�ons. L�m�ted recent data obta�ned w�th p�n-n�peds tested �n a hem�-anecho�c test�ng chamber �n a�r (descr�bed �n Kastak et al., 2005) suggest that mask�ng from env�ronmental no�se �n test�ng enclosures may have s�gn�f�cantly affected mea-surements of “absolute” hear�ng; thresholds �n a harbor seal (Phocavitulina) were �n fact ≥ 30 dB lower �n very low background no�se cond�t�ons (Holt et al., 2001).

Wh�le the above concepts and stud�es are essen-t�al �n understand�ng general hear�ng capab�l�t�es (e.g., funct�onal bandw�dth, range of best hear�ng sens�t�v�ty) of mar�ne mammals, an�mals �n the “real world” rarely l�sten for s�mple acoust�c s�g-nals from po�nt sources and do not l�ve �n a no�se-controlled env�ronment. Rather, they are presented w�th spat�ally complex and t�me-vary�ng streams of acoust�c �nformat�on �n often no�sy env�ron-ments. Measurements us�ng s�mple sound st�mul� have �nd�cated that mar�ne mammals are generally qu�te adept at local�z�ng acoust�c sources �n labo-ratory cond�t�ons (Møhl, 1964; Gentry, 1967; Terhune, 1974; Moore & Au, 1975; Renaud & Popper, 1975; Holt et al., 2004, 2005). Many of the behav�oral observat�ons d�scussed �n Chapter 4 (and �n Append�ces B & C) �nd�cated relat�vely prec�se or�entat�on behav�ors to sound sources (or sound local�zat�on) �n the f�eld as well. L�m�ted laboratory data are also ava�lable regard�ng how mar�ne mammals detect relat�vely s�mple st�m-ul� over background mask�ng no�se (d�scussed below). A more complex perceptual matter related to local�zat�on and detect�on over mask�ng no�se �s the manner �n wh�ch vertebrates process com-plex �nformat�on to perce�ve the acoust�c (or aud�-tory) scene—that �s, ga�n useful �nformat�on from

422 Southalletal.

the su�te of sounds around them �n the real world (e.g., Fay & Popper, 2000).

Bregman (1990) cons�dered how the human aud�tory system constructs a perceptual acoust�c �mage of the surround�ng env�ronment and events occurr�ng �n that env�ronment. He pos�ts that, as �n v�sual percept�on, hear�ng systems are organ�zed �n such a manner that related acoust�c events (such as the frequency structure of a harmon�c s�gnal or a repeated s�gnal from the same source �n a 3-d�mens�onal space) are grouped perceptually �n a mean�ngful way. Accord�ng to the process of auditorysceneanalysis, the aud�tory system sorts-out related elements of a complex natural acous-t�c env�ronment �nto those ar�s�ng from d�fferent sound sources. Furthermore, prev�ous exper�ence can have powerful effects on the process�ng and �nterpretat�on of sounds. Th�s too �s s�m�lar to psy-cholog�cal processes underly�ng v�sual percept�on �n wh�ch the range to an object may be �nferred from knowledge of an object’s general s�ze and phys�cal appearance.

Presum�ng such capab�l�t�es occur �n mar�ne vertebrates, wh�ch �s log�cal g�ven the �mportance of sound to mar�ne mammals, �t seems l�kely that they could perce�ve range and the general nature (e.g., movement) of sound sources. Acousticstreamsegregation, the �dent�f�cat�on of relat�vely s�mple st�mul� from d�fferent, overlapp�ng patterns, has been demonstrated �n several b�rd and bat spe-c�es (MacDougall-Shackleton et al., 1998; Moss & Surlykke, 2001). Ne�ther acoust�c stream seg-regat�on nor aud�tory scene analys�s has yet been �nvest�gated �n mar�ne mammals (but see Madsen et al., 2005a). Each of these processes, along w�th more data on sound local�zat�on, may be relevant �n the cont�nued development of appropr�ate mar�ne mammal no�se exposure cr�ter�a (see the “Mar�ne Mammal Funct�onal Hear�ng Groups” sect�on of Chapter 5, for research recommendat�ons).

AuditoryMaskingNo�se may part�ally or ent�rely reduce the aud�-b�l�ty of s�gnals, a process known as auditorymasking. The extent of �nterference depends on the spectral, temporal, and spat�al relat�onsh�ps between s�gnals and mask�ng no�se, �n add�t�on to other factors. Human aud�tory systems per-form frequency-based assessment (s�m�lar to Four�er analys�s) on �ncom�ng s�gnals such that, for most exposure levels, s�gn�f�cant mask�ng of tonal s�gnals �s almost exclus�vely by no�se �n a narrow band (called the cr�t�cal band) of s�m�lar frequenc�es (Wegel & Lane, 1924; Fletcher, 1940; Greenwood, 1961). W�th �ncreas�ng masker level, however, there �s an asymmetr�cal spread �n the mask�ng effect such that detect�on of frequenc�es

above those of the mask�ng st�mulus �s more s�g-n�f�cantly �mpeded (see Buus, 1997; Yost, 2000).

Because of common b�omechan�cal cochlear propert�es across taxa (Echteler et al., 1994), mask�ng �s expected to follow s�m�lar pr�nc�ples �n other mammals (�nclud�ng mar�ne mammals). The structure and funct�on of the outer and m�ddle ear d�ffer profoundly between terrestr�al and mar�ne mammals (Wartzok & Ketten, 1999); however, the character�st�cs of aud�tory mask�ng are str�k-�ngly s�m�lar among nonspec�al�zed mammals �n general (Fay, 1988; Echteler et al., 1994), �nclud-�ng mar�ne mammals tested �n a�r and �n water (Turnbull & Terhune, 1990; Southall et al., 2000, 2003). S�m�lar�t�es �n morphology and mamma-l�an cochlear funct�onal dynam�cs (as revealed by mask�ng stud�es) suggest that aud�tory data from terrestr�al mammals may be rel�ably used �n some s�tuat�ons where mar�ne mammal data are lack�ng. Data on aud�tory mask�ng �n mar�ne mammals are not presented �n deta�l here because they are not d�rectly used �n formulat�ng the recommended no�se exposure cr�ter�a (but see Southall et al., 2000, 2003, for rev�ews).

AuditoryThresholdShiftAn�mals exposed to suff�c�ently �ntense sound exh�b�t an �ncreased hear�ng threshold (�.e., poorer sens�t�v�ty) for some per�od of t�me follow�ng exposure; th�s �s called a noise-induced thresh-oldshift (TS). Factors that �nfluence the amount of TS �nclude the ampl�tude, durat�on, frequency content, temporal pattern, and energy d�str�but�on of no�se exposure. The magn�tude of TS normally decreases over t�me follow�ng cessat�on of the no�se exposure. The amount of TS just after expo-sure �s called the �n�t�al TS.

If TS eventually returns to zero (�.e., the thresh-old returns to the pre-exposure value), �t �s called TTS. The follow�ng phys�olog�cal mechan�sms are thought to play some role �n �nduc�ng TTS, also referred to as aud�tory fat�gue: effects on sen-sory ha�r cells �n the �nner ear that reduce the�r sens�t�v�ty, mod�f�cat�on of the chem�cal env�ron-ment w�th�n sensory cells, res�dual m�ddle-ear muscular act�v�ty, d�splacement of certa�n �nner ear membranes, �ncreased blood flow, and post-st�mulatory reduct�on �n both efferent and sensory neural output (Kryter, 1994; Ward, 1997). Where these effects result �n TTS rather than a permanent change �n hear�ng sens�t�v�ty, they are w�th�n the nom�nal bounds of phys�olog�cal var�ab�l�ty and tolerance and do not represent phys�cal �njury (Ward, 1997). Recovery of nom�nal hear�ng func-t�on may occur qu�ckly, and the amount of TTS measured depends on the t�me elapsed s�nce the cessat�on of no�se exposure; subscr�pts are used to �nd�cate the t�me �n m�nutes after exposure. For


example, TTS2 means TTS measured 2 m�n after exposure cessat�on.

If TS does not return to zero after a relat�vely long �nterval (on the order of weeks), the res�dual TS �s called a no�se-�nduced permanent threshold sh�ft (PTS). The d�st�nct�on between PTS and TTS depends on whether there �s a complete recovery of TS follow�ng no�se exposure. PTS �s cons�dered to be aud�tory �njury. Some of the apparent causes of PTS �n mammals are severe extens�ons of effects underly�ng TTS (e.g., �rreparable damage to the sensory ha�r cells). Others �nvolve d�fferent mechan�sms, such as exceed�ng the elast�c l�m�ts of certa�n t�ssues and membranes �n the m�ddle and �nner ears and resultant changes �n the chem�-cal compos�t�on of �nner ear flu�ds (Ward, 1997; Yost, 2000). The relat�onsh�p between TTS and PTS depends on a h�ghly complex su�te of var�-ables concern�ng the study subject and the expo-sure. Th�s relat�onsh�p rema�ns poorly understood, even for humans and small terrestr�al mammals �n wh�ch th�s top�c has been �nvest�gated �ntens�vely (see Kryter, 1994; Yost, 2000).

In add�t�on to the potent�al for d�screte, �ntense sounds to result �n TTS or PTS, chron�c sound exposure, common �n �ndustr�al�zed soc�et�es, can result �n no�se-�nduced PTS �n humans as they age (see Kryter, 1994). Reduced hear�ng sens�t�v�ty as a s�mple funct�on of development and ag�ng (presbycusis) has been demonstrated �n both ch�l-dren (Roche et al., 1978) and adults (e.g., Brant & Fozard, 1990). In the long-term, no�se-�nduced hear�ng loss and presbycus�s appear to result �n a progress�ve PTS that �s a complex, nonl�near process and part�cularly affects h�gh-frequency hear�ng. L�m�ted research �n cetaceans and p�n-n�peds has revealed patterns of presbycus�s that are s�m�lar to those observed �n humans (R�dgway & Carder, 1997; Br�ll et al., 2001; Schusterman et al., 2002; Houser & F�nneran, 2006b; Re�chmuth et al., 2007), further underscor�ng certa�n gen-eral s�m�lar�t�es �n aud�tory processes across mammals.

PTS and TTS data from humans and non-human terrestr�al mammals were used to develop safe exposure gu�del�nes for human work env�ron-ments (e.g., NIOSH, 1998). For mar�ne mammals, recent data are ava�lable regard�ng sounds that cause modest TTS (generally < 20 dB decrease �n sens�t�v�ty) �n a few spec�es of odontocetes and p�nn�peds. No data ex�st on exposures that would cause PTS �n these taxa, however (see Chapter 2 for deta�led d�scuss�ons). Consequently, the only current opt�on for est�mat�ng exposure cond�t�ons that would cause PTS-onset �n mar�ne mammals �s to use the ava�lable mar�ne mammal TTS data comb�ned w�th data from terrestr�al mammals on TTS growth rates w�th �ncreas�ng acoust�c

exposure (see the “Cr�ter�a for Injury: TTS and PTS” sect�on of Chapter 3).

BehavioralReactionstoSoundBehav�oral responses to sound are h�ghly var�able and context-spec�f�c (see Wartzok et al., 2004, for a d�scuss�on). Some sounds that are aud�ble to an�-mals may el�c�t no overt behav�oral response. Th�s �s most common when the sound does not greatly exceed the m�n�mum detectable level and �s not �ncreas�ng or fluctuat�ng (R�chardson et al., 1995). Inab�l�ty to detect an overt response does not nec-essar�ly mean that there �s no subtle behav�oral (or other) effect, however.

When observable react�ons do occur, they may �nclude or�entat�on or attract�on to a sound source; �ncreased alertness; mod�f�cat�on of character�st�cs of the�r own sounds; cessat�on of feed�ng or soc�al �nteract�on; alterat�on of movement/d�v�ng behav-�or; temporary or permanent hab�tat abandonment; and, �n severe cases, pan�c, fl�ght, stampede, or strand�ng, somet�mes result�ng �n �njury or death (e.g., R�chardson et al., 1995; Evans & England, 2001; Gordon et al., 2004; Sche�fele et al., 2005; Cox et al., 2006; Nowacek et al., 2007). M�nor or temporary behav�oral effects are often s�mply ev�dence that an an�mal has heard a sound and may not �nd�cate last�ng consequence for exposed �nd�v�duals. For the purposes of sett�ng cr�te-r�a, the effects of greatest concern are those that may negat�vely �mpact reproduct�on or surv�val. Ult�mately, �t �s the b�olog�cal relevance of the react�on �n terms of v�tal parameters that must be determ�ned. In propos�ng no�se exposure cr�ter�a, one must clearly and expl�c�tly d�fferent�ate tr�v-�al effects from those w�th the potent�al to affect v�tal rates. However, �t has proven to be exceed-�ngly challeng�ng to d�st�ngu�sh among and rank the var�ous effects and to establ�sh a generally accepted def�n�t�on of b�olog�cally mean�ngful behav�oral d�sturbance (see NRC, 2005).

Except for naïve �nd�v�duals, behav�oral responses depend cr�t�cally on the pr�nc�ples of habituation and sensitization. An an�mal’s exposure h�story w�th a part�cular sound affects whether �t �s subsequently less l�kely (hab�tua-t�on) or more l�kely (sens�t�zat�on) to respond to a st�mulus such as sound exposure. The processes of hab�tuat�on and sens�t�zat�on do not necessar-�ly requ�re an assoc�at�on w�th a part�cular adverse or ben�gn outcome. Rather, �nd�v�duals may be �nnately pred�sposed to respond to certa�n st�mul� �n certa�n ways. These responses may �nteract w�th the processes of hab�tuat�on and sens�t�za-t�on for subsequent exposure. Where assoc�at�ve learn�ng occurs, �nd�v�duals l�nk a part�cular expo-sure w�th a known outcome (pos�t�ve, negat�ve, or neutral) and use that �nformat�on �n gu�d�ng

424 Southalletal.

future dec�s�ons on whether and how to respond to s�m�lar st�mul�. The relat�onsh�p between these two categor�es of learn�ng (non-assoc�at�ve and assoc�at�ve) can be h�ghly complex, part�cularly for exper�enced �nd�v�duals (see Deecke et al., 2002).

Many contextual var�ables may be power-ful contr�butors to an an�mal’s percept�on of and react�on to the acoust�c scene. These �nclude the percept�on of source prox�m�ty (nearness), relat�ve movement (encroachment or retreat), and general novelty or fam�l�ar�ty, all of wh�ch may affect the type and magn�tude of the result�ng behav�oral response(s). In terms of prox�m�ty, the presence of h�gh-frequency components �n a sound and the lack of reverberat�on, both of wh�ch are �nd�ca-t�ve of prox�m�ty, may be more relevant acoust�c cues of spat�al relat�onsh�p than s�mply exposure level alone (see P. M�ller, 2002). If a source �s per-ce�ved to be approach�ng, the response �s often stronger. In add�t�on, the act�v�ty of the �nd�v�dual and �ts f�del�ty to a current locat�on often affect the response.

Thus, �n add�t�on to source character�st�cs, other factors that may be cr�t�cal �n determ�n�ng behav�oral effects �nclude past exper�ence, s�tu-at�onal var�ables, rece�ver aud�tory systems, and the extent to wh�ch the sound resembles fam�l�ar ben�gn or nox�ous st�mul� (e.g., Irv�ne et al., 1981; NRC, 2005). An�mals that fa�l to exh�b�t general avo�dance when exposed to a certa�n sound source may st�ll detect the sound but are e�ther hab�tuated to exposure or may d�splay less dramat�c behav-�oral responses (e.g., alter�ng vocal behav�or, mod�fy�ng or�entat�on/movement patterns).

The magn�tude of a g�ven behav�oral response may not be a d�rect funct�on of exposure levels or even of the an�mal’s exper�ent�al h�story. If the sound tr�ggers an ant�-predator response �n the subject (e.g., Irv�ne et al., 1981; F�nley et al., 1990), the response magn�tude may reflect the �nd�v�dual’s underly�ng phys�olog�cal con-d�t�on, the relat�ve costs �n f�tness of fa�l�ng to respond, the ava�lab�l�ty of alternat�ve refuges, and other factors spec�f�c to predator defense (G�ll & Sutherland, 2000; Fr�d & D�ll, 2002; Beale & Monaghan, 2004).

For all these reasons, behav�oral responses to anthropogen�c sounds are h�ghly var�able. Mean�ngful �nterpretat�on of behav�oral response data (and b�olog�cally relevant conservat�on dec�-s�ons) must cons�der not only the relat�ve mag-n�tude and apparent sever�ty of behav�oral reac-t�ons to human d�sturbance but also the relevant acoust�c, contextual, and ecolog�cal var�ables. In many cases, spec�f�c acoust�c features of the sound and contextual var�ables (e.g., prox�m�ty, subject exper�ence and mot�vat�on, durat�on, or

recurrence of exposure) may be of cons�derably greater relevance to the behav�oral response than s�mple acoust�c var�ables such as exposure RL. For example, �f an anthropogen�c sound �s per-ce�ved as �nd�cat�ng the presence of a predator, �t �s l�kely to tr�gger a strong defens�ve react�on at relat�vely low RLs. On the other hand, sounds that resemble conspec�f�c s�gnals may be �gnored or �nduce approach or avo�dance, depend�ng upon the context. Further, typ�cally neutral sounds may cause �ncreas�ng annoyance react�ons (such as avo�dance) as a funct�on of exposure level. Th�s makes �t d�ff�cult or �mposs�ble to just�fy bas�ng broad, object�ve determ�nat�ons of �mpact thresh-olds on RL alone. Th�s �s the pr�mary reason why th�s paper does not propose expl�c�t behav�oral d�sturbance cr�ter�a levels for certa�n sound types. Rather, we collated ava�lable data relat�ng acous-t�c exposure to the sever�ty of observed behav-�oral response �n a form that allows a var�ety of relat�onsh�ps to be est�mated (Chapter 4). When research allows the separat�on of annoyance from cases where an an�mal �nterprets sounds as s�g-nals from predators, prey, or conspec�f�cs, �t may become poss�ble to class�fy s�gnals and pred�ct responses more prec�sely.

Non-AuditoryEffectsThe aud�tory system appears to �nclude the organs most suscept�ble to no�se exposure, at least �n humans (e.g., Ward, 1997). The l�m�ted data on capt�ve mar�ne mammals exposed to var�ous k�nds of no�se support a s�m�lar conclus�on, sug-gest�ng that TTS-onset occurs at levels wh�ch may be below those requ�red for d�rect non-aud�tory phys�olog�cal trauma (but see d�scuss�on of deep-d�v�ng spec�es below). No�se exposure does have the potent�al to �nduce a range of d�rect or �nd�-rect phys�olog�cal effects on non-aud�tory struc-tures. These may �nteract w�th or cause certa�n behav�oral or aud�tory effects, or they may occur ent�rely �n the absence of those effects.

No�se exposure may affect the vest�bular and neurosensory systems. For �nstance, �n humans, d�zz�ness and vert�go can result from exposure to h�gh levels of no�se, a cond�t�on known as nys-tagmus (see Oosterveld et al., 1982; Ward, 1997; Halmagy� et al., 2005). L�ttle �s known about ves-t�bular funct�ons �n mar�ne mammals. There are s�gn�f�cant d�fferences �n vest�bular structures �n some mar�ne mammal spec�es compared to most land mammals (Wartzok & Ketten, 1998; Ketten, 2000). In cetaceans �n part�cular, the vest�bular components are suff�c�ently reduced and have such low neural representat�on that the pr�nc�-pal funct�on may be essent�ally to prov�de l�m-�ted grav�tat�onal and l�near accelerat�on cues. P�nn�peds by contrast have a well-developed,


more convent�onal vest�bular apparatus that l�kely prov�des mult�ple sensory cues s�m�lar to those of most land mammals. Both p�nn�peds and cetaceans reta�n the d�rect coupl�ng through the vest�bule of the vest�bular and aud�tory systems; therefore, �t �s poss�ble, albe�t not known, that mar�ne mammals may be subject to no�se-�nduced effects on vest�bular funct�on as has been shown �n land mammals and humans. Responses to underwater sound exposures �n human d�vers and other �mmersed land mammals suggest that ves-t�bular effects are produced from �ntense under-water sound at some lower frequenc�es (Steevens et al., 1997). Theoret�cal effects on the human ves-t�bular system as well as other organs (e.g., lungs) from underwater sound exposures also have been explored through models (Cudahy & Ell�son, 2002); however, there are no comparable mea-surements or models for mar�ne mammals at th�s po�nt from wh�ch to est�mate such effects. Data are clearly needed for all major mar�ne mammal taxa to more fully assess potent�al �mpacts on non-aud�tory systems.

Relat�vely low-level phys�olog�cal responses �nclude changes �n card�ac rate (bradycardia or tachycardia) and resp�ratory patterns, wh�ch may lead to changes �n metabol�sm. Stress react�ons �n humans and other vertebrates �nclude var�ous phys�olog�cal changes to pulmonary, card�ac, metabol�c, neuro-endocr�ne, �mmune, and repro-duct�ve funct�ons (e.g., Hales, 1973; Lee, 1992; Vr�jkotte et al., 2000). Stud�es of no�se-�nduced stress �n mar�ne mammals are very l�m�ted, but endocr�ne secret�ons of glucocort�co�ds and altered card�ovascular funct�on have been documented �n odontocetes exposed to h�gh-level sound (Romano et al., 2004; cf. Thomas et al., 1990c). No�se expo-sure also often leads to changes �n surfac�ng-res-p�rat�on-d�ve cycles of cetaceans (e.g., R�chardson & Malme, 1993), wh�ch may have var�ous phys�-olog�cal effects. Assum�ng that effects �n mar�ne and terrestr�al mammals are s�m�lar, �ntermed�ate phys�olog�cal responses to stressors (�nclud�ng no�se) may accompany avo�dance or aggres-s�ve behav�ors and �nclude s�ngle aud�tory star-tle responses, the �n�t�at�on and sustenance of the catecholam�ne response, and phys�olog�cal preparat�on for f�ght or fl�ght. The most severe phys�olog�cal responses would �nclude mult�ple or repeated aud�tory startle responses, tr�gger-�ng of the hypothalam�c-p�tu�tary-adrenal (HPA) ax�s and assoc�ated elevated blood glucocort�co�d level, substant�ally altered metabol�sm or energy reserves, lowered �mmune response, d�m�n�shed reproduct�ve effort, and potent�al t�ssue trauma (e.g., Sapolsky et al., 2000). [The �ssue of stress responses to no�se exposure has been d�scussed recently by Wr�ght et al. (�n press).]

Sound at certa�n frequenc�es can cause an a�r-f�lled space to v�brate at �ts resonant frequency (acoust�c resonance), wh�ch may �ncrease the l�ke-l�hood of mechan�cal trauma �n the adjacent or sur-round�ng t�ssue. The resonant frequenc�es of most mar�ne mammal lungs are below the operat�ng frequenc�es of many anthropogen�c sound sources (F�nneran, 2003). Further, b�olog�cal t�ssues are heav�ly damped, est�mated t�ssue d�splacement at resonant frequenc�es �s pred�cted to be exceed-�ngly small, and lung t�ssue damage �s generally uncommon �n acoust�c-related mar�ne mammal strand�ng events. For these reasons, spec�al�sts do not regard lung resonance as a l�kely s�gn�f�cant non-aud�tory effect for mar�ne mammals exposed to anthropogen�c no�se sources that operate above 100 Hz (U.S. Department of Commerce, 2002). Th�s conclus�on m�ght not apply to lower-fre-quency sources that operate at a part�cular fre-quency for a s�gn�f�cant durat�on.

The non-aud�tory effect now be�ng most act�vely d�scussed �n mar�ne mammalogy �s n�tro-gen gas bubble growth, result�ng �n effects s�m�lar to decompress�on s�ckness �n humans. Jepson et al. (2003) and Fernández et al. (2004, 2005) hypoth-es�zed that les�ons (gas and fat embol�) observed �n �nd�v�dual beaked whales found stranded after m�l�tary sonar exerc�ses were somehow caused by invivo n�trogen bubble format�on. Osteonecros�s �n sperm whales has further been suggested as a chron�c result of n�trogen bubble format�on (Moore & Early, 2004).

To date, the gas bubble hypothes�s rema�ns untested, and the acoust�c causat�ve mechan�sm for format�on of embol�, �f any, �s unknown. Theoret�cally, bubble precursors �n supersaturated, homogen�zed t�ssue may �ncrementally enlarge dur�ng the success�ve passage of compress�on and rarefact�on port�ons of acoust�c waves that exceed stat�c pressure (rect�f�ed d�ffus�on; Crum & Mao, 1996). Alternat�vely, a s�ngle acoust�c exposure could act�vate bubble precursors, allow�ng them to grow by gradual expans�on �nto bubbles �n n�trogen-supersaturated t�ssue (stat�c d�ffus�on; see Potter, 2004). The d�v�ng patterns of some mar�ne mammals �ncrease gas-t�ssue saturat�on and potent�ally could �ncrease the suscept�b�l�ty of no�se-exposed an�mals to bubble growth v�a e�ther mechan�sm (R�dgway & Howard, 1979; Houser et al., 2001b). N�trogen supersaturat�on levels for deep-d�v�ng spec�es of �nterest, �nclud�ng beaked whales, are based on theoret�cal models, however (Houser et al., 2001b). No unequ�vocal support for e�ther pathway presently ex�sts.

The ev�dence for bubble format�on as a causal mechan�sm between certa�n types of acoust�c exposure and strand�ng events rema�ns equ�vo-cal. At a m�n�mum, sc�ent�f�c d�sagreement and/or

426 Southalletal.

complete lack of �nformat�on ex�sts regard�ng the follow�ng �mportant po�nts: (1) rece�ved acous-t�c exposure cond�t�ons for an�mals �nvolved �n strand�ng events; (2) patholog�cal �nterpretat�on of observed les�ons �n stranded mar�ne mammals (Fernández et al., 2004; P�antados� & Thalmann, 2004); (3) acoust�c exposure cond�t�ons requ�red to �nduce such phys�olog�cal trauma d�rectly; (4) whether no�se exposure may cause behav-�oral react�ons (e.g., atyp�cal d�v�ng behav�or) that secondar�ly �nduce bubble format�on and t�ssue damage (Jepson et al., 2003; Fernández et al., 2005; Z�mmer & Tyack, 2007); and (5) the extent that postmortem art�facts �ntroduced by decompo-s�t�on before sampl�ng, handl�ng, freez�ng, or nec-ropsy procedures affect �nterpretat�on of observed les�ons. Tests of the gas bubble hypothes�s may y�eld data pert�nent to future mar�ne mammal no�se exposure cr�ter�a, but too l�ttle �s currently known to establ�sh expl�c�t exposure cr�ter�a for th�s proposed mechan�sm.

Courtesy: A. Fr�edlander

2. Structure of the Noise Exposure Criteria

When de facto no�se exposure gu�del�nes are used by management agenc�es, they generally are based on a small number of categor�es of mar�ne mammals and sound types. Though �t would be conven�ent to have a s�ngle exposure cr�ter�on for all spec�es and sound sources, such a s�mpl�-f�ed approach �s not supported by ava�lable sc�-ence. However, some categor�zat�on of spec�es and sources �s warranted based on current �nfor-mat�on. The many anthropogen�c sound sources used �n mar�ne env�ronments can be categor�zed based on certa�n acoust�c and operat�onal features. S�m�larly, there �s great d�vers�ty �n hear�ng and �n the b�olog�cal effects of no�se among mar�ne mammals, but current knowledge supports some funct�onal and/or phylogenet�c group�ngs.

It �s also ne�ther poss�ble nor des�rable to der�ve d�st�nct exposure cr�ter�a for every spec�es and sound source. Important general�zat�ons across taxa would be m�ssed even �f resources and t�me were adequate to study each spec�es and expo-sure cond�t�on. Further, �t �s �mpract�cal to apply numerous, spec�es-spec�f�c cr�ter�a when pred�ct-�ng and/or attempt�ng to m�t�gate effects.

A standard sc�ent�f�c approach �n such s�tua-t�ons �s to categor�ze an�mals based on funct�onal character�st�cs and sound sources based on phys�-cal s�m�lar�t�es, and to summar�ze the �nformat�on �n a matr�x format. We subd�v�de cetaceans and p�n-n�peds �nto f�ve funct�onal hear�ng categor�es based on the frequenc�es they hear. Other methods of cat-egor�zat�on are, of course, poss�ble. For �nstance, Verboom (2002) rel�ed heav�ly on d�rect measure-ments of no�se �mpacts on hear�ng to quant�fy the effects of no�se exposure on mar�ne mammals. Some of h�s proposed cr�ter�a are comparable w�th those presented here. The present effort makes broader use of laboratory and f�eld behav�oral and aud�omet-r�c data, add�t�onal recent data, and extrapolat�ons from terrestr�al mammals not used by Verboom. We d�v�de sound sources �nto three types accord�ng to acoust�c character�st�cs def�ned at the source. Note that at a d�stance, a sound may have s�gn�f�cantly d�fferent features; categor�z�ng sounds based on source character�st�cs �s a precaut�onary and prag-mat�c approach (as �s descr�bed �n the next sect�on). The just�f�cat�ons for and assumpt�ons underly�ng our categor�zat�on of funct�onal hear�ng groups and sound types are descr�bed here. The number of sub-d�v�s�ons �n future no�se exposure cr�ter�a w�ll l�kely �ncrease as more support�ng data are acqu�red.

The format of the recommended mar�ne mammal no�se exposure cr�ter�a �s thus a matr�x of 15 “cells” that systemat�cally cons�ders three sound types (see next sect�on) and f�ve funct�onal mar�ne mammal hear�ng groups (see the “Mar�ne Mammal Funct�onal Hear�ng Groups” sect�on of th�s chap-ter). W�th�n each of those 15 cells, we cons�der two general acoust�c metr�cs (see the “Exposure Cr�ter�a Metr�cs” sect�on) and two levels of expo-sure effect (“Levels of No�se Effect: Injury and Behavor�al D�sturbance” sect�on of th�s chapter). S�xty poss�ble cr�ter�a result (�.e., 3 sound types × 5 mar�ne mammal groups × 2 metr�cs × 2 �mpact levels), although fewer than 60 are reported due to data l�m�tat�ons. Whereas sound types are def�ned by source features, cr�ter�a values represent levels rece�ved by �nd�v�dual mar�ne mammals.

Sound Types

Three sound types are used: (1) a s�ngle pulse, (2) mult�ple pulses, and (3) nonpulses. The separa-t�on between pulses and nonpulses �s supported by data on aud�tory fat�gue and acoust�c trauma �n ter-restr�al mammals (e.g., Dunn et al., 1991; Hamern�k et al., 1993) and �s generally cons�stent w�th the sound types d�st�ngu�shed for damage r�sk cr�ter�a �n humans (e.g., U.S. DoD, 1997; NIOSH, 1998).

Pulses and nonpulses are d�st�ngu�shed by numerous def�n�t�ons and mathemat�cal d�st�nc-t�ons (e.g., Burd�c, 1984). The emp�r�cal d�st�nc-t�on used here �s based on a measurement proce-dure us�ng several temporal we�ght�ngs. Var�ous exponent�al t�me-we�ght�ng funct�ons appl�ed �n measur�ng pulse and nonpulse sounds may y�eld d�fferent measured rece�ved levels (RLs) (see Harr�s, 1998). Most sound level meters (SLM) pro-v�de opt�ons for apply�ng e�ther a “slow” or “fast” t�me constant (1,000 or 125 ms, respect�vely) for measur�ng nonpulses or an �mpulse t�me con-stant (35 ms) appropr�ate for measur�ng pulses. For a sound pulse, the slow or fast SLM sett�ngs result �n lower sound pressure level (SPL) mea-surements than those obta�ned us�ng the �mpulse sett�ng. Each of these t�me constants �s selected based on propert�es of the human aud�tory system. These may be at least generally relevant for other mammal�an aud�tory systems, although further emp�r�cal data on temporal resolut�on �n mar�ne mammals are needed (see Chapter 5, “Research Recommendat�ons”).


428 Southalletal.

Harr�s (1998) proposed a measurement-based d�st�nct�on of pulses and nonpulses that �s adopted here �n def�n�ng sound types. Spec�f�cally, a ≥ 3-dB d�fference �n measurements between cont�nuous and �mpulse SLM sett�ngs �nd�cates that a sound �s a pulse; a < 3-dB d�fference �nd�cates that a sound �s a nonpulse. We note the �nter�m nature of th�s d�st�nct�on for underwater s�gnals and the need for an expl�c�t d�st�nct�on and measurement standard such as ex�sts for aer�al s�gnals (ANSI, 1986).

Harr�s’s (1998) def�n�t�ons assumed use of A-we�ght�ng as do most human-or�ented def�n�t�ons of acoust�cal measurements; however, d�fferent frequency-we�ght�ng funct�ons should be used for var�ous an�mal taxa (as d�scussed below). Leav�ng that quest�on as�de temporar�ly, �t �s �nstruct�ve to compare the �mpulse equ�valent-cont�nuous sound level (LIeqT) for a sound that �ncreases �n level w�th the correspond�ng equ�valent-cont�nuous level (LeqT). Here, LIeqT has an �mpulse �ntegrat�on t�me of 35 ms and LeqT, def�ned as sound exposure d�v�ded by T, �s expressed as a level. As an example, sup-pose that a source �s exam�ned over a 2-s per�od (T = 2 s). The h�ghest LAIeq2s (“A” here denotes A-we�ght�ng) dur�ng th�s per�od �s 75.2 dB, and the h�ghest LALeq2s �s 65.1 dB. The d�fference of 10.1 dB �s greater than the 3-dB cr�ter�on g�ven by Harr�s (1998); therefore, the sound �s cons�dered to be a pulse.

The d�st�nct�on between pulses and nonpulses �s not always clear �n pract�ce. For �nstance, certa�n s�gnals (e.g., acoust�c deterrent and harassment dev�ces) have character�st�cs of both pulses and nonpulses. Also, certa�n sound sources (e.g., se�s-m�c a�rguns and p�le dr�v�ng) may produce pulses at the source but, through var�ous propagat�on effects, may meet the nonpulse def�n�t�on at greater d�stances (e.g., Greene & R�chardson, 1988). Th�s means that a g�ven sound source m�ght be subject to d�fferent exposure cr�ter�a, depend�ng on the d�stance to the rece�ver and �nterven�ng propaga-t�on var�ables. Wh�le th�s �s certa�nly real�st�c for many real-world exposures, measurements at the an�mal are often not pract�cal. Changes �n sound character�st�cs w�th d�stance generally result �n exposures becom�ng less phys�olog�cally damag-�ng w�th �ncreas�ng d�stance because sharp tran-s�ent peaks become less prom�nent. Therefore, these cr�ter�a use a precaut�onary approach and class�fy sound types based on acoust�c character-�st�cs at the source. Add�t�onal emp�r�cal measure-ments are needed to advance our understand�ng of sound type class�f�cat�on as a funct�on of source, range, and env�ronmental var�ables. We empha-s�ze that the use of source parameters to class�fy sound types does not negate our dec�s�on to rec-ommend exposure cr�ter�on levels relat�ve to RLs at the an�mal.

Treat�ng pulses and nonpulses as d�screte sound types �s just�f�ed by data on mammals �n general and several cetacean spec�es �n part�cular (Dunn et al., 1991; Hamern�k et al., 1993; also see the “Effects of No�se on Hear�ng �n Mar�ne Mammals TTS Data” sect�on �n Chapter 3). Mammal�an hear�ng �s most read�ly damaged by trans�ent sounds w�th rap�d r�se-t�me, h�gh peak pressures, and susta�ned durat�on relat�ve to r�se-t�me (for humans: Th�ery & Meyer-B�sch, 1988; for ch�nch�llas [Chinchillalanigera], Dunn et al., 1991). Cons�stent w�th these results, those odontocetes tested thus far have been shown to exper�ence TTS-onset at lower respect�ve exposure levels �f the sound �s a pulse rather than a nonpulse (F�nneran et al., 2002b, 2005a).

Mammals are also apparently at greater r�sk from rap�dly repeated trans�ents and those w�th h�gh �mpulse ampl�tude kurtosis (Erdre�ch, 1986). Hamern�k et al. (1993, 2003) argued that the d�s-t�nct�on between exposures w�th relat�vely h�gh and low “peakedness” �s to some extent an over-s�mpl�f�cat�on. H�ghly var�able threshold sh�fts can result from exposures of var�able peaked-ness but comparable overall levels, depend�ng on a host of factors. Hamern�k et al. (1993, 2003) also noted that peak pressure levels suff�c�ent to exceed mechan�cal l�m�ts of the cochlea, and thus more l�kely to �nduce acoust�c trauma, tend to be more typ�cal of pulses than nonpulses.

The present cr�ter�a also categor�ze sound types based on repet�t�on. For mammals, s�ngle and mul-t�ple no�se exposures at var�ous levels and dura-t�ons generally d�ffer �n the�r potent�al to �nduce aud�tory fat�gue or trauma. Th�s results pr�nc�pally from the temporal �nteract�on between exposure and recovery per�ods (e.g., Kryter, 1994) and d�f-ferences �n rece�ved total acoust�c energy. Further, mult�ple exposures may �ncrease the l�kel�hood of behav�oral responses because of �ncreased prob-ab�l�ty of detect�on and the (generally) greater b�olog�cal s�gn�f�cance of cont�nued exposure as opposed to a s�ngle, trans�ent event (although see d�scuss�on of hab�tuat�on �n the “Responses to Sound” sect�on of Chapter 1).

S�ngle exposures are cons�dered here as d�s-crete acoust�c events �n wh�ch rece�ved sound levels exceed amb�ent no�se �n at least some por-t�on of the frequency band of funct�onal mar�ne mammal hear�ng once �n a 24-h per�od; mult�-path recept�ons of a s�ngle exposure are not cons�d-ered mult�ple exposures. Mult�ple exposures are cons�dered to be acoust�c events caus�ng RLs to exceed amb�ent no�se w�th�n the funct�onal band-w�dth more than once, w�th an �nterven�ng qu�et per�od not exceed�ng 24 h. If the exposure event �s �nterrupted, even br�efly (other than as a result of the an�mal’s own act�on—e.g., breach�ng), �t �s cons�dered a mult�ple exposure.


Exposures should be categor�zed as e�ther pulsed or nonpulsed sounds as descr�bed above. S�ngle and mult�ple exposures to e�ther pulse or nonpulse sounds (or both) are poss�ble. Examples of s�ngle pulses and s�ngle nonpulses are sounds from a s�ngle f�r�ng of an a�rgun or a s�ngle vessel passage, respect�vely.

Mult�ple pulse or mult�ple nonpulse sounds are more d�ff�cult to del�neate, g�ven the d�vers�ty and complex�ty of sound sources. A ser�es exclus�vely cons�st�ng of two or more nonpulses would clearly be a mult�ple nonpulse exposure (e.g., mult�ple vessel passages). A mult�ple pulse exposure would s�m�-larly be descr�bed as a ser�es exclus�vely conta�n�ng pulses (e.g., repeated p�le str�kes) or a comb�nat�on of pulses and nonpulses (e.g., the comb�ned vessel no�se and a�rgun transm�ss�ons of a se�sm�c vessel). One just�f�cat�on for treat�ng comb�ned pulses and nonpulses as pulses �s that the proposed exposure cr�ter�a for �njury are more precaut�onary (lower) �n the case of pulses than for nonpulses. Spec�f�c cons�derat�on should be g�ven, on a case-by-case bas�s, as to whether such a d�st�nct�on would neces-sar�ly be the more precaut�onary. For �nstance, �f a compound exposure �ncluded relat�vely h�gh-level nonpulses as well as relat�vely low-level pulses, the more appropr�ate and protect�ve d�st�nct�on m�ght be to class�fy �t as a nonpulse exposure.

The proposed exposure cr�ter�a for �njury from s�ngle and mult�ple exposures to both sound types are numer�cally �dent�cal (Chapter 3). Th�s �s another precaut�onary dec�s�on, ar�s�ng from the fact that no mar�ne mammal data were ava�lable regard�ng the effects of �nter-exposure �nterval on recovery from aud�tory effects (e.g., TTS). A summat�on procedure �s appl�ed to quant�fy the fat�gu�ng effects of mult�-ple exposures w�th an equ�valent SEL value (Chapter 1; also Append�x A, eq. 5). The SEL metr�c takes account of the pressure waveform and durat�on of e�ther s�ngle or mult�ple sound events; �t represents cumulat�ve rece�ved energy. Th�s approach effect�vely

negates the need for numer�cally d�fferent �njury cr�-ter�a for s�ngle and mult�ple exposures at the expense of neglect�ng assumed, but as-yet poorly understood recovery phenomena dur�ng �ntervals between expo-sures. Th�s �s a precaut�onary approach, pend�ng ava�lab�l�ty of data on acoust�c recovery by mar�ne mammals dur�ng �ntervals between exposures.

When cons�der�ng behav�oral responses, s�ngle and mult�ple nonpulse exposures are cons�dered as a s�ngle category. Insuff�c�ent �nformat�on ex�sts to assess the use of SEL as a relevant metr�c �n the con-text of mar�ne mammal behav�oral d�sturbance for anyth�ng other than a s�ngle pulse exposure. Future no�se exposure cr�ter�a for behav�oral d�sturbance may d�st�ngu�sh SPL and SEL exposure cr�ter�a for add�t�onal cond�t�ons, but for most sound types (the except�on be�ng s�ngle pulses), the ava�lable data are best assessed �n relat�on to SPL (d�scussed �n deta�l �n Chapter 4). Consequently, the structure of the exposure cr�ter�a matr�x �ncludes a categor�cal d�st�nct�on between s�ngle and mult�ple pulses g�ven that numer�cal SEL thresholds are recommended for a s�ngle pulse, but not for mult�ple pulses. No such d�st�nct�on �s made for nonpulses where the ava�lable data do not (at least currently) support d�fferent�al behav�oral cr�ter�a for s�ngle vs mult�ple exposures.

Thus, the current state of sc�ent�f�c knowledge regard�ng mammal�an hear�ng and var�ous no�se �mpacts supports three d�st�nct sound types as relevant for mar�ne mammal no�se exposure cr�-ter�a: (1) s�ngle pulse, (2) mult�ple pulses, and (3) nonpulses. Examples of sound sources belong-�ng �n each of these categor�es (based on character-�st�cs of the sound em�tted at the source) are g�ven �n Table 1. A s�mpl�st�c measurement procedure us�ng source character�st�cs (the 3-dB d�st�nct�on based on Harr�s, 1998, descr�bed above) �s used here to d�st�ngu�sh a pulse from a nonpulse, wh�le the s�mple def�n�t�ons above d�st�ngu�sh s�ngle and mult�ple exposures.

Table 1. Sound types, acoust�c character�st�cs, and selected examples of anthropogen�c sound sources; note sound types are based on character�st�cs measured at the source. In certa�n cond�t�ons, sounds class�f�ed as pulses at the source may lack these character�st�cs for d�stant rece�vers.

Sound type Acoust�c character�st�cs (at source) Examples

S�ngle pulse S�ngle acoust�c event; > 3-dB d�fference between rece�ved level us�ng �mpulse vs equ�valent cont�nuous t�me constant

S�ngle explos�on; son�c boom; s�ngle a�rgun, watergun, p�le str�ke, or sparker pulse; s�ngle p�ng of certa�n sonars, depth sounders, and p�ngers

Mult�ple pulses Mult�ple d�screte acoust�c events w�th�n 24 h; > 3-dB d�fference between rece�ved level us�ng �mpulse vs equ�valent cont�nuous t�me constant

Ser�al explos�ons; sequent�al a�rgun, watergun, p�le str�kes, or sparker pulses; certa�n act�ve sonar (IMAPS); some depth sounder s�gnals

Nonpulses S�ngle or mult�ple d�screte acoust�c events w�th�n 24 h; < 3-dB d�fference between rece�ved level us�ng �mpulse vs equ�valent cont�nuous t�me constant

Vessel/a�rcraft passes; dr�ll�ng; many construc-t�on or other �ndustr�al operat�ons; certa�n sonar systems (LFA, tact�cal m�d-frequency); acoust�c harassment/deterrent dev�ces; acoust�c tomogra-phy sources (ATOC); some depth sounder s�gnals

430 Southalletal.

Marine Mammal Functional Hearing Groups

Spec�es of cetaceans and p�nn�peds were ass�gned to one of f�ve funct�onal hear�ng groups based on behav�oral psychophys�cs, evoked potent�al aud�-ometry, aud�tory morphology, and (for p�nn�peds) the med�um �n wh�ch they l�sten. Cetaceans and p�nn�peds are broadly separable based on phylo-genet�c and funct�onal d�fferences (Reynolds & Rommel, 1999). Cetaceans were further subd�-v�ded accord�ng to d�fferences �n the�r measured or est�mated hear�ng character�st�cs and not neces-sar�ly accord�ng to the�r phylogeny (as �n Wartzok & Ketten, 1999). P�nn�peds are cons�dered a s�ngle group, but as amph�b�ous mammals, the�r hear�ng d�ffers �n a�r and �n water (Kastak & Schusterman, 1998); separate cr�ter�a were requ�red for each med�um. The taxa �n each funct�onal hear�ng group (based on R�ce, 1998) are g�ven �n Table 2.

MarineMammalHearingAll mar�ne mammals evolved from terrestr�al, a�r-adapted ancestors (Domn�ng et al., 1982; Barnes et al., 1985) and, at least �n part, reta�n the nom�nal mammal�an tr�part�te per�pheral aud�tory system

(�.e., external aud�tory meatus, a�r-f�lled m�ddle ear, and sp�ral-shaped cochlea). Most of the mech-an�sms of mammal�an hear�ng are also conserved such as the bas�c lever structure of the oss�cles and the tonotop�c organ�zat�on of the ha�r cells along the �nner ear’s bas�lar membrane.

However, mar�ne mammal aud�tory systems d�ffer �n hav�ng some adaptat�ons that seem to be related to pressure, hydrodynam�cs, and sound recept�on �n water (see Wartzok & Ketten, 1999). For �nstance, the p�nna has been reduced or el�m�nated �n most spec�es, ow�ng to hydrodynam�c adaptat�ons. T�ssue mod�f�cat�ons may enable the reduct�on or el�m�nat�on of gas spaces �n the m�ddle ear of some mar�ne mammals. Consequently, bone conduct�on, rather than the convent�onal oss�cular cha�n, may be an add�t�onal (or pr�mary) sound transm�ss�on path to the cochlea (e.g., Repenn�ng, 1972; Au, 1993). There are �mportant d�fferences �n these adaptat�ons w�th�n and between mar�ne mammal taxa.

Knowledge of mar�ne mammal hear�ng var�es w�dely among groups, but for most spec�es �t �s qu�te l�m�ted compared to knowledge of terrestr�al mammal hear�ng. Because of the sheer s�ze, l�m-�ted and d�sproport�onate ava�lab�l�ty �n capt�ve

Table 2. Funct�onal mar�ne mammal hear�ng groups, aud�tory bandw�dth (est�mated lower to upper frequency hear�ng cut-off), genera represented �n each group, and group-spec�f�c (M) frequency-we�ght�ngs

Funct�onal hear�ng group

Est�mated aud�tory bandw�dth

Genera represented (Number spec�es/subspec�es)

Frequency-we�ght�ng network

Low-frequency cetaceans

7 Hz to 22 kHz Balaena,Caperea,Eschrichtius,Megaptera,Balaenoptera (13 spec�es/subspec�es)

Mlf (lf: low-frequency cetacean)

M�d-frequency cetaceans

150 Hz to 160 kHz Steno,Sousa,Sotalia,Tursiops,Stenella,Delphinus,Lagenodelphis,Lagenorhynchus,

Lissodelphis,Grampus,Peponocephala,Feresa,Pseudorca,Orcinus,Globicephala,

Orcaella,Physeter,Delphinapterus,Monodon,Ziphius,Berardius,

Tasmacetus,Hyperoodon,Mesoplodon (57 spec�es/subspec�es)

Mmf (mf: m�d-frequency

cetaceans)

H�gh-frequency cetaceans

200 Hz to 180 kHz Phocoena,Neophocaena,Phocoenoides,Platanista,Inia,Kogia,Lipotes,Pontoporia,Cephalorhynchus

(20 spec�es/subspec�es)

Mhf (hf: h�gh-frequency

cetaceans)

P�nn�peds �n water 75 Hz to 75 kHz Arctocephalus,Callorhinus,Zalophus,Eumetopias,Neophoca,

Phocarctos,Otaria,Erignathus,Phoca,Pusa,Halichoerus,Histriophoca,

Pagophilus,Cystophora,Monachus,Mirounga,Leptonychotes,Ommatophoca,

Lobodon,Hydrurga,and Odobenus (41 spec�es/subspec�es)

Mpw (pw: p�nn�peds �n water)

P�nn�peds �n a�r 75 Hz to 30 kHz Same spec�es as p�nn�peds �n water (41 spec�es/subspec�es)

Mpa (pa: p�nn�peds �n a�r)


sett�ngs, and, for many spec�es and jur�sd�ct�ons, the protected status of mar�ne mammals, there are l�m�tat�ons �n obta�n�ng hear�ng data for many spec�es. Behav�oral or electrophys�olog�cal aud�o-grams ex�st for fewer than 20 mar�ne mammal spec�es (of ~128 spec�es and subspec�es; R�ce, 1998). By comb�n�ng these data w�th comparat�ve anatomy, model�ng, and response measured �n ear t�ssues from spec�es that are d�ff�cult to study, however, �t �s poss�ble to descr�be the frequency sens�t�v�ty and cr�t�cal adaptat�ons for underwa-ter hear�ng �n each of the f�ve funct�onal hear�ng groups of mar�ne mammals cons�dered here.

Low-frequency cetaceans cons�st of 13 spec�es and subspec�es of myst�cete (baleen) whales �n f�ve genera (based on R�ce, 1998; see Table 2). No d�rect measurements of hear�ng ex�st for these an�-mals, and theor�es regard�ng the�r sensory capab�l-�t�es are consequently speculat�ve (for a deta�led assessment by spec�es us�ng the l�m�ted ava�lable �nformat�on, see Erbe, 2002). They are too large to ma�nta�n �n the laboratory for psychophys�cal test-�ng. The l�m�ted evoked potent�al measurements on an�mals of th�s s�ze have not yet y�elded hear�ng thresholds (R�dgway & Carder, 2001), but techno-log�cal advances may soon enable evoked poten-t�al aud�ometry on relat�vely small and/or young myst�cetes. In these spec�es, hear�ng sens�t�v�ty has been est�mated from behav�oral responses (or lack thereof) to sounds at var�ous frequenc�es, vocal�zat�on frequenc�es they use most, body s�ze, amb�ent no�se levels at the frequenc�es they use most, and cochlear morphometry (R�chardson et al., 1995; Wartzok & Ketten, 1999; Houser et al., 2001a; Erbe, 2002; Clark & Ell�son, 2004). Unt�l better �nformat�on �s ava�lable regard-�ng the relat�onsh�p between aud�tory sens�t�v�ty and mar�ne env�ronmental no�se, the sens�t�v�ty of myst�cetes cannot be eas�ly �nferred from the acoust�c env�ronment.

The comb�ned �nformat�on strongly suggests that myst�cetes are l�kely most sens�t�ve to sound from perhaps tens of Hz to ~10 kHz. However, recent data �nd�cated that humpback whales (Megapteranovaeangliae) produce some s�gnals w�th harmon�cs extend�ng above 24 kHz (Au et al., 2006). These harmon�cs have cons�derably lower levels than occur at lower frequenc�es, and the�r presence does not necessar�ly �nd�cate they are aud�ble to the whales. Nonetheless, some h�gh-frequency energy �s present. [Add�t�onally, some recent anatom�cal model�ng work by Ketten et al. (2007) suggested that some myst�-cetes may have funct�onal hear�ng capab�l�t�es at frequenc�es as h�gh as 30 kHz.] Wh�le we do not �nclude these recent results at th�s t�me, we note the�r presence and the poss�b�l�ty that the upper frequency l�m�t of the M-we�ght�ng funct�on

for myst�cetes may need to be rev�s�ted based on emerg�ng knowledge. At present, we est�-mate the lower and upper frequenc�es for func-t�onal hear�ng �n myst�cetes, collect�vely, to be 7 Hz and 22 kHz (Ketten et al., 2007).

M�d- and h�gh-frequency cetaceans are all odontocetes (toothed whales). Unl�ke the myst�ce-tes, all odontocete cetaceans appear to have h�ghly advanced echolocat�on (b�osonar) systems that use �ntermed�ate to very h�gh frequenc�es (tens of kHz to 100+ kHz: see Au, 1993; R�chardson et al., 1995; Wartzok & Ketten, 1999). They also produce soc�al sounds �n a lower-frequency band, �nclud�ng generally low to �ntermed�ate frequenc�es (1 kHz to tens of kHz). Consequently, the�r funct�onal hear-�ng would be expected to cover a w�der absolute frequency range than �s assumed for myst�cetes or has been demonstrated for p�nn�peds (d�scussed below). Th�s has been exper�mentally conf�rmed �n the odontocete spec�es whose hear�ng has been measured (d�scussed below); however, the�r best hear�ng sens�t�v�ty typ�cally occurs at or near the frequency where echolocat�on s�gnals are stron-gest. Based on the d�fferent�al character�st�cs of echolocat�on s�gnals �n two groups of odontocetes (see Au, 1993) and on the hear�ng data descr�bed below, odontocetes were d�v�ded �nto m�d- and h�gh-frequency funct�onal groups (as seen gener-ally �n Wartzok & Ketten, 1999).

M�d-frequency cetaceans �nclude 32 spec�es and subspec�es of “dolph�ns,” s�x spec�es of larger toothed whales, and 19 spec�es of beaked and bot-tlenose whales (see Table 2). “Funct�onal” hear-�ng �n th�s group was est�mated to occur over a w�de range of low to very h�gh frequenc�es. Based on the comb�ned ava�lable data, m�d-frequency spec�es are est�mated to have lower and upper frequency “l�m�ts” of nom�nal hear�ng at approx�-mately 150 Hz and 160 kHz, respect�vely. As for the other hear�ng groups, there �s var�ab�l�ty w�th�n and among spec�es, �ntense s�gnals below and above the stated bounds may be weakly detect-able, and there �s a progress�ve rather than �nstan-taneous reduct�on �n hear�ng sens�t�v�ty near these l�m�ts. M�d-frequency cetaceans generally do not appear well-adapted to detect or to d�scr�m�nate s�gnals outs�de th�s frequency band, however. The scarc�ty (and var�ab�l�ty) of emp�r�cal data pre-cludes a f�ner subd�v�s�on of th�s relat�vely d�verse and large group of mar�ne mammals, though �t �s acknowledged that some m�d-frequency spec�es l�kely have a narrower funct�onal hear�ng band than the range g�ven above.

Behav�oral hear�ng data are ava�lable for the follow�ng m�d-frequency cetacean spec�es: bot-tlenose dolph�n (Tursiops truncatus: Johnson, 1967; Ljungblad et al., 1982; F�nneran et al., 2005a), beluga (Delphinapterus leucas: Wh�te

432 Southalletal.

et al., 1978; Awbrey et al., 1988; Johnson, 1992; R�dgway et al., 2001; F�nneran et al., 2005b), k�ller whale (Orcinus orca: Hall & Johnson, 1972; Szymansk� et al., 1999), false k�ller whale (Pseudorca crassidens: Thomas et al., 1988, 1990a; Au et al., 1997), R�sso’s dolph�n (Grampusgriseus: Nacht�gall et al., 1995; Au et al., 1997); and Pac�f�c wh�te-s�ded dolph�n (Lagenorhynchusobliquidens: Tremel et al., 1998).

Aud�ograms der�ved us�ng aud�tory evoked potent�al (AEP) methodology (Sup�n et al., 2001) have been obta�ned for a number of cetacean spe-c�es. Spec�f�c AEP techn�ques, wh�ch �nvolve measur�ng electrophys�olog�cal responses to sound, �nclude those measur�ng trans�ent evoked responses, such as the aud�tory bra�nstem response (ABR) or m�d-latency response, and those mea-sur�ng steady-state evoked responses such as the envelope follow�ng response (EFR) or aud�tory steady-state response (ASSR). M�d-frequency cetacean spec�es tested �nclude the bottlenose dolph�n (Bullock et al., 1968; Seeley et al., 1976; Popov & Sup�n, 1990; Houser & F�nneran, 2006b; F�nneran et al., 2007a; Hernandez et al., 2007; Popov et al., 2007), k�ller whale (Szymansk� et al., 1999), beluga (Popov & Sup�n, 1990; Kl�sh�n et al., 2000), common dolph�n (Delphinusdelphis: Popov & Kl�sh�n, 1998), R�sso’s dolph�n (Dolph�n, 2000; Nacht�gall et al., 2005, 2007), tucux� dolph�n (Sotaliafluviatilis: Popov & Sup�n, 1990), str�ped dolph�n (Stenella coeruleoalba: Kastele�n et al., 2003), Pac�f�c wh�te-s�ded dol-ph�n (Au et al., 2007), false k�ller whale (Sup�n et al., 2003), and Gerva�s’ beaked whale (Cook et al., 2006). Add�t�onally, Yuen et al. (2005) con-ducted a comparat�ve study of behav�oral and AEP thresholds for the false k�ller whale, and F�nneran & Houser (2006), Houser & F�nneran (2006a), and F�nneran et al. (2007b) have compared behav-�oral and AEP thresholds �n mult�ple bottlenose dolph�ns.

The h�gh-frequency cetaceans �nclude e�ght spec�es and subspec�es of true porpo�ses, s�x spe-c�es and subspec�es of r�ver dolph�ns plus the fran-c�scana, Kogia, and four spec�es of cephalorhyn-ch�ds (see Table 2). “Funct�onal” hear�ng �n th�s group was est�mated to occur between 200 Hz and 180 kHz. Behav�oral aud�ograms are ava�lable for the follow�ng h�gh-frequency cetacean spec�es: harbor porpo�se (Phocoenaphocoena: Andersen, 1970; Kastele�n et al., 2002a), Ch�nese r�ver dol-ph�n (Lipotes vexillifer: Wang et al., 1992), and Amazon r�ver dolph�n (Iniageoffrensis: Jacobs & Hall, 1972). Aud�ograms us�ng AEP methodol-ogy have been obta�ned for three spec�es: harbor porpo�se (Popov et al., 1986, 2006; Beedholm & M�ller, 2007; Lucke et al., 2007b); f�nless porpo�se (Neophocaena phocaenoides: Popov

et al., 2006); and Amazon r�ver dolph�n (Popov & Sup�n, 1990).

The p�nn�peds �nclude 16 spec�es and subspec�es of sea l�ons and fur seals (otar��ds), 23 spec�es and subspec�es of true seals (phoc�ds), and two sub-spec�es of walrus (odoben�ds). P�nn�peds produce a w�de range of soc�al s�gnals, most occurr�ng at relat�vely low frequenc�es. They lack the h�ghly-spec�al�zed act�ve b�osonar systems of odontocete cetaceans, poss�bly as a result of the�r amph�b�ous l�festyle (see Schusterman et al., 2000). Because of th�s aspect of the�r l�fe h�story, p�nn�peds com-mun�cate acoust�cally �n a�r and water, have s�g-n�f�cantly d�fferent hear�ng capab�l�t�es �n the two med�a, and may be subject to both aer�al and underwater no�se exposure (Schusterman, 1981; Kastak & Schusterman, 1998, 1999). These d�f-ferences necess�tate separate no�se exposure cr�te-r�a for p�nn�peds �n each med�um.

For p�nn�peds �n water, behav�oral measures of hear�ng are ava�lable for the northern fur seal (Callorhinus ursinus: Moore & Schusterman, 1987; Babush�na et al., 1991), Cal�forn�a sea l�on (Zalophuscalifornianus: Schusterman et al., 1972; Moore & Schusterman, 1987; Kastak & Schusterman, 1998, 2002; Southall et al., 2004), northern elephant seal (Miroungaangustirostris: Kastak & Schusterman, 1998, 1999; Southall et al., 2004), Hawa��an monk seal (Monachusschauinslandi: Thomas et al., 1990b), harp seal (Pagophilus groenlandicus: Terhune & Ronald, 1972), r�nged seal (Phoca hispida: Terhune & Ronald, 1975), harbor seal (Møhl, 1967, 1968; Terhune & Turnbull, 1995; Kastak & Schusterman, 1995, 1998; Southall et al., 2004), and walrus (Odobenus rosmarus: Kastele�n et al., 2002b). R�dgway & Joyce (1975) measured the gray seal’s (Halichoerusgrypus) underwater hear�ng us�ng evoked potent�al aud�ometry.

For p�nn�peds �n a�r, behav�oral measures of hear-�ng are ava�lable for the northern fur seal (Moore & Schusterman, 1987; Babush�na et al., 1991), Cal�forn�a sea l�on (Schusterman, 1974; Kastak & Schusterman, 1998; Kastak et al., 2004b), north-ern elephant seal (Kastak & Schusterman, 1998, 1999; Kastak et al., 2004b), harp seal (Terhune & Ronald, 1971), and harbor seal (Møhl, 1968; Kastak & Schusterman, 1998; Kastak et al., 2004b). Aer�al hear�ng �n p�nn�peds has also been measured us�ng evoked potent�al aud�ometry �n the gray seal (R�dgway & Joyce, 1975), Cal�forn�a sea l�on (Bullock et al., 1971; R�dgway & Joyce, 1975; Mulsow & Re�chmuth, 2007; Re�chmuth et al., 2007), harbor seal (Thorson et al., 1998; Wolsk� et al., 2003; Mulsow & Re�chmuth, 2007; Re�chmuth et al., 2007), and northern elephant seal (Houser et al., 2007; Mulsow & Re�chmuth, 2007; Re�chmuth et al., 2007).


The comb�ned results of these stud�es �nd�-cate that p�nn�peds are sens�t�ve to a broader range of sound frequenc�es �n water than �n a�r. The data further suggest d�fferences �n the func-t�onal hear�ng range among otar��ds, phoc�ds, and odoben�ds, espec�ally under water (Kastak & Schusterman, 1998; Kastele�n et al., 2002b). For these proposed no�se exposure cr�ter�a, however, p�nn�peds are cons�dered a s�ngle funct�onal hear-�ng group because the data are too l�m�ted, both �n terms of absolute hear�ng data and TTS measure-ments (see “The Effects of No�se on Hear�ng �n Mar�ne Mammals: TTS Data” sect�on �n Chapter 3), to support f�ner subd�v�s�ons. We est�mate that p�nn�peds have “funct�onal” underwater hear�ng between 75 Hz and 75 kHz and “funct�onal” aer�al hear�ng between 75 Hz and 30 kHz. These ranges are essent�ally based on data for phoc�d seals, wh�ch have the broadest aud�tory bandw�dths of the p�nn�peds. Th�s approach results �n a precau-t�onary funct�onal bandw�dth for est�mat�ng fre-quency-we�ght�ng funct�ons (below) and no�se �mpacts on p�nn�peds.

In summary, based on current knowledge of funct�onal hear�ng �n mar�ne mammals, f�ve d�st�nct, funct�onal hear�ng categor�es were def�ned: (1) low-frequency cetaceans (�.e., mys-t�cetes), (2) m�d-frequency cetaceans (�.e., most odontocetes), (3) h�gh-frequency cetaceans (�.e., porpo�ses, r�ver dolph�ns, pygmy sperm whale, and Cephalorhynchus), (4) p�nn�peds �n water, and (5) p�nn�peds �n a�r. The genera �n each group, and the est�mated lower and upper frequency hear�ng “l�m�ts,” are shown �n Table 2. Because the f�ve funct�onal hear�ng groups of mar�ne mam-mals d�ffer �n hear�ng bandw�dth, each may be affected d�fferently by �dent�cal no�se exposures. Therefore, frequency-we�ght�ng funct�ons are requ�red to develop mar�ne mammal no�se expo-sure cr�ter�a.

Frequency-WeightingFunctionsAs a general statement, an�mals do not hear equally well at all frequenc�es w�th�n the�r func-t�onal hear�ng range. Frequency we�ght�ng �s a method of quant�tat�vely compensat�ng for the d�fferent�al frequency response of sensory sys-tems. General�zed frequency-we�ght�ng funct�ons were der�ved for each funct�onal hear�ng group of mar�ne mammals us�ng pr�nc�ples from human frequency-we�ght�ng parad�gms, w�th adjustments for the d�fferent hear�ng bandw�dths of the var�ous mar�ne mammal groups.

For humans, substant�al �mprovement �n dose-response models �s obta�ned by f�lter�ng no�se through equal-loudness funct�ons, part�cularly the 40-phon, equal-loudness funct�on (“A-we�ght-�ng”) and the 100-phon funct�on (“C-we�ght�ng”).

These frequency-we�ght�ng funct�ons take �nto account both the frequency bandw�dth of human hear�ng and loudness percept�on. For use as fre-quency f�lters, the funct�ons are �nverted; normal-�zed to 0 dB �n the frequency range of best hear�ng (spec�f�cally at 1,000 Hz for humans); and �deal-�zed for �mplementat�on �n hear�ng a�ds, sound level meters, and other measurement dev�ces.

At m�n�mum, metr�cs used for an�mals should el�m�nate �naud�ble frequenc�es both below and above the range of funct�onal hear�ng. The “abso-lute” aud�tory threshold funct�on (aud�ogram) has been suggested as a frequency-we�ght�ng func-t�on for mar�ne spec�es exposed to underwater sound (e.g., Malme et al., 1989; Thorson et al., 1998; Heathershaw et al. 2001; Nedwell et al., 2007) as well as for terrestr�al an�mals (Delaney et al., 1999; Bjork et al., 2000). However, the aud�tory threshold funct�on does not character�ze the flatten�ng of equal-loudness percept�on w�th the �ncreas�ng st�mulus level that has been dem-onstrated �n humans (Fletcher & Munson, 1933). Acoust�c �njury would only be expected to occur at levels far above the detect�on threshold—that �s, levels for wh�ch the flatten�ng effect would be expected. Consequently, �t �s unclear how useful or appropr�ate the aud�tory threshold funct�on �s �n der�v�ng frequency-we�ght�ng f�lters �n mar�ne mammals for wh�ch psychophys�cal equal-loud-ness measurements are generally unava�lable (although see prel�m�nary measurements by R�dgway & Carder, 2000). Further, the l�m�ted TTS data for cetaceans exposed to tones at d�ffer-ent frequenc�es (d�scussed below) suggest that an aud�ogram-based frequency-we�ght�ng funct�on would produce too much f�lter�ng at lower fre-quenc�es (�.e., the we�ght�ng funct�on for hear�ng effects should be flatter than the �nverted aud�o-gram procedure would �nd�cate).

Therefore, a precaut�onary procedure was used to der�ve frequency-spec�f�c, mar�ne mammal we�ght�ng funct�ons. Each was based on an algo-r�thm that requ�res only the est�mated (as ~80 dB above best hear�ng sens�t�v�ty) lower and upper frequenc�es of funct�onal hear�ng as g�ven �n the above descr�pt�on of each mar�ne mammal group and �n Table 2. The result�ng funct�ons were des�gned to reasonably represent the bandw�dth where acoust�c exposures can have aud�tory effects and were des�gned to be most accurate for descr�b-�ng the adverse effects of h�gh-ampl�tude no�se where loudness funct�ons are expected to flatten s�gn�f�cantly. The we�ght�ng funct�ons (des�gnated “M” for mar�ne mammal) are analogous to the C-we�ght�ng funct�on for humans, wh�ch �s com-monly used �n measur�ng h�gh-ampl�tude sounds. In the general absence of emp�r�cal data, however, the upper and lower frequency roll-offs of the

434 Southalletal.

M-we�ght�ng funct�ons are symmetr�cal, whereas C-we�ght�ng adm�ts more energy at the lower than at the upper frequency l�m�ts (ANSI, 2001).

The M-we�ght�ng funct�ons assume a logar�th-m�c reduct�on �n aud�tory sens�t�v�ty outs�de of the range of best hear�ng sens�t�v�ty, w�th the funct�on be�ng 6 dB down from peak sens�t�v�ty at the lower and upper frequency “l�m�ts.” Aud�tory detect�on thresholds at these “l�m�ts” (see above d�scuss�on of lower and upper frequency “cut-offs”) can be ≥ 80 dB h�gher (less sens�t�ve) than those at the fre-quenc�es of best hear�ng sens�t�v�ty. Consequently, these frequency f�lters are much “flatter” than aud�ograms and probably qu�te precaut�onary even cons�der�ng the expected flatten�ng of equal-loudness contours at h�gh exposure levels. The M-we�ght�ng funct�ons are also precaut�onary �n that reg�ons of best hear�ng sens�t�v�ty for most spec�es are l�kely cons�derably narrower than the M-we�ght�ng funct�ons (des�gned for the overall mar�ne mammal group) would suggest. The gen-eral express�on for M-we�ght�ng (M[f]), us�ng the est�mated lower and upper “funct�onal” hear-�ng l�m�ts (flow and fh�gh) for each of the f�ve func-t�onal mar�ne mammal hear�ng groups, �s g�ven �n Append�x A (eq. 7 & 8). These frequency-we�ght-�ng funct�ons are �dent�f�ed �n Table 2, and each �s dep�cted graph�cally �n F�gure 1.

The M-we�ght�ng funct�ons de-emphas�ze fre-quenc�es that are near the lower and upper fre-quency ends of the est�mated hear�ng range as �nd�cated by negat�ve relat�ve values (F�gure 1). Th�s de-emphas�s �s appropr�ate because, to have a g�ven aud�tory effect, sound at these frequenc�es must have h�gher absolute ampl�tude than sound �n the reg�on of best hear�ng sens�t�v�ty. As a corol-lary, sound at a g�ven level w�ll have less effect �f �t �s near or (espec�ally) beyond the lower or upper bounds of the funct�onal hear�ng range than �f �t �s well w�th�n that frequency range. It �s �mportant to note the �ncremental nature of the frequency-we�ght�ng funct�ons, wh�ch approx�mate the gradual reduct�on �n aud�tory effect at frequenc�es outs�de the range of greatest sens�t�v�ty.

Use of such M-frequency-we�ght�ng funct�ons �s super�or to flat we�ght�ng across all frequenc�es because �t accounts for known or est�mated d�ffer-ences �n the frequency response character�st�cs for each funct�onal hear�ng group. At least �n the context of �njury cr�ter�a, �t �s super�or to frequency-we�ght-�ng v�a the �nverse-aud�ogram method as �t takes �nto account the expected “flatten�ng” of equal-loudness curves at the h�gh exposure levels where TTS and PTS are expected. It �s also super�or to a “boxcar-type” step funct�on because �t more closely approx�mates the gradual roll-off of sens�t�v�ty below and above the range of opt�mum sens�t�v�ty. Furthermore, each of the recommended “shallow”

frequency-we�ght�ng funct�ons �ncludes, w�th�n �ts relat�vely flat port�on, the full aud�ble range for each spec�es for wh�ch aud�tory data are ava�lable. In other words, none of the spec�es �ncluded w�th�n each funct�onal hear�ng group has been shown or �s expected to have any port�on of �ts best hear�ng sens�t�v�ty outs�de the flat port�on of the relevant frequency-we�ght�ng funct�on. Thus, the funct�ons are qu�te precaut�onary, wh�ch �s appropr�ate g�ven that data are l�m�ted or lack�ng for most spec�es.

Exposure Criteria Metrics

Many acoust�c metr�cs (e.g., RMS or peak SPL, SEL, kurtos�s) could be cons�dered �n relat�on to no�se �mpacts on an�mals. It �s �mposs�ble to pred�ct unequ�vocally wh�ch one �s best assoc�-ated w�th the l�kel�hood of �njury or s�gn�f�cant behav�oral d�sturbance across all taxa because of spec�es d�fferences and the fact that real-world sound exposures conta�n many w�dely d�ffer�ng temporal patterns and pressure s�gnatures. To account for such d�fferences and to allow for cur-rent sc�ent�f�c understand�ng of t�ssue �njury from no�se exposure, the proposed �njury cr�ter�a �ncor-porate a dual-cr�ter�a approach based on both peak pressure and energy. For an exposed �nd�v�dual, wh�chever cr�ter�on �s exceeded f�rst (�.e., the more precaut�onary of the two measures) �s used as the operat�ve �njury cr�ter�on. S�m�larly, a dual-cr�te-r�on approach (peak sound pressure and energy) �s also proposed for behav�oral d�sturbance from a s�ngle pulse.

The pressure cr�ter�a for �njury are def�ned as those peak SPLs above wh�ch t�ssue �njury �s pre-d�cted to occur, �rrespect�ve of exposure durat�on. Any s�ngle exposure at or above th�s peak pressure �s cons�dered to cause t�ssue �njury, regardless of the SPL or SEL of the ent�re exposure. For each mar�ne mammal group, the recommended pres-sure-based �njury cr�ter�a are the same for all sound types and are based on the cr�ter�on for a s�ngle pulse. Th�s �s a precaut�onary procedure; pressure cr�ter�a based on TTS data for nonpulses would y�eld much h�gher est�mates of the exposure nec-essary for PTS-onset. By propos�ng, for all cases, pressure cr�ter�a appropr�ate to a s�ngle pulse, we protect aga�nst the poss�b�l�ty that, for some sound sources, one or more �ntense pulses may occas�on-ally be embedded �n nonpulse sounds.

For exposures lack�ng �ntense peak pressure components, ava�lable data �nd�cate that measure-ments �ntegrat�ng �nstantaneous pressure squared over the durat�on of sound exposure are well corre-lated w�th the probab�l�ty of TTS-onset and t�ssue �njury. Consequently, for exposures other than those conta�n�ng �ntense peak pressure trans�ents, SEL �s the (or at least one of the) appropr�ate


(A)(A )

(B )

Wei

gh

tin

g (d

B)

Wei

gh

tin

g (d

B)

Frequency (kHz)

Frequency (kHz)

M-weighting

M-weighting

pinnipeds in water, Mpw

pinnipeds in air, Mpa

low-frequency cetaceans, Mlf

mid-frequency cetaceans, Mmf

high-frequency cetaceans, Mhf

(B)

(A )

(B )

Wei

gh

tin

g (d

B)

Wei

gh

tin

g (d

B)

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M-weighting

pinnipeds in water, Mpw

pinnipeds in air, Mpa

low-frequency cetaceans, Mlf

mid-frequency cetaceans, Mmf

high-frequency cetaceans, Mhf

Figure 1. The M-weighting functions for (A) low-, mid-, and high-frequency cetaceans, as well as for (B) pinnipeds in water and air.

436 Southalletal.

metr�c(s) for est�mat�ng TTS-onset and pred�ct�ng PTS-onset �n humans (ISO, 1990).

Th�s use of SEL �s based on the assumpt�on that sounds of equ�valent energy w�ll have generally s�m�lar effects on the aud�tory systems of exposed human subjects, even �f they d�ffer �n SPL, dura-t�on, and/or temporal exposure pattern (Kryter, 1970; N�elsen et al., 1986; Yost, 1994; NIOSH, 1998). Under the equal-energy assumpt�on, at exposure levels above TTS-onset, each doubl�ng of sound durat�on �s assoc�ated w�th a 3 dB reduc-t�on �n the SPL theoret�cally requ�red to cause the same amount of TTS. Th�s relat�onsh�p has been used �n the der�vat�on of exposure gu�del�nes for humans (e.g., NIOSH, 1998). Numerous authors have quest�oned the pred�ct�ve power of us�ng a s�mpl�st�c total energy approach �n all cond�-t�ons. It fa�ls to account for vary�ng levels and temporal patterns of exposure/recovery, among other factors, and w�ll thus l�kely overest�mate the TTS result�ng from a complex no�se exposure (Hamern�k & Hsueh, 1991; Hamern�k et al., 1993, 2002; Ahroon et al., 1993; Ward, 1997; Strasser et al., 2003). A comparat�ve assessment of TTS as a funct�on of exposure level �n mammals, f�sh, and b�rds suggests that there are d�rect relat�onsh�ps but that the slopes vary among taxa (Sm�th et al., 2004). The debate over the val�d�ty of the equal energy “rule” of no�se exposure rema�ns unre-solved, even for humans.

Some l�m�ted ev�dence favor�ng an SEL approach ex�sts for mar�ne mammals, how-ever. Spec�f�cally, an equal-energy relat�onsh�p for TTS-onset appears to hold reasonably well for certa�n no�se exposure types w�th�n sev-eral m�d-frequency cetacean spec�es (F�nneran et al., 2002b, 2005a; see “Effects of No�se on Hear�ng �n Mar�ne An�mals: TTS Data” sect�on �n Chapter 3). A recent study of �n-a�r TTS �n a Cal�forn�a sea l�on (Kastak et al., 2007) �llustrates some cond�t�ons �n wh�ch exposures w�th �dent�cal SEL result �n cons�der-ably d�fferent levels of TTS. Nevertheless, because the very l�m�ted mar�ne mammal data agree rea-sonably well (at least as a f�rst-order approx�ma-t�on) w�th equal-energy pred�ct�ons, and pred�c-t�ons based on SEL w�ll be precaut�onary for �nterm�ttent exposures, we regard �t as appropr�ate to apply the SEL metr�c for certa�n no�se exposure cr�ter�a unt�l future research �nd�cates an alter-nate and more spec�f�c course. In certa�n appl�ca-t�ons, there �s much more sc�ent�f�c just�f�cat�on for use of SEL-based cr�ter�a than for prev�ous ad hoc SPL cr�ter�a (d�scussed �n the “H�stor�cal Perspect�ve” sect�on �n Chapter 1). In appl�cat�ons �nvolv�ng aud�tory effects, SEL-based cr�ter�a w�ll l�kely more rel�ably d�st�ngu�sh cases where

phenomena of concern (TTS, PTS, etc.) w�ll and w�ll not l�kely occur.

Levels of Noise Effect: Injury and Behavioral Disturbance

D�rect aud�tory t�ssue effects (�njury) and behav-�oral d�srupt�on are the two categor�es of no�se effect that are cons�dered �n these mar�ne mammal exposure cr�ter�a. Chapter 3 summar�zes all ava�lable data on the effects of no�se on mar�ne mammal hear�ng. It also descr�bes how these data are appl�ed and extrapolated us�ng precaut�onary measures to pred�ct aud�tory �njury and to der�ve thresholds and proposed cr�ter�a for �njury.

In Chapter 4 and Append�ces B & C, we summa-r�ze the current understand�ng and ava�lable data regard�ng mar�ne mammal behav�oral responses to no�se. Chapter 4 �ncludes a quant�tat�ve sever-�ty scale based generally on the NRC’s (2005) Populat�on Consequences of Acoust�c D�sturbance (PCAD) Model. Chapter 4 also �ncludes a l�m�ted and caut�ous entry of behav�oral-response data �nto a matr�x of sever�ty scal�ng as a funct�on of RL. Currently ava�lable data, pooled by funct�onal hear�ng group, do not support spec�f�c numer�cal cr�ter�a for the onset of d�sturbance. Rather, they �nd�cate the context-spec�f�c�ty of behav�oral reac-t�ons to no�se exposure and po�nt to some general conclus�ons about response sever�ty �n certa�n, spec�f�c cond�t�ons.

3. Criteria for Injury: TTS and PTS

The cr�ter�a for �njury for all mar�ne mammal groups and sound types are rece�ved levels (fre-quency-we�ghted where appropr�ate) that meet the def�n�t�on of PTS-onset used here (40 dB-TTS, descr�bed below). Cr�ter�a were der�ved from mea-sured or assumed TTS-onset thresholds for each mar�ne mammal group plus TTS growth rate est�-mates (g�ven below). Ava�lable TTS data for two m�d-frequency cetacean spec�es and three spec�es of p�nn�peds are used as the bas�s for est�mat�ng PTS-onset thresholds �n all cetaceans (“cetacean procedure” descr�bed below; see “PTS-Onset for Pulses”) and �n all p�nn�peds (see “PTS-Onset for Nonpulse Sounds”), respect�vely. The pro-posed �njury cr�ter�a are presented by sound type because, for a g�ven sound type, many of the same extrapolat�on and summat�on procedures apply across mar�ne mammal hear�ng groups.

A dual-cr�ter�on approach was used for the rec-ommended �njury cr�ter�a. That �s, any rece�ved no�se exposure that exceeds e�ther a peak pressure or a SEL cr�ter�on for �njury �s assumed to cause t�ssue �njury �n an exposed mar�ne mammal. Of the two measures of sound exposure, peak pres-sures are to be unwe�ghted (�.e., “flat-we�ghted”), whereas SEL metr�cs are to be M-we�ghted for the relevant mar�ne mammal group (F�gure 1). In prac-t�ce, the rece�ved no�se cond�t�ons should be com-pared to the two exposure cr�ter�a for that sound type and funct�onal hear�ng group, and the more precaut�onary of the two outcomes accepted.

Effects of Noise on Hearing in Marine Mammals: TTS Data

No�se exposure cr�ter�a for aud�tory �njury �deally should be based on exposures emp�r�cally shown to �nduce PTS-onset; however, no such data presently ex�st for mar�ne mammals. Instead, PTS-onset must be est�mated from TTS-onset measurements and from the rate of TTS growth w�th �ncreas�ng expo-sure levels above the level el�c�t�ng TTS-onset. PTS �s presumed to be l�kely �f the threshold �s reduced by ≥ 40 dB (�.e., 40 dB of TTS). We used ava�lable mar�ne mammal TTS data and precaut�onary extrap-olat�on procedures based on terrestr�al mammal data (see “Level of No�se Effect” �n Chapter 2) to est�mate exposures assoc�ated w�th PTS-onset. Ex�st�ng TTS measurements for mar�ne mammals are rev�ewed �n deta�l here s�nce they serve as the quant�tat�ve foundat�on for the �njury cr�ter�a.

To date, TTSs measured �n mar�ne mammals have generally been of small magn�tude (mostly < 10 dB). The onset of TTS has been def�ned as be�ng a temporary elevat�on of a hear�ng thresh-old by 6 dB (e.g., Schlundt et al., 2000), although smaller threshold sh�fts have been demonstrated to be stat�st�cally s�gn�f�cant w�th a suff�c�ent number of samples (e.g., Kastak et al., 1999; F�nneran et al., 2005a). Normal threshold var�ab�l�ty w�th�n and between both exper�mental and control ses-s�ons (no no�se) does warrant a TTS-onset cr�te-r�on at a level that �s always clearly d�st�ngu�sh-able from that of no effect. We cons�dered a 6 dB TTS suff�c�ent to be recogn�zed as an unequ�vo-cal dev�at�on and thus a suff�c�ent def�n�t�on of TTS-onset.

Most of the frequenc�es used �n TTS exper�-ments to date are w�th�n the flat port�ons of the M-we�ght�ng funct�ons g�ven here, but not nec-essar�ly w�th�n the reg�ons of greatest hear�ng sens�t�v�ty. W�th�n the range of best hear�ng sen-s�t�v�ty for a g�ven �nd�v�dual, detect�on thresholds are generally s�m�lar. W�th�n th�s band, exposures w�th the same absolute level but d�fferent fre-quency are thus s�m�lar �n terms of the�r effect�ve sensat�on level. Sensationlevel �s the amount (�n dB) by wh�ch an RL exceeds the threshold RL for that s�gnal type w�th�n a prescr�bed frequency band (Yost, 2000). If two exposures w�th �dent�cal absolute level are both aud�ble, but one �s outs�de the frequency range of best hear�ng sens�t�v�ty, sensat�on level w�ll be less for the latter exposure, and �ts potent�al effects w�ll be d�m�n�shed. By creat�ng frequency-we�ghted funct�ons that are flat across v�rtually the ent�re funct�onal hear�ng band, rather than just the reg�on of best sens�t�v�ty, we have made another precaut�onary dec�s�on �n the absence of underly�ng data on equal-loudness funct�ons.

Aud�tory fat�gue (�.e., TTS) �n m�d-frequency cetaceans has been measured after exposure to tones, �mpuls�ve sounds, and octave-band no�se (OBN). In p�nn�peds, �t has been measured upon exposure to construct�on no�se and OBN �n both a�r and water.

CetaceanTTSThe sound exposures that el�c�t TTS �n cetaceans have been measured �n two m�d-frequency spe-c�es—bottlenose dolph�n and beluga (spec�f�c ref-erences g�ven below)—w�th at least l�m�ted data


438 Southalletal.

be�ng ava�lable for exposures to a s�ngle pulse and to nonpulsed sounds rang�ng from 1-s to ~50-m�n durat�on. There are no publ�shed TTS data for any other odontocete cetaceans (e�ther m�d- or h�gh-frequency) or for any myst�cete cetaceans (low-frequency). Th�s rev�ew �s organ�zed accord�ng to the durat�on of the fat�gu�ng st�mulus, w�th short-est exposures d�scussed f�rst.

F�nneran et al. (2000) exposed two bottlenose dolph�ns and one beluga to s�ngle pulses from an “explos�on s�mulator” (ES). The ES cons�sted of an array of p�ezoelectr�c sound projectors that generated a pressure waveform resembl�ng that from a d�stant underwater explos�on. The pressure waveform was generally s�m�lar to waveforms pred�cted by the Navy REFMS model (Br�tt et al., 1991). The ES fa�led to produce real�st�c energy at frequenc�es below 1 kHz, however. No substan-t�al (�.e., ≥ 6 dB) threshold sh�fts were observed �n any of the subjects exposed to a s�ngle pulse at the h�ghest rece�ved exposure levels (peak: 70 kPa [10 ps�]; peak-to-peak: 221 dB re: 1 µPa (peak-to-peak); SEL: 179 dB re: 1 µPa2-s)].

F�nneran et al. (2002b) repeated th�s exper�ment us�ng a se�sm�c watergun that produced a s�ngle acoust�c pulse. Exper�mental subjects cons�sted of one beluga and one bottlenose dolph�n. Measured TTS2 was 7 and 6 dB �n the beluga at 0.4 and 30 kHz, respect�vely, after exposure to �ntense s�ngle pulses (peak: 160 kPa [23 ps�]; peak-to-peak: 226 dB re: 1 µPa (peak-to-peak); SEL: 186 dB re: 1 µPa2-s). Thresholds returned to w�th�n ± 2 dB of the pre-exposure value w�th�n 4 m�n of exposure. No TTS was observed �n the bottlenose dolph�n at the h�ghest exposure cond�t�on (peak: 207 kPa [30 ps�]; peak-to-peak: 228 dB re: 1 µPa (peak-to-peak); SEL: 188 dB re: 1 µPa2-s). These stud�es demonstrated that, for very br�ef pulses, h�gher sound pressures were requ�red to �nduce TTS than had been found for longer tones (d�scussed below).

Schlundt et al. (2000) reported TTS �n f�ve bot-tlenose dolph�ns and two belugas exposed to 1-s pure tones (nonpulses). Th�s paper also �ncluded a re-analys�s of TTS data from a techn�cal report by R�dgway et al. (1997). At frequenc�es of 3 kHz, 10 kHz, and 20 kHz, SPLs necessary to �nduce TTS-onset were 192 to 201 dB re: 1 µPa (SEL: 192 to 201 dB re: 1 µPa2-s). The mean exposure SPL for TTS-onset was 195 dB re: 1 µPa (195 dB re: 1 µPa2-s). Note the appropr�ately d�ffer-ent metr�cs for the nonpulse sources used �n th�s study and those �nvolv�ng pulses. Also note that the SPL and SEL values are �dent�cal �n th�s spe-c�al case because of the 1-s durat�on fat�gu�ng st�mul�. At 0.4 kHz, no subjects exh�b�ted sh�fts after exposures up to SPL exposures of 193 dB re: 1 µPa (193 dB re: 1 µPa2-s). Data at 75 kHz

were �nconclus�ve: one dolph�n exh�b�ted a TTS after exposure at 182 dB SPL re: 1 µPa (182 dB re: 1 µPa2-s) but not at h�gher exposure levels. The other dolph�n exper�enced no threshold sh�ft after exposure to max�mum SPL levels of 193 dB re: 1 µPa (193 dB re: 1 µPa2-s). The sh�fts occurred most often at frequenc�es above the fat�gu�ng st�mulus.

F�nneran et al. (2005a) measured TTS �n bot-tlenose dolph�ns exposed to 3 kHz tones w�th durat�ons of 1, 2, 4, and 8 s and at var�ous SPL values. Tests were conducted �n a qu�et pool �n contrast to prev�ous stud�es �n San D�ego Bay, where thresholds were masked by broadband no�se. Small amounts of TTS (3 to 6 dB) occurred �n one dolph�n follow�ng exposures w�th SELs of 190 to 204 dB re: 1 µPa2-s. These results are con-s�stent w�th those of Schlundt et al. (2000), �nd�-cat�ng that the�r results had not been s�gn�f�cantly affected by the use of masked hear�ng thresholds �n quant�fy�ng TTS. In general, the SEL necessary for TTS-onset was relat�vely cons�stent across the range of exposure durat�ons, whereas exposure SPL values caus�ng TTS-onset tended to decrease w�th �ncreas�ng exposure durat�on. These results conf�rmed that, for these test�ng cond�t�ons (bot-tlenose dolph�ns exposed to £ 8-s tones of var�able SPL), TTS magn�tude was best correlated w�th exposure SEL rather than SPL.

Schlundt et al. (2006) reported on the growth and recovery of TTS �n a bottlenose dolph�n exposed to 3 kHz tones w�th SPLs up to 200 dB re 1 µPa and durat�ons up to 128 s. The max�mum exposure SEL was 217 dB re 1 µPa2-s, wh�ch pro-duced a TTS4 of ~23 dB. All thresholds recovered to basel�ne values w�th�n 24 h, most w�th�n 30 m�n. The growth of TTS4 w�th �ncreas�ng expo-sure SEL was ~1 dB TTS per dB SEL for TTS4 of ~15 to 18 dB.

F�nneran et al. (2007b) measured TTS �n a bottlenose dolph�n after s�ngle and mult�ple expo-sures to 20 kHz tones. Hear�ng thresholds were est�mated at mult�ple frequenc�es (10 to 70 kHz) both behav�orally and electrophys�olog�cally (by measurement of mult�ple aud�tory steady-state responses). Three exper�ments were performed. The f�rst two featured s�ngle exposures (20 kHz, 64-s tones at 185 and 186 dB re 1 µPa). The th�rd featured three 20 kHz, 16-s exposures separated by 11 and 12 m�n, w�th a mean SPL of 193 dB re 1 µPa (SD = 0.8 dB). Hear�ng loss was frequency-dependent, w�th the largest TTS occurr�ng at 30 kHz, less at 40, and then 20 kHz, and l�ttle or no TTS at other measured frequenc�es. AEP thresh-old sh�fts reached 40 to 45 dB and were always larger than behav�oral sh�fts, wh�ch were 19 to 33 dB. Complete recovery requ�red up to 5 d, w�th the recovery rate at 20 kHz be�ng ~2 dB/doubl�ng


of t�me and the rate at 30 and 40 kHz ~5 to 6 dB/doubl�ng of t�me.

Nacht�gall et al. (2003) measured TTS (ca. 20 m�n after no�se cessat�on) �n a bottlenose dolph�n and found an average 11 dB sh�ft follow�ng a 30-m�n net exposure to OBN w�th a 7.5 kHz center frequency (CF) (max SPL: 179 dB re: 1 µPa; SEL: ~212 to 214 dB re: 1 µPa2-s). The net exposure t�me was calculated as the total exper�mental t�me m�nus the t�me requ�red for the subject to surface to breathe. Exposure dur�ng breath�ng per�ods was measured and factored �nto the SEL measurement. No TTS was observed after exposure to the same OBN at max�mum SPL values of 165 and 171 dB re: 1 µPa (SEL: ~198 to 200 dB re: 1 µPa2-s and 204 to 206 dB re: 1 µPa2-s, respect�vely).

Us�ng AEP methods, Nacht�gall et al. (2004) found TTS5 of ca. 4 to 8 dB follow�ng nearly 50-m�n exposures to OBN w�th a CF of 7.5 kHz (max SPL: 160 dB re: 1 µPa; SEL: ~193 to 195 dB re: 1 µPa2-s). The d�fference �n results between the two Nacht�gall et al. stud�es (sl�ghtly lower TTS after exposure to much lower exposure energy) was attr�buted to measur�ng TTS at a shorter �nterval after the exposure ended (5 vs ~20 m�n), and thus allow�ng less opportun�ty for hear�ng recovery. Further, Nacht�gall et al. (2004) repeatedly mea-sured hear�ng unt�l recovery had occurred. TTS recovery was shown to occur w�th�n m�nutes or tens of m�nutes, depend�ng on the amount of the threshold sh�ft. Generally, the recovery rate was 1.5 dB of recovery per doubl�ng of t�me and was cons�stent �n both stud�es (Nacht�gall et al., 2003, 2004).

The Nat�onal Research Counc�l (NRC) (1994) �dent�f�ed the need to know whether mar�ne mam-mals exper�ence greatest TTS at a frequency 1⁄2-octave above the frequency of exposure when exposed to loud tones as has been shown �n terres-tr�al mammals. Nacht�gall et al. (2004) observed an average threshold sh�ft of 4 dB at 8 kHz but 8 dB sh�ft at 16 kHz follow�ng the exposure to OBN centered at 7.5 kHz as descr�bed above. A s�m�lar upward frequency sh�ft also has been observed by Schlundt et al. (2000) and F�nneran et al. (2007b) for m�d-frequency cetaceans. These f�nd�ngs pro-v�de “strong ev�dence for fundamental s�m�lar�t�es �n cochlear m�cromechan�cs �n mar�ne and land mammals” (NRC, 1994, p. 51) and further just�fy the jud�c�ous extrapolat�on of TTS data w�th�n mar�ne mammal funct�onal hear�ng groups and from terrestr�al to mar�ne mammals.

The above results prov�de emp�r�cal measures of exposure cond�t�ons assoc�ated w�th TTS-onset �n m�d-frequency cetaceans exposed to s�ngle pulses and nonpulses. Comb�ned, these data demonstrate that, as compared w�th the exposure levels neces-sary to el�c�t TTS when exposure durat�on �s short,

lower SPLs (but s�m�lar SEL values) are requ�red to �nduce TTS when exposure durat�on �s longer. These f�nd�ngs are generally cons�stent w�th mea-surements �n humans and terrestr�al mammals (Kryter, 1970; Harr�s, 1998; NIOSH, 1998) and support the use of SEL to approx�mate the aud�-tory effects of var�able exposure level/durat�on cond�t�ons. Although there are certa�n (poss�bly many) cond�t�ons under wh�ch an expl�c�t “equal-energy rule” may fa�l to adequately descr�be the aud�tory effects of var�able and/or �nterm�ttent no�se exposure, the comb�ned cetacean TTS data presented above generally support the use of SEL as a f�rst-order approx�mat�on, at least unt�l add�-t�onal data are ava�lable.

For cetaceans, publ�shed TTS data are l�m�ted to the bottlenose dolph�n and beluga (F�nneran et al., 2000, 2002b, 2005a; Schlundt et al., 2000; Nacht�gall et al., 2003, 2004). Where data ex�st for both spec�es, we use the more precaut�onary result (usually for beluga) to represent TTS-onset for all m�d-frequency cetaceans. No publ�shed data ex�st on aud�tory effects of no�se �n e�ther low- or h�gh-frequency cetaceans (an area of needed research as d�scussed �n Chapter 5); therefore, data from m�d-frequency cetaceans are used as surrogates for these two other groups (cetacean proce-dure). [We are aware of some very recent TTS measurements for an �nd�v�dual harbor porpo�se exposed to s�ngle pulses (Lucke et al., 2007a) but lack suff�c�ent deta�ls regard�ng methodology and data analys�s to d�rectly cons�der those data quant�tat�vely.]

Low-frequency cetaceans (myst�cetes), based on the�r aud�tory anatomy (Wartzok & Ketten, 1999) and amb�ent no�se levels �n the frequency ranges they use (Clark & Ell�son, 2004), almost certa�nly have poorer absolute sens�t�v�ty (�.e., h�gher thresholds) across much of the�r hear�ng range than do the m�d-frequency spec�es (but see earl�er d�scuss�on). M�d-frequency cetaceans exper�ence TTS-onset at relat�vely h�gh levels compared w�th the�r absolute hear�ng sens�t�v�ty at s�m�lar frequenc�es (�.e., h�gh sensat�on levels), although �t �s not known that th�s �s s�m�larly char-acter�st�c of low-frequency cetaceans. Our use of TTS data from m�d-frequency cetaceans as a sur-rogate for low-frequency cetaceans presumes that the two groups have s�m�lar aud�tory mechan�sms and are not rad�cally d�fferent �n relat�ve sens�t�v-�ty to fat�gu�ng no�se, and that relat�ve d�fferences �n absolute sens�t�v�ty between the two groups are generally as expected.

For h�gh-frequency spec�es, data from m�d-frequency cetaceans are currently used as a sur-rogate �n the absence of ava�lable group-spec�f�c data. As�de from the�r extended upper-frequency hear�ng, h�gh-frequency cetaceans appear to be

440 Southalletal.

generally s�m�lar �n aud�tory anatomy and hear-�ng capab�l�t�es to m�d-frequency spec�es, though there are some general d�fferences between the groups �n sound product�on. Based on ava�lable �nformat�on and our extrapolat�on procedures, sl�ghtly lower est�mates of TTS-onset may be war-ranted for h�gh-frequency cetaceans exposed to very h�gh-frequency sounds (≥ 100 kHz). [Also, prel�m�nary measurements of TTS �n a harbor porpo�se exposed to a s�ngle a�rgun pulse (Lucke et al., 2007a) suggest that th�s spec�es may exper�-ence TTS-onset at levels lower than would be sug-gested by extrapolat�ng from m�d-frequency ceta-ceans. Those results, �f conf�rmed, may prov�de a more emp�r�cal bas�s for est�mat�ng TTS-onset �n h�gh-frequency cetaceans and der�v�ng group-spe-c�f�c �njury cr�ter�a.]

PinnipedTTS(UnderWater)Sound exposures that el�c�t TTS �n p�nn�peds under water have been measured �n �nd�v�dual subjects of three p�nn�ped spec�es (harbor seal, Cal�forn�a sea l�on, and northern elephant seal). Ava�lable data �nvolved exposures to e�ther broadband or octave-band nonpulse no�se over durat�ons rang�ng from ~12 m�n to several hours, plus l�m�ted data on exposure to underwater pulses. Interest�ngly, there were cons�stent among-spec�es d�fferences �n the exposure cond�t�ons that el�c�ted TTS under water. For the cond�t�ons tested, the harbor seal exper�enced TTS at lower exposure levels than d�d the Cal�forn�a sea l�on or northern elephant seal. There are no underwater TTS data for any other p�nn�ped spec�es.

The follow�ng rev�ew f�rst cons�ders expo-sure to nonpulses, organ�zed chronolog�cally, followed by a br�ef d�scuss�on of the lone study on exposure to pulses. All but one of the stud�es (F�nneran et al., 2003) came from one laboratory and from the same �nd�v�dual test subjects. Kastak & Schusterman (1996) reported a TTS of ~8 dB (measured under water at 100 Hz) �n a harbor seal follow�ng exposure to broadband a�rborne, non-pulse no�se from nearby construct�on. Under con-trolled cond�t�ons, Kastak et al. (1999) measured TTS of ca. 4 to 5 dB �n a harbor seal, Cal�forn�a sea l�on, and northern elephant seal follow�ng 20- to 22-m�n exposure to underwater OBN centered at frequenc�es from 100 Hz to 2 kHz. Exposures were normal�zed to octave-band levels 60 to 75 dB above each subject’s hear�ng threshold (�.e., 60 to 75 dB sensat�on level) to present s�m�lar effec-t�ve exposure cond�t�ons to each of the three sub-jects. Because of th�s approach, absolute exposure values (�n terms of both SPL and SEL) were qu�te var�able depend�ng on subject and test frequency.

Subsequently, Kastak et al. (2005) made TTS measurements on the same subjects us�ng 2.5

kHz OBN, h�gher sensat�on levels (up to 95 dB), and longer exposure durat�ons (up to 50-m�n net exposure). These data largely corroborate prev�-ous f�nd�ngs concern�ng TTS-onset �n these p�n-n�peds. They also support sensat�on level as a rele-vant metr�c for normal�z�ng exposures w�th s�m�lar durat�ons across spec�es hav�ng d�fferent absolute hear�ng capab�l�t�es. Comparat�ve analyses of the comb�ned underwater p�nn�ped data (Kastak et al., 2005) �nd�cated that, �n the harbor seal, a TTS of ca. 6 dB occurred w�th 25-m�n exposure to 2.5 kHz OBN w�th SPL of 152 dB re: 1 µPa (SEL: 183 dB re: 1 µPa2-s). Under the same test cond�-t�ons, a Cal�forn�a sea l�on showed TTS-onset at 174 dB re: 1 µPa (SEL: 206 dB re: 1 µPa2-s), and a northern elephant seal exper�enced TTS-onset at 172 dB re: 1 µPa (SEL: 204 dB re: 1 µPa2-s).

Data on underwater TTS-onset �n p�nn�peds exposed to pulses are l�m�ted to a s�ngle study. F�nneran et al. (2003) exposed two Cal�forn�a sea l�ons to s�ngle underwater pulses from an arc-gap transducer. They found no measurable TTS follow�ng exposures up to 183 dB re: 1 µPa (peak-to-peak) (SEL: 163 dB re: 1 µPa2-s). Based on the Kastak et al. (2005) measurements us�ng nonpulse sounds, the absence of TTS for the sea l�ons follow�ng such exposures �s generally not surpr�s�ng.

PinnipedTTS(InAir)Aud�tory fat�gue has been measured follow�ng exposure of p�nn�peds to s�ngle pulses of �n-a�r sound and to nonpulse no�se.

Bowles et al. (unpub. data) measured TTS-onset for harbor seals exposed to s�mulated son�c booms at peak SPLs of 143 dB re: 20 µPa (peak) (SEL: 129 dB re: [20 µPa]2-s). H�gher exposure levels were requ�red to �nduce TTS-onset �n both Cal�forn�a sea l�ons and northern elephant seals �n the same test sett�ng, cons�stent w�th the results for nonpulse sound both under water and �n a�r.

Aud�tory fat�gue to a�rborne sound has also been measured �n the same three spec�es of p�nn�-peds after exposure to nonpulse no�se, spec�f�cally 2.5 kHz CF OBN for 25 m�n (Kastak et al., 2004a). The harbor seal exper�enced ca. 6 dB of TTS at 99 dB re: 20 µPa (SEL: 131 dB re: [20 µPa]2-s). Onset of TTS was �dent�f�ed �n the Cal�forn�a sea l�on at 122 dB re: 20 µPa (SEL: 154 dB re: [20 µPa]2-s). The northern elephant seal exper�-enced TTS-onset at 121 dB re: 20 µPa (SEL: 163 dB re: [20 µPa]2-s). The subjects �n these tests were the same �nd�v�duals tested �n water (Southall et al., 2001; Kastak et al., 2005).

Kastak et al. (2007) measured TTS-onset and growth funct�ons for the same Cal�forn�a sea l�on exposed to a w�der range of no�se cond�t�ons. A total of 192 exposure sequences were conducted


w�th OBN (centered at 2.5 kHz) at levels 94 to 133 dB re: 20 µPa and durat�ons 1.5 to 50 m�n net exposure durat�on. In these more �ntense no�se exposures, TTS magn�tudes up to 30 dB were measured at the 2.5 KHz test frequency. Full recovery was observed follow�ng all exposures; th�s occurred rap�dly (l�kely w�th�n tens of m�n-utes) for small sh�fts but took as long as 3 d �n the case of the largest TTS. The est�mated SEL value co�nc�d�ng w�th TTS-onset across these var�ed exposure cond�t�ons was 159 dB re: (20 µPa)2-s w�th a TTS growth funct�on of ~2.5 dB TTS/dB no�se. For TTS exceed�ng 20 dB, a recovery rate of ~2.6 dB/doubl�ng of t�me was calculated. These results generally agree w�th those of Kastak et al. (2004a) but prov�de a larger data set, across a w�der range of exposure cond�t�ons w�th wh�ch to der�ve an emp�r�cal TTS-growth funct�on. They also support the conclus�on that patterns of TTS growth and recovery are generally s�m�lar to those of terrestr�al mammals and that sensat�on level for the part�cular spec�es and med�um (water or a�r) �s the appropr�ate metr�c for compar�ng the effects of underwater and aer�al no�se exposure.

Injury from Noise Exposure: PTS-Onset Calculation

As d�scussed �n Chapter 1, PTS �s an �rrevers�ble elevat�on of the hear�ng threshold (�.e., a reduct�on �n sens�t�v�ty) at a spec�f�c frequency (Yost, 2000). Th�s permanent change follow�ng �ntense no�se exposure results from damage or death of �nner or outer cochlear ha�r cells. It �s often followed by retrograde neuronal losses and pers�stent chem�cal and metabol�c cochlear abnormal�t�es (Saunders et al., 1991; Ward, 1997; Yost, 2000).

No�se-�nduced PTS represents t�ssue �njury, but TTS does not. Although TTS �nvolves reduced hear�ng sens�t�v�ty follow�ng exposure, �t results pr�mar�ly from the fat�gue (as opposed to loss) of cochlear ha�r cells and support�ng structures and �s, by def�n�t�on, revers�ble (Nordmann et al., 2000). Many mammals, �nclud�ng some p�nn�peds (Kastak et al., 1999, 2005) and cetaceans (e.g., Schlundt et al., 2000; Nacht�gall et al., 2004), demonstrate full recovery even after repeated TTS. S�nce TTS represents a temporary change �n sens�t�v�ty w�thout permanent damage to sensory cells or support structures, �t �s not cons�dered to represent t�ssue �njury (Ward, 1997). Instead, the onset of t�ssue �njury from no�se exposure �s con-s�dered here as PTS-onset.

PTS as a funct�on of age (presbycusis; d�scussed �n Chapter 1) generally appears to be a normal pro-cess of ag�ng �n mammals (�nclud�ng humans and mar�ne mammals), but no spec�f�c allowance for th�s �s �ncluded �n our proposed exposure cr�ter�a.

Data that would be needed to support alternate cr�ter�a allow�ng for presbycus�s are lack�ng. Our approach, wh�ch uses TTS data from subjects pre-sumed to have “normal” hear�ng as the start�ng po�nt for est�mat�ng PTS-onset, �s precaut�onary. It �s expected to overest�mate damag�ng effects for those �nd�v�duals w�th d�m�n�shed absolute hear-�ng sens�t�v�ty and/or funct�onal bandw�dth pr�or to the exposure.

Data on the effects of no�se on terrestr�al mam-mals can be useful �n cons�der�ng the effects on mar�ne mammals �n certa�n cond�t�ons (as d�s-cussed �n Chapter 1) because of s�m�lar�t�es �n morphology and funct�onal dynam�cs among mammal�an cochleae. Under that prem�se, �t �s assumed that a no�se exposure capable of �nduc-�ng 40 dB of TTS w�ll cause PTS-onset �n mar�ne mammals. Based on ava�lable data for terrestr�al mammals, th�s assumpt�on �s l�kely somewhat precaut�onary as there �s often complete recov-ery from TTS of th�s magn�tude or greater. Such precaut�on �s appropr�ate, however, because the prec�se relat�onsh�p between TTS and PTS �s not fully understood, even for humans and small ter-restr�al mammals desp�te hundreds of stud�es (see Kryter, 1994; Ward, 1997). For mar�ne mammals, th�s presumably complex relat�onsh�p �s unknown, and l�kely w�ll rema�n so. The ava�lable mar�ne mammal TTS data prov�de a bas�s for establ�sh-�ng a max�mum allowable amount of TTS up to wh�ch PTS �s unl�kely, however, and for conclud-�ng that PTS �s �ncreas�ngly l�kely to occur above th�s po�nt. In us�ng TTS data to est�mate the expo-sure that w�ll cause PTS-onset, our approach �s to acknowledge sc�ent�f�c uncerta�nty and to err on the s�de of overest�mat�ng the poss�b�l�ty of PTS (�.e., on the s�de of underest�mat�ng the exposure requ�red to cause PTS-onset).

In humans, when TTS2 magn�tude for a s�ngle exposure exceeds ca. 40 dB, the l�kel�hood of PTS beg�ns to �ncrease substant�ally (Kryter et al., 1966; Kryter, 1994). Threshold sh�fts greater than 40 dB have been demonstrated to be fully recoverable after some per�od of t�me �n some terrestr�al mammal spec�es (human: Ward, 1959; Ahroon et al., 1996; ch�nch�lla: M�ller et al., 1971; Mongol�an gerb�l [Merionesunguicu-latus]: Boettcher, 1993). Generally, however, TTS exceed�ng 40 dB requ�res a longer recovery t�me than smaller sh�fts, suggest�ng a h�gher probab�l�ty of �rrevers�ble damage (Ward, 1970) and poss�bly d�fferent underly�ng mechan�sms (Kryter, 1994; Nordman et al., 2000).

Our der�vat�on of proposed �njury cr�ter�a for mar�ne mammals beg�ns w�th measured or est�-mated no�se exposure cond�t�ons assoc�ated w�th TTS-onset �n cetaceans and p�nn�peds. Procedures for est�mat�ng PTS-onset, assumed to occur �n

442 Southalletal.

cond�t�ons caus�ng 40 dB of TTS, were der�ved by comb�n�ng (1) measured or est�mated TTS-onset levels �n mar�ne mammals and (2) the est�mated “growth” of TTS �n certa�n terrestr�al mammals exposed to �ncreas�ng no�se levels. The general PTS-onset procedures d�ffer accord�ng to sound type (pulses and nonpulses), the extent of ava�lable �nformat�on, and requ�red extrapolat�on. To est�-mate exposure cond�t�ons that w�ll result �n PTS-onset, SEL and SPL were cons�dered separately.

PTS-OnsetforPulsesHenderson & Hamern�k (1986) reported that �n ch�nch�llas exposed to pulses up to a certa�n level, for each dB of added exposure above that wh�ch caused TTS-onset, a further TTS of about 0.5 dB resulted. For the h�ghest exposure levels, as much as 3 dB of add�t�onal TTS was found per add�t�onal dB of no�se. Thus, �n extrapolat�ng TTS growth funct�ons from terrestr�al to mar�ne mammals, a precaut�onary approach �s just�f�ed such as us�ng a slope nearer the upper extreme of th�s range to est�mate the growth of TTS w�th exposure level.

When deal�ng w�th pulsed sound, to est�mate SEL exposures co�nc�dent w�th PTS-onset, we assume a slope of 2.3 dB TTS/dB no�se. Th�s �s relat�vely precaut�onary �n relat�on to the data by Henderson & Hamern�k (1986) on ch�nch�llas. Th�s slope trans-lates to an �njury cr�ter�on (for pulses) that �s 15 dB above the SEL of exposures caus�ng TTS-onset (def�ned above as 6 dB TTS). That �s, PTS-onset (40 dB TTS) �s expected to occur on exposure to an M-we�ghted SEL 15 dB above that assoc�ated w�th TTS-onset ([40 dB TTS – 6 dB TTS] / [2.3 dB TTS/dB no�se exposure] ª 15 dB no�se exposure above TTS-onset).

In terms of sound pressure, TTS-onset thresh-olds �n mar�ne mammals, part�cularly cetaceans, are qu�te h�gh (see above). The pred�cted PTS-onset values would be very h�gh (perhaps unreal-�st�cally so as they would approach the cav�tat�on l�m�t of water) �f the aforement�oned 15 dB d�f-ference between TTS-onset and PTS-onset were assumed. Consequently, an add�t�onal precaut�on-ary measure was appl�ed by arb�trar�ly assum�ng that the pressure d�fference between TTS-onset and PTS-onset for pulses m�ght be just 6 dB. Th�s results �n a TTS “growth” relat�onsh�p of 6 dB TTS/dB no�se (�.e., [40 dB TTS – 6 dB TTS] / [6 dB TTS/dB no�se exposure] ª 6 dB no�se expo-sure above TTS-onset). That �s an extremely con-servat�ve slope funct�on g�ven that �t �s double the h�ghest rate found �n ch�nch�llas by Henderson & Hamern�k (1986). Th�s 6 dB of added exposure, above the exposure el�c�t�ng TTS-onset, essen-t�ally establ�shes a proposed (unwe�ghted) peak-pressure ce�l�ng value for all sound types.

PTS-OnsetforNonpulseSoundsThe peak pressure values assumed to be assoc�ated w�th onset of �njury (PTS-onset) are numer�cally equ�valent for nonpulse and pulse sounds. Among other cons�derat�ons, th�s allows for the poss�b�l�ty that �solated pulses could be embedded w�th�n the predom�nantly nonpulse sound.

To est�mate the SEL value that would cause PTS-onset for nonpulse sounds, we used the fol-low�ng procedure. In humans, each added dB of nonpulse no�se exposure above TTS-onset results �n up to 1.6 dB of add�t�onal TTS (Ward et al., 1958, 1959). Assum�ng th�s relat�onsh�p appl�es to mar�ne mammals, ~20 dB of add�t�onal no�se exposure above that caus�ng TTS-onset �s requ�red to �nduce PTS-onset (�.e., [40 dB TTS – 6 dB TTS] / [1.6 dB TTS/dB no�se exposure] = 21.3 dB of add�t�onal no�se exposure). We rounded th�s down to a sl�ghtly more precaut�onary value of 20 dB of add�t�onal no�se exposure above TTS-onset. Consequently, to est�mate PTS-onset and der�ve the SEL �njury cr�ter�a for nonpulses, we add 20 dB to the M-we�ghted SEL values est�-mated to cause TTS-onset. The lone except�on to th�s approach �s for p�nn�peds �n a�r (d�scussed below) where a more precaut�onary TTS growth rate was used based on a relat�vely large emp�r�cal data set (Kastak et al., 2007).

Criteria for Injury from a Single Pulse

As per the “PTS-Onset Calculat�on” sect�on of th�s chapter, the recommended cr�ter�a for �njury from exposure to a s�ngle pulse, expressed �n terms of peak pressure, are TTS-onset levels plus 6 dB of add�t�onal exposure. In terms of SEL, the recom-mended cr�ter�a are TTS-onset levels plus 15 dB of add�t�onal exposure.

For all cetaceans exposed to pulses, the data of F�nneran et al. (2002b) were used as the bas�s for est�mat�ng exposures that would lead to TTS-onset (and, consequently, PTS-onset). They est�-mated that, �n a beluga exposed to a s�ngle pulse, TTS-onset occurred w�th unwe�ghted peak levels of 224 dB re: 1 µPa (peak) and 186 dB re: 1 µPa2-s. The latter �s equ�valent to a we�ghted (Mmf) SEL exposure of 183 dB re: 1 µPa2-s as some of the energy �n the pulse was at low frequenc�es to wh�ch the beluga �s less sens�t�ve. Add�ng 6 dB to the former (224 dB) values, the pressure cr�-ter�on for �njury for m�d-frequency cetaceans �s therefore 230 dB re: 1 µPa (peak) (Table 3, Cell 4). Add�ng 15 dB to the latter (183 dB) value, the M-we�ghted SEL �njury cr�ter�on �s 198 dB re: 1 µPa2-s (Table 3, Cell 4). These results are assumed to apply (see cetacean procedure, p. 439) to low- and perhaps h�gh-frequency cetaceans (Table 3, Cells 1 & 7, respect�vely) as well as to


m�d-frequency cetaceans. These �njury cr�ter�a, expressed �n SEL, are sl�ghtly more precaut�onary than, but generally cons�stent w�th, Ketten’s 1998 pred�ct�on (pers. comm.) that 30% of �nd�v�dual cetaceans exposed to pulses w�th an SEL of 205 dB re: 1 µPa2-s would exper�ence PTS.

For p�nn�peds �n water, there are no emp�r�cal data concern�ng the levels of s�ngle pulses that would lead to TTS-onset. At least for the Cal�forn�a sea l�on, the requ�red exposure �s expected to be greater than 183 dB re: 1 µPa (peak) and 163 dB re: 1 µPa2-s) because F�nneran et al. (2003) found no TTS �n two Cal�forn�a sea l�ons follow�ng such exposures. In the absence of spec�f�c data on the level of a sound pulse that would cause TTS-onset for p�nn�peds �n water, we used a three-step pro-cess to est�mate th�s value:(1) We began w�th the F�nneran et al. (2002b)

data on TTS-onset from s�ngle pulse expo-sures �n a m�d-frequency cetacean. TTS-onset occurred w�th a peak pressure of 224 dB re: 1 µPa (peak) and Mmf-we�ghted SEL of 183 dB re: 1 µPa2-s.

(2) We assumed that the known p�nn�ped-to-cetacean d�fference �n TTS-onset upon exposure to nonpulse sounds would also apply (�n a relat�ve sense) to pulses. Spec�f�cally, w�th nonpulse sounds, harbor seals exper�ence TTS-onset at ca. 12 dB lower RLs than do belugas (�.e., 183 vs 195 dB re: 1 µPa2-s; Kastak et al., 1999,

2005; Southall et al., 2001; Schusterman et al., 2003 vs F�nneran et al., 2000, 2005a; Schlundt et al., 2000; Nacht�gall et al., 2003, 2004). Assum�ng that th�s d�fference for nonpulse sounds ex�sts for pulses as well, TTS-onset �n p�nn�peds exposed to s�ngle underwater pulses �s est�mated to occur at a peak pressure of 212 dB re: 1 µPa (peak) and/or an SEL exposure of 171 dB re: 1 µPa2-s. Each of these metr�cs �s 12 dB less than the comparable value for m�d-frequency cetaceans (see F�nneran et al., 2002b, and above).

(3) As per the “PTS-onset Procedure” (d�scussed earl�er), we added 6 dB to the former (212 dB) value to der�ve the recommended �njury pressure cr�ter�on of 218 dB re: 1 µPa (peak) (unwe�ghted) for p�nn�peds �n water exposed to a s�ngle pulse. S�m�larly, we added 15 dB to the latter value (171 dB) to der�ve the rec-ommended M-we�ghted SEL �njury cr�ter�on of 186 dB re: 1 µPa2-s (Table 3, Cell 10). These proposed cr�ter�a are l�kely precaut�on-ary because the harbor seal �s the most sen-s�t�ve p�nn�ped spec�es tested to date, based on results from a s�ngle �nd�v�dual (Kastak et al., 1999, 2005).

For p�nn�peds �n a�r exposed to a s�ngle sound pulse, the proposed cr�ter�a for �njury were based on measurements by Bowles et al. (unpub. data), wh�ch �nd�cated that TTS-onset �n harbor

Table 3. Proposed �njury cr�ter�a for �nd�v�dual mar�ne mammals exposed to “d�screte” no�se events (e�ther s�ngle or mult�ple exposures w�th�n a 24-h per�od; see Chapter 2)

Sound type

Mar�ne mammal group S�ngle pulses Mult�ple pulses Nonpulses

Low-frequency cetaceans Cell 1 Cell 2 Cell 3Sound pressure level 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat)Sound exposure level 198 dB re: 1 µPa2-s (Mlf) 198 dB re: 1 µPa2-s (Mlf) 215 dB re: 1 µPa2-s (Mlf)

M�d-frequency cetaceans Cell 4 Cell 5 Cell 6Sound pressure level 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat)Sound exposure level 198 dB re: 1 µPa2-s (Mmf) 198 dB re: 1 µPa2-s (Mmf) 215 dB re: 1 µPa2-s (Mmf)

H�gh-frequency cetaceans Cell 7 Cell 8 Cell 9Sound pressure level 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat) 230 dB re: 1 µPa (peak) (flat)Sound exposure level 198 dB re: 1 µPa2-s (Mhf) 198 dB re: 1 µPa2-s (Mhf) 215 dB re: 1 µPa2-s (Mhf)

P�nn�peds (�n water) Cell 10 Cell 11 Cell 12Sound pressure level 218 dB re: 1 µPa (peak) (flat) 218 dB re: 1 µPa (peak) (flat) 218 dB re: 1 µPa (peak) (flat)Sound exposure level 186 dB re: 1 µPa2-s (Mpw) 186 dB re: 1 µPa2-s (Mpw) 203 dB re: 1 µPa2-s (Mpw)

P�nn�peds (�n a�r) Cell 13 Cell 14 Cell 15Sound pressure level 149 dB re: 20 µPa (peak) (flat) 149 dB re: 20 µPa (peak) (flat) 149 dB re: 20 µPa (peak) (flat)Sound exposure level 144 dB re: (20 µPa)2-s (Mpa) 144 dB re: (20 µPa)2-s (Mpa) 144.5 dB re: (20 µPa)2-s (Mpa)

Note: All cr�ter�a �n the “Sound pressure level” l�nes are based on the peak pressure known or assumed to el�c�t TTS-onset, plus 6 dB. Cr�ter�a �n the “Sound exposure level” l�nes are based on the SEL el�c�t�ng TTS-onset plus (1) 15 dB for any type of mar�ne mammal exposed to s�ngle or mult�ple pulses, (2) 20 dB for cetaceans or p�nn�peds �n water exposed to nonpulses, or (3) 13.5 dB for p�nn�peds �n a�r exposed to nonpulses. See text for deta�ls and der�vat�on.

444 Southalletal.

seals occurs follow�ng exposure to 143 dB re: 20 µPa (peak) and 129 dB re: (20 µPa)2-s. As for underwater exposures to nonpulse sounds (Kastak et al., 1999, 2005), h�gher exposure levels were requ�red to �nduce TTS �n Cal�forn�a sea l�ons and northern elephant seals. Consequently, us�ng harbor seal TTS data to establ�sh �njury cr�ter�a for expo-sure to a s�ngle aer�al pulse �n p�nn�peds �s l�kely a precaut�onary approx�mat�on. Based on these est�-mates of peak pressure and SEL assoc�ated w�th TTS-onset, plus 6 dB and 15 dB, respect�vely, to est�mate PTS-onset, the �njury cr�ter�a for p�nn�-peds exposed to a s�ngle aer�al pulse are 149 dB re: 20 µPa (peak) (unwe�ghted) and 144 dB re: (20 µPa)2-s, M-we�ghted (Table 3, Cell 13).

Criteria for Injury from Multiple Pulses

For all mar�ne mammal groups, the recommended cr�ter�a for exposure to mult�ple pulses, expressed �n both SPL and SEL un�ts, were numer�cally �dent�cal to the cr�ter�a for a s�ngle pulse. Any exposure �n a ser�es that exceeds the peak pressure cr�ter�on would be cons�dered potent�ally �njur�-ous. In add�t�on, the cumulat�ve SEL for mult�ple exposures should be calculated us�ng the summa-t�on techn�que descr�bed �n Chapter 1 (Append�x A, eq. 5). The result�ng SEL value for mult�ple pulses �s then compared to the SEL �njury cr�te-r�on for a s�ngle pulse �n the same funct�onal hear-�ng group. As for the s�ngle pulse cr�ter�a, peak pressures are unwe�ghted (�.e., “flat-we�ghted”), but SEL should be we�ghted by the appropr�ate M-we�ght�ng funct�on (F�gure 1).

For cetaceans, the proposed cr�ter�a for �njury by mult�ple pulses are therefore 230 dB re: 1 µPa (peak) and, follow�ng summat�on, 198 dB re: 1 µPa2-s �n terms of SEL (Table 3, Cells 2, 5 & 8). As for s�ngle pulses, th�s approach �s cons�dered precaut�onary for m�d- and low-fre-quency spec�es, but some caut�on �s warranted �n apply�ng �t to h�gh-frequency spec�es (cf. Lucke et al., 2007a).

Follow�ng the same log�c, the proposed �njury pressure cr�ter�on for p�nn�peds �n water exposed to mult�ple pulses �s 218 dB re: 1 µPa (peak) and the �njury SEL cr�ter�on �s 186 dB re: 1 µPa2-s (Table 3, Cell 11). For p�nn�peds �n a�r, the pro-posed �njury pressure cr�ter�on for mult�ple pulses �s 149 dB re: 20 µPa (peak) and the �njury SEL cr�-ter�on �s 144 dB re: (20 µPa)2-s (Table 3, Cell 14).

Criteria for Injury from Nonpulses

SPL and SEL appear to be appropr�ate metr�cs for quant�fy�ng exposure to nonpulse sounds. But because SPL measures �nvolve averag�ng over some durat�on, they may not adequately quant�fy

h�gh peak pressure trans�ents embedded w�th�n exposures of longer durat�on but lower-pressure magn�tude. There are related l�m�tat�ons w�th SEL �n that temporal �ntegrat�on �s �nvolved.

To account for the potent�ally damag�ng aspects of h�gh-pressure trans�ents embedded w�th�n nonpulse exposures, a precaut�onary approach was taken, and the same peak pressure cr�ter�on for �njury proposed for s�ngle pulses �s also rec-ommended as the cr�ter�on for mult�ple pulses �n all funct�onal hear�ng groups. Thus, �f any compo-nent of a nonpulse exposure (unwe�ghted) exceeds the peak pressure cr�ter�on, �njury �s assumed to occur. We expect that only rarely w�ll the �njury pressure cr�ter�on for nonpulse sound be exceeded �f the �njury SEL cr�ter�on �s not exceeded (�.e., the SEL cr�ter�on w�ll be the effect�ve cr�ter�on �n most exposure cond�t�ons).

For nonpulsed sounds, the recommended SEL cr�ter�a for �njury (PTS-onset) are M-we�ghted exposures 20 dB h�gher than those requ�red for TTS-onset (see “PTS-Onset Calculat�on: Nonpulses”). Injury SEL cr�ter�a for mult�ple non-pulses are numer�cally �dent�cal to those for s�ngle nonpulses for all hear�ng groups. We make no d�st�nct�on between s�ngle and mult�ple nonpulses except that the cumulat�ve SEL for mult�ple expo-sures �s calculated as descr�bed �n Chapter 1 and Append�x A, eq. 5.

For all cetaceans exposed to nonpulses, the rec-ommended pressure cr�ter�on for �njury �s 230 dB re: 1 µPa (peak) (Table 3, Cells 3, 6, & 9), the same cr�ter�on as for s�ngle pulses �n these funct�onal hear�ng groups. Injury SEL cr�ter�a are based on TTS data for m�d-frequency spec�es and extrapo-lated to the other cetacean groups (see cetacean procedure, p. 439). The SEL cr�ter�on for non-pulse �njury �n cetaceans �s calculated to be an M-we�ghted exposure of 215 dB re: 1 µPa2-s (Table 3, Cells 3, 6 & 9). Th�s �s based on 195 dB re: 1 µPa2-s as an est�mate of TTS-onset �n m�d-frequency ceta-ceans (F�nneran et al., 2002b, 2005a; Schlundt et al., 2000; Nacht�gall et al., 2003, 2004) plus 20 dB to est�mate PTS-onset. Apply�ng th�s approach to low-frequency cetaceans �s cons�dered pre-caut�onary, but some caut�on may be warranted �n extrapolat�ng to h�gh-frequency cetaceans (cf. s�ngle-pulse data of Lucke et al., 2007a).

We note that spec�al �njury cr�ter�a, d�fferent from those shown �n Cell 6 of Table 3, are l�kely needed for exposure of beaked whale spec�es to nonpulses. Under certa�n cond�t�ons, beaked whales of several spec�es (pr�mar�ly Cuv�er’s, Bla�nv�lle’s, and Gerva�s’ beaked whales) have stranded �n the presence of sound s�gnals from tact�cal m�d-frequency m�l�tary sonars (Frantz�s, 1998; Evans & England, 2001; Fernández et al., 2005; Cox et al., 2006). There have been other


�nc�dents (e.g., NMFS, 2005; Hohn et al., 2006) where mar�ne mammal strand�ngs or other anom-alous events �nvolv�ng other mar�ne mammal spec�es have occurred �n assoc�at�on w�th m�d-frequency sonar operat�ons. They are, how-ever, much more amb�guous, d�ff�cult to �nterpret, and appear fundamentally d�fferent than the spe-c�f�c beaked whale events. L�ttle �s known about the exposure levels, or about the pos�t�ons or reac-t�ons of other mar�ne mammals �n the areas dur�ng m�d-frequency sonar tra�n�ng operat�ons. The most extreme, ult�mate response of some beaked whales �n spec�f�c cond�t�ons (strand�ng and sub-sequent death) does not appear to be typ�cal of other mar�ne mammals.

Sound f�elds result�ng from sonar operat�ons have been modeled �n several of the above cases (e.g., the 1996 event �n Greece and the 2000 event �n the Bahamas), and �t �s poss�ble to at least roughly bound the est�mated exposures for some of the �nd�v�duals that stranded (D’Spa�n et al., 2006). Wh�le the spec�f�c exposure levels w�ll never be quant�tat�vely known, �t does appear l�kely that the exposures for some of the beaked whales that stranded were below the cr�ter�a for t�ssue �njury proposed above.

Consequently, the general �njury cr�ter�a do not seem suff�c�ently precaut�onary for beaked whales exposed to some nonpulse sounds under certa�n cond�t�ons. Emp�r�cal data to support d�screte, sc�ence-based �njury cr�ter�a spec�f�c to beaked whales exposed to tact�cal, m�d-frequency, m�l�-tary sonar are lack�ng, however. Regulatory agen-c�es should cons�der adopt�ng prov�s�onal �njury cr�ter�a for beaked whales exposed to act�ve, m�d-frequency, m�l�tary sonars that are lower (�n terms of RL) than the cr�ter�a used for m�d-frequency cetaceans and nonpulse sources generally. Of foremost �mportance, spec�f�c stud�es are needed to better def�ne the mechan�sm of �njury �n these apparently sens�t�ve spec�es (see Chapter 5).

For p�nn�peds �n water, the recommended pres-sure cr�ter�on for �njury from exposure to nonpulse sounds �s the same value as appl�ed to pulses: an unwe�ghted value of 218 dB re: 1 µPa (peak) (Table 3, Cell 12). To der�ve the assoc�ated SEL cr�ter�on, we began w�th the measured nonpulse exposure el�c�t�ng TTS-onset �n a harbor seal, 183 dB re: 1 µPa2-s (Kastak et al., 1999, 2005). Th�s �s l�kely a precaut�onary cho�ce because SEL values ~10 to 20 dB h�gher were requ�red to �nduce TTS-onset �n a Cal�forn�a sea l�on and a northern ele-phant seal. We assume that 20 dB of add�t�onal no�se exposure w�ll el�c�t PTS-onset (see “Effects of No�se on Hear�ng” sect�on of th�s chapter), result�ng �n an Mpw-we�ghted SEL cr�ter�on of 203 dB re: 1 µPa2-s for p�nn�peds exposed to nonpulse sound �n water (Table 3, Cell 12).

For p�nn�peds �n a�r exposed to nonpulse sound, the �njury pressure cr�ter�on �s a flat-we�ghted value of 149 dB re: 20 µPa (peak) (Table 3, Cell 15), con-s�stent w�th that for pulses. The SEL cr�ter�on �s based on occurrence of TTS-onset �n a harbor seal exposed �n a�r to 131 dB re: (20 µPa)2-s (Kastak et al., 2004a). In est�mat�ng the exposure that would cause PTS-onset, we use emp�r�cal mea-surements of TTS growth as a funct�on of expo-sure SEL �n a Cal�forn�a sea l�on. Kastak et al. (2007) found a TTS growth rate of 2.5 dB TTS/dB no�se based on nearly 200 exposure sequences �nvolv�ng var�able exposure level and durat�on cond�t�ons. Th�s growth rate �mpl�es a 13.5 dB d�f-ference between TTS- and PTS-onset as opposed to the 20 dB value used for mar�ne mammals �n water. When the 13.5 dB f�gure �s added to the TTS-onset value for harbor seals (131 dB re: [20 µPa]2-s), we obta�n a proposed Mpa-we�ghted SEL cr�ter�on of 144.5 dB re: (20 µPa)2-s for p�nn�peds �n a�r (Table 3, Cell 15).

The use for all p�nn�peds of harbor seal TTS data comb�ned w�th the sea l�on growth funct�on would be an exceed�ngly precaut�onary procedure. Th�s PTS-onset est�mate �s cons�derably below the TTS-onset est�mates for both the northern ele-phant seal (163 dB re: [20 µPa]2-s; Kastak et al., 2004a) and the Cal�forn�a sea l�on (159 dB re: [20 µPa]2-s; Kastak et al., 2007). Apply�ng the TTS growth funct�on of 2.5 dB TTS/dB no�se from Kastak et al. (2007) to these TTS-onset est�mates would y�eld PTS-onset values of 172.5 and 176.5 dB re: (20 µPa)2-s for the Cal�forn�a sea l�on and northern elephant seal, respect�vely. As noted �n the “Overv�ew,” where spec�f�c data are ava�lable for the spec�es or genus of concern, �t �s appropr�-ate for cr�ter�a to be based on those data rather than the general�zed cr�ter�a that are recommended for the overall group of mar�ne mammals.

4. Criteria for Behavioral Disturbance

Behav�oral react�ons to acoust�c exposure are generally more var�able, context-dependent, and less pred�ctable than effects of no�se exposure on hear�ng or phys�ology. An�mals detect�ng one k�nd of s�gnal may s�mply or�ent to hear �t, whereas they m�ght pan�c and flee for many hours upon hear�ng a d�fferent sound, potent�ally even one that �s qu�eter, but w�th some part�cular s�gn�f�-cance to the an�mal. The conservat�on of cochlear propert�es across mammals just�f�es jud�c�ous appl�cat�on of aud�tory data from terrestr�al mam-mals where data on mar�ne mammals are m�ss�ng. However, the context-spec�f�c�ty of behav�oral responses �n an�mals generally makes extrapola-t�on of behav�oral data �nappropr�ate. Assess�ng the sever�ty of behav�oral d�sturbance must conse-quently rely more on emp�r�cal stud�es w�th care-fully controlled acoust�c, contextual, and response var�ables than on extrapolat�ons based on shared phylogeny or morphology.

Cons�derable research has been conducted to descr�be the behav�oral responses of mar�ne mammals to var�ous sound sources. Fortunately, at least l�m�ted data are ava�lable on behav�oral responses by each of the f�ve funct�onal mar�ne mammal groups to each sound type cons�dered here. As ev�dent �n the extens�ve l�terature rev�ew summar�zed below and descr�bed �n deta�l �n Append�ces B & C, however, very few stud�es �nvolv�ng suff�c�ent controls and measurements ex�st. In add�t�on, the �nfluence of exper�ence w�th the exper�mental st�mulus or s�m�lar sounds has usually been unknown.

To assess and quant�fy adverse behav�oral effects of no�se exposure, a metr�c for the �mpact such changes m�ght have on cr�t�cal b�olog�cal parameters such as growth, surv�val, and reproduc-t�on �s needed. Behav�oral d�sturbances that affect these v�tal rates have been �dent�f�ed as part�cularly �mportant �n assess�ng the s�gn�f�cance of no�se exposure (NRC, 2005). Unfortunately, as Wartzok et al. (2004) po�nted out, no such metr�c �s cur-rently ava�lable, and �t �s l�kely to take decades of research to prov�de the analyt�cal framework and emp�r�cal results needed to create such a metr�c, �f one �n fact �s ult�mately even v�able.

In humans, a common and useful means of est�-mat�ng behav�oral d�sturbance from no�se expo-sure �s to ask �nd�v�duals to rate or descr�be the degree to wh�ch var�ous sounds are bothersome. Subject�ve percept�on of no�se “annoyance” has

been quant�f�ed (e.g., Schultz, 1978; Angerer et al., 1991) and used to develop dose-response relat�onsh�ps for no�se exposure �n human com-mun�ty no�se appl�cat�ons (see Kryter, 1994, Chapter 10). Pract�cal �ssues (e.g., d�ff�cult�es �n tra�n�ng nonverbal spec�es to prov�de �nterpretable responses and quest�ons about the appl�cab�l-�ty of capt�ve data to free-rang�ng an�mals) have prevented th�s or s�m�lar approaches from be�ng appl�ed to mar�ne mammals. Instead, most efforts have focused on analyses of observable react�ons to known no�se exposure.

For most free-rang�ng mar�ne mammals, behav-�oral responses are often d�ff�cult to observe. Also, prec�se measurements of rece�ved no�se exposure and other relevant var�ables (e.g., movement of source, presence of h�gh-frequency harmon�cs �nd�cat�ng relat�ve prox�m�ty, and pr�or exper�ence of exposed �nd�v�duals) can be d�ff�cult to obta�n. Only a subset of d�sturbance stud�es have est�-mated rece�ved sound levels, and only a very small number have actually measured RLs at the subject. Further, exposures are often compl�cated by mul-t�ple contextual covar�ants such as the presence of vessels and/or humans close to subjects e�ther for observat�on or to deploy playback sources (e.g., Frankel & Clark, 1998). Interpretat�on of the observed results �s h�ghly l�m�ted by uncerta�nty as to what does and does not const�tute a mean-�ngful response. Also, most behav�oral-response stud�es have concentrated on short-term and local-�zed behav�oral changes whose relevance to �nd�-v�dual well-be�ng and f�tness, let alone populat�on parameters, �s l�kely to be low.

A further compl�cat�on �s that observat�ons from laboratory and f�eld sett�ngs cannot be d�rectly equated. Laboratory stud�es are usually prec�se �n quant�fy�ng exposures and responses. The expo-sure cond�t�ons very rarely approx�mate those �n the f�eld, however, and measured behav�or may have l�ttle or no relevance to the ways �n wh�ch unconstra�ned, untra�ned w�ld an�mals respond. Conversely, f�eld measurements may address responses of free-rang�ng mammals to a spec�f�c sound source but often lack adequate controls and prec�s�on �n quant�fy�ng acoust�c exposures and responses. Clearly, there �s a need for a framework to �ntegrate laboratory and f�eld data, desp�te the challenges �n construct�ng that framework.

Another d�ff�cult �ssue concerns the appropr�-ate no�se exposure metr�c for assess�ng behav�oral



react�ons. Most b�oacoust�c�ans recommend report�ng several d�fferent measures of acoust�c exposure, such as SPL and SEL (as �n Blackwell et al., 2004a, 2004b). Of the many stud�es that report source SPL, relat�vely few spec�fy whether RMS, peak, peak-to-peak, or other sound pressure measurements were made. Add�t�onally, relat�vely few papers prov�de suff�c�ent relevant �nforma-t�on about sound transm�ss�on loss �n the study area. A small number of papers report est�mates or d�rect measurements of rece�ved SPL, but very few report SEL. The appropr�ate measure for pred�ct-�ng probab�l�ty of a behav�oral response �s l�kely to vary depend�ng upon the behav�oral context. For example, �f an an�mal �nterprets a sound as �nd�cat-�ng the presence of a predator, a short fa�nt s�gnal may evoke as strong a response as a longer, strong sound. But �f an an�mal �s respond�ng to a context-neutral st�mulus that �s merely annoy�ng, the prob-ab�l�ty of response may well scale w�th durat�on and level of exposure.

It �s d�ff�cult to def�ne the SEL for �nd�v�dual an�mals �n the w�ld exposed to a spec�f�c sound source. Ideally, rece�ved SEL over the an�mal’s full durat�on of exposure would be measured (Madsen et al., 2005a). We expect that the prob-ab�l�ty and sever�ty of some k�nds of response w�ll vary w�th durat�on as well as level of exposure; for those s�tuat�ons, an SEL metr�c may be most appropr�ate. However, the most pract�cal way to look for cons�stent patterns of response as a func-t�on of RL and durat�on, g�ven the current state of sc�ence, �s to evaluate how d�fferent an�mals respond to s�m�lar sound sources used �n s�m�lar contexts. For example, the relat�onsh�p between acoust�c exposure and an�mal responses �s l�kely to be qu�te d�fferent for mammals exposed to sounds from a slow-mov�ng se�sm�c survey vessel operat�ng �n a g�ven hab�tat for many weeks as compared w�th a torpedo transm�tt�ng d�rect�onal h�gh-frequency sonar p�ngs as �t trans�ts an area once at many tens of knots. S�m�larly, an acous-t�c harassment dev�ce placed �n a hab�tat for years �s l�kely to evoke a d�fferent sever�ty of response than would several short pulses at a comparable SPL. Unt�l more controlled stud�es become ava�l-able w�th cal�brated measurements of RLs and amb�ent no�se measurements (�nclud�ng s�gnal-to-no�se rat�o), the best way to pred�ct l�kely effects w�ll be a common-sense approach that assesses ava�lable data from s�tuat�ons s�m�lar to the s�tu-at�on of concern.

Cons�der�ng all of these l�m�tat�ons and the nature of the ava�lable data, as a pract�cal matter, we use SPL as the acoust�c metr�c for the behav-�oral analyses g�ven below. Where necessary and appropr�ate, s�mple assumpt�ons regard�ng trans-m�ss�on loss were appl�ed to pred�ct RLs. Th�s

was done only for stud�es that prov�ded suff�c�ent �nformat�on on source and env�ronmental charac-ter�st�cs. Our approach does not presume that SPL �s necessar�ly the acoust�c metr�c best correlated w�th behav�oral changes (s�gn�f�cant or otherw�se). In part�cular, SPL fa�ls to account for the dura-t�on of exposure whereas th�s �s captured us�ng SEL. SPL �s the metr�c that has most often been measured or est�mated dur�ng d�sturbance stud�es, however. Thus, �t �s currently the best metr�c w�th wh�ch to assess the ava�lable behav�oral response data. Future stud�es should report the full range of standard acoust�c measurements appropr�ate to the sound source �n quest�on and should also �nclude measurements of background no�se levels �n order to assess s�gnal-to-no�se rat�os. These add�t�onal data should eventually clar�fy wh�ch exposure metr�cs best pred�ct d�fferent k�nds of behav�oral responses and wh�ch are most appropr�ate for use �n pol�cy gu�del�nes appl�cable to d�fferent types of no�se exposures.

Beyond the d�scuss�on of wh�ch metr�c �s most appropr�ate to quant�fy the exposure level of a sound, �t �s recogn�zed that many other var�ables affect the nature and extent of responses to a par-t�cular st�mulus. Wartzok et al. (2004) d�scussed �n deta�l the h�ghly var�able response of belugas exposed to s�m�lar sounds �n d�fferent locat�ons—for example, Frost et al. (1984) vs F�nley et al. (1990). In those cases, �t appears that the context (recent exper�ence of the belugas w�th the sound st�mulus, the�r current act�v�ty, and the�r mot�va-t�on to rema�n or leave) was much more s�gn�f�cant �n govern�ng the�r behav�oral responses. S�m�larly, react�ons of bowhead whales to se�sm�c a�rgun sounds depend on whether the whales are feed�ng (R�chardson et al., 1986; M�ller et al., 2005) vs m�grat�ng (R�chardson et al., 1999). React�ons of bowheads and other cetaceans to boats depend on whether the boats are mov�ng or stat�onary, and on the relat�ve movement of the boat and the whale (see R�chardson et al., 1995; Wartzok et al., 2004). In these and some other cases, s�mple metr�cs of exposure (w�thout cons�der�ng context) w�ll not rel�ably pred�ct the type and sever�ty of behav-�oral response(s). Our analyses here, wh�ch use exposure SPL alone, are adm�ttedly rud�mentary and l�m�ted by the fact that—for most spec�es and s�tuat�ons—current data do not support a more soph�st�cated approach.

Another key cons�derat�on �nvolves d�ffer-ent�at�ng br�ef, m�nor, b�olog�cally un�mportant react�ons from profound, susta�ned, and/or b�o-log�cally mean�ngful responses related to growth, surv�val, and reproduct�on. The b�olog�cal rel-evance of a behav�oral response to no�se expo-sure may depend �n part on how long �t pers�sts. Many mammals perform v�tal funct�ons (e.g.,

448 Southalletal.

feed�ng, rest�ng, travel�ng, soc�al�z�ng) on a d�el cycle. Repeated or susta�ned d�srupt�on of these funct�ons �s more l�kely to have a demonstrable effect on v�tal rates than a s�ngle, br�ef d�sturbance ep�sode. The NRC (2005) argued that, although the durat�on of behav�ors l�kely to affect v�tal rates �s bel�eved to be part�cularly s�gn�f�cant, current sc�ent�f�c knowledge �s �nsuff�c�ent to support an analyt�cal treatment of b�olog�cal s�gn�f�cance and ad hoc cr�ter�a are needed �n the �nter�m. Here, substant�ve behav�oral react�ons to no�se expo-sure (such as d�srupt�on of cr�t�cal l�fe funct�ons, d�splacement, or avo�dance of �mportant hab�tat) are cons�dered more l�kely to be s�gn�f�cant �f they last more than one d�el per�od, or recur on subse-quent days. Consequently, a react�on last�ng less than 24 h and not recurr�ng on subsequent days �s not regarded as part�cularly severe unless �t could d�rectly affect surv�val or reproduct�on.

In the absence of an overarch�ng means of quan-t�fy�ng the b�olog�cal s�gn�f�cance of an effect, we had to adopt a more descr�pt�ve method of assess-�ng the range of poss�ble responses and the sever-�ty of behav�oral response. To do th�s, we took two d�fferent approaches. For the unusual case of exposure to a s�ngle pulse, where the exposure �s very br�ef and responses are usually br�ef as well, a procedure for determ�n�ng recommended cr�ter�a �s �dent�f�ed and appl�ed. For all other cond�t�ons, an ord�nal and subject�ve response sever�ty scal-�ng was developed and appl�ed to those data on mar�ne mammal behav�oral responses for wh�ch est�mates of rece�ved SPL were ava�lable. These analyses were l�m�ted to peer-rev�ewed l�terature (publ�shed or �n press) and peer-rev�ewed techn�-cal reports, w�th some except�ons on a case-by-case bas�s.

The sever�ty scale was des�gned to prov�de some analyt�cal bas�s for assess�ng b�olog�cal s�gn�f�cance, but �t had to be rooted �n the k�nds of descr�pt�ons prov�ded �n the ava�lable sc�en-t�f�c l�terature. Our current understand�ng of the �nfluences of contextual var�ables on behav�oral responses �n free-rang�ng mar�ne mammals �s very l�m�ted. The analyses presented here should be cons�dered w�th these caut�ons and caveats �n m�nd. Our goal was to rev�ew the relevant sc�en-t�f�c l�terature, tally behav�oral effects by the type of acoust�c exposure for each category of mar�ne mammal and sound type, and draw what conclu-s�ons were appropr�ate based on the �nformat�on ava�lable.

The general procedures for determ�n�ng behav-�oral response exposure cr�ter�a for a s�ngle pulse, and for conduct�ng the sever�ty analyses of �nd�-v�dual behav�oral responses vs rece�ved SPL, are d�scussed �n the next sect�on. Subsequent sect�ons d�scuss the exposure cr�ter�on levels for s�ngle

pulses and summar�ze the l�terature cons�dered �n the sever�ty scal�ng analyses for mult�ple pulses and nonpulse sources. More deta�led d�scus-s�ons of th�s l�terature are g�ven �n Append�x B for mult�ple pulses and Append�x C for nonpulse sources.

Behavioral Response Data Analysis Procedures: Disturbance Criteria and Severity Scaling

SinglePulseDue to the trans�ent nature of a s�ngle pulse, the most severe behav�oral react�ons w�ll usually be temporary responses, such as startle, rather than prolonged effects, such as mod�f�ed hab�tat ut�l�-zat�on. A trans�ent behav�oral response to a s�ngle pulse �s unl�kely to result �n demonstrable effects on �nd�v�dual growth, surv�val, or reproduct�on. Consequently, for the un�que cond�t�on of a s�ngle pulse, an aud�tory effect �s used as a defacto d�s-turbance cr�ter�on. It �s assumed that s�gn�f�cant behav�oral d�sturbance m�ght occur �f no�se expo-sure �s suff�c�ent to have a measurable trans�ent effect on hear�ng (�.e., TTS-onset). Although TTS �s not a behav�oral effect per se, th�s approach �s used because any comprom�se, even temporar-�ly, to hear�ng funct�ons has the potent�al to affect v�tal rates by �nterfer�ng w�th essent�al commun�-cat�on and/or detect�on capab�l�t�es. Th�s approach �s expected to be precaut�onary because TTS at onset levels �s unl�kely to last a full d�el cycle or to have ser�ous b�olog�cal consequences dur�ng the t�me TTS pers�sts. Because th�s approach �s based on an aud�tory phenomenon, the exposure cr�ter�a can reasonably be developed for ent�re funct�onal hear�ng groups (as �n the �njury cr�ter�a) rather than on a spec�es-by-spec�es bas�s. The extrapo-lat�on procedures used to est�mate TTS-onset for s�ngle pulse exposures for each hear�ng group are descr�bed �n Chapter 3 (see the “Injury from No�se Exposure: PTS-Onset Calculat�on” sect�on).

A dual-cr�ter�on approach (us�ng both SPL [peak] and SEL) was used to determ�ne behav�oral cr�ter�a for a s�ngle pulse exposure. Cons�stent w�th the �njury cr�ter�a, wh�ch also were based on aud�tory fat�gue data, RLs that exceed the cr�ter�on for e�ther metr�c are cons�dered to have greater potent�al to el�c�t a b�olog�cally s�gn�f�cant behav-�oral response. Proposed cr�ter�a for exposure to a s�ngle pulse for each funct�onal hear�ng group are g�ven �n the next sect�on. These cr�ter�a are the TTS-onset thresholds d�scussed �n Chapter 3.

An except�on was made �n any case where behav�oral data �nd�cate that a s�ngle pulse expo-sure may el�c�t a susta�ned and potent�ally s�gn�f�-cant response when the RL �s below that requ�red for TTS-onset. Th�s can apply to hauled-out p�n-n�peds, wh�ch somet�mes stampede from a beach


upon exposure to a son�c boom and may not return for many hours (e.g., Holst et al., 2005a, 2005b). In cases where such behav�oral responses may result �n the �njury or death of pups or other �nd�-v�duals, exposure levels should be cons�dered �n the context of �njury cr�ter�a. Conversely, �f ava�l-able behav�oral data �nd�cate that the response threshold for exposure to a s�ngle pulse �s above the level requ�red for TTS-onset, then the TTS-onset level �s reta�ned as the behav�oral cr�ter�on as a further precaut�onary procedure.

MultiplePulsesandNonpulsesFor all other sound types than s�ngle pulses, we expect that s�gn�f�cant behav�oral effects w�ll occur more commonly at levels below those �nvolved �n temporary or permanent losses of hear�ng sens�-t�v�ty. Th�s argues aga�nst bas�ng threshold cr�ter�a exclus�vely on TTS and �nd�cates the need for a parad�gm to pred�ct the probab�l�ty of s�gn�f�cant behav�oral response as a funct�on of no�se expo-sure. However, because of the extreme degree of group, spec�es, and �nd�v�dual var�ab�l�ty �n behav�oral responses �n var�ous contexts and con-d�t�ons, �t �s less appropr�ate to extrapolate behav-�oral effects as opposed to aud�tory responses. The ava�lable data on mar�ne mammal behav�oral responses to mult�ple pulse and nonpulse sounds are s�mply too var�able and context-spec�f�c to jus-t�fy propos�ng s�ngle d�sturbance cr�ter�a for broad categor�es of taxa and of sounds.

Th�s should not, however, lead to the conclus�on that there are �nsuff�c�ent data to conduct a system-at�c assessment of the l�kel�hood that certa�n sound exposures w�ll �nduce behav�oral effects of var�able ser�ousness �n mar�ne mammals. On the contrary, th�s f�eld has seen many and accelerat�ng str�des �n character�z�ng how certa�n k�nds of sounds can affect mar�ne mammal behav�or. Quant�f�cat�on of the sever�ty or s�gn�f�cance of these effects w�ll cont�nue to be challeng�ng. However, based on the NRC (2005) model descr�bed above �n wh�ch behav�oral react�ons w�th a greater potent�al to affect v�tal rates are of part�cular concern, a s�m-pl�st�c scal�ng parad�gm �n wh�ch to cons�der the ava�lable data appears to prov�de the most just�f�-able way forward at present.

F�rst, we developed an ord�nal rank�ng of behav�oral response sever�ty (see Table 4). The �ntent of th�s scal�ng was to del�neate those behav-�ors that are relat�vely m�nor and/or br�ef (scores 0-3); those w�th h�gher potent�al to affect forag-�ng, reproduct�on, or surv�val (scores 4-6); and those cons�dered l�kely to affect these v�tal rates (scores 7-9). Th�s �s an adm�ttedly s�mpl�st�c way of scal�ng the str�k�ngly complex and poorly understood behav�oral patterns of mar�ne mam-mals �n real-world cond�t�ons. It does prov�de a

rud�mentary framework for assess�ng the relat�ve b�olog�cal �mportance of behav�oral responses and �s l�kely a closer approx�mat�on of real�ty than pre-v�ous step-funct�on thresholds (as d�scussed �n the “H�stor�cal Perspect�ves” sect�on of Chapter 1). Th�s approach emphas�zes that “d�sturbance” �s a graduated, rather than a “yes-or-no,” phenomenon and that some no�se-�nduced changes �n behav�or are more s�gn�f�cant than others. We expect that future stud�es �nvolv�ng mult�var�ate analys�s of mult�ple behav�oral response var�ables, mult�ple measures of acoust�c exposure, and mult�ple con-textual var�ables w�ll prov�de a foundat�on for more soph�st�cated �nterpretat�ons.

Second, we rev�ewed ava�lable research and observat�ons for each of the f�ve mar�ne mammal funct�onal hear�ng groups exposed to e�ther mul-t�ple pulse or nonpulse sounds (�.e., Cells 2, 3, 5, 6, 8, 9, 11, 12, 14 & 15 �n our matr�x of sound type by an�mal group). We cons�dered measure-ments of behav�oral response both �n the f�eld and �n the laboratory accord�ng to the behav�oral sever�ty scale. Stud�es w�th �nsuff�c�ent �nforma-t�on on exposures and/or responses were con-s�dered but not �ncluded �n the sever�ty analys�s. Where �nd�v�dual (and/or groups cons�dered as an “�nd�v�dual”; see below) behav�oral responses and assoc�ated rece�ved sound levels were reported, the observat�ons were ass�gned the appropr�ate behav�oral “score” from Table 4 and the case was �ncluded �n a sever�ty scor�ng table for the relevant matr�x cell. One d�mens�on �n th�s type of table was the behav�oral score (def�ned �n Table 4); the other d�mens�on was the rece�ved SPL w�th�n 10-dB ranges. Where mult�ple responses were reported for the same �nd�v�dual and/or group �n a study (or where �t was poss�ble that th�s had been done—pseudorepl�cat�on), appropr�ate fract�ons of a s�ngle observat�on were ass�gned to relevant cells �n the scor�ng table. As a result, there are frac-t�onal responses for some �nd�v�dual and/or group responses �n the tabular sever�ty-scal�ng forms. For example, a s�ngle behav�oral observat�on for one �nd�v�dual was we�ghted as equ�valent to ten observat�ons for another �nd�v�dual by ass�gn�ng each observat�on (some potent�ally �n d�fferent RL/sever�ty score b�ns) of the second �nd�v�dual a relat�ve we�ght of 0.1.

Many observat�ons of mar�ne mammals �nvolve mult�ple �nd�v�duals because many spec�es occur �n large soc�al groups and are followed as a group. In th�s case, �f one �nd�v�dual responds to a sound, the other group members may respond to the response as opposed to the sound. In such obser-vat�ons, the full group was cons�dered to repre-sent an “�nd�v�dual” (�.e., the group became the un�t of analys�s). As a precaut�onary approach, the most severe response by any �nd�v�dual observed

450 Southalletal.

Table 4. Sever�ty scale for rank�ng observed behav�oral responses of free-rang�ng mar�ne mammals and laboratory subjects to var�ous types of anthropogen�c sound

Response score1

Correspond�ng behav�ors (Free-rang�ng subjects)2

Correspond�ng behav�ors (Laboratory subjects)2

0 - No observable response - No observable response

1 - Br�ef or�entat�on response (�nvest�gat�on/v�sual or�entat�on) - No observable response

2 - Moderate or mult�ple or�entat�on behav�ors- Br�ef or m�nor cessat�on/mod�f�cat�on of vocal behav�or- Br�ef or m�nor change �n resp�rat�on rates

- No observable negat�ve response; may approach sounds as a novel object

3 - Prolonged or�entat�on behav�or- Ind�v�dual alert behav�or- M�nor changes �n locomot�on speed, d�rect�on, and/or d�ve

prof�le but no avo�dance of sound source- Moderate change �n resp�rat�on rate- M�nor cessat�on or mod�f�cat�on of vocal behav�or (durat�on

< durat�on of source operat�on), �nclud�ng the Lombard Effect

- M�nor changes �n response to tra�ned behav�ors (e.g., delay �n stat�on�ng, extended �nter-tr�al �ntervals)

4 - Moderate changes �n locomot�on speed, d�rect�on, and/or d�ve prof�le but no avo�dance of sound source

- Br�ef, m�nor sh�ft �n group d�str�but�on- Moderate cessat�on or mod�f�cat�on of vocal behav�or (durat�on

ª durat�on of source operat�on)

- Moderate changes �n response to tra�ned behav�ors (e.g., reluctance to return to stat�on, long �nter-tr�al �ntervals)

5 - Extens�ve or prolonged changes �n locomot�on speed, d�rect�on, and/or d�ve prof�le but no avo�dance of sound source

- Moderate sh�ft �n group d�str�but�on- Change �n �nter-an�mal d�stance and/or group s�ze (aggregat�on

or separat�on)- Prolonged cessat�on or mod�f�cat�on of vocal behav�or

(durat�on > durat�on of source operat�on)

- Severe and susta�ned changes �n tra�ned behav�ors (e.g., break�ng away from stat�on dur�ng exper�mental sess�ons)

6 - M�nor or moderate �nd�v�dual and/or group avo�dance of sound source

- Br�ef or m�nor separat�on of females and dependent offspr�ng- Aggress�ve behav�or related to no�se exposure (e.g., ta�l/fl�pper

slapp�ng, fluke d�splay, jaw clapp�ng/gnash�ng teeth, abrupt d�rected movement, bubble clouds)

- Extended cessat�on or mod�f�cat�on of vocal behav�or- V�s�ble startle response- Br�ef cessat�on of reproduct�ve behav�or

- Refusal to �n�t�ate tra�ned tasks

7 - Extens�ve or prolonged aggress�ve behav�or- Moderate separat�on of females and dependent offspr�ng- Clear ant�-predator response- Severe and/or susta�ned avo�dance of sound source- Moderate cessat�on of reproduct�ve behav�or

- Avo�dance of exper�mental s�tuat�on or retreat to refuge area (£ durat�on of exper�ment)

- Threaten�ng or attack�ng the sound source

8 - Obv�ous avers�on and/or progress�ve sens�t�zat�on- Prolonged or s�gn�f�cant separat�on of females and dependent

offspr�ng w�th d�srupt�on of acoust�c reun�on mechan�sms- Long-term avo�dance of area (> source operat�on)- Prolonged cessat�on of reproduct�ve behav�or

- Avo�dance of or sens�t�zat�on to exper-�mental s�tuat�on or retreat to refuge area (> durat�on of exper�ment)

9 - Outr�ght pan�c, fl�ght, stampede, attack of conspec�f�cs, or strand�ng events

- Avo�dance behav�or related to predator detect�on

- Total avo�dance of sound exposure area and refusal to perform tra�ned behav�ors for greater than a day

1Ord�nal scores of behav�oral response sever�ty are not necessar�ly equ�valent for free-rang�ng vs laboratory cond�t�ons.2Any s�ngle response results �n the correspond�ng score (�.e., all group members and behav�oral responses need not be observed). If mult�ple responses are observed, the one w�th the h�ghest score �s used for analys�s.


w�th�n a group was used as the rank�ng for the whole group.

A spec�f�c category of behav�oral stud�es was one �n wh�ch mar�ne mammal d�str�but�ons were measured around a sound source dur�ng qu�et and act�ve per�ods. The ava�lable data typ�cally �nvolve compar�sons of the d�str�but�on of an�mals before exposure (“control” or “reference”) vs dur�ng expo-sure (“exper�mental”); the d�fference �n d�str�but�on of the group was the behav�oral response. Us�ng th�s method, and g�ven equ�valent range measure-ments for control and exper�mental observat�ons, “phantom” RLs for mammals detected dur�ng control per�ods (RLs that would have ex�sted �f �n fact the source was act�ve) can be calculated and compared to actual RLs dur�ng exper�mental con-d�t�ons. In th�s way, the percentage of avo�dance responses by �nd�v�duals dur�ng the exposure was then calculated.

For the stud�es used �n th�s analys�s, no�se exposure (�nclud�ng source and RL, frequency, durat�on, duty cycle, and other factors) was e�ther d�rectly reported or was reasonably est�mated us�ng s�mple sound propagat�on models deemed appropr�ate for the sources and operat�onal env�-ronment. Because of the general lack of prec�s�on �n many stud�es and the d�ff�cult�es �n pool�ng the results from d�sparate stud�es here, we pooled �nd�v�dual exposure SPL �nto 10-dB b�ns.

Our analys�s of the ava�lable behav�oral response stud�es presents raw, �nd�v�dual obser-vat�ons of react�ons to mult�ple pulses and non-pulses as a funct�on of exposure RL. The bas�c output of th�s procedure �s a ser�es of tables, one for each comb�nat�on of the f�ve mar�ne mammal funct�onal hear�ng groups and these two sound types (mult�ple pulses and nonpulses). The over-all tally w�th�n each cell represents the number of �nd�v�duals and/or �ndependent group behav�oral responses w�th est�mated and/or measured RL �n the spec�f�ed 10-dB category.

Th�s analys�s �s �ntended to prov�de some foundat�on for judg�ng the degree to wh�ch ava�l-able data suggest the ex�stence of dose-response relat�onsh�ps between no�se exposure and mar�ne mammal behav�or. An example of such a dose-response funct�on �s the Schultz (1978) curve used to pred�ct growth of human annoyance w�th �ncreas�ng no�se level. The reader should note, however, that the substant�al, acknowledged cave-ats and l�m�tat�ons of the current approach, part�c-ularly those related to contextual var�ables other than s�mply exposure level. Any appl�cat�on of the sever�ty analyses g�ven below should carefully cons�der the nature of the ava�lable �nformat�on regard�ng sound source, spec�es, sex/age class, sound-propagat�on env�ronment, and espec�ally the overall context of exposure relat�ve to that

shown �n the stud�es rev�ewed here. The results from pr�or behav�oral stud�es �n wh�ch these var�-ables are fa�rly s�m�lar to those �n the ant�c�pated exposure s�tuat�on w�ll very l�kely be the most rel-evant. Informat�on from those stud�es should be most strongly we�ghted �n assess�ng the l�kel�hood of s�gn�f�cant behav�oral d�sturbance.

Criteria for Behavioral Disturbance: Single Pulse

For all cetaceans exposed to s�ngle pulses, the cr�ter�a were based on the F�nneran et al. (2002b) results for TTS-onset �n a beluga exposed to a s�ngle pulse. The unwe�ghted peak sound pressure values of 224 dB re: 1 µPa (peak) and we�ghted (Mmf) SEL values of 183 dB re: 1 µPa2-s are rec-ommended as “behav�oral” d�sturbance cr�ter�a for m�d-frequency cetaceans (Table 5, Cell 4). By extrapolat�on (see cetacean procedure, Chapter 3, p. 439), the same values were also proposed for low- and h�gh-frequency cetaceans (Table 5, Cells 1 & 7, respect�vely). The only d�fference �n the appl�cat�on of these cr�ter�a to the three ceta-cean groups �s the �nfluence of the respect�ve fre-quency-we�ght�ng funct�ons for SEL cr�ter�a (Mlf and Mhf vs Mmf).

For p�nn�peds exposed to s�ngle pulses �n water, the proposed “behav�oral” d�sturbance cr�ter�a are also the est�mated TTS-onset values. For p�nn�-peds as a whole, these are 212 dB re: 1 µPa (peak) and we�ghted (Mpw) SEL of 171 dB re: 1 µPa2-s (Table 5, Cell 10) as d�scussed �n Chapter 3.

For p�nn�peds �n a�r, the proposed behav�oral cr�ter�a are based on the strong responses (stam-ped�ng behav�or that could �njure some �nd�-v�duals or separate mothers from pups) of some spec�es, espec�ally harbor seals, to son�c booms from a�rcraft and m�ss�le launches �n certa�n cond�t�ons (Berg et al., 2001, 2002; Holst et al., 2005a, 2005b). No responses result�ng �n �njury were observed �n these spec�f�c stud�es, but the behav�oral responses were, �n some cases, among those that would be cons�dered relat�vely severe �n regards to v�tal rates. It was therefore deter-m�ned appropr�ate to use results from these stud-�es rather than TTS-based thresholds for behav-�oral response cr�ter�a. The proposed cr�ter�a are 109 dB re: 20 µPa (peak) and frequency-we�ghted (Mpa) SEL of 100 dB re: (20 µPa)2-s (Table 5, Cell 13). These levels are substant�ally below TTS-onset values. They are also probably qu�te precaut�onary as behav�oral response cr�ter�a for the group as a whole, espec�ally for spec�es other than harbor seals where h�gher exposures were not observed to �nduce strong (or �n some cases any) responses.

452 Southalletal.

Behavioral Response Severity Scaling: Multiple Pulses

Low-FrequencyCetaceans/MultiplePulses(Cell2)Numerous f�eld observat�ons have been made of low-frequency cetaceans react�ng to mult�ple pulses e�ther �nc�dentally dur�ng ongo�ng opera-t�ons or �ntent�onally dur�ng exper�ments. A mod-erate number of spec�es and exper�mental cond�-t�ons have been cons�dered, but the sources have usually been se�sm�c a�rgun arrays. Some of the stud�es focused on m�grat�ng whales seen from f�xed observat�on platforms or �n/near m�gratory corr�dors. Th�s approach m�n�m�zes pseudorepl�-cat�on w�thout the need for �dent�fy�ng �nd�v�duals because �nd�v�duals are unl�kely to pass observers more than once.

Table 6 summar�zes the methods used to obta�n acoust�c measurements and observat�ons of behav-�oral or d�str�but�onal responses (see Append�x B for more deta�ls). As �n most cells, a number of reported observat�ons were not scored or reported here due to lack of some key �nformat�on and, �n some cases, d�ff�cult�es �n account�ng for var�ous

contextual var�ables. A few of these “excluded” stud�es are l�sted at the bottom of Table 6. Table 7 shows the results of the sever�ty scal�ng analy-ses of �nd�v�dual and/or group responses, con-s�der�ng the stud�es deemed to conta�n suff�c�ent data on exposure cond�t�ons and behav�oral responses. For m�grat�ng bowhead whales, the onset of s�gn�f�cant behav�oral d�sturbance from mult�ple pulses occurred at RLs (RMS over pulse durat�on) around 120 dB re: 1 µPa (R�chardson et al., 1999). For all other low-frequency cetaceans (�nclud�ng bowhead whales not engaged �n m�gra-t�on), th�s onset was at RLs around 140 to 160 dB re: 1 µPa (Malme et al., 1983, 1984; R�chardson et al., 1986; Ljungblad et al., 1988; Todd et al., 1996; McCauley et al., 1998, 2000) or perhaps h�gher (M�ller et al., 2005). There �s essent�ally no overlap �n the RLs assoc�ated w�th onset of behav-�oral responses by members of these two groups based on the �nformat�on currently ava�lable.

Mid-FrequencyCetaceans/MultiplePulses(Cell5)A l�m�ted number of behav�oral observat�ons have been made of m�d-frequency cetaceans exposed to

Table 5. Proposed behav�oral response cr�ter�a for �nd�v�dual mar�ne mammals exposed to var�ous sound types; spec�f�c threshold levels are proposed for s�ngle pulses. See the referenced text sect�ons and tables for sever�ty scale analyses of behav�oral responses to mult�ple pulses and nonpulses.

Sound type

Mar�ne mammal group S�ngle pulses Mult�ple pulses Nonpulses

Low-frequency cetaceans Cell 1 Cell 21 Cell 36

Sound pressure level 224 dB re: 1 µPa (peak) (flat) Tables 6 & 7 Tables 14 & 15Sound exposure level 183 dB re: 1 µPa2-s (Mlf) Not appl�cable Not appl�cable

M�d-frequency cetaceans Cell 4 Cell 52 Cell 67

Sound pressure level 224 dB re: 1 µPa (peak) (flat) Tables 8 & 9 Tables 16 & 17Sound exposure level 183 dB re: 1 µPa2-s (Mmf) Not appl�cable Not appl�cable

H�gh-frequency cetaceans Cell 7 Cell 83 Cell 98

Sound pressure level 224 dB re: 1 µPa (peak) (flat) [Tables 18 & 19] Tables 18 & 19Sound exposure level 183 dB re: 1 µPa2-s (Mhf) Not appl�cable Not appl�cable

P�nn�peds (�n water) Cell 10 Cell 114 Cell 129

Sound pressure level 212 dB re: 1 µPa (peak) (flat) Tables 10 & 11 Tables 20 & 21Sound exposure level 171 dB re: 1 µPa2-s (Mpw) Not appl�cable Not appl�cable

P�nn�peds (�n a�r) Cell 13 Cell 145 Cell 1510

Sound pressure level 109 dB re: 20 µPa (peak) (flat) Tables 12 & 13 Tables 22 & 23Sound exposure level 100 dB re: (20 µPa)2-s (Mpa) Not appl�cable Not appl�cable

1 “Low-Frequency Cetaceans/Mult�ple Pulses (Cell 2)” sect�on2 “M�d-Frequency Cetaceans/Mult�ple Pulses (Cell 5)” sect�on3 “H�gh-Frequency Cetaceans/Mult�ple Pulses (Cell 8)” sect�on4 “P�nn�peds �n Water/Mult�ple Pulses (Cell 11)” sect�on5 “P�nn�peds �n A�r/Mult�ple Pulses (Cell 14)” sect�on6 “Low-Frequency Cetaceans/Nonpulses (Cell 3)” sect�on7 “M�d-Frequency Cetaceans/Nonpulses (Cell 6)” sect�on8 “H�gh-Frequency Cetaceans/Nonpulses (Cell 9)” sect�on9 “P�nn�peds �n Water/Nonpulses (Cell 12)” sect�on10 “P�nn�peds �n A�r/Nonpulses (Cell 15)” sect�on


Tabl

e 6.

Sum

mar

y of

beh

av�o

ral

resp

onse

s by

d�f

fere

nt s

pec�

es o

f lo

w-f

requ

ency

cet

acea

ns e

xpos

ed t

o m

ult�p

le p

ulse

s (C

ell

2) b

y ty

pe o

f so

und

sour

ce, a

va�la

ble

acou

st�c

met

r�cs

, de

scr�

pt�o

n of

beh

av�o

ral r

espo

nse

(by

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al a

nd/o

r gr

oup)

, and

a s

umm

ary

of c

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spon

d�ng

sev

er�ty

sco

re(s

); w

here

a�r

gun

arra

y vo

lum

e �s

sta

ted,

th�s

�s th

e to

tal v

olum

e fo

r al

l op

erat

�ng

a�rg

uns

�n th

e ar

ray;

1 L

= 6

1 �n

3 . Sp

ec�f

�c s

ever

�ty s

core

s fo

r ea

ch s

tudy

are

g�v

en �n

Tab

le 7

, and

mor

e de

ta�ls

are

g�v

en �n

App

end�

x B

. Exp

osur

e R

Ls

are

g�ve

n �n

dB

SPL

, w

h�ch

are

RM

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und

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leve

ls (

dB r

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num

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mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

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beha

v�or

al r

espo

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Stud

y �n

clud

ed �n

se

ver�

ty s

cale

Sum

mar

y of

se

ver�

ty s

cale

ana

lys�

s (s

ee T

able

7)

Mal

me

et a

l. (1

983)

1G

ray

wha

les

S�ng

le a

�rgu

n (1

.64

L)

& 2

0-gu

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ay

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RL

mea

sure

-m

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ps; m

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ttern

s du

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and

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Yes

Exp

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Ls

140-

180

dB S

PL; r

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seve

r-�ty

sco

res:

0, 1

, 3, 5

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me

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wha

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ttern

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and

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Yes

Exp

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140-

180

dB S

PL; r

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seve

r-�ty

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res:

0, 1

, 3, 5

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6)3

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head

w

hale

s (f

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ng)

S�ng

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and

30-g

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mea

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mad

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sit

u ne

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area

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Aer

�al o

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; m

ovem

ent a

nd r

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rat�o

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ttern

s du

r�ng

an

d w

�thou

t a�r

guns

Yes

Exp

osur

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140-

180

dB S

PL; r

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seve

r-�ty

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res:

0, 1

& 6

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wha

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(f

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or 1

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20-

gun

arra

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Cal

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mea

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mad

e in

sit

u ne

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area

s of

exp

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Aer

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vat�o

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f �n

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; m

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and

beha

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resp

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s du

r�ng

and

w�th

out a

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Yes

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Ls

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180

dB S

PL; r

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nse

seve

r-�ty

sco

re: 6

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et a

l. (1

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L�m

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to n

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f ex

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�ves

us

ed (

not m

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on o

r ne

ar s

ubje

cts)

V�s

ual o

bser

vat�o

ns o

f w

hale

beh

av�o

r be

fore

and

dur

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use

of e

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sY

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s 15

0-16

0 dB

SPL

; res

pons

e se

ver-

�ty s

core

: 3

McC

aule

y

et a

l. (1

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6H

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wha

les

(m�g

rat�n

g)

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le a

�rgu

n (0

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L)

and

seve

ral

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Cal

�bra

ted

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mea

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sit

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area

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nd b

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base

d ob

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ns o

f �n

d�-

v�du

als/

grou

ps; m

ovem

ent a

nd b

ehav

�ora

l pa

ttern

s du

r�ng

and

w�th

out a

�rgu

ns

Yes

Exp

osur

e R

Ls

150-

170

dB S

PL; r

espo

nse

seve

r-�ty

sco

res:

6 &

7R

�cha

rdso

n

et a

l. (1

999)

7B

owhe

ad

wha

les

(m�g

rat�n

g)

A�r

gun

arra

y (6

to

16 g

uns;

9 to

25

L)

Cal

�bra

ted

RL

mea

sure

-m

ents

mad

e in

sit

u ne

ar

area

s of

exp

osur

e

Aer

�al s

urve

ys o

f d�

str�

but�o

n of

�nd�

v�du

-al

s/gr

oups

Yes

Exp

osur

e R

Ls

110-

140

dB S

PL; r

espo

nse

seve

r-�ty

sco

res:

0, 1

, 5 &

6M

cCau

ley

et

al.

(200

0)8

Hum

pbac

k w

hale

s (s

oc�a

l�z�n

g)

S�ng

le a

�rgu

n

(0.3

3 L

)C

al�b

rate

d R

L m

easu

re-

men

ts m

ade

ins

itu

near

ar

eas

of e

xpos

ure

Boa

t-ba

sed

obse

rvat

�ons

of

�nd�

v�du

als/

grou

ps; m

ovem

ent a

nd b

ehav

�ora

l pat

tern

s du

r�ng

and

w�th

out a

�rgu

ns

Yes

Exp

osur

e R

Ls

140-

180

dB S

PL; r

espo

nse

seve

r-�ty

sco

re: 6

M�ll

er e

t al.

(200

5)9

Bow

head

w

hale

s

(fee

d�ng

)

A�r

gun

arra

y (2

4 gu

ns; 3

6.9

L)

Cal

�bra

ted

RL

mea

sure

-m

ents

mad

e in

sit

u ne

ar

area

s of

exp

osur

e

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

s;

aer�

al s

urve

ys o

f d�

str�

but�o

n; m

ovem

ent/

d�v�

ng p

atte

rns

and

beha

v�or

al r

espo

nses

du

r�ng

and

w�th

out a

�rgu

ns

Yes

Exp

osur

e R

Ls

140-

180

dB S

PL; r

espo

nse

seve

r-�ty

sco

res:

0 &

6

Ree

ves

et a

l. (1

984)

Not

�ncl

uded

Bow

head

w

hale

s (m

�gra

t�ng)

Se�s

m�c

a�r

gun

arra

yIn

suff

�c�e

nt d

ata

for

th�s

an

alys

�sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Mal

me

et a

l. (1

985)

Not

�ncl

uded

Hum

pbac

k w

hale

sSe

�sm

�c a

�rgu

n ar

ray

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Mal

me

et a

l. (1

986,

198

8)N

ot �n

clud

edG

ray

wha

les

S�ng

le a

�rgu

n an

d a�

rgun

arr

ayIn

suff

�c�e

nt d

ata

for

th�s

an

alys

�sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Kos

k� &

Jo

hnso

n (1

987)

Not

�ncl

uded

Bow

head

w

hale

s (m

�gra

t�ng)

Se�s

m�c

a�r

gun

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

454 Southalletal.

mult�ple pulses. F�eld observat�ons have �nvolved sperm whales and a few other odontocete spe-c�es exposed to se�sm�c a�rguns and explos�ves. Laboratory �nvest�gat�ons have cons�dered behav-�oral responses to var�ous k�nds of mult�ple pulse sources. Aga�n, some observat�ons were excluded due to lack of relevant �nformat�on. Four stud�es of �nd�v�dual m�d-frequency cetacean responses to mult�ple pulse exposures conta�ned suff�c�ent acoust�c and behav�oral �nformat�on for �nclus�on �n th�s analys�s. These �nclude f�eld observat�ons of free-rang�ng sperm whales and belugas stud�ed by Madsen & Møhl (2000), Madsen et al. (2002), and M�ller et al. (2005), as well as laboratory observa-t�ons of capt�ve false k�ller whales by Akamatsu et al. (1993). The �nformat�on from these stud�es �s summar�zed �n Table 8 and d�scussed �n deta�l �n Append�x B; the compan�on sever�ty scal�ng analys�s �s shown �n Table 9.

The comb�ned data for m�d-frequency ceta-ceans exposed to mult�ple pulses do not �nd�cate a clear tendency for �ncreas�ng probab�l�ty and sever�ty of response w�th �ncreas�ng RL. In cer-ta�n cond�t�ons, mult�ple pulses at relat�vely low RLs (~80 to 90 dB re: 1 µPa) temporar�ly s�lence �nd�v�dual vocal behav�or for one spec�es (sperm whales). In other cases w�th sl�ghtly d�fferent st�mul�, RLs �n the 120 to 180 dB re: 1 µPa range fa�led to el�c�t observable react�on from a s�gn�f�-cant percentage of �nd�v�duals e�ther �n the f�eld or �n the laboratory.

High-FrequencyCetaceans/MultiplePulses(Cell8)Based on our source type d�st�nct�on (see Chapter 2), v�rtually all sources of trans�ent sound used �n quant�tat�ve behav�oral stud�es of h�gh-frequency cetaceans—for example, acoust�c harassment dev�ces (AHDs) and acoust�c deterrent dev�ces (ADDs)—would be character�zed as nonpulse sounds. Wh�le �nd�v�dual elements produced by some of these sources could be character�zed as pulses, and sequences of them as mult�ple pulses, they are generally em�tted �n such rap�d fash�on that some mammal�an aud�tory systems l�kely perce�ve them as nonpulses. Further, some AHDs and ADDs, and most other sources used �n behav-�oral stud�es w�th h�gh-frequency cetaceans, lack the character�st�cs of pulses such as extremely fast r�se-t�me, correspond�ngly broad frequency band-w�dth, and h�gh kurtos�s. Due to uncerta�nty over the extent to wh�ch some of these s�gnals may be perce�ved and the overarch�ng pauc�ty of data, �t �s not poss�ble to present any data on behav�oral responses of h�gh-frequency cetaceans as a func-t�on of rece�ved levels of mult�ple pulses. Ava�lable data for nonpulse sounds are cons�dered below (see the “H�gh-Frequency Cetaceans/Nonpulses [Cell 9]” sect�on). We note the need for emp�r�cal behav�oral research �n these an�mals us�ng sound sources (such as a�rgun or p�le-dr�v�ng st�mul�) unequ�vocally class�f�ed as mult�ple pulses (see Chapter 5).

Table 7. Number (�n bold) of low-frequency cetaceans (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to mult�ple pulse no�se; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “Low-Frequency Cetaceans/Mult�ple Pulses (Cell 2)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 6.

Rece�ved RMS sound pressure level (dB re: 1 µPa)

Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

987 1.0

(6)

6 9.5 (7)

47.4 (7)

2.2 (7)

3.4 (4, 6, 8)

5.8 (1, 2, 3, 6)

4.5 (1, 2, 3, 4, 6)

8.3 (1, 2, 4, 8, 9)

5 1.0 (7)

1.0 (4)

1.0 (1, 2)

43 1.0

(1, 2)1.0 (1, 2)

21 5.0

(7)6.0

(7)1.0

(7)2.5

(1, 2, 3)3.0

(5)

0 59.8 (7)

17.7 (7)

1.1 (7, 9)

0.1 (9)

0.6 (3, 9)

6.8 (1, 2, 3, 9)

6.3 (1, 2, 9)


Tabl

e 8.

Sum

mar

y of

beh

av�o

ral

resp

onse

s by

d�f

fere

nt s

pec�

es o

f m

�d-f

requ

ency

cet

acea

ns e

xpos

ed t

o m

ult�p

le p

ulse

s (C

ell

5) b

y ty

pe o

f so

und

sour

ce, a

va�la

ble

acou

st�c

met

r�cs

, de

scr�

pt�o

n of

beh

av�o

ral r

espo

nse

(by

�nd�

v�du

al a

nd/o

r gro

up),

and

a s

umm

ary

of c

orre

spon

d�ng

sev

er�ty

sco

re(s

); s

pec�

f�c

seve

r�ty

sco

res

for e

ach

stud

y ar

e g�

ven

�n T

able

9 a

nd m

ore

deta

�ls a

re g

�ven

�n A

ppen

d�x

B. E

xpos

ure

RL

s ar

e g�

ven

�n d

B S

PL, w

h�ch

are

RM

S so

und

pres

sure

leve

ls (

dB r

e: 1

mPa

) ov

er th

e du

rat�o

n of

a p

ulse

.

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

9)Su

bjec

t sp

ec�e

sSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

9)

Mad

sen

&

Møh

l (20

00)

1Sp

erm

wha

les

Smal

l exp

los�

ves

(s

ever

al p

er d

ay)

Cal

�bra

ted

RL

mea

sure

-m

ents

mad

e in

sit

u ne

ar

area

s of

exp

osur

e

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

du-

als,

�ncl

ud�n

g v�

sual

det

ect�o

n an

d pa

ss�v

e ac

oust

�c m

on�to

r�ng

of

voca

l�zat

�ons

Yes

Exp

osur

e R

Ls

170-

180

dB S

PL; r

espo

nse

seve

r�ty

sco

re: 0

M

adse

n et

al.

(200

2)2

Sper

m w

hale

sA

�rgu

n ar

ray

(d�s

tant

)C

al�b

rate

d R

L m

easu

re-

men

ts m

ade

ins

itu

near

ar

eas

of e

xpos

ure

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

du-

als,

�ncl

ud�n

g v�

sual

det

ect�o

n an

d pa

ss�v

e ac

oust

�c m

on�to

r�ng

of

voca

l�zat

�ons

Yes

Exp

osur

e R

Ls

120-

140

dB S

PL; r

espo

nse

seve

r�ty

sco

re: 0

M�ll

er e

t al.

(200

5)3

Bel

uga

A�r

gun

arra

y (2

4 gu

ns;

36.9

L)

Cal

�bra

ted

RL

mea

sure

-m

ents

mad

e in

sit

u ne

ar

area

s of

exp

osur

e

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

s;

aer�

al s

urve

ys o

f d�

str�

but�o

n; m

ovem

ent/

d�v�

ng p

atte

rns

and

beha

v�or

al r

espo

nses

du

r�ng

and

w�th

out a

�rgu

ns

Yes

Exp

osur

e R

Ls

100-

150

dB S

PL; r

espo

nse

seve

r�ty

sco

res:

0 &

6

Aka

mat

su

et a

l. (1

993)

4Fa

lse

k�lle

r w

hale

s

(cap

t�ve)

Num

erou

s so

unds

, �n

clud

�ng

puls

e se

quen

ces

Cal

�bra

ted

RL

mea

sure

-m

ents

mad

e in

sit

u w

�th�n

ex

per�

men

tal e

nclo

sure

V�s

ual o

bser

vat�o

ns o

f be

hav�

oral

res

pons

es

w�th

�n e

xper

�men

tal c

onte

xt �n

labo

rato

ry

cond

�t�on

s

Yes

Exp

osur

e R

Ls

170-

180

dB S

PL; r

espo

nse

seve

r�ty

sco

res:

0 &

6A

ndré

et a

l. (1

997)

Not

�ncl

uded

Sper

m w

hale

sN

atur

al a

nd a

rt�f

�c�a

l pu

lses

(re

peat

ed)

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

s;

d�v�

ng p

atte

rns

and

voca

l beh

av�o

rN

oN

/A

Ston

e (2

003)

Not

�ncl

uded

Seve

ral m

�d-

freq

. cet

acea

n sp

ec�e

s

Se�s

m�c

a�r

gun

arra

ys

(var

�ous

)In

suff

�c�e

nt d

ata

for

th�s

an

alys

�sV

esse

l-ba

sed

obse

rvat

�ons

of

�nd�

v�du

als;

s�

ght�n

gs d

ata

and

avo�

danc

e be

hav�

orN

oN

/A

456 Southalletal.

PinnipedsinWater/MultiplePulses(Cell11)Informat�on on behav�oral react�ons of p�nn�peds �n water to mult�ple pulses �nvolves exposures to small explos�ves used �n f�sher�es �nteract�ons, �mpact p�le dr�v�ng, and se�sm�c surveys. Several stud�es lacked matched data on acoust�c expo-sures and behav�oral responses by �nd�v�duals. As a result, the quant�tat�ve �nformat�on on react�ons of p�nn�peds �n water to mult�ple pulses �s very l�m�ted (see Table 10). The sever�ty scal�ng analy-s�s for �nd�v�dual behav�oral responses for Cell 11 �s g�ven �n Table 11.

Our general f�nd�ng �s that, based on the l�m�ted data on p�nn�peds �n water exposed to mult�ple pulses, exposures �n the ~150 to 180 dB re: 1 µPa range (RMS values over the pulse durat�on) gen-erally have l�m�ted potent�al to �nduce avo�dance behav�or �n p�nn�peds. RLs exceed�ng 190 dB re: 1 µPa are l�kely to el�c�t responses, at least �n some r�nged seals (Harr�s et al., 2001; Blackwell et al., 2004b; M�ller et al., 2005). Note that the SEL assoc�ated w�th a s�ngle 190 dB re: 1 µPa (RMS) pulse from an a�rgun �s typ�cally ca. 175 dB re: 1 µPa2-s. That exceeds the est�mated TTS threshold for the closely related harbor seal (171 dB re: 1 µPa2-s; see Chapter 3). Thus, �n the case of r�nged seals exposed to sequences of a�rgun pulses from an approach�ng se�sm�c vessel, most an�mals may show l�ttle avo�dance unless the RL �s h�gh enough for m�ld TTS to be l�kely.

PinnipedsinAir/MultiplePulses(Cell14)How mult�ple pulses produced �n a�r affect p�nn�-peds was among the least well-documented of the cond�t�ons we cons�dered. Most of the ava�lable

data on responses to pulses were from s�ngle pulse events (e.g., rocket launches) over populat�ons of p�nn�peds exposed to such s�gnals repeatedly (e.g., Thorson et al., 1998, 1999, 2000a, 2000b; Berg et al., 2001, 2002, 2004). These events do not occur frequently enough for the exposures to be cons�d-ered mult�ple pulses, and many of them conta�ned nonpulse as well as pulse exposures. They are d�scussed �n some deta�l �n Append�x B (as well as �n Append�x C when nonpulses are �nvolved). Append�x B also d�scusses several other stud�es potent�ally relevant to Cell 14 but ult�mately not used �n th�s analys�s. Consequently, the quant�ta-t�ve �nformat�on analyzed for react�ons of p�nn�-peds �n a�r exposed to mult�ple pulses (see Tables 12 & 13) focused on the aer�al data by Blackwell et al. (2004b). These extremely l�m�ted data sug-gest very m�nor, �f any, observable behav�oral responses by p�nn�peds exposed to a�rborne pulses w�th RLs 60 to 80 dB re: 20 µPa.

Behavioral Response Severity Scaling: Nonpulses

Low-FrequencyCetaceans/Nonpulses(Cell3)Wh�le there are clearly major areas of uncerta�nty rema�n�ng, there has been relat�vely extens�ve behav�oral observat�on of low-frequency ceta-ceans exposed to nonpulse sources. As summa-r�zed �n Table 14 (and d�scussed �n greater deta�l �n Append�x C), these f�eld observat�ons �nvolve the major�ty of low-frequency cetacean spec�es exposed to a w�de range of �ndustr�al, act�ve sonar, and tomograph�c research act�ve sources (Baker et al., 1982; Malme et al., 1983, 1984, 1986;

Table 9. Number (�n bold) of m�d-frequency cetaceans (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to mult�ple pulse no�se; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “M�d-Frequency Cetaceans/Mult�ple Pulses (Cell 5)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 8.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200+

9876 0.17

(3)0.17

(3)0.17

(3)1.3

(4)

543210 0.25

(3)0.25

(3)3.0

(2)4.0

(2)6.7 (1, 4)


Tabl

e 10

. Su

mm

ary

of b

ehav

�ora

l re

spon

ses

by d

�ffe

rent

spe

c�es

of

p�nn

�ped

s �n

wat

er e

xpos

ed t

o m

ult�p

le p

ulse

s (C

ell

11)

by t

ype

of s

ound

sou

rce,

ava

�labl

e ac

oust

�c m

etr�

cs,

desc

r�pt

�on

of b

ehav

�ora

l res

pons

e (b

y �n

d�v�

dual

and

/or

grou

p), a

nd a

sum

mar

y of

cor

resp

ond�

ng s

ever

�ty s

core

(s);

spe

c�f�

c se

ver�

ty s

core

s fo

r ea

ch s

tudy

are

g�v

en �n

Tab

le 1

1 an

d m

ore

deta

�ls a

re g

�ven

�n A

ppen

d�x

B. E

xpos

ure

RL

s ar

e g�

ven

�n d

B S

PL, w

h�ch

are

RM

S so

und

pres

sure

leve

ls (

dB r

e: 1

mPa

) ov

er th

e du

rat�o

n of

a p

ulse

.

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

11)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

grou

p be

hav�

oral

res

pons

es

Stud

y �n

clud

ed �n

se

ver�

ty s

cale

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

11)

Har

r�s

et a

l. (2

001)

1R

�nge

d (m

a�nl

y),

bear

ded,

and

sp

otte

d se

als

S�ng

le a

�rgu

n an

d 11

-gun

, 21.

6-L

arr

ayR

Ls

mea

sure

d in

sit

u ne

ar �n

d�v�

dual

s ob

serv

ed

�n d

ef�n

ed s

pat�a

l zon

es

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

s w

�th�n

spe

c�f�

ed

zone

s ov

er a

l�m

�ted

rang

e

Yes

Exp

osur

e R

Ls

160-

200

dB S

PL; r

espo

nse

seve

r�ty

sco

res:

0 &

6B

lack

wel

l et a

l. (2

004b

)2

R�n

ged

seal

sP�

pe-d

r�v�

ng s

ound

s (c

onst

ruct

�on)

RL

s m

easu

red

ins

itu

near

�nd�

v�du

als

obse

rved

(d

eta�

led

mea

sure

men

ts,

�ncl

ud�n

g pe

ak p

ress

ure,

R

MS,

SE

L, a

nd d

urat

�on)

Lan

d-ba

sed

obse

rvat

�ons

of

�nd�

v�du

als;

mov

emen

t and

re

spon

se p

atte

rns

dur�

ng p

�pe-

dr�v

�ng

(not

e th

at c

onst

ruct

�on

act�v

�t�es

had

bee

n un

derw

ay

for

a co

ns�d

erab

le p

er�o

d be

fore

obs

erva

t�ons

)

Yes

Exp

osur

e R

Ls

150-

160

dB S

PL; r

espo

nse

seve

r�ty

sco

res:

0 &

1

M�ll

er e

t al.

(200

5)3

R�n

ged

and

bear

ded

seal

sA

�rgu

n ar

ray

(24

a�rg

uns;

36.

9 L

)C

al�b

rate

d R

L m

easu

re-

men

ts m

ade

ins

itu

near

ar

eas

of e

xpos

ure

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

s; m

ovem

ent p

at-

tern

s an

d be

hav�

oral

res

pons

es

dur�

ng a

nd w

�thou

t a�r

guns

Yes

Exp

osur

e R

Ls

170-

200

dB S

PL; r

espo

nse

seve

r�ty

sco

re: 0

Shau

ghne

ssy

et

al.

(198

1)N

ot �n

clud

edC

al�f

orn�

a se

a l�o

nsSe

al b

ombs

(sm

all

expl

os�v

es)

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

V�s

ual o

bser

vat�o

ns o

f �n

d�-

v�du

al r

espo

nses

ove

r m

ult�p

le

expo

sure

s

No

N/A

Mat

e &

Har

vey

(198

7)N

ot �n

clud

edC

al�f

orn�

a se

a l�o

nsSe

al b

ombs

(sm

all

expl

os�v

es)

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

V�s

ual o

bser

vat�o

ns o

f �n

d�-

v�du

al r

espo

nses

ove

r m

ult�p

le

expo

sure

s

No

N/A

Mou

lton

et a

l. (2

003,

200

5)N

ot �n

clud

edR

�nge

d se

als

Cal

�bra

ted

mea

sure

men

ts

mad

e �n

the

area

of

expo

sure

Com

pl�c

ated

by

s�m

ulta

neou

s ex

posu

re to

pul

se a

nd n

onpu

lse

sour

ces

No

N/A

458 Southalletal.

R�chardson et al., 1990b; McCauley et al., 1996; B�asson� et al., 2000; Croll et al., 2001; Palka & Hammond, 2001; Nowacek et al., 2004).

The comb�ned �nformat�on generally �nd�cates no (or very l�m�ted) responses at RLs 90 to 120 dB re: 1 µPa and an �ncreas�ng probab�l�ty of avo�dance and other behav�oral effects �n the 120 to 160 dB re: 1 µPa range (sever�ty scal�ng: Table 15). However, these data also �nd�cated cons�d-erable var�ab�l�ty �n RLs assoc�ated w�th behav-�oral responses. Contextual var�ables (e.g., source prox�m�ty, novelty, operat�onal features) appear to have been at least as �mportant as exposure level �n pred�ct�ng response type and magn�tude.

Mid-FrequencyCetaceans/Nonpulses(Cell6)A relat�vely large number of m�d-frequency cetaceans have been observed �n the f�eld and �n the laboratory respond�ng to nonpulse sounds, �nclud�ng vessels and watercraft (LGL & Greener�dge, 1986; Gordon et al., 1992; Palka & Hammond, 2001; Buckstaff, 2004; Mor�saka et al., 2005), pulsed p�ngers and AHDs/ADDs (Watk�ns & Schev�ll, 1975; Morton & Symonds, 2002; Monte�ro-Neto et al., 2004), �ndus-tr�al act�v�t�es (Awbrey & Stewart, 1983; R�chardson et al., 1990b), m�d-frequency act�ve sonar (NRL, 2004a, 2004b; NMFS, 2005), and tones or bands of no�se �n laboratory cond�t�ons (Nacht�gall et al., 2003; F�nneran & Schlundt, 2004). Summary �nfor-mat�on on these stud�es �s g�ven �n Table 16; deta�led descr�pt�ons are g�ven �n Append�x C. As �n other cond�t�ons, a number of potent�ally relevant f�eld stud�es are not �ncluded �n the sever�ty scal�ng anal-ys�s due to lack of suff�c�ently deta�led �nformat�on.

An add�t�onal challenge �n �nterpret�ng many of the f�eld data for th�s cond�t�on �s �solat�ng the effect of RL from the effects of mere source presence (as poss�bly �nd�cated by v�sual st�mul� or other aspects of acoust�c exposure such as the presence of h�gh-frequency components) and other contextual var�ables. For th�s reason, several stud�es were cons�dered but not �ntegrated �nto the analys�s. The laboratory observat�ons are of cap-t�ve cetaceans exposed to prec�sely controlled and known no�se exposures �n the context of hear�ng and TTS exper�ments. However, the relevance of behav�oral react�ons of tra�ned, food-re�nforced capt�ve an�mals exposed to no�se to the react�ons of free-rang�ng mar�ne mammals �s debatable. Th�s �s d�scussed �n greater deta�l �n Append�x C.

The comb�ned f�eld and laboratory data for m�d-frequency cetaceans exposed to nonpulse sounds do not lead to a clear conclus�on about RLs co�nc�-dent w�th var�ous behav�oral responses (see sever-�ty scal�ng, Table 17). In some sett�ngs, �nd�v�duals �n the f�eld showed behav�oral responses w�th h�gh sever�ty scores to exposures from 90 to 120 dB re: 1 µPa, wh�le others fa�led to exh�b�t such responses for exposure RLs from 120 to 150 dB re: 1 µPa. Contextual var�ables other than exposure RL, and probable spec�es d�fferences, are the l�kely rea-sons for th�s var�ab�l�ty �n response. Context may also expla�n why there �s great d�spar�ty �n results from f�eld and laboratory cond�t�ons—exposures �n capt�ve sett�ngs generally exceeded 170 dB re: 1 µPa before �nduc�ng behav�oral responses.

Table 11. Number (�n bold) of p�nn�peds �n water (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to mult�ple pulse no�se. Responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score; a summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “P�nn�peds �n Water/Mult�ple Pulses (Cell 11)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 10.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

9876 1.7

(1)2.1

(1)45.4

(1)

54321 0.3

(2)

0 0.7 (2)

5.3 (1)

30.3 (1, 3)

0.3 (3)

9.9 (1, 3)


Tabl

e 12

. Sum

mar

y of

beh

av�o

ral r

espo

nses

by

d�ff

eren

t spe

c�es

of p

�nn�

peds

�n a

�r e

xpos

ed to

mul

t�ple

pul

ses

(Cel

l 14)

by

type

of s

ound

sou

rce,

ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�pt�o

n of

beh

av�o

ral r

espo

nse

(by

�nd�

v�du

al a

nd/o

r gr

oup)

, and

a s

umm

ary

of c

orre

spon

d�ng

sev

er�ty

sco

re(s

); s

pec�

f�c

seve

r�ty

sco

res

for

each

stu

dy a

re g

�ven

�n T

able

13

and

mor

e de

ta�ls

ar

e g�

ven

�n A

ppen

d�x

B. E

xpos

ure

RL

s ar

e g�

ven

�n d

B S

PL, w

h�ch

are

RM

S so

und

pres

sure

leve

ls (

dB r

e: 2

0 mP

a) o

ver

the

dura

t�on

of a

pul

se.

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

13)

Subj

ect

spec

�es

Soun

d so

urce

Type

of

acou

st�c

m

easu

rem

ents

Type

of

�nd�

v�du

al a

nd/o

r

grou

p be

hav�

oral

res

pons

es

Stud

y �n

clud

ed �n

se

ver�

ty s

cale

Sum

mar

y of

se

ver�

ty s

cale

ana

lys�

s (s

ee T

able

13)

Bla

ckw

ell

et a

l. (2

004b

)

1R

�nge

d se

als

P�pe

-dr�

v�ng

sou

nds

(con

stru

ct�o

n)R

Ls

mea

sure

d in

sit

u ne

ar

�nd�

v�du

als

obse

rved

(de

ta�le

d m

easu

rem

ents

, �nc

lud�

ng

peak

pre

ssur

e, R

MS,

SE

L,

and

dura

t�on)

Lan

d-ba

sed

obse

rvat

�ons

of

�nd�

-v�

dual

s; m

ovem

ent a

nd r

espo

nse

patte

rns

dur�

ng p

�pe-

dr�v

�ng

(not

e th

at c

onst

ruct

�on

act�v

�t�es

had

bee

n un

derw

ay f

or a

con

s�de

rabl

e pe

r�od

be

fore

obs

erva

t�ons

)

Yes

Exp

osur

e R

Ls

60-8

0 dB

SPL

re: 2

0 µP

a;

resp

onse

sev

er�ty

sc

ores

: 0 &

1

Perr

y et

al.

(200

2)N

ot �n

clud

edH

arbo

r an

d gr

ay s

eals

Rep

eate

d so

n�c

boom

sM

easu

red

soun

d ov

erpr

essu

re

leve

ls o

n br

eed�

ng b

each

es,

but n

ot R

Ls

at p

os�t�

ons

of

expo

sed

an�m

als

Lan

d-ba

sed

obse

rvat

�ons

of

an�m

al

pres

ence

, beh

av�o

r, an

d he

art r

ate

(not

e lo

ng h

�sto

ry o

f so

n�c

boom

s �n

the

area

)

No

N/A

460 Southalletal.

High-FrequencyCetaceans/Nonpulses(Cell9)Numerous controlled stud�es have been conducted on the behav�oral react�ons of h�gh-frequency cetaceans to var�ous nonpulse sound sources both �n the f�eld (Cul�k et al., 2001; Oles�uk et al., 2002; Johnston, 2002) and �n labora-tory sett�ngs (Kastele�n et al., 1997, 2000, 2005, 2006a). However, only one h�gh-frequency spe-c�es (harbor porpo�se) has been extens�vely stud�ed and that spec�es prov�ded all the ava�l-able data on behav�oral response magn�tude vs rece�ved exposure cond�t�ons. The or�g�nal stud-�es were attempts to reduce harbor porpo�se by-catch by attach�ng warn�ng p�ngers to f�sh�ng gear. More recent stud�es cons�der whether AHDs and ADDs also exclude harbor porpo�ses from cr�t�-cal hab�tat areas, and whether these dev�ces affect harbor porpo�se behav�or �n controlled laboratory cond�t�ons.

The comb�ned w�ld and capt�ve an�mal data (summar�zed �n Table 18 and d�scussed �n deta�l �n Append�x C) clearly support the observat�on that harbor porpo�ses are qu�te sens�t�ve to a w�de range of human sounds at very low exposure RLs (~90 to 120 dB re: 1 µPa), at least for �n�t�al exposures. Th�s observat�on �s also ev�dent �n the sever�ty scal�ng analys�s for Cell 9 (Table 19). All recorded expo-sures exceed�ng 140 dB re: 1 µPa �nduced profound and susta�ned avo�dance behav�or �n w�ld harbor porpo�ses. Whether th�s apparently h�gh degree of behav�oral sens�t�v�ty to anthropogen�c acoust�c sources extends to other h�gh-frequency cetacean spec�es (or nonpulse sources other than AHDs and ADDs) �s unknown. G�ven the lack of �nforma-t�on to the contrary, however, such a relat�onsh�p should be assumed as a precaut�onary measure.

Hab�tuat�on to sound exposure was noted �n some but not all stud�es. Strong �n�t�al react�ons of h�gh-frequency cetaceans at relat�vely low levels may �n some cond�t�ons wane w�th repeated exposure and subject exper�ence.

PinnipedsinWater/Nonpulses(Cell12)The effects of nonpulse exposures on p�nn�-peds �n water are poorly understood. Stud�es for wh�ch enough �nformat�on was ava�lable for analys�s �nclude f�eld exposures of harbor seals to AHDs (Jacobs & Terhune, 2002) and exposure of translocated freely d�v�ng northern elephant seals to a research tomography source (Costa et al., 2003), as well as responses of capt�ve harbor seals to underwater data commun�cat�on sources (Kastele�n et al., 2006b). These l�m�ted ava�lable data (see Table 20 & Append�x C) suggested that exposures between ~90 and 140 dB re: 1 µPa generally do not appear to �nduce strong behav-�oral responses �n p�nn�peds exposed to nonpulse sounds �n water; no data ex�st regard�ng exposures at h�gher levels. The sever�ty scale results for Cell 12 are g�ven �n Table 21.

It �s �mportant to note that among these stud-�es of p�nn�peds respond�ng to nonpulse exposures �n water, there are some apparent d�fferences �n responses between f�eld and laboratory cond�-t�ons. Spec�f�cally, �n th�s case, capt�ve subjects responded more strongly at lower levels than d�d an�mals �n the f�eld. Aga�n, contextual �ssues are the l�kely cause of th�s d�fference. Capt�ve sub-jects �n the Kastele�n et al. (2006b) study were not re�nforced w�th food for rema�n�ng �n no�se f�elds, �n contrast to the laboratory stud�es for m�d-fre-quency cetaceans descr�bed above. Subjects �n the

Table 13. Number (�n bold) of p�nn�peds �n a�r (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to mult�ple pulse no�se; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “P�nn�peds �n A�r/Mult�ple Pulses (Cell 14)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 12.


Response score 50 to < 60 60 to < 70 70 to < 80 80 to < 90 90 to < 100 100 to < 110 110 to < 120

987654321 0.125

(1)

0 0.625 (1)

0.25 (1)


Tabl

e 14

. Sum

mar

y of

beh

av�o

ral r

espo

nses

by

d�ff

eren

t spe

c�es

of

low

-fre

quen

cy c

etac

eans

exp

osed

to n

onpu

lses

(C

ell 3

) by

type

of

soun

d so

urce

, ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�p-

t�on

of b

ehav

�ora

l res

pons

e (b

y �n

d�v�

dual

and

/or g

roup

), a

nd a

sum

mar

y of

cor

resp

ond�

ng s

ever

�ty s

core

(s);

spe

c�f�

c se

ver�

ty s

core

s fo

r eac

h st

udy

are

g�ve

n �n

Tab

le 1

5 an

d m

ore

deta

�ls

are

g�ve

n �n

App

end�

x C

. Exp

osur

e R

Ls

are

g�ve

n �n

dB

SPL

, wh�

ch a

re R

MS

soun

d pr

essu

re le

vels

(dB

re:

1 m

Pa).

Stud

y

Ref

eren

ce

num

ber

(for

Tab

le 1

5)Su

bjec

t spe

c�es

Soun

d so

urce

Type

of

acou

st�c

m

easu

rem

ents

Type

of

�nd�

v�du

al a

nd/o

r

grou

p be

hav�

oral

res

pons

es

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

15)

Bak

er e

t al.

(198

2)1

Hum

pbac

k w

hale

sV

esse

l no�

se

and

pres

ence

Ind�

v�du

al R

Ls

not r

epor

ted

but

vess

els

�den

t�cal

to p

rev�

ous

m

easu

rem

ents

Ves

sel-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

m

ovem

ent a

nd b

ehav

�ora

l pat

tern

s ar

ound

ve

ssel

s

Yes

Exp

osur

e R

Ls

100-

140

dB S

PL; s

ever

-�ty

sco

res:

0 &

6

Mal

me

et a

l. (1

983,

198

4)2

Gra

y w

hale

s (m

�gra

t�ng)

Play

back

s of

dr

�ll�n

g an

d m

ach�

nery

no

�se

RL

s m

easu

red

ins

itu

near

�n

d�v�

dual

s ob

serv

edSh

ore-

base

d ob

serv

at�o

ns o

f �n

d�v�

dual

m

ovem

ent a

nd b

ehav

�ora

l pat

tern

s ar

ound

s�

mul

ated

dr�

ll�ng

ope

rat�o

ns/p

latf

orm

s

Yes

Exp

osur

e R

Ls

90-

150

dB S

PL; s

ever

-�ty

sco

res:

0 &

6

Mal

me

et a

l. (1

986)

3G

ray

wha

les

(fee

d�ng

)Pl

ayba

cks

of

dr�ll

�ng

no�s

eR

Ls

mea

sure

d in

sit

u ne

ar

�nd�

v�du

als

obse

rved

V

esse

l-ba

sed

obse

rvat

�ons

of

�nd�

v�du

al

mov

emen

t and

beh

av�o

ral p

atte

rns

befo

re a

nd

dur�

ng p

layb

acks

Yes

Exp

osur

e R

Ls

100-

120

dB S

PL; s

ever

-�ty

sco

res:

0 &

6R

�cha

rdso

n

et a

l. (1

990b

)4

Bow

head

w

hale

s

(m�g

rat�n

g)

Dr�

ll�ng

no

�se

pl

ayba

cks

Det

a�le

d an

d ca

l�bra

ted

sour

ce a

nd

tran

sm�s

s�on

loss

mea

sure

men

ts

allo

wed

goo

d R

L e

st�m

ates

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

mov

emen

t an

d be

hav�

oral

pat

tern

s be

fore

, dur

�ng,

and

af

ter

expo

sure

to d

r�ll�

ng s

ound

s

Yes

Exp

osur

e R

Ls

100-

140

dB S

PL; s

ever

-�ty

sco

res:

0 &

6M

cCau

ley

et

al.

(199

6)5

Hum

pbac

k w

hale

sV

esse

l no�

se

and

pres

ence

RL

s m

easu

red

ins

itu

near

�nd�

-v�

dual

s ob

serv

edV

�sua

l obs

erva

t�ons

of

�nd�

v�du

al

mov

emen

t and

beh

av�o

ral p

atte

rns

dur�

ng

vess

el a

ppro

ache

s

Yes

Exp

osur

e R

Ls

110-

130

dB S

PL; s

ever

-�ty

sco

re: 6

Fran

kel &

C

lark

(19

98)

6H

umpb

ack

wha

les

Low

- fr

eque

ncy

M-s

eque

nce

play

back

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u ne

ar a

reas

of

ex

posu

re

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

mov

emen

t an

d be

hav�

oral

pat

tern

s be

fore

, dur

�ng,

and

af

ter

play

back

s

Yes

Exp

osur

e R

Ls

120-

130

dB S

PL; s

ever

-�ty

sco

re: 6

B�a

sson

� et

al.

(200

0);

M�ll

er e

t al.

(200

0)

7H

umpb

ack

wha

les

Low

- fr

eque

ncy

sona

r

play

back

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u ne

ar a

reas

of

ex

posu

re

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

mov

emen

t an

d be

hav�

oral

pat

tern

s be

fore

, dur

�ng,

and

af

ter

play

back

s

Yes

Exp

osur

e R

Ls

110-

160

dB S

PL; s

ever

-�ty

sco

res:

2 &

4

Cro

ll et

al.

(200

1)8

Blu

e an

d f�

n w

hale

s

(fee

d�ng

)

Low

- fr

eque

ncy

sona

r

play

back

Cal

�bra

ted

RL

mea

sure

men

ts a

nd

mod

el�n

g fo

r ar

ea o

f ex

posu

reIn

d�v�

dual

res

pons

es n

ot r

epor

ted

but a

gen

eral

ob

serv

at�o

n of

fee

d�ng

beh

av�o

r w

�th/w

�thou

t so

nar

Yes

Exp

osur

e R

Ls

140-

150

dB S

PL; s

ever

-�ty

sco

re: 0

462 Southalletal.

Stud

y

Ref

eren

ce

num

ber

(for

Tab

le 1

5)Su

bjec

t spe

c�es

Soun

d so

urce

Type

of

acou

st�c

m

easu

rem

ents

Type

of

�nd�

v�du

al a

nd/o

r

grou

p be

hav�

oral

res

pons

es

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

15)

Palk

a &

H

amm

ond

(200

1)

9M

�nke

wha

les

Ves

sel n

o�se

an

d pr

esen

ceR

L e

st�m

ates

bas

ed o

n so

urce

and

en

v�ro

nmen

tal c

hara

cter

�st�c

sV

�sua

l obs

erva

t�ons

of

�nd�

v�du

al a

nd g

roup

m

ovem

ents

and

beh

av�o

ral p

atte

rns

dur�

ng

vess

el a

ppro

ache

s

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL; s

ever

-�ty

sco

re: 3

Now

acek

et

al.

(200

4)10

R�g

ht w

hale

sPl

ayba

cks

of

seve

ral

nonp

ulse

s

Subj

ects

wor

e ca

l�bra

ted

tags

that

m

easu

red

RL

and

beh

av�o

r/

mov

emen

t

Det

a�le

d m

easu

rem

ents

of

voca

l and

phy

s�ca

l re

act�o

ns o

f an

�mal

s be

fore

, dur

�ng,

and

aft

er

play

back

s

Yes

Exp

osur

e R

Ls

120-

150

dB S

PL; s

ever

-�ty

sco

res:

0 &

7D

ahlh

e�m

(1

987)

Not

�ncl

uded

Gra

y w

hale

sPl

ayba

cks

of

non

puls

esIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l and

aco

ust�c

obs

erva

t�ons

of

�nd�

v�du

als

No

N/A

Bor

ggaa

rd

et a

l. (1

999)

Not

�ncl

uded

Var

�ous

ce

tace

ans

Indu

str�

al

no�s

eSo

me

RL

mea

sure

men

ts a

nd

mod

el�n

g �n

are

aIn

suff

�c�e

nt d

ata

on �n

d�v�

dual

res

pons

es f

or

th�s

ana

lys�

sN

oN

/A

Fran

kel &

C

lark

(20

00)

Not

�ncl

uded

Hum

pbac

k w

hale

sA

TO

C

sour

ceSo

me

RL

mea

sure

men

ts a

nd

mod

el�n

g �n

are

aIn

suff

�c�e

nt d

ata

on �n

d�v�

dual

res

pons

es f

or

th�s

ana

lys�

sN

oN

/A

Sch�

ck &

U

rban

(20

00)

Not

�ncl

uded

Bow

head

wha

les

Dr�

llsh�

psIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l obs

erva

t�ons

of

�nd�

v�du

als

arou

nd r

�gs

No

N/A

Fran

kel &

C

lark

(20

02)

Not

�ncl

uded

Hum

pbac

k w

hale

sA

TO

C

sour

ceSo

me

RL

mea

sure

men

ts a

nd

mod

el�n

g �n

are

aIn

suff

�c�e

nt d

ata

on �n

d�v�

dual

res

pons

es f

or

th�s

ana

lys�

sN

oN

/A

Jaho

da e

t al.

(200

3)N

ot �n

clud

edF�

n w

hale

sV

esse

l no�

se

and

pres

ence

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

s du

r�ng

ap

proa

ches

No

N/A

Mob

ley

(200

5)N

ot �n

clud

edH

umpb

ack

wha

les

AT

OC

so

urce

Som

e R

L m

easu

rem

ents

and

m

odel

�ng

�n a

rea

Insu

ff�c

�ent

dat

a on

�nd�

v�du

al r

espo

nses

for

th

�s a

naly

s�s

No

N/A

Tabl

e 14

(co

ntin

ued)


f�eld may have been more tolerant of exposures because of mot�vat�on to return to a safe locat�on (Costa et al., 2003) or mot�vat�on to approach enclosures hold�ng prey �tems (Jacobs & Terhune, 2002).

PinnipedsinAir/Nonpulses(Cell15)There has been cons�derable effort to study the effects of aer�al nonpulse sounds on p�nn�ped behav�or, pr�mar�ly �nvolv�ng rocket launches, a�rcraft overfl�ghts, powerboat approaches, and construct�on no�se. Unfortunately, as d�scussed �n Append�x C, many of the stud�es are d�ff�cult to �nterpret �n terms of exposure RL and �nd�v�dual or group behav�oral responses. In many cases, �t was d�ff�cult or �mposs�ble to d�scern whether the reported behav�oral response was �nduced by the no�se from a spec�f�c operat�on or some cor-related var�able such as �ts v�sual presence. For these reasons, most of the observat�onal stud�es of behav�oral d�sturbance were not appropr�ate for scor�ng behav�oral responses relat�ve to exposure RL. However, a number of the techn�cal reports and analyses of rocket launches are relevant for th�s cell and conta�n suff�c�ently deta�led �nfor-mat�on regard�ng est�mated RLs. These observa-t�ons are, however, compl�cated by the fact that all stud�es were conducted �n the same general area w�th subjects l�kely hab�tuated to the pres-ence of launch no�se. Further, �n many cases, exposures conta�ned both a nonpulse component and a pulse component (descr�bed below). Only

those observat�ons (Thorson et al., 1999, 2000b; Berg et al., 2002) for wh�ch there was clearly just nonpulse exposure were cons�dered �n the sever�ty scal�ng analyses for th�s cond�t�on.

The l�m�tat�ons of these and other potent�ally appl�cable stud�es resulted �n a very l�m�ted data set for use �n th�s analys�s (see summary �n Table 22 and sever�ty scal�ng analys�s �n Table 23). As a general statement from the ava�lable �nformat�on, p�nn�peds exposed to �ntense (~110 to 120 dB re: 20 µPa) nonpulse sounds tended to leave haulout areas and seek refuge temporar�ly (m�nutes to a few hours) �n the water, whereas p�nn�peds exposed to d�stant launches at RLs ~60 to 70 dB re: 20 µPa tended to �gnore the no�se. It �s d�ff�cult to assess the relevance of e�ther of these observat�ons to naïve �nd�v�duals, however, g�ven the repeated exposure of study colon�es to such no�se events and the potent�al that observed �nd�v�duals were hab�tu-ated. Due to the l�m�tat�ons of ava�lable data, �t �s not currently poss�ble to make any further general character�zat�ons regard�ng th�s cond�t�on.

Table 15. Number (�n bold) of low-frequency cetaceans (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to nonpulses; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�-v�dual stud�es �ncluded �n th�s table �s g�ven �n the “Low-Frequency Cetaceans/Nonpulses (Cell 3)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 14.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

987 2.5

(10)1.5 (10)

6 4.9 (2)

7.4 (1, 2, 4)

16.2 (1, 2, 3, 5)

13.6 (2, 5)

4.2 (1, 2)

0.8 (2)

54 3.0

(5, 7)1.0

(7)1.0

(7)

3 1,117 (9)

0.27 (6)

2 0.5 (7)

4.0

(7)5.0

(7)2.0

(7)1.0

(7)

10 1.1

(2)82.6 (2, 3, 4)

33.9 (1, 2, 3, 4)

7.08 (2, 4, 6, 10)

7.2 (4, 10)

1.45 (2, 8, 10)

464 Southalletal.

Tabl

e 16

. Sum

mar

y of

beh

av�o

ral r

espo

nses

by

d�ff

eren

t spe

c�es

of m

�d-f

requ

ency

cet

acea

ns e

xpos

ed to

non

puls

es (C

ell 6

) by

type

of s

ound

sou

rce,

ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�p-

t�on

of b

ehav

�ora

l re

spon

se (

by �

nd�v

�dua

l an

d/or

gro

up),

and

a s

umm

ary

of c

orre

spon

d�ng

sev

er�ty

sco

re(s

); s

pec�

f�c

seve

r�ty

sco

res

for

each

stu

dy a

re g

�ven

�n

Tabl

e 17

and

mor

e de

ta�ls

are

g�v

en �n

App

end�

x C

. Exp

osur

e R

Ls

are

g�ve

n �n

dB

SPL

, wh�

ch a

re R

MS

soun

d pr

essu

re le

vels

(dB

re:

1 m

Pa).

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

17)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

17)

Wat

k�ns

&

Sch

ev�ll

(1

975)

1Sp

erm

wha

les

P�ng

ers

RL

s m

easu

red

ins

itu

near

�nd�

-v�

dual

s ob

serv

edPa

ss�v

e ac

oust

�c m

on�to

r�ng

of

voca

l out

put o

f �n

d�v�

dual

s du

r�ng

exp

osur

eY

esE

xpos

ure

RL

s 80

-90

dB S

PL; s

ever

�ty

scor

e: 3

Aw

brey

&

Ste

war

t (1

983)

2B

elug

asPl

ayba

cks

of d

r�ll�

ng

soun

ds

RL

est

�mat

es b

ased

on

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

and

gro

up

mov

emen

ts a

nd b

ehav

�ora

l pat

tern

s du

r�ng

ex

posu

re a

nd c

ontr

ol tr

�als

Yes

Exp

osur

e R

Ls

110-

150

dB S

PL;

seve

r�ty

sco

res:

0, 1

, 2

& 6

L

GL

&

Gre

ener

�dge

(1

986)

3B

elug

as a

nd

narw

hals

Sh�p

and

�c

e-br

eak�

ng

no�s

e

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

une

ar a

reas

of

ex

posu

re

Ice-

base

d an

d ae

r�al

obs

erva

t�ons

of

grou

ps o

f an

�mal

s; m

ovem

ent a

nd b

ehav

�ora

l pat

tern

s be

fore

, dur

�ng,

and

aft

er �c

e-br

eak�

ng

Yes

Exp

osur

e R

Ls

90-

120

dB S

PL; s

ever

-�ty

sco

res:

0, 1

, 2,

3 &

8R

�cha

rdso

n

et a

l. (1

990b

)4

Bel

ugas

Play

back

s of

dr�

ll�ng

so

unds

RL

est

�mat

es b

ased

on

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

plus

so

nobu

oy d

ata

Ice-

base

d an

d ae

r�al

obs

erva

t�ons

of

�nd�

v�du

al

and

grou

p m

ovem

ents

and

beh

av�o

r du

r�ng

ex

posu

re a

nd c

ontr

ol tr

�als

Yes

Exp

osur

e R

Ls

100-

130

dB S

PL;

seve

r�ty

sco

res:

0, 1

, 3

& 4

Gor

don

et a

l. (1

992)

5Sp

erm

wha

les

Ves

sel n

o�se

an

d pr

esen

ceC

al�b

rate

d R

L m

easu

rem

ents

m

ade

ins

itu

near

are

as o

f

expo

sure

Ves

sel-

base

d ob

serv

at�o

ns a

nd p

ass�

ve a

cous

t�c

mon

�tor�

ng o

f �n

d�v�

dual

s; m

ovem

ent p

atte

rns

and

beha

v�or

al r

espo

nses

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL; s

ever

-�ty

sco

re: 3

Palk

a &

H

amm

ond

(200

1)

6W

h�te

-s�d

ed

and

wh�

te-

beak

ed

dolp

h�ns

Ves

sel n

o�se

an

d pr

esen

ceR

L e

st�m

ates

bas

ed o

n so

urce

and

en

v�ro

nmen

tal c

hara

cter

�st�c

sV

�sua

l obs

erva

t�ons

of

�nd�

v�du

al a

nd g

roup

m

ovem

ents

and

beh

av�o

ral p

atte

rns

dur�

ng

vess

el a

ppro

ache

s

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL; s

ever

-�ty

sco

re: 3

Mor

ton

&

Sym

onds

(2

002)

7K

�ller

wha

les

Var

�ous

A

HD

sR

L e

st�m

ates

bas

ed o

n so

urce

and

en

v�ro

nmen

tal c

hara

cter

�st�c

sC

ensu

s da

ta f

or �n

d�v�

dual

and

gro

up s

�ght

�ngs

us

ed to

est

�mat

e “e

xclu

s�on

” zo

nes

Yes

Exp

osur

e R

Ls

140-

150

dB S

PL; s

ever

-�ty

sco

re: 8

Buc

ksta

ff

(200

4)8

Bot

tleno

se

dolp

h�ns

Ves

sel n

o�se

an

d pr

esen

ce

(app

roac

hes)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

ein

sit

u ne

ar a

reas

of

ex

posu

re

Pass

�ve

acou

st�c

mon

�tor�

ng o

f �n

d�v�

dual

voc

al

outp

ut d

ur�n

g ve

ssel

app

roac

hes

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL; s

ever

-�ty

sco

re: 2

NR

L (

2004

a,

2004

b);

NM

FS (

2005

)

9K

�ller

wha

les

M�d

- fr

eque

ncy

act�v

e m

�l�-

tary

son

ar

Som

e ca

l�bra

ted

RL

mea

sure

-m

ents

and

RL

est

�mat

es f

rom

m

odel

�ng

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

and

gro

up

mov

emen

ts a

nd b

ehav

�ora

l pat

tern

s be

fore

, du

r�ng

, and

aft

er �n

c�de

ntal

exp

osur

e

Yes

Exp

osur

e R

Ls

160-

170

dB S

PL; s

ever

-�ty

sco

re: 6


Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

17)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(se

e Ta

ble

17)

Mon

te�r

o-N

eto

et a

l. (2

004)

10T

ucux

� (r�

ver

dolp

h�ns

)D

ukan

e®

Net

mar

k A

DD

s

RL

est

�mat

es b

ased

on

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

and

gro

up

mov

emen

ts a

nd b

ehav

�ora

l pat

tern

s du

r�ng

ex

posu

re a

nd c

ontr

ol tr

�als

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL; s

ever

-�ty

sco

re: 6

Mor

�sak

a

et a

l. (2

005)

11In

do-P

ac�f

�c

dolp

h�ns

Ves

sel n

o�se

an

d pr

esen

ceC

al�b

rate

d R

L m

easu

rem

ents

m

ade

ins

itu

near

are

as o

f

expo

sure

Pass

�ve

acou

st�c

mon

�tor�

ng o

f �n

d�v�

dual

vo

cal o

utpu

t dur

�ng

vess

el a

ppro

ache

sY

esE

xpos

ure

RL

s 12

0-13

0 dB

SPL

; sev

er-

�ty s

core

: 5N

acht

�gal

l et

al.

(200

3)12

Bot

tleno

se

dolp

h�ns

(c

apt�v

e)

Non

puls

e no

�se

(ban

ds)

Cal

�bra

ted

RL

mea

sure

men

ts in

si

tu w

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

beha

v�or

al r

espo

nses

w

�th�n

exp

er�m

enta

l lab

con

text

Y

esE

xpos

ure

RL

s 17

0-18

0 dB

SPL

; sev

er-

�ty s

core

: 6F�

nner

an &

Sc

hlun

dt

(200

4)

13B

ottle

nose

do

lph�

ns

(cap

t�ve)

Non

puls

e no

�se

(ton

es)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

ein

sit

u w

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

beha

v�or

al r

espo

nses

w

�th�n

exp

er�m

enta

l con

text

�n la

bora

tory

co

nd�t�

ons

Yes

Exp

osur

e R

Ls

180-

200

dB S

PL; s

ever

-�ty

sco

res:

0 &

8R

ende

ll &

Gor

don

(199

9)

Not

�ncl

uded

Lon

g-f�

nned

p�

lot w

hale

sA

ct�v

e m

�l�-

tary

son

arIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sPa

ss�v

e ac

oust

�c m

easu

rem

ents

of

wh�

stle

rat

esN

oN

/A

Ch�

lver

s &

C

orke

ron

(200

1)

Not

�ncl

uded

Bot

tleno

se

dolp

h�ns

Ves

sel n

o�se

an

d pr

esen

ceIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l obs

erva

t�ons

of

�nd�

v�du

al f

orag

�ng

beha

v�or

No

N/A

Bor

d�no

et a

l. (2

002)

Not

�ncl

uded

Fran

c�sc

ana

dolp

h�ns

AD

Ds

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

W�ll

�am

s et

al.

(200

2)N

ot �n

clud

edK

�ller

wha

les

Ves

sel n

o�se

an

d pr

esen

ceA

cous

t�c m

easu

rem

ents

of

sour

ce

leve

ls b

ut n

o es

t�mat

es o

f R

LV

�sua

l obs

erva

t�ons

of

mov

emen

t and

d�v

�ng

beha

v�or

No

N/A

Cox

et a

l. (2

003)

Not

�ncl

uded

Bot

tleno

se

dolp

h�ns

AD

Ds

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

V�s

ual o

bser

vat�o

ns o

f m

ovem

ent a

nd d

�v�n

g be

hav�

orN

oN

/A

Has

t�e e

t al.

(200

3)N

ot �n

clud

edB

ottle

nose

do

lph�

nsV

esse

l no�

se

and

pres

ence

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

V�s

ual o

bser

vat�o

ns o

f m

ovem

ent a

nd d

�v�n

g be

hav�

orN

oN

/A

Lus

seau

(2

003)

Not

�ncl

uded

Bot

tleno

se

dolp

h�ns

Ves

sel n

o�se

an

d pr

esen

ceIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l obs

erva

t�ons

of

mov

emen

t beh

av�o

rN

oN

/A

Foot

e et

al.

(200

4)N

ot �n

clud

edK

�ller

wha

les

Gen

eral

�n

crea

se �n

ve

ssel

s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

Insu

ff�c

�ent

dat

a on

�nd�

v�du

al e

xpos

ures

/re

spon

ses

for

th�s

ana

lys�

sN

oN

/A

Tabl

e 16

(co

ntin

ued)

466 Southalletal.

Table 17. Number (�n bold) of m�d-frequency cetaceans (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to nonpulses; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�-v�dual stud�es �ncluded �n th�s table �s g�ven �n the “M�d-Frequency Cetaceans/Nonpulses (Cell 6)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 16.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

98 1.0

(3)7.0

(3)5.0

(2)1.0

(7)5.0 (13)

1.5 (13)

76 3.0

(2, 10)1.0

(2)1.0

(9)6.0 (12)

5 1.0 (11)

4 1.0 (4)

2.0 (4)

3 5.0 (1)

4.0 (3, 5)

134 (4, 6)

1.0 (4)

2 15.0 (2, 3, 8)

1 1.0 (4)

1.0 (2, 3)

1.0 (2, 4)

0 8.0 (3, 4)

2.0 (2, 4)

1.0 (2, 4)

1.0 (2)

3.0 (13)

1.5 (13)



Tabl

e 18

. Sum

mar

y of

beh

av�o

ral r

espo

nses

of

h�gh

-fre

quen

cy c

etac

eans

exp

osed

to n

onpu

lses

(C

ell 9

) by

type

of

soun

d so

urce

, ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�pt�o

n of

beh

av�o

ral

resp

onse

(by

�nd

�v�d

ual

and/

or g

roup

), a

nd a

sum

mar

y of

cor

resp

ond�

ng s

ever

�ty s

core

(s);

spe

c�f�

c se

ver�

ty s

core

s fo

r ea

ch s

tudy

are

g�v

en �

n Ta

ble

19 a

nd m

ore

deta

�ls a

re g

�ven

�n

App

end�

x C

. Exp

osur

e R

Ls

are

g�ve

n �n

dB

SPL

, wh�

ch a

re R

MS

soun

d pr

essu

re le

vels

(dB

re:

1 m

Pa).

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

19)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(s

ee T

able

19)

Cul

�k e

t al.

(200

1)1

Har

bor

po

rpo�

ses

(w�ld

)

PIC

E p

�nge

rR

L e

st�m

ates

bas

ed o

n so

urce

and

en

v�ro

nmen

tal c

hara

cter

�st�c

sV

�sua

l obs

erva

t�ons

of

�nd�

v�du

al a

nd g

roup

m

ovem

ents

and

beh

av�o

ral p

atte

rns

befo

re

and

follo

w�n

g de

ploy

men

t

Yes

Exp

osur

e R

Ls

80-1

20 d

B S

PL;

resp

onse

sev

er�ty

sc

ores

: 0 &

6

Ole

s�uk

et a

l. (2

002)

2H

arbo

r

porp

o�se

s (w

�ld)

A�r

mar

®

AH

Ds

RL

est

�mat

es b

ased

on

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

and

gro

up

mov

emen

ts a

nd b

ehav

�ora

l pat

tern

s be

fore

an

d fo

llow

�ng

depl

oym

ent

Yes

Exp

osur

e R

Ls

140-

160

dB S

PL;

resp

onse

sev

er�ty

sc

ore:

6Jo

hnst

on

(200

2)3

Har

bor

po

rpo�

ses

(w�ld

)

A�r

mar

®

AH

Ds

RL

est

�mat

es b

ased

on

sour

ce a

nd

env�

ronm

enta

l cha

ract

er�s

t�cs

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

and

gro

up

mov

emen

ts a

nd b

ehav

�ora

l pat

tern

s be

fore

an

d fo

llow

�ng

depl

oym

ent

Yes

Exp

osur

e R

Ls

120-

130

dB S

PL;

resp

onse

sev

er�ty

sc

ores

: 0 &

6K

aste

le�n

et

al.

(199

7)4

Har

bor

po

rpo�

ses

(c

apt�v

e)

Var

�ous

non

-pu

lse

soun

ds

(lab

orat

ory)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

uw

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

mov

emen

t, re

sp�r

at�o

n,

and

beha

v�or

�n la

bora

tory

con

d�t�o

nsY

esE

xpos

ure

RL

s 80

-120

dB

SPL

; re

spon

se s

ever

�ty

scor

es: 0

, 4 &

6K

aste

le�n

et

al.

(200

0)5

Har

bor

po

rpo�

ses

(c

apt�v

e)

Var

�ous

non

-pu

lse

soun

ds

(lab

orat

ory)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u w

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

mov

emen

t, re

sp�r

at�o

n,

and

beha

v�or

�n la

bora

tory

con

d�t�o

nsY

esE

xpos

ure

RL

s 90

-120

dB

SPL

; re

spon

se s

ever

�ty

scor

es: 0

& 6

Kas

tele

�n

et a

l. (2

005)

6H

arbo

r

porp

o�se

s(c

apt�v

e)

Var

�ous

no

npul

se

soun

ds(l

abor

ator

y)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u w

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

mov

emen

t, re

sp�r

at�o

n,

and

beha

v�or

�n la

bora

tory

con

d�t�o

nsY

esE

xpos

ure

RL

s 90

-120

dB

SPL

; re

spon

se s

ever

�ty

scor

es: 0

& 6

Kas

tele

�n

et a

l. (2

006a

)7

Har

bor

po

rpo�

ses

(c

apt�v

e)

Var

�ous

non

-pu

lse

soun

ds

(lab

orat

ory)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

uw

�th�n

test

enc

losu

reV

�sua

l obs

erva

t�ons

of

mov

emen

t, re

sp�r

at�o

n,

and

beha

v�or

�n la

bora

tory

con

d�t�o

nsY

esE

xpos

ure

RL

s 10

0-12

0 dB

SPL

; re

spon

se s

ever

�ty

scor

es: 0

& 6

468 Southalletal.

Stud

y

Ref

eren

ce

num

ber

(for

Ta

ble

19)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(s

ee T

able

19)

Kra

us e

t al.

(199

7)N

ot �n

clud

edH

arbo

r

porp

o�se

s (w

�ld)

Duk

ane®

p�

nger

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sM

easu

rem

ents

of

by-c

atch

rat

es �n

com

mer

c�al

f�

sher

�es

No

N/A

Tayl

or e

t al.

(199

7)N

ot �n

clud

edH

arbo

r

porp

o�se

s (w

�ld)

Gen

eral

no

npul

se

soun

ds

Rev

�ew

ana

lys�

sR

ev�e

w a

naly

s�s

No

N/A

John

ston

&

Woo

dley

(1

998)

Not

�ncl

uded

Har

bor

po

rpo�

ses

(w�ld

)

Var

�ous

A

HD

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l obs

erva

t�ons

of

“exc

lus�

on”

zone

sN

oN

/A

Cox

et a

l. (2

001)

Not

�ncl

uded

Har

bor

po

rpo�

ses

(w�ld

)

Var

�ous

A

DD

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sV

�sua

l obs

erva

t�ons

of

“exc

lus�

on”

zone

sN

oN

/A

Kas

tele

�n

et a

l. (2

001)

Not

�ncl

uded

(sam

e

subj

ects

as

2000

stu

dy)

Har

bor

po

rpo�

ses

(c

apt�v

e)

Var

�ous

non

-pu

lse

soun

ds

(lab

orat

ory)

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u ne

ar a

reas

of

ex

posu

re

Aer

�al o

bser

vat�o

ns o

f �n

d�v�

dual

s; m

ovem

ent

and

resp

�rat

�on

patte

rns

dur�

ng a

nd w

�thou

t a�

rgun

s

No

N/A

Bar

low

&

Cam

eron

(2

003)

Not

�ncl

uded

Har

bor

po

rpo�

ses

(w�ld

)

Var

�ous

A

DD

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sM

easu

rem

ents

of

by-c

atch

rat

es �n

com

mer

c�al

f�

sher

�es

No

N/A

Kos

ch�n

sk�

et a

l. (2

003)

Not

�ncl

uded

Har

bor

po

rpo�

ses

(w�ld

)

S�m

ulat

ed

w�n

d tu

rb�n

e no

�se

Cal

�bra

ted

sour

ce-l

evel

mea

sure

-m

ents

mad

e bu

t �ns

uff�

c�en

t dat

a on

RL

V�s

ual m

on�to

r�ng

of

gene

ral d

�str

�but

�on

pa

ttern

sN

oN

/A

Tabl

e 18

(co

ntin

ued)


Table 19. Number (�n bold) of h�gh-frequency cetaceans (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to nonpulses; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�-v�dual stud�es �ncluded �n th�s table �s g�ven �n the “H�gh-Frequency Cetaceans/Nonpulses (Cell 9)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 18.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

9876 0.3

(4)0.3

(4)0.9

(1, 2, 4, 5, 6, 7)3.3

(1, 2, 4, 5, 6, 7)1.0 (3, 7)

52.1 (2)

9.3 (2)

4.6 (2)

54 0.1

(4)0.1

(4)

3210 12.8

(1, 5)23.1

(1, 2, 5, 6)0.4 (4, 7)

0.1 (7)

0.3 (3)


470 Southalletal.

Tabl

e 20

. Sum

mar

y of

beh

av�o

ral r

espo

nses

by

d�ff

eren

t spe

c�es

of

p�nn

�ped

s �n

wat

er e

xpos

ed to

non

puls

es (

Cel

l 12)

by

type

of

soun

d so

urce

, ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�pt�o

n of

beh

av�o

ral r

espo

nse

(by

�nd�

v�du

al a

nd/o

r gr

oup)

, and

a s

umm

ary

of c

orre

spon

d�ng

sev

er�ty

sco

re(s

); s

pec�

f�c

seve

r�ty

sco

res

for

each

stu

dy a

re g

�ven

�n T

able

21

and

mor

e de

ta�ls

ar

e g�

ven

�n A

ppen

d�x

C. E

xpos

ure

RL

s ar

e g�

ven

�n d

B S

PL, w

h�ch

are

RM

S so

und

pres

sure

leve

ls (

dB r

e: 1

mPa

).

Stud

y

Ref

eren

ce

num

ber

(f

or T

able

21)

Subj

ect s

pec�

esSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

sev

er�ty

sc

ale

anal

ys�s

(s

ee T

able

21)

Jaco

bs &

Te

rhun

e (2

002)

1H

arbo

r se

als

A�r

mar

® d

B p

lus

II A

HD

RL

s m

easu

red

ins

itu

�n a

reas

w

here

�nd�

v�du

als

obse

rved

V�s

ual o

bser

vat�o

ns o

f �n

d�v�

dual

s an

d gr

oups

of

seal

s; m

ovem

ent a

nd b

ehav

�ora

l pa

ttern

s du

r�ng

and

w�th

out A

HD

s

Yes

Exp

osur

e R

Ls

120-

130

dB S

PL;

resp

onse

sev

er�ty

sc

ore:

0

Cos

ta e

t al.

(200

3)2

Ele

phan

t sea

lsA

TO

C (

see

App

end�

x B

)R

Ls

mea

sure

d us

�ng

cal�b

rate

d ar

ch�v

al ta

gs in

sit

u on

�nd�

v�du

als

dur�

ng e

xpos

ure

Arc

h�va

l tag

s pl

aced

on

an�m

als

resu

lted

�n

deta

�led

quan

t�tat

�ve

mea

sure

s of

�nd�

v�du

al

d�v�

ng b

ehav

�or,

resp

onse

s, a

nd e

xpos

ure

RL

s �n

wel

l-ch

arac

ter�

zed

cont

exts

Yes

Exp

osur

e R

Ls

110-

140

dB S

PL;

resp

onse

sev

er�ty

sc

ores

: 0, 3

& 4

Kas

tele

�n

et a

l. (2

006b

)3

Har

bor

seal

sV

ar�o

us n

on-

puls

e so

unds

us

ed �n

und

er-

wat

er d

ata

co

mm

un�c

at�o

ns

Cal

�bra

ted

RL

mea

sure

men

ts

mad

e in

sit

u w

�th�n

exp

er�m

enta

l en

clos

ure

Ind�

v�du

al s

ubje

ct p

os�t�

ons

and

the

mea

n nu

mbe

r of

sur

fac�

ng b

ehav

�ors

dur

�ng

con-

trol

and

exp

osur

e �n

terv

als

Yes

Exp

osur

e R

Ls

80-1

10 d

B S

PL;

resp

onse

sev

er�ty

sc

ores

: 0 &

6

Fros

t &

Low

ry (

1988

)N

ot �n

clud

edR

�nge

d se

als

Und

erw

ater

dr

�ll�n

g so

unds

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

R�c

hard

son

et a

l. (1

990b

, 19

91)

Not

�ncl

uded

R�n

ged

and

bear

ded

seal

sU

nder

wat

er

dr�ll

�ng

soun

dsIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Nor

berg

&

Ba�

n (1

994)

Not

�ncl

uded

Cal

�for

n�a

se

a l�o

nsC

asca

de A

ppl�e

d Sc

�enc

es® A

HD

sC

al�b

rate

d ac

oust

�c m

easu

rem

ents

ta

ken

arou

nd a

rray

s of

the

dev�

ces

Insu

ff�c

�ent

dat

a on

�nd�

v�du

al r

espo

nses

fo

r th

�s a

naly

s�s

No

N/A

Nor

berg

(2

000)

Not

�ncl

uded

Cal

�for

n�a

se

a l�o

nsA

�rm

ar® d

B p

lus

II A

HD

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

Som

e be

hav�

oral

mea

sure

men

ts b

ut

�nsu

ff�c

�ent

dat

a on

�nd�

v�du

al r

espo

nses

as

a f

unct

�on

of R

L

No

N/A

Yur

k (2

000)

Not

�ncl

uded

Har

bor

seal

sA

HD

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Kos

ch�n

sk�

et a

l. (2

003)

Not

�ncl

uded

Har

bor

seal

sS�

mul

ated

w�n

d tu

rb�n

e no

�se

RL

s m

easu

red

ins

itu

�n a

reas

w

here

�nd�

v�du

als

obse

rved

Insu

ff�c

�ent

dat

a on

�nd�

v�du

al r

espo

nses

fo

r th

�s a

naly

s�s

No

N/A

Mou

lton

et a

l. (2

003)

Not

�ncl

uded

R�n

ged

seal

sC

onst

ruct

�on

no�s

eIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sIn

suff

�c�e

nt d

ata

on �n

d�v�

dual

res

pons

es

for

th�s

ana

lys�

sN

oN

/A


Table 21. Number (�n bold) of p�nn�peds �n water (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to nonpulses; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “P�nn�peds �n Water/Nonpulses (Cell 12)” sect�on of th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 20.


Response score

80 to < 90

90 to < 100

100 to < 110

110 to < 120

120 to < 130

130 to < 140

140 to < 150

150 to < 160

160 to < 170

170 to < 180

180 to < 190

190 to < 200

9876 1.0

(3)

54 1.0

(2)5.0

(2)

3 1.0 (2)

2.0 (2)

210 1.0

(3)1.0

(3)1.0

(2)5.0 (1, 2)


472 Southalletal.Ta

ble

22. S

umm

ary

of b

ehav

�ora

l res

pons

es b

y d�

ffer

ent s

pec�

es o

f p�

nn�p

eds

�n a

�r e

xpos

ed to

non

puls

es (

Cel

l 15)

by

type

of

soun

d so

urce

, ava

�labl

e ac

oust

�c m

etr�

cs, d

escr

�pt�o

n of

be

hav�

oral

res

pons

e (b

y �n

d�v�

dual

and

/or

grou

p), a

nd a

sum

mar

y of

cor

resp

ond�

ng s

ever

�ty s

core

(s);

spe

c�f�

c se

ver�

ty s

core

s fo

r ea

ch s

tudy

are

g�v

en �n

Tab

le 2

3 an

d m

ore

deta

�ls a

re

g�ve

n �n

App

end�

x C

. Exp

osur

e R

Ls

are

g�ve

n �n

dB

SPL

, wh�

ch a

re R

MS

soun

d pr

essu

re le

vels

(dB

re:

20 mP

a).

Stud

y

Ref

eren

ce

num

ber

(for

Tab

le 2

3)Su

bjec

t sp

ec�e

sSo

und

sour

ceTy

pe o

f ac

oust

�c

mea

sure

men

tsTy

pe o

f �n

d�v�

dual

and

/or

gr

oup

beha

v�or

al r

espo

nses

Stud

y �n

clud

ed

�n s

ever

�ty

scal

e

Sum

mar

y of

se

ver�

ty s

cale

an

alys

�s (

see

Ta

ble

23)

Tho

rson

et a

l. (1

999)

1H

arbo

r se

als,

nor

th-

ern

elep

hant

sea

ls,

Cal

�for

n�a

sea

l�ons

, an

d no

rthe

rn f

ur s

eals

Ath

ena

2 IK

ON

OS-

1 m

�ss�

le

laun

ch

RL

s m

easu

red

ins

itu

�n a

nd

arou

nd b

reed

�ng

rook

er�e

sV

�sua

l obs

erva

t�ons

of

mov

emen

t and

be

hav�

or o

f �n

d�v�

dual

s �n

bre

ed�n

g ro

oker

�es

befo

re, d

ur�n

g, a

nd a

fter

ro

cket

laun

ches

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL;

resp

onse

sev

er�ty

sc

ore:

6

Tho

rson

et a

l. (2

000b

)2

Har

bor

seal

s, n

orth

ern

elep

hant

sea

ls, a

nd

Cal

�for

n�a

sea

l�ons

T�ta

n IV

B-2

8

m�s

s�le

la

unch

RL

s m

easu

red

ins

itu

�n a

nd

arou

nd b

reed

�ng

rook

er�e

sV

�sua

l obs

erva

t�ons

of

mov

emen

t and

be

hav�

or o

f �n

d�v�

dual

s �n

bre

ed�n

g ro

oker

�es

befo

re, d

ur�n

g, a

nd a

fter

ro

cket

laun

ches

Yes

Exp

osur

e R

Ls

60-

70 a

nd 1

10-1

20

dB S

PL; r

espo

nse

seve

r�ty

sco

res:

0

& 6

Ber

g et

al.

(200

2)3

Har

bor

seal

sT

�tan

IV B

-34

m

�ss�

le

laun

ch

RL

s m

easu

red

ins

itu

�n a

nd

arou

nd b

reed

�ng

rook

er�e

sV

�sua

l obs

erva

t�ons

of

mov

emen

t and

be

hav�

or o

f �n

d�v�

dual

s �n

bre

ed�n

g ro

oker

�es

befo

re, d

ur�n

g, a

nd a

fter

ro

cket

laun

ches

Yes

Exp

osur

e R

Ls

110-

120

dB S

PL;

resp

onse

sev

er�ty

sc

ore:

6A

llen

et a

l. (1

984)

Not

�ncl

uded

Har

bor

seal

sA

er�a

l ves

sel n

o�se

an

d pr

esen

ceIn

suff

�c�e

nt d

ata

for

th�s

an

alys

�sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Gen

try

et a

l. (1

990)

Not

�ncl

uded

Nor

ther

n fu

r se

als

Und

ergr

ound

ex

plos

�ons

an

d qu

arry

�ng

oper

at�o

ns

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Sury

an &

H

arve

y (1

998)

Not

�ncl

uded

Har

bor

seal

sA

er�a

l ves

sel n

o�se

an

d pr

esen

ceIn

suff

�c�e

nt d

ata

for

th�s

an

alys

�sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Tho

rson

et a

l. (1

998)

Not

�ncl

uded

Har

bor

seal

sT

�tan

IV A

-18

m

�ss�

le la

unch

RL

s m

easu

red

ins

itu

�n a

nd

arou

nd b

reed

�ng

rook

er�e

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Bor

n et

al.

(199

9)N

ot �n

clud

edR

�nge

d se

als

A�r

craf

t no�

se a

nd

pres

ence

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Tho

rson

et a

l. (2

000a

)N

ot �n

clud

edH

arbo

r se

als

T�ta

n II

G-1

3

m�s

s�le

laun

chR

Ls

mea

sure

d in

sit

u �n

and

ar

ound

bre

ed�n

g ro

oker

�es

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Ber

g et

al.

(200

1)N

ot �n

clud

edC

al�f

orn�

a se

a l�o

ns

and

nort

hern

ele

phan

t se

als

Del

ta I

I E

O-1

m

�ss�

le la

unch

RL

s m

easu

red

ins

itu

�n a

nd

arou

nd b

reed

�ng

rook

er�e

sIn

suff

�c�e

nt d

ata

for

th�s

ana

lys�

sN

oN

/A

Mou

lton

et

al.

(200

2)N

ot �n

clud

edR

�nge

d se

als

Indu

str�

al

equ�

pmen

t no�

se

& p

rese

nce

Insu

ff�c

�ent

dat

a fo

r th

�s

anal

ys�s

Insu

ff�c

�ent

dat

a fo

r th

�s a

naly

s�s

No

N/A

Hol

st e

t al.

(200

5a, 2

005b

)N

ot �n

clud

edH

arbo

r sea

ls, C

al�f

orn�

a se

a l�o

ns, a

nd n

orth

ern

elep

hant

sea

ls

Smal

l- a

nd m

�d-

s�ze

d m

�ss�

le

laun

ches

RL

s m

easu

red

near

obs

erve

d p�

nn�p

eds,

�ncl

ud�n

g pe

ak,

RM

S, S

EL

, and

dur

at�o

n

V�s

ual o

bser

vat�o

ns o

f an�

mal

pre

senc

e an

d d�

str�

but�o

n be

fore

laun

ches

and

be

hav�

or d

ur�n

g an

d fo

llow

�ng

laun

ches

No

N/A


Table 23. Number (�n bold) of p�nn�peds �n a�r (�nd�v�duals and/or groups) reported as hav�ng behav�oral responses to non-pulses; responses were categor�zed �nto 10-dB RL b�ns, ranked by sever�ty of the behav�oral response (see Table 4 for sever-�ty scal�ng), and comb�ned w�th other observat�ons hav�ng the same RL/sever�ty score. A summary of the �nd�v�dual stud�es �ncluded �n th�s table �s g�ven �n the “P�nn�peds �n A�r/Nonpulses (Cell 15)” sect�on �n th�s chapter. Parenthet�cal subscr�pts �nd�cate the reference report�ng the observat�ons as l�sted �n Table 22.


Response score

50 to < 60

60 to < 70

70 to < 80

80 to < 90

90 to < 100

100 to < 110

110 to < 120

9876 1.0

(1, 2, 3)

543210 1.0

(2)

Courtesy: Peter M. Sche�fele

5. Research Recommendations

The mar�ne mammal no�se exposure cr�ter�a proposed here represent a synthes�s and precau-t�onary appl�cat�on of current sc�ent�f�c �nforma-t�on. Clearly, the rel�ance on extrapolat�on proce-dures, extreme data gaps and l�m�tat�ons �n many areas, and precaut�onary assumpt�ons throughout po�nt to the need for targeted research to f�ll spe-c�f�c gaps �n support of subsequent cr�ter�a. We cons�der the current no�se exposure cr�ter�a to be merely an �n�t�al step �n an �terat�ve process to understand and better pred�ct the effects of no�se on mar�ne mammal hear�ng and behav�or.

Research recommendat�ons are g�ven below �n several broad categor�es relevant to �mprov�ng mar�ne mammal no�se exposure cr�ter�a. No pr�-or�t�zat�on �s �mpl�ed �n the order�ng of these areas or research top�cs w�th�n them, however, and th�s �s by no means an exhaust�ve l�st. We present, �n abbrev�ated form, what we regard as cr�t�cal, tar-geted research needs to �mprove future �terat�ons of these exposure cr�ter�a. Some of the most �mpor-tant research recommendat�ons are summar�zed �n Table 24; each �s d�scussed �n more deta�l �n the relevant sect�on below. Many of these research recommendat�ons are s�m�lar to recommendat�ons made prev�ously (NRC, 1994, 2000, 2003, 2005; R�chardson et al., 1995). Although there has been progress �n the last decade, much �mportant work rema�ns to be done.

Measurements of Anthropogenic Sound Sources and Ambient Noise

Comprehens�ve and systemat�c measurements are needed of all relevant anthropogen�c sound sources that have a reasonable l�kel�hood of adversely affect�ng mar�ne mammal hear�ng or behav�or. Emp�r�cal measures of sound f�elds enable more accurate est�mat�on of RLs us�ng propagat�on models and val�date the select�on of d�fferent propagat�on models as appropr�ate. Such stud�es must report the full range of relevant stan-dard acoust�c measurements and should �nclude deta�led �nformat�on about equ�pment cal�brat�on and/or propagat�on model�ng methods used (e.g., Goold & F�sh, 1998; Wales & He�tmeyer, 2002; Blackwell et al., 2004a). Measurements are also needed to descr�be cond�t�ons where sounds clas-s�f�ed as pulses at the source trans�t�on to non-pulse exposures. To measure in situ exposures from spec�f�c sound sources, arch�val acoust�c

tags should be deployed on free-rang�ng mar�ne mammals and/or platforms near the an�mals �n controlled exposure cond�t�ons.

If future no�se exposure cr�ter�a are to cons�der the �mportant matters of aud�tory mask�ng, cumu-lat�ve exposure effects on �nd�v�duals, and ecosys-tem effects (d�scussed below), add�t�onal data are needed concern�ng amb�ent ocean no�se on var�-ous spat�al and temporal scales. These data should be used to determ�ne how amb�ent no�se “budgets” vary as a funct�on of natural and human act�v�-t�es. These data w�ll need to be �ntegrated w�th expanded �nformat�on on mar�ne mammal abun-dance and d�str�but�on. The NRC (2003) recom-mended that a systemat�c effort be made to obta�n pass�ve acoust�c data, �nclud�ng average (steady-state) amb�ent no�se from 1 Hz to 200 kHz, and �nclud�ng trans�ent human sources not �dent�f�ed �n class�cal amb�ent no�se measurements. We concur and call for w�de-rang�ng acoust�c measurements des�gned to test expl�c�t hypotheses about spat�al and temporal var�ab�l�ty �n mar�ne amb�ent no�se.

Marine Mammal Auditory Processes

“Absolute”HearingDataFuture �terat�ons of these cr�ter�a w�ll be s�g-n�f�cantly �mproved by �ncreased knowledge of hear�ng sens�t�v�ty der�ved from behav�oral and electrophys�olog�cal measurements and anatom�-cal models. The most press�ng needs are for data on deep-d�v�ng cetaceans such as beaked whales and on low-frequency spec�al�sts (myst�cetes). Better �nformat�on on �nter-spec�es d�fferences �s also needed to val�date the funct�onal hear�ng groups used here or alternat�vely to �dent�fy other relevant subd�v�s�ons (e.g., phoc�d vs otar��d p�n-n�peds or potent�al part�t�on�ng of m�d-frequency cetaceans). The number of �nd�v�duals tested should be �ncreased �n all spec�es, w�th the pos-s�ble except�on of the bottlenose dolph�n, �n order to better understand �nd�v�dual d�fferences w�th�n spec�es. Hear�ng sens�t�v�ty across the full func-t�onal hear�ng range should be measured, where poss�ble, rather than just those frequenc�es con-ta�ned w�th�n the commun�cat�on s�gnals of spe-c�es be�ng �nvest�gated.

Improvements are needed �n both electro-phys�olog�cal and behav�oral test�ng methods to �ncrease the number of �nd�v�duals of each spe-c�es that can be tested, and to d�st�ngu�sh absolute



Table 24. Research recommendat�ons �n var�ous subject areas needed to enhance future mar�ne mammal no�se exposure cr�ter�a (as d�scussed �n Chapter 5)

Research top�c General descr�pt�on Cr�t�cal �nformat�on needs

Acousticmeasurementsofrelevantsoundsources

Deta�led measurements needed of source levels, frequency content, and rad�ated sound f�elds around �ntense and/or chron�c no�se sources.

Comprehens�ve, cal�brated measurements of the propert�es of human-generated sound sources, �nclud�ng frequency-dependent propagat�on and rece�ved character�st�cs �n d�fferent env�ronments.

Ambientnoisemeasurements

Systemat�c measurements of underwa-ter amb�ent no�se are needed to quan-t�fy how human act�v�t�es are affect�ng the acoust�c env�ronment.

Comprehens�ve, cal�brated measurements of amb�-ent no�se, �nclud�ng spectral, temporal, and d�rect�onal aspects, �n d�fferent ocean�c env�ronments; amb�ent no�se “budgets” �nd�cat�ng relat�ve contr�but�on of natural and anthropogen�c sources and trends over t�me.

“Absolute”hearingmeasurements

Aud�ometr�c data are needed to deter-m�ne funct�onal bandw�dth, spec�es and �nd�v�dual d�fferences, dynam�c hear�ng ranges, and detect�on thresholds for real�st�c b�olog�cal st�mul�.

Carefully controlled behav�oral and electrophys�olog�cal measurements of hear�ng sens�t�v�ty vs frequency for more �nd�v�duals and spec�es, part�cularly for h�gh-pr�or�ty spe-c�es, such as beaked whales and myst�cetes. Also, detec-t�on thresholds for complex b�olog�cal s�gnals.

Auditorysceneanalysis

Measurements to determ�ne the soph�s-t�cated perceptual and process�ng capa-b�l�t�es of mar�ne mammals that enable them to detect and local�ze sources �n complex, 3-D env�ronments.

Measurements of stream segregat�on, spat�al percept�on, mult�d�mens�onal source local�zat�on, frequency d�scr�m�-nat�on, temporal resolut�on, and feedback mechan�sms between sound product�on and hear�ng systems.

Marinemammalbehavioralresponsestosoundexposure

Measurements of behav�oral react�ons to var�ous sound types are needed, �nclud�ng all relevant acoust�c, contex-tual, and response var�ables.

Carefully constructed observat�onal and exposure exper�-ments that cons�der not only RL but also source range, mot�on, s�gnal-to-no�se rat�o, and deta�led �nformat�on on rece�vers, �nclud�ng basel�ne behav�or, pr�or exper�ence w�th the sound, and responses dur�ng exposure.

Effectsofsoundexposureonmarinemammalhearing:masking,TTS,andPTS

Cont�nued effort �s needed on the s�multaneous and res�dual phys�olog�-cal effects of no�se exposure on mar�ne mammal hear�ng.

Masked hear�ng thresholds for s�mple st�mul� �n more spe-c�es and �nd�v�duals, as well as complex b�olog�cal s�gnals and real�st�c maskers; allowance for d�rect�onal effects; comparat�ve data on TTS-onset and growth �n a greater number of spec�es and �nd�v�duals for nonpulse and pulsed anthropogen�c sources; recovery funct�ons after exposures and between repeated exposures.

Effectsofsoundexposureonmarinemammalnon-auditorysystems

Phys�olog�cal measurements are needed for both acute and chron�c sound expo-sure cond�t�ons to �nvest�gate effects on non-aud�tory systems.

Var�ous basel�ne and exposure-cond�t�on measurements, �nclud�ng n�trogen saturat�on levels; bubble nucle�; the format�on of hemorrhages, embol�, and/or les�ons; stress hormones; and card�ovascular responses to acute and chron�c no�se exposure.

Particularlysensitivespecies:beakedwhales

Basel�ne and exposure data on these poorly understood taxa to assess the�r apparent sens�t�v�ty to certa�n anthropo-gen�c sound sources.

Var�ous stud�es, �nclud�ng measurements and model�ng related to (1) hear�ng sens�t�v�ty, (2) d�v�ng and vocal�za-t�on parameters, (3) t�ssue propert�es, (4) gas/fat embol� format�on and s�gn�f�cance, (5) advanced detect�on capa-b�l�t�es for local�z�ng and track�ng them, and (6) behav-�oral react�ons to var�ous anthropogen�c and natural sound sources.

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from masked thresholds. Aud�tory evoked poten-t�al (AEP) techn�ques should cont�nue to be �mproved and standard�zed for p�nn�peds and small cetaceans. Researchers should cont�nue to develop procedures appl�cable to stranded �nd�-v�duals of spec�es generally not represented �n capt�ve sett�ngs, part�cularly for spec�es that may be espec�ally sens�t�ve to certa�n types of acous-t�c exposure. The mass�ve body s�ze of myst�cetes may requ�re that AEP stud�es beg�n us�ng smaller spec�es (e.g., m�nke whale) that may be stranded, trapped �n t�dal f�sh�ng enclosures (we�rs), or tem-porar�ly ava�lable �n a hold�ng fac�l�ty. Behav�oral aud�ometr�c methods, wh�ch �nvest�gate the effect of the overall perceptual and cogn�t�ve system on detect�on, should also cont�nue to be employed and �mproved, part�cularly those that �ncrease the speed w�th wh�ch results are obta�ned w�thout sac-r�f�c�ng prec�s�on of measurements.

Add�t�onally, behav�oral methods should be developed to measure hear�ng character�st�cs that requ�re a subject�ve judgment of percept�on such as evaluat�on of equal loudness between two acoust�c st�mul�. Equal-loudness hear�ng contours for mar�ne mammals are needed to ref�ne the broad frequency-we�ght�ng networks der�ved here.

A f�nal cons�derat�on �s that behav�oral aud�o-metr�c research should eventually move beyond the use of relat�vely s�mple art�f�c�al st�mul� (e.g., pure tones, no�se bands, broadband cl�cks, tone p�ps). Such st�mul� can be prec�sely controlled and can be used to clearly �nd�cate wh�ch acoust�c feature tr�ggers the response �n the whole an�mal or �ts aud�tory system. An�mals �n nature, how-ever, rarely encounter such sounds. Wh�le some b�olog�cal s�gnals cons�st of comb�nat�ons of tonal elements, most are exceed�ngly complex. Mar�ne mammal detect�on thresholds for complex, b�o-log�cally relevant st�mul� may be poorly pred�cted by exper�ments us�ng s�mple art�f�c�al st�mul�. Humans, for example, are part�cularly adept at �dent�fy�ng speech-l�ke sounds �n no�se (Yost, 2000). An�mals are expected to be s�m�larly sens�-t�ve to �mportant natural sounds. To base future no�se cr�ter�a on more relevant aud�ometr�c data, research �s needed on detect�on thresholds for b�o-log�cally mean�ngful sounds, such as vocal�zat�ons of conspec�f�cs, prey, and predators, and sounds needed for act�ve or pass�ve acoust�c nav�gat�on. Such measurements w�ll further be useful �n �nves-t�gat�ng the potent�al act�ve space (detect�on range �n three d�mens�ons) for acoust�c commun�cat�on (e.g., Brenow�tz, 1982; Jan�k, 2000; Au et al., 2004) and the effects of anthropogen�c sound on the act�ve space. F�eld stud�es us�ng b�olog�cally relevant sounds would be more relevant to real-world commun�cat�on and mask�ng than stud�es �nvolv�ng s�mple, art�f�c�al test st�mul�.

AuditorySceneAnalysisWh�le basel�ne hear�ng �nformat�on �s clearly needed, urgently �n some cases, more advanced, comprehens�ve, and �nnovat�ve measurements are also needed that prov�de �ns�ght �nto the ways �n wh�ch an�mals use the�r aud�tory sense to der�ve deta�led �nformat�on about the�r surround�ng env�-ronment. For future �terat�ons of no�se exposure cr�ter�a to cons�der mult�ple st�mul� and cumula-t�ve effects, add�t�onal data w�ll be needed on sound local�zat�on �n three-d�mens�onal aud�tory space, frequency d�scr�m�nat�on, temporal resolu-t�on, and, spec�f�cally, detect�on of b�olog�cal s�g-nals �n complex sound f�elds.

Several stud�es of terrestr�al an�mals (MacDougall-Shackleton et al., 1998; Moss & Surlykke, 2001) have �nvest�gated how subjects process mult�ple acoust�c st�mul� that are s�mul-taneously present but d�ffer �n acoust�c s�gnature e�ther temporally or spat�ally. The acoust�c scene concept, ow�ng largely to the work of Bregman (1990), has the potent�al to play a major role �n the development and progress�on of acoust�c expo-sure cr�ter�a. Bregman draws powerful analog�es between modal�t�es of percept�on, �nclud�ng the fundamental ways �n wh�ch h�gher process�ng sys-tems assoc�ate common elements of complex st�m-ul� �n h�ghly cluttered perceptual env�ronments.

One analogy that Bregman (1990) makes w�th regard to the �nnate power of v�sual scene analys�s �s the ab�l�ty of the v�sual process�ng port�on of the human bra�n to est�mate object s�ze w�thout regard to d�stance. The �mpl�cat�on �s that the reverse �s true as well—�f the s�ze of someth�ng �s known, �ts d�stance can be �nferred from v�sual appear-ance. Extend�ng th�s ab�l�ty to an�mals that rely on underwater hear�ng to determ�ne d�stance, s�m�lar perceptual processes may occur. If so, mammals may determ�ne range by us�ng var�ous effects of the propagat�on med�um on sound transm�ss�on (e.g., presence of structured mult�-path s�gnal spread�ng, frequency dependent mult�-path losses, and absorpt�on effects �n part�cular; Ell�son & We�xel, 1994). Further, both loudness modulat�on and source movement relat�ve to the rece�ver pro-v�de s�gn�f�cant clues as to the d�stance and general nature of the sound source. If one cons�ders sound to play a role �n the l�fe of mar�ne w�ldl�fe s�m�lar to that of s�ght �n terrestr�al an�mals, then context clues such as tempo, encroachment, and prox�m�ty must take on a powerful role �n determ�n�ng an an�-mal’s response to any g�ven sound. These hypoth-eses need to be stud�ed �n mar�ne mammals.


Behavioral Responses of Marine Mammals to Sound

There �s an urgent need for better and more exten-s�ve data on behav�oral responses to sound, �nclud-�ng measurement of the spec�f�c acoust�c features of exposures and cons�derat�on of prev�ous expe-r�ence w�th the sound and all relevant contextual var�ables. The current behav�oral exposure cr�ter�a are qu�te l�m�ted �n several ways. Insuff�c�ent data ex�st to support cr�ter�a other than those based on SPL alone, and th�s metr�c fa�ls to account for the durat�on of exposure beyond the separat�on of pulse from nonpulse sounds. Also, there �s much var�ab�l�ty �n responses among spec�es of the same funct�onal hear�ng group and also w�th�n spec�es.

Because of the poorly understood mod�fy-�ng �nfluences of numerous var�ables, behav�oral responses usually cannot be pred�cted a prioriw�th much conf�dence g�ven present �nformat�on. In add�t�on, the b�olog�cal s�gn�f�cance of any observed behav�oral response �s even more d�ff�-cult to assess (NRC, 2005).

Research �s needed to quant�fy behav�oral reac-t�ons of a greater number of free-rang�ng mar�ne mammal spec�es to spec�f�cally controlled or well-character�zed exposures from d�fferent human sound sources. The most d�rect way to obta�n these k�nds of extremely deta�led data would be to attach acoust�c dos�meter tags to �nd�v�duals and d�rectly measure no�se exposure, behav�oral response, and phys�olog�cal changes, �f any. It �s essent�al that future research �nvest�gates responses �n con-texts as s�m�lar as poss�ble to those of �nterest. Responses of both naïve and prev�ously exposed �nd�v�duals should be stud�ed and d�st�ngu�shed to the greatest extent poss�ble.

Further, such exper�ments must ensure that all relevant acoust�c measurements of sound exposure be reported more systemat�cally than �n many pre-v�ous stud�es. Spec�f�cally, behav�oral responses need to be d�rectly correlated w�th the phys�cal parameters (e.g., SPL, SEL) of the st�mul� most l�kely to evoke the responses. Such research clearly requ�res greater knowledge of exposure parameters (�nclud�ng SPL over some durat�on) than currently ex�sts for most stud�es.

The relat�onsh�p between exposure SPL and/or SEL and behav�oral react�on should be determ�ned for representat�ve spec�es w�th�n each funct�onal hear�ng group. Whether the relat�onsh�p follows a dose-response-l�ke funct�on for var�ous sound types, and under what cond�t�ons, �s a s�gn�f�cant and press�ng open quest�on.

We need more data on the magn�tude and t�me course of behav�oral responses to known no�se exposures to test the val�d�ty of concepts outl�ned here, and to make progress toward �dent�fy�ng

spec�f�c behav�oral cr�ter�a. Duty cycle (the pro-port�on of t�me when the no�se �s present) �s also l�kely to be �mportant. Magn�tude and durat�on of response are the most read�ly quant�f�ed param-eters that may be useful �n determ�n�ng whether a behav�oral response �s l�kely to have a b�olog�-cally mean�ngful outcome. No�se exposure cr�ter�a should attempt to d�st�ngu�sh between m�nor, tem-porary behav�oral changes and those w�th greater s�gn�f�cance. Th�s �s necessary �n order to focus on b�olog�cally s�gn�f�cant behav�oral responses (see NRC, 2005) and the exposure cond�t�ons that el�c�t them.

Cons�der�ng the many contextual cues that free-rang�ng an�mals use to perce�ve and character�ze sound sources and to determ�ne a response, �t �s not surpr�s�ng that our analys�s revealed a h�gh degree of var�ab�l�ty �n behav�oral responses as a funct�on of RL. Consequently, the log�c of rely�ng solely on exposure RL as the metr�c for behav-�oral responses �s substant�ally d�m�n�shed. A host of var�ables add�t�onal to RL may be �mportant to mar�ne mammals �n assess�ng a sound and determ�n�ng how to react. Th�s argues for care-ful des�gn and execut�on of controlled exposure exper�ments to repl�cate the s�gnal of �nterest �n as many d�mens�ons as poss�ble. Ser�ous con-s�derat�on should be g�ven to develop�ng a broad mult�-var�able approach to behav�oral research that takes �nto account not only source type and exposure level but also d�stance, mot�on, and rela-t�ve s�gnal-to-no�se rat�o. Some stud�es are already develop�ng data of the scale and qual�ty needed for such an approach. Th�s �ncludes stud�es pro-v�d�ng broad, long-term measurements of amb�-ent sounds �n areas cohab�ted by anthropogen�c sources and mar�ne w�ldl�fe. Where these stud�es �nclude remotely deployed pass�ve acoust�c sen-sors and tagged an�mals, they approach what may become the new standard. As add�t�onal �nfor-mat�on becomes ava�lable, future no�se exposure cr�ter�a may assess behav�oral react�ons not only accord�ng to RL measured w�th mult�ple acoust�c parameters, range (near and far), relat�ve mot�on (towards, parallel, etc.), and rate of change, but also �n relat�on to the an�mal’s act�v�ty or per-ceptual s�tuat�on (e.g., neutral; threatened, as by a predator; or pos�t�ve, related to food, mat�ng, etc.).

The role of hab�tuat�on and sens�t�zat�on �n behav�oral react�ons to no�se exposure �s a cr�t�-cal subject for future research. These processes can only be stud�ed under controlled or well-def�ned cond�t�ons (as �n Deecke et al., 2002). A key quest�on �s how hab�tuat�on and sens�t�zat�on develop w�th repeated exposure �n spec�f�c eco-log�cally relevant c�rcumstances. For example, the pattern of hab�tuat�on to a neutral st�mulus

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�s l�kely to follow qu�te a d�fferent pattern from select�ve hab�tuat�on to a harmless st�mulus that �s �n�t�ally perce�ved as a threat (Deecke et al., 2002). Furthermore, �t would be des�rable to know �f there are common acoust�c features �n sounds to wh�ch mar�ne mammals become sens�t�zed. For example, to wh�ch acoust�c features of a threat, such as a vessel used to hunt an�mals, does an an�mal become sens�t�zed?

Analyses of the behav�or of var�ous an�mal spe-c�es �n the presence of predators suggest that they have evolved ant�-predator responses that m�rror the�r responses to human d�sturbance. Accord�ng to predat�on r�sk theory, var�ous ecolog�cal con-s�derat�ons beyond s�mply d�sturbance magn�tude are very l�kely �nvolved �n determ�n�ng and pre-d�ct�ng behav�oral response (Fr�d & D�ll, 2002).

The b�olog�cal relevance of behav�oral changes can only be determ�ned �n natural populat�ons �n wh�ch v�tal l�fe h�story parameters (e.g., reproduc-t�on, growth, and surv�val rates) can be measured before and after no�se exposure and �n cond�t�ons where other potent�al stressors have been controlled (NRC, 2005). One �mportant quest�on �s whether these l�fe h�story parameters are the same �n popu-lat�ons that have apparently hab�tuated to expo-sure and rema�n �n relat�vely no�sy env�ronments as they are �n populat�ons l�v�ng �n qu�eter cond�-t�ons. Because of the apparently major �nfluence of exper�ence and the strong context-spec�f�c�ty of behav�oral responses to no�se, f�eld measurements must be made for long per�ods follow�ng repeated or cont�nual exposure. Long�tud�nal stud�es should be conducted to assess the t�me course of expo-sure to var�ous ex�st�ng sound sources known or suspected to cause relat�vely long-term (seasonal) hab�tat abandonment. Where poss�ble, parallel stud�es should be done �n ne�ghbor�ng areas w�th d�fferent levels of no�se exposure. Such stud�es should allow for other non-acoust�c factors l�kely to affect d�str�but�on such as predators, prey, and other �mportant env�ronmental covar�ates. These stud�es w�ll often need to extend over long per�-ods (many years) �n order to be effect�ve, and they should be planned and funded recogn�z�ng that. Ideally, such a study should start collect�ng data well �n advance of the �ntroduct�on of anthropo-gen�c no�se, and cont�nue throughout the per�od of ant�c�pated �mpact and for long enough thereafter to observe return to basel�ne.

Effects of Noise Exposure on Marine Mammal Hearing and Other Systems

AuditoryMaskingAud�tory mask�ng �s l�kely the most w�despread effect of anthropogen�c no�se on populat�ons of mar�ne mammals. The pr�nc�ples of mask�ng are

reasonably well-known from laboratory stud�es �n mammals, �nclud�ng mar�ne mammals. To enable mask�ng to be �ncluded �n subsequent no�se expo-sure cr�ter�a, however, data are needed on mask-�ng and �ts effects �n real-world cond�t�ons for all funct�onal hear�ng groups. Data are needed on the mask�ng effects of natural and anthropo-gen�c no�se sources; on detect�on of s�mple, art�f�-c�al st�mul�; and, �ncreas�ngly, on more complex, b�olog�cally mean�ngful s�gnals. D�rect�onal�ty �n the mask�ng sound and/or the s�gnal of �nterest �s very l�kely to affect the sever�ty of mask�ng and needs to be cons�dered. Basel�ne measurements are needed on funct�onal commun�cat�on ranges for d�fferent acoust�c s�gnals and on the reduct�on of those ranges caused by e�ther natural or anthro-pogen�c maskers. Also needed are add�t�onal f�eld measurements of the behav�oral adjustments that mar�ne mammals make to offset mask�ng effects (e.g., Lesage et al., 1999; Serrano & Terhune, 2002; Foote et al., 2004; Sche�fele et al., 2005).

TemporaryThresholdShift(TTS)TTS stud�es �n mar�ne mammals rema�n l�m�ted to a very few spec�es and �nd�v�duals, l�m�t�ng the certa�nty w�th wh�ch they may be extrapolated w�th�n and among groups. A number of spec�f�c TTS stud�es are needed to �mprove future cr�te-r�a. For �nstance, �t �s cr�t�cal to future �terat�ons of these no�se exposure cr�ter�a that research on TTS-onset, TTS growth w�th no�se exposure, and recovery rates expands to larger numbers of �nd�-v�duals and spec�es, and to spec�es �n the low- and h�gh-frequency cetacean groups. Presently, extrap-olat�on procedures must be used because TTS data are unava�lable for certa�n funct�onal hear�ng groups. Add�t�onally, certa�n h�ghly precaut�onary procedures are used here �n the est�mat�on of PTS-onset because the growth rate of TTS w�th �ncreas-�ng exposure level �s generally poorly understood, even for the few mar�ne mammal spec�es �n wh�ch TTS has been stud�ed. The relat�onsh�p between aud�tory sens�t�v�ty and suscept�b�l�ty to TTS/PTS should be determ�ned by group.

To the extent poss�ble, electrophys�olog�cal techn�ques should be used to obta�n these TTS data to �ncrease sample s�ze and knowledge of recovery funct�ons.

More data for p�nn�peds also are needed, par-t�cularly for pulse exposures where extrapolat�ons of cetacean data currently must be used. Part�cular emphas�s should be placed on determ�n�ng whether harbor seals have �ncreased sens�t�v�ty to no�se exposure relat�ve to other p�nn�ped spec�es, as current �nformat�on suggests, and �f so, whether spec�es closely related to the harbor seal also are more sens�t�ve than are other p�nn�peds.


To m�n�m�ze the need for such extrapolat�on and reduce the assumpt�ons requ�red to pred�ct PTS-onset, emp�r�cal data are needed on TTS growth rates up to greater sh�ft magn�tudes (10 to 30 dB). These data are needed for both pulse and nonpulse sound types, at a var�ety of exposure fre-quenc�es, �n both s�ngle and mult�ple exposures. These results should further eluc�date whether, and �n what cond�t�ons, the “equal energy hypoth-es�s” may be appropr�ate for compar�ng the effects of var�able no�se exposures �n mar�ne mammals. For pulse exposures, part�cular attent�on should be pa�d to whether TTS growth �s d�rectly related to overall no�se energy, and whether the kurtos�s of exposure �s also a factor (see Erdre�ch, 1986; Th�ery & Meyer-B�sch, 1988; Dunn et al., 1991; Hamern�k et al., 1993, 2003).

A further top�c for future research �s deter-m�n�ng whether us�ng 40 dB of TTS as a proxy for PTS-onset �s a precaut�onary approach, and whether TTSs on the order of 25 to 35 dB are fully recoverable �n mar�ne mammals as expected from terrestr�al mammal data. To avo�d any poss�b�l�ty of �njury, such stud�es should cont�nue to take a precaut�onary approach, us�ng gradual �ncreases �n exposure level and durat�on.

A related quest�on �s how TTS recovers fol-low�ng no�se cessat�on �n var�able cond�t�ons. Data on recovery funct�ons and TTS magn�tude are needed for representat�ve spec�es from each funct�onal hear�ng group. Electrophys�olog�cal techn�ques may be part�cularly useful �n th�s regard. These data may be useful �n compar�ng bas�c aud�tory system responses to no�se exposure and determ�n�ng how summat�on procedures for mult�ple exposures should be mod�f�ed to more prec�sely cons�der exposure �nterm�ttence. Levels of relat�vely long durat�on no�se exposure caus�ng asymptot�c TTS, �n wh�ch TTS values do not con-t�nue to �ncrease �n magn�tude w�th exposure but may have longer-last�ng effects, should be deter-m�ned. Recovery funct�ons from asymptot�c TTS of var�ous levels should be compared w�th recov-ery funct�ons from non-asymptot�c TTS.

F�nally, the ex�stence of a staped�al reflex �n mar�ne mammals and �ts poss�ble role �n m�t�gat-�ng TTS and other effects of �ntense no�se expo-sure are areas of needed research. For certa�n no�se exposures, part�cularly those w�th relat�vely low frequenc�es and long durat�on, the m�ddle ear muscles (tensor tympan� and staped�al) of terres-tr�al mammals may contract and reduce the ampl�-fy�ng funct�on of the oss�cular cha�n (Yost, 2000). Th�s muscular contract�on reduces the amount of acoust�c energy transm�tted �nto the cochlea v�a the stapes. Th�s staped�al reflex has been demon-strated �n humans exposed to �ntense sound (Dav�s et al., 1955) as well as echolocat�ng bats exposed

to the�r own �ntense outgo�ng cl�cks (Henson, 1965). The m�ddle ears of mar�ne mammals have some spec�al�zed adaptat�ons relat�ve to terrestr�al mammals (see Wartzok & Ketten, 1999). In water, �f bone conduct�on (rather than oss�cular conduc-t�on) �s the predom�nant transm�ss�on path, �t �s poss�ble that a staped�al reflex, �f present, may have l�m�ted or no protect�ve funct�on for �ntense acoust�c exposures. Research �s also needed on the role of meatal closure �n p�nn�peds dur�ng no�se exposure. Such closures could be an alternat�ve or add�t�onal way of reduc�ng aud�tory sens�t�v�ty. E�ther mechan�sm could also affect the �nterpreta-t�on of threshold �f performed dur�ng aud�ometr�c measurements.

PermanentThresholdShift(PTS)Sound exposures caus�ng PTS-onset, used here to def�ne �njury from acoust�c exposure, have not been measured �n mar�ne mammals. Instead, exposures that would cause PTS-onset are est�-mated from measured TTS-onset us�ng assump-t�ons about the growth of TTS w�th no�se expo-sure level. D�rect measurements of PTS �n mar�ne mammals are h�ghly des�rable for establ�sh�ng future �njury cr�ter�a, but they are unl�kely to be obta�ned due to eth�cal, legal, and/or pract�cal cons�derat�ons. Data from model�ng and exposure of cadavers to very �ntense acoust�c st�mul� g�ve some �nd�cat�on of cond�t�ons caus�ng PTS but do not reveal the exposure cond�t�ons that produce PTSinvivo, nor act�ve processes that affect bas�-lar membrane d�splacement. Consequently, our research recommendat�ons for �mprov�ng PTS-onset pred�ct�ons for mar�ne mammals �nvolve more �nd�rect measures.

One recommended type of �nd�rect measure �s to compare age-related hear�ng changes �n capt�ve �nd�v�duals that have been �nvolved �n TTS exper�-ments w�th those that have not. Th�s compar�son may prov�de some �ns�ght �nto the complex rela-t�onsh�p between repeated TTS and PTS, wh�ch rema�ns poorly understood for terrestr�al mam-mals, �nclud�ng humans. One ma�n �mped�ment, however, �s that confound�ng var�ables l�kely ex�st other than controlled no�se exposure. For capt�ve �nd�v�duals used �n TTS stud�es, absolute hear-�ng should be tested both dur�ng and follow�ng sequences of no�se exposure exper�ments. For capt�ve �nd�v�duals not used �n TTS exper�ments, absolute hear�ng should be measured at regular �ntervals over extended per�ods. The latter group may more read�ly d�splay natural age-related hear-�ng loss (presbycusis) than the former, as well as potent�al sex d�fferences. For both groups, efforts should be made to character�ze long-term amb�ent no�se cond�t�ons exper�enced by test an�mals.

480 Southalletal.

Non-AuditoryEffectsofNoiseExposureLack of spec�f�c data on acoust�c exposures caus-�ng non-aud�tory effects �n mar�ne mammals cur-rently prevents der�v�ng expl�c�t exposure cr�ter�a for such effects. Research �s underway, however, that may make th�s poss�ble �n future vers�ons of the cr�ter�a. Non-aud�tory effects of no�se are potent�ally s�gn�f�cant but rema�n generally poorly understood.

A current hypothes�s regard�ng non-aud�-tory effects �s that acoust�c exposure may pro-duce n�trogen bubbles �n blood or other t�ssues. Hemorrhages, gas and fat embol�, and other les�ons have been reported �n some mar�ne mam-mals exposed to m�d-frequency m�l�tary sonar (Jepson et al., 2003; Fernández et al., 2004, 2005). Substant�al emp�r�cal quest�ons rema�n, however. F�rst among these �s whether n�trogen bubbles are �n fact respons�ble for the hemorrhages, embol�, and other les�ons reported. Conversely, are enough n�trogen bubbles produced to pose a r�sk of related t�ssue �njur�es, under any set of c�rcumstances, ar�s�ng from h�gh n�trogen supersaturat�on levels, acoust�c exposure, and/or drast�c changes �n behav-�or? Do h�gh levels of n�trogen supersaturat�on or gas or fat embol� occur �n d�v�ng mammals that have not been exposed to �ntense anthropogen�c sound? Do these or related phenomena occur �n spec�es other than beaked whales? If bubble for-mat�on �s acoust�cally med�ated, does �t occur as a d�rect result of acoust�c exposure of bubble precursors (nucle�) �n t�ssue, or �nd�rectly through changes �n d�v�ng behav�or? If the pathway �s d�rect, how does bubble format�on and/or growth occur? A more thorough understand�ng �s needed of l�p�d b�ochem�stry �n t�ssues that may be par-t�cularly sens�t�ve to acoust�cally med�ated bubble format�on (e.g., acoust�c fats). Model�ng stud�es are needed on t�ssue propert�es and the�r relevance to n�trogen bubble format�on at spec�f�c frequen-c�es of �nterest. These stud�es should cons�der the growth of d�screte bubbles from precursors �n var-�ous t�ssues, and the �nteract�on among coalesced aggregat�ons of acoust�cally act�vated bubbles.

If the pathway �s �nd�rect and med�ated by behav-�or, �s rap�d surfac�ng more r�sky than rema�n�ng submerged too long and exceed�ng phys�olog�cal l�m�ts? How does the d�ve prof�le affect the l�m�ts of n�trogen supersaturat�on �n normal d�v�ng? Do h�gh levels of n�trogen supersaturat�on and gas embol� occur �n mar�ne mammals that have voluntary control over depth, d�v�ng prof�le, and �nter-d�ve �nterval? Resolut�on of these quest�ons �s l�kely to requ�re �nterplay between model�ng and emp�r�cal measurements (Z�mmer & Tyack, 2007).

In conjunct�on w�th the above phys�olog�cal model�ng and measurements, controlled expo-sure exper�ments should be conducted w�th

deep-d�v�ng mar�ne mammals to determ�ne behav-�oral responses to sound sources, �nclud�ng sonar. These exper�ments should use real�st�c source and rece�ved levels. If responses are �dent�f�ed, th�s may �dent�fy s�tuat�ons where �t would be useful to conduct observat�onal stud�es of responses dur�ng uncontrolled use of anthropogen�c sound sources. Research should character�ze the changes �n d�v�ng behav�or and should determ�ne what they mean �n terms of bubble format�on or growth w�th cont�nued exposure.

Other poss�ble non-aud�tory effects of acoust�c exposure should be �nvest�gated as well. Stress hormone levels assoc�ated w�th no�se exposure should be more fully �nvest�gated. As of now, they have been �nvest�gated follow�ng exposure of capt�ve odontocetes to h�gh-level sound (Thomas et al., 1990c; Romano et al., 2004). The ab�l�ty of an�mals to recru�t effect�ve stress responses should also be stud�ed dur�ng chron�c exposures—for example, �n capt�ve an�mals that l�ve permanently �n no�sy vs qu�et env�ronments. Effects of no�se exposure on mar�ne mammal vest�bular and car-d�ovascular systems should also be stud�ed.

Particularly Sensitive Species

In rare c�rcumstances, mar�ne mammals (pr�mar-�ly beaked whales) have been known to strand and ult�mately d�e follow�ng exposure to tact�cal, m�d-frequency act�ve sonar (see Cox et al., 2006; Nowacek et al., 2007). Our knowledge of these k�nds of extreme react�ons to acute exposures rema�ns poor. However, the ava�lable �nforma-t�on suggests that at least some spec�es of beaked whales are part�cularly sens�t�ve to th�s one spe-c�f�c category of sound sources.

Gas bubble format�on �s a hypothes�zed path-way of th�s effect (e.g., Fernández et al., 2005), but �t rema�ns poorly understood and the prec�se mechan�sm underly�ng these strand�ngs rema�ns unknown (e.g., Cox et al., 2006). The controlled exposure exper�ments outl�ned above are essent�al to reveal�ng the cond�t�ons and responses underly-�ng th�s effect. Unt�l such research �s conducted, der�v�ng sc�ence-based exposure cr�ter�a spec�f�-cally for beaked whales or other deep-d�v�ng ceta-ceans exposed to act�ve sonar w�ll prove d�ff�cult or �mposs�ble.

One current hypothes�s �s that behav�oral reac-t�ons �nfluence beaked whale d�v�ng patterns �n a way that �nduces phys�cally deb�l�tat�ng or d�sor�-ent�ng �njur�es (Cox et al., 2006). Both the spec�f-�cs of th�s potent�al mechan�sm and whether �t �s spec�f�c to beaked whales rema�ns unknown, how-ever. Mammals, �nclud�ng some mar�ne mammals, show strong avo�dance responses when evad�ng predators. Sounds from tact�cal m�d-frequency


sonars somewhat resemble, �n frequency band and modulat�on, the soc�al s�gnals of one of the only predators of large mar�ne mammals, the k�ller whale. If beaked whales �nher�t a broad tem-plate for acoust�c detect�on of these predators, as waterfowl do for v�sual detect�on of aer�al preda-tors (Lorenz, 1939; T�nbergen, 1948), they m�ght respond to sonar as �f �t were a predator. Learn�ng �s requ�red for select�ve hab�tuat�on to safe st�m-ul� that resemble those from predators (Deecke et al., 2002). Many of the strand�ngs that co�nc�de w�th sonar exerc�ses have occurred �n s�tes where k�ller whales are rare. Poss�bly these stranded an�mals have not had enough exper�ence w�th e�ther sonar or k�ller whales to learn the d�ffer-ence. Propagat�on of sound �n the ocean may also degrade acoust�c features that help d�fferent�ate the two classes of st�mul� at a d�stance. It �s plau-s�ble that th�s type of react�on could occur at rela-t�vely long d�stances from the source �f the sound �s alarm�ng based on propert�es other than h�gh RL.

Whether beaked whales �n certa�n cond�t�ons m�stake tact�cal m�d-frequency sonar s�gnals for k�ller whales and consequently change the�r behav�or �n a way that �njures them �s an emp�r�-cal quest�on. Th�s should be carefully �nvest�gated us�ng controlled exper�ments that take �nto account the relevant contextual var�ables d�scussed above. Add�t�onal basel�ne data on beaked whale phys�-ology, l�fe h�story, and behav�or are also needed to appropr�ately address quest�ons regard�ng the apparent sens�t�v�ty of these an�mals to certa�n k�nds of anthropogen�c sound. F�nally, �n some spec�f�c cond�t�ons, such as sonar tra�n�ng ranges, where soph�st�cated l�sten�ng arrays make �t pos-s�ble to detect mar�ne mammals over large ranges before and dur�ng act�ve sonar operat�ons, act�ve or pass�ve detect�on of mar�ne mammal behav-�oral patterns may become �ncreas�ngly poss�ble. Wh�le these observat�ons have l�m�tat�ons, g�ven that they may be able to detect more �nd�v�duals w�thout requ�r�ng tagg�ng efforts, they may be an �mportant complement to d�rected exper�ments.

Some other spec�es of mar�ne mammals are unusually respons�ve to certa�n anthropogen�c sounds, e�ther generally or under part�cular cond�-t�ons, and th�s can result �n strong and somet�mes large-scale avo�dance. Examples �nclude harbor porpo�ses and, �n some but not all s�tuat�ons, beluga and bowhead whales (F�nley et al., 1990; R�chardson et al., 1999; Oles�uk et al., 2002; M�ller et al., 2005). There �s a need for add�t�onal behav�oral and acoust�c �nformat�on to better char-acter�ze these extreme responses, the s�tuat�ons �n wh�ch they occur, and whether s�m�lar responses can occur �n other related spec�es or �n response to other s�m�lar st�mul�.

Necessary Progressions of Marine Mammal Noise Exposure Criteria

The currently proposed no�se exposure cr�ter�a are for �nd�v�dual sound exposures and �nd�v�dual mar�ne mammals. The research recommended above �s needed to substant�ate and �mprove future �terat�ons of these types of cr�ter�a. Future �tera-t�ons of behav�oral d�sturbance cr�ter�a may der�ve dose-response funct�ons based on an ord�nal scor-�ng parad�gm s�m�lar to that prov�ded. Th�s may occur for subcategor�es of sound sources w�th�n the general categor�es here (e.g., se�sm�c s�gnals as a subset of mult�ple pulses, vessel no�se as a subset of nonpulses). It may also occur for sub-groups of spec�es w�th�n the broad categor�es rec-ogn�zed here (e.g., phoc�d vs otar��d p�nn�peds) and for other types of mar�ne mammals not addressed here (e.g., s�ren�ans, sea otters, polar bears).

Future �terat�ons of these no�se exposure cr�ter�a should also perhaps d�st�ngu�sh several d�fferent categor�es of response that are expected, for both theoret�cal and emp�r�cal reasons, to vary w�th RL �n d�fferent ways. For example, �f an an�mal responds to a sound as �f �t were from a predator (Fr�d & D�ll, 2002), one would expect the dose-response funct�on to have a very d�fferent shape as compared to that �f the an�mal responds based on �nterference w�th the an�mal’s ab�l�ty to com-mun�cate acoust�cally or echolocate. Pred�ct�ng whether a sound m�ght tr�gger an ant�-predator response would requ�re more deta�led analyses of acoust�c parameters of the anthropogen�c sound compared to s�gnals of predators. Further, �n some non-mar�ne taxa, d�fferent ant�-predator responses may be tr�ggered depend�ng on levels and other character�st�cs of acoust�c st�mul� (Spangler, 1988; Hoy, 1989) and may be modulated by the cost of the response as well as the perce�ved r�sk (Fr�d & D�ll, 2002). Behav�oral ecolog�sts hypothes�ze that ant�-predator behav�or should balance r�sk of predat�on aga�nst cost of response, �nclud�ng cost of foregone benef�ts from alternat�ve act�v�t�es (Fr�d & D�ll, 2002). These non-acoust�c param-eters must be taken �nto account �n order to under-stand d�sturbance responses. The acoust�c param-eters affect�ng ant�-predator behav�or may �nvolve detect�on thresholds, amb�ent no�se cond�t�ons, source d�stance and source movement, as well as the more d�rect measures of rece�ved sound. In future stud�es, most or all of these parameters should be measured.

Add�t�onally, further exposure cr�ter�a are needed to fully cons�der the effects of anthropo-gen�c no�se on other types of mar�ne l�fe, �nclud-�ng the effects of s�ngle and mult�ple exposures on �nd�v�dual �nvertebrates, f�sh, and sea turtles as well as s�ren�ans, sea otters, and polar bears. There

482 Southalletal.

are fewer data to support cr�ter�a for mar�ne b�ota other than cetaceans and p�nn�peds, and cr�ter�a are perhaps as urgently (or more urgently) needed for some other groups. Some f�sh and most sea turtle spec�es are cons�dered threatened or endan-gered. The effects of anthropogen�c no�se on f�sh are also of part�cular �mportance g�ven the�r central role as both predators and prey �n many mar�ne ecosystems and because of human depen-dence on f�sher�es.

Add�t�onal cr�ter�a are also needed for the cumu-lat�ve effects of repet�t�ve or long-term no�se expo-sure on mar�ne mammals. Ideally, spat�otemporal data on mar�ne amb�ent no�se and long-term expo-sure h�stor�es of �nd�v�duals should be �ntegrated w�th v�tal rate data for mar�ne mammal popula-t�ons to address th�s quest�on. Cons�derably more data are needed on how no�se �mpacts �n s�ngle an�mals can be extended to the populat�on level. Such measurements w�ll l�kely requ�re extens�ve measurements on a few representat�ve spec�es and conservat�ve extrapolat�ons w�th�n and between funct�onal hear�ng groups.

No�se exposure cr�ter�a that cons�der ecosystem-level effects are needed as well. It �s poss�ble that the effects of no�se exposure on some elements of local food webs may have a cascade effect to other elements w�th�n the web. No data are ava�lable on the ecolog�cal effects of underwater no�se, even at a local scale. However, g�ven the upward trend �n human act�v�t�es �n many nearshore areas, such ecolog�cal effects should be ant�c�pated.

Progress �n each of these research areas w�ll �nvolve �terat�ve processes that depend on the ava�lab�l�ty of relevant sc�ent�f�c data. L�ke the process of �mprov�ng and expand�ng future no�se exposure cr�ter�a, our ab�l�ty to understand and pred�ct the effects of anthropogen�c no�se expo-sure on mar�ne ecosystems w�ll cont�nue to evolve over a per�od of many decades.

Acknowledgments

The authors acknowledge three former mem-bers of the mar�ne mammal no�se exposure cr�-ter�a group: Wh�tlow Au, Sam R�dgway, and Ronald Schusterman. Part�al f�nanc�al support for meet�ngs of the no�se exposure cr�ter�a group was prov�ded by the U.S. Nat�onal Ocean�c and Atmospher�c Adm�n�strat�on, Nat�onal Mar�ne F�sher�es Serv�ce, Ocean Acoust�cs Program.

The authors also apprec�ate the expert�se, rev�ew, and ass�stance of the follow�ng people: Laur�e Allen, Robyn Angl�ss, Dan Costa, Tara Cox, Ned Cyr, Adam Frankel, Ron Kastele�n, Steve Leathery, Rob McCauley, Dav�d Mell�nger, R�chard Merr�ck, Douglas Nowacek, Deborah Palka, M�chael Payne, Arthur Popper, Andrew

Solow, Sof�e Van Par�js, W�llem Verboom, Donna W�et�ng, and f�ve anonymous rev�ewers.

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Appendix A. Acoustic Measures and Terminology

Th�s append�x prov�des a more deta�led descr�p-t�on of many key acoust�c measurements and terms used throughout the no�se exposure cr�te-r�a. It �s not �ntended as an exhaust�ve or �nstruc-t�ve text on these exceed�ngly complex �ssues (for more deta�led treatments, see K�nsler et al., 1982; ANSI, 1986, 1994; R�chardson et al., 1995; Harr�s, 1998; NRC, 2003). Rather, �t �s �ntended to prov�de fa�rly stra�ghtforward def�n�t�ons and equat�ons related to the mar�ne mammal no�se exposure cr�ter�a.

Pulses and Nonpulse Sounds

The d�st�nct�on between these two general sound types �s �mportant because they have d�ffer�ng potent�al to cause phys�cal effects, part�cularly w�th regard to hear�ng (e.g., Ward, 1997).

Pulses, as used �n the context of th�s paper, are def�ned as br�ef, broadband, atonal, tran-s�ents (ANSI, 1986; Harr�s, 1998, Chapter 12). Examples of pulses (at least at the source) are explos�ons, gunshots, son�c booms, se�sm�c a�rgun pulses, and p�le dr�v�ng str�kes. These sounds are all character�zed by a relat�vely rap�d r�se from amb�ent pressure to a max�mal pressure value fol-lowed by a decay per�od that may �nclude a per�od of d�m�n�sh�ng, osc�llat�ng max�mal and m�n�mal pressures. The rap�d r�se-t�me character�st�c of these sounds ensures that they are also broad-band �n nature, w�th the h�gher-frequency com-ponents be�ng related to the rap�d�ty of the r�se-t�me. Pulses, e�ther as �solated events or repeated �n some success�on, generally have an �ncreased capac�ty to �nduce phys�cal �njury as compared w�th sounds that lack these features.

Nonpulse (intermittent or continuous) sounds can be tonal, broadband, or both. Some of these nonpulse sounds can be trans�ent s�gnals of short durat�on but w�thout the essent�al propert�es of pulses (e.g., rap�d r�se-t�me). Examples of sources produc�ng nonpulse sounds �nclude vessels; a�r-craft; mach�nery operat�ons, such as dr�ll�ng or w�nd turb�nes; and many act�ve sonar systems. The durat�on of such sounds, as rece�ved at a d�stance, can be greatly extended �n h�ghly reverberant env�-ronments. It �s cr�t�cal to note that a sound that has character�st�cs of a pulse at the source may, as a result of propagat�on effects, lose those charac-ter�st�cs at some (var�able) d�stance and could be character�zed as a nonpulse for certa�n rece�vers.

Pulses and nonpulses are d�st�ngu�shed here by an emp�r�cal approach based on several temporal we�ght�ngs. Var�ous exponent�al t�me-we�ght�ng funct�ons appl�ed �n measur�ng pulse and nonpulse sounds may y�eld d�fferent measured rece�ved levels (RLs) (see Harr�s, 1998). By way of �llus-trat�on, most sound level meters (SLM) prov�de opt�ons for apply�ng e�ther a slow or fast t�me constant (1,000 or 125 ms, respect�vely) for mea-sur�ng nonpulses, or an �mpulse t�me constant (35 ms) appropr�ate for measur�ng pulses. If appl�ed to a sound pulse, the slow or fast SLM sett�ngs result �n lower sound pressure level (SPL) mea-surements than those obta�ned us�ng the �mpulse sett�ng. Each of these t�me constants was selected based on the phys�cal propert�es of the human aud�tory system. It �s clear that further emp�r�-cal measures of temporal resolut�on �n mar�ne mammals are needed, part�cularly for an�mal taxa whose hear�ng extends to s�gn�f�cantly h�gher or lower frequenc�es than �n humans (see Chapter 5, “Research Recommendat�ons”). Future no�se cr�-ter�a are expected to �nclude d�st�nct�ons between pulse and nonpulse sounds that may be more spe-c�f�cally appropr�ate for mar�ne mammals than �s th�s current s�mple approach. We note also the need for an expl�c�t d�st�nct�on and measurement standard, such as ex�sts for aer�al s�gnals (ANSI, 1986).

Peak sound pressure �s the max�mum absolute value of the �nstantaneous sound pressure dur�ng a spec�f�ed t�me �nterval and �s denoted as Pmax �n un�ts of Pascals (Pa). It �s not an averaged pressure. Peak pressure �s a useful metr�c for e�ther pulse or nonpulse sounds, but �t �s part�cularly �mportant for character�z�ng pulses (ANSI, 1986; Harr�s, 1998, Chapter 12). Because of the rap�d r�se-t�me of such sounds, �t �s �mperat�ve to use an adequate sampl�ng rate, espec�ally when measur�ng peak pressure levels (Harr�s, 1998, Chapter 18).

Peak-to-peak sound pressure �s the algebra�c d�fference between the max�mum pos�t�ve and max�mum negat�ve �nstantaneous peak pressure.

The mean-squared pressure �s the average of the squared pressure over some durat�on. For nonpulse sounds, the averag�ng t�me �s any con-ven�ent per�od suff�c�ently long enough to perm�t averag�ng the var�ab�l�ty �nherent �n the type of sound. Note that some of the var�ab�l�ty of the rece�ved sound typ�cally ar�ses s�mply from the



relat�ve movement of a free-rang�ng an�mal and a source, whether the latter �s mov�ng or stat�onary.

Sound pressure levels (SPLs) are g�ven as the dec�bel (dB) measures of the pressure metr�cs def�ned above. The root-mean-square (RMS) SPL �s g�ven as dB re: 1 µPa for underwater sound and dB re: 20 µPa for aer�al sound. Peak SPLs are g�ven as dB re: 1 µPa (peak) �n water and dB re: 20 µPa (peak) �n a�r. Peak-to-peak SPLs are dB re: 1 µPa (peak-to-peak) �n water and dB re: 20 µPa (peak-to-peak) �n a�r. Source level (SL) �s the rece�ved level measured or est�mated 1 m from the source.

Duration �s the length of a sound, generally �n seconds. Durat�on �s �mportant because �t affects var�ous acoust�c metr�cs, �nclud�ng mean-square and/or RMS sound pressure (Madsen, 2005). Because of background no�se and reverbera-t�on, durat�on can be d�ff�cult to def�ne prec�sely. Var�ous def�n�t�ons of durat�on ex�st �n the l�tera-ture such as the t�me between the po�nts on the pressure-t�me waveform P(t) determ�ned to be e�ther 10 dB (0.316 t�mes) or 20 dB (0.1 t�mes) below the �nstantaneous peak pressure (Hamern�k & Hsueh, 1991). Malme et al. (1983, 1984) used a s�m�lar approach. Harr�s (1998, Chapter 11) sug-gested alternat�ve constructs, �nclud�ng exponen-t�al t�me we�ght�ng. Th�s top�c �s d�scussed below w�th regard to updat�ng measurement standards for �mpulse sounds. Greene (1997) descr�bed a pract�cal def�n�t�on of pulse durat�on based on the �nterval over wh�ch 90% of the sound energy arr�ved at the rece�ver. Th�s �nterval could also be used as the averag�ng t�me for mean-square pres-sure (Madsen, 2005). Th�s approach has been w�dely used �n measur�ng exposure durat�on and SPL values for se�sm�c a�rgun and p�le dr�v�ng s�g-nals (e.g., McCauley et al., 1998; Blackwell et al., 2004b). Def�ned as such, durat�on �s the �nterval between the 5% and 95% bounds of the t�me-�nte-gral of the �nstantaneous sound-pressure squared (sound exposure [E(t)] as def�ned below) wh�le account�ng for background no�se and low-level reverberat�on (assumed to be cont�nuous). That �s, the background no�se �s measured over a per�od of t�me before the pulse occurs and then �s subtracted from the cumulat�ve sum-of-square pressures to determ�ne the sum-of-square pressures from the �mpuls�ve sound alone. Th�s �s done by manually �dent�fy�ng a per�od of t�me (t1, t2) preced�ng the event, deemed to be representat�ve of amb�ent no�se. The mean-square pressure (�n Pa2) of the amb�ent (Pamb)2 �s determ�ned w�th the follow�ng relat�onsh�p:

Ú-=

2

1

)(1 2

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2t

t

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( )Ú -=t

t

ambtemp dtPtPtE2

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ÔÔ˝

¸

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P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(2) eq. The 0% sound exposure po�nt (ta) s�gn�f�es the

“start” of the acoust�c event and the 100% sound exposure po�nt (tb) s�gn�f�es the “end” of the event. These two po�nts are where the E(t) curve beg�ns to r�se and where �t levels off, respect�vely. The�r select�on can be d�ff�cult due to var�at�on �n amb�-ent no�se preced�ng (and overlapp�ng) the acoust�c event, as well as reverberat�on plus amb�ent no�se follow�ng the event. Consequently, many �nvest�-gators �dent�fy these po�nts subject�vely.

The sound exposure E(t) (�n Pa2-s), where t £ tb, �s then calculated as

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(3) eq.where E100 = E(tb) �s 100% of the sound expo-sure. For the 5% po�nt, E(t) �s determ�ned as E5 = 0.05•E100 = E(t5), wh�le E(t) for the 95% energy po�nt �s determ�ned as E95 = 0.95•E100 = E(t95). Thus, E90 = E95 – E5 and durat�on (Td) = t95 – t5 (s) where the rece�ved pressure level greatly exceeds the amb�ent level, eq. 3 can be reduced to

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(4) eq.Sound exposure level (SEL) �s the dec�bel

level of the cumulat�ve sum-of-square pressures over the durat�on of a sound (e.g., dB re: 1 µPa2-s) for susta�ned nonpulse sounds where the exposure �s of a constant nature (�.e., source and an�mal pos�t�ons are held roughly constant). However, th�s measure �s also extremely useful for pulses and trans�ent nonpulse sounds because �t enables sounds of d�ffer�ng durat�on to be character�zed �n terms of total energy for purposes of assess�ng exposure r�sk.

The SEL metr�c also enables �ntegrat�ng sound energy across mult�ple exposures from sources such as se�sm�c a�rguns, p�le dr�v�ng, and most sonar s�gnals. Several methods ex�st for summ�ng energy over mult�ple exposures. We use a rela-t�vely stra�ghtforward approach here, spec�f�cally

500 Southalletal.

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(5) eq. where �nstantaneous sound-pressure (p) �s mea-sured �n µPa for n exposures and the reference pressure (pref) �s 1 µPa under water and 20 µPa �n a�r. Th�s summat�on procedure essent�ally generates a s�ngle exposure “equ�valent” value that assumes no recovery of hear�ng between repeated expo-sures. The appropr�ate un�ts for underwater SEL are dB re: 1 µPa²-s, and the appropr�ate un�ts for aer�al SEL are dB re: (20 µPa)2-s.

Kurtosis �s a stat�st�cal measure of the prob-ab�l�ty d�str�but�on of sound pressure ampl�tudes (Hamern�k & Hsueh, 1991; Le� et al., 1994; Hamern�k et al., 2003) that descr�bes the shape of the ampl�tude d�str�but�on. In some regards, �t appears to be a h�ghly relevant metr�c �n that �mpuls�ve sound w�th h�gh kurtos�s and h�gh �nstantaneous peak pressure may be part�cularly �njur�ous to some mammals (Hamern�k et al., 2003). Kurtos�s �s related to the fourth central-moment and �s def�ned for random var�able X as

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(6) eq.where O �s the expectat�on operator, µ �s the mean, and S �s the standard dev�at�on. When kurtos�s �s h�gh, ampl�tude d�str�but�on �s generally more cen-trally peaked and may have broader ta�ls. Normal d�str�but�ons have a kurtos�s value of 3 �ndepen-dent of the mean or standard dev�at�on.

Frequency-selective weighting �s often employed to measure (as a s�ngle number) sound pressure or energy �n a spec�f�c frequency band, w�th emphas�s or de-emphas�s on part�cular frequenc�es as a func-t�on of the sens�t�v�ty to those frequenc�es. For aer�al hear�ng �n humans, A-we�ght�ng �s der�ved from the �nverse of the �deal�zed 40-phon equal loudness hear-�ng funct�on across frequenc�es standard�zed to 0 dB at 1 kHz (Harr�s, 1998), prov�d�ng level measures denoted as dB(A). C-we�ght�ng �s determ�ned from the �nverse of the �deal�zed 100-phon equal loudness hear�ng funct�on (wh�ch d�ffers �n several regards from the 40-phon funct�on) standard�zed to 0 dB at 1 kHz (Harr�s, 1998); level measures are denoted as dB(C).

Absent equal-loudness contours for mar�ne mammals, spec�al we�ght�ng funct�ons based loosely on human we�ght�ng funct�ons and general knowledge of funct�onal hear�ng band-w�dth, were developed here for the f�ve funct�onal

mar�ne mammal hear�ng groups (see the “Mar�ne Mammal Funct�onal Hear�ng Groups” sect�on �n Chapter 2). M-we�ght�ng has a mathemat�cal structure s�m�lar to the C-we�ght�ng used �n human hear�ng, wh�ch reflects the fact that sounds must be more �ntense at h�gh and low frequenc�es for them to have equal aud�tory effect. C-we�ght�ng �s most appropr�ate for determ�n�ng the effects of �ntense sounds—that �s, those w�th loudness equal to that of a tone 100 dB above threshold at 1,000 Hz. The M-we�ght�ng was des�gned to do much the same for the d�fferent mar�ne mammal groups w�th the only d�fference be�ng the�r vary�ng low- and h�gh-frequency cutoffs. The M-we�ght�ng for mar�ne mammals, l�ke the C-we�ght�ng used �n humans, rolls off at a rate of 12 dB per octave.

The general express�on for M-we�ght�ng (M[f]), us�ng est�mated frequency cutoffs for each func-t�onal mar�ne mammal hear�ng group, �s g�ven as

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8)

(7) eq.where

Ú-=

2

1

)(1 2

12

2t

t

amb dttPtt

P (1)

( )Ú -=t

t

ambtemp dtPtPtE2

22 )()( (2)

( )Ú -=t

t

amb

a

dtPtPtE 22 )()( (3)

( )Ú=t

ta

dttPtE )()( 2 (4)

ÔÔ˛

ÔÔ˝

¸

ÔÔÓ

ÔÔÌ

Ï

=ÂÚ=

2

1 0

2

10 )(

)(

log10ref

N

n

T

n

p

dttp

SEL (5)

( )[ ]4

4

)(s

m-=

XOXkurt (6)

})(max{)(

log20)( 10 fRfR

fM = (7)

))(()(

2222

22

lowhigh

high

ffff

fffR

++=

(8) (8) eq.

The est�mated lower and upper “funct�onal” hear-�ng l�m�ts (flow and fh�gh) for each of the f�ve func-t�onal mar�ne mammal hear�ng groups and the names of the frequency-we�ght�ng funct�ons are g�ven �n Table 2. The we�ght�ng funct�ons de-emphas�ze frequenc�es that are near the lower and upper frequency ends of the est�mated hear�ng range as �nd�cated by the negat�ve relat�ve values �n F�gure 1.

Audition (hearing) �s a well-developed and pr�-mary sensory modal�ty for most, �f not all, mar�ne vertebrates (Schusterman, 1981; Tyack, 1998; Fay & Popper, 2000). The vertebrate hear�ng system �nvolves cod�ng, process�ng, �ntegrat�ng, and respond�ng to sound �n a var�ety of ways, some not outwardly ev�dent (Yost, 2000).

Hearing (auditory) threshold �s most com-monly measured by behav�oral or electrophys�-olog�cal responses and �s def�ned as the SPL of the qu�etest sound aud�ble �n some percentage of exper�mental tr�als. In a�r, measurements are often conducted �n spec�ally constructed sound chambers. When that �s not poss�ble, tests must be conducted �n low background no�se cond�t�ons to y�eld mean�ngful threshold data.

Sensation level represents the d�fference (�n dB) between the overall level of a sound and the rece�ver’s aud�tory threshold at s�m�lar sound fre-quenc�es. It �s part�cularly useful as a means of compar�ng the relat�ve exposure level of a sound


for �nd�v�duals that may have d�fferent hear�ng capab�l�t�es. Sensat�on level �s somet�mes abbre-v�ated SL, but th�s �s not done �n th�s document to avo�d confus�on w�th the very d�fferent concept of source level.

Auditory masking �s the part�al or complete reduct�on �n the aud�b�l�ty of s�gnals due to the presence of �nterfer�ng no�se (see Buus, 1997). The degree of mask�ng depends on the spectral and temporal relat�onsh�ps between s�gnals and mask�ng no�se as well as the�r respect�ve RLs (e.g., Fletcher, 1940).

Sound localization �s the determ�nat�on of source locat�on based on features of rece�ved sounds. Th�s cr�t�cal, complex process of the aud�tory system can �nvolve the detect�on of sounds produced d�rectly by a source (pass�ve l�s-ten�ng) or the detect�on of echoes reflected off a target (as �n the case of b�osonar).

Auditory scene analysis �s the process by wh�ch the aud�tory system sorts out related elements of a complex acoust�c env�ronment �nto those ar�s�ng from d�screte sound sources. Th�s process �s s�m�-lar to psycholog�cal processes underly�ng v�sual percept�on whereby many d�fferent v�sual �mages are perce�ved as d�screte elements w�th�n a v�sual scene.

Temporary Threshold Shift (TTS) �s a revers-�ble elevat�on �n hear�ng threshold (�.e., a non-permanent reduct�on �n hear�ng sens�t�v�ty) most commonly result�ng from no�se exposure.

Permanent Threshold Shift (PTS) �s a perma-nent elevat�on �n hear�ng threshold (�.e., an unre-coverable reduct�on �n hear�ng sens�t�v�ty). PTS can occur from a var�ety of causes, but �t �s most often the result of �ntense and/or repeated no�se exposures. In that case �t �s also referred to as no�se �nduced hear�ng loss (NIHL) or no�se �nduced per-manent threshold sh�ft (NIPTS).


Appendix B. Studies Involving Marine Mammal Behavioral Responses to Multiple Pulses

Low-Frequency Cetaceans/Multiple Pulses (Cell 2)

Numerous f�eld observat�ons have been made of low-frequency cetaceans react�ng to mult�ple pulses, e�ther opportun�st�cally exposed to ongo-�ng operat�ons or by �ntent�onal exposures. A mod-erate number of spec�es and exper�mental cond�-t�ons have been cons�dered, but the source was usually a se�sm�c a�rgun or arrays of these �ntense sources. Some stud�es focused on m�grat�ng an�-mals observed from f�xed observat�on platforms or �n/near m�grat�on corr�dors.

The general results of the sever�ty scal�ng analys�s for th�s cond�t�on suggest the onset of more s�gn�f�cant behav�oral d�sturbances from mult�ple pulses for m�grat�ng bowhead whales at RLs (RMS over pulse durat�on) around 120 dB re: 1 µPa (R�chardson et al., 1999). For all other low-frequency cetaceans (�nclud�ng feed�ng bow-head whales), th�s onset was at RLs around 150 to 160 dB re: 1 µPa (Malme et al., 1983, 1984; R�chardson et al., 1986; Ljungblad et al., 1988; Todd et al., 1996; McCauley et al., 1998). There �s essent�ally no overlap �n the RLs assoc�ated w�th the onset of behav�oral responses by members of these two groups based on the �nformat�on cur-rently ava�lable.

Se�sm�c a�rguns operated near bowhead whales generally �n�t�ate avo�dance react�ons as well as changes �n locomot�on and resp�rat�on (Reeves et al., 1984; R�chardson et al., 1985, 1986, 1999; Ljungblad et al., 1988). Dur�ng the autumn m�gra-t�on, avo�dance behav�or has been observed at rel-at�vely great (20+ km) ranges from source opera-t�ons (Kosk� & Johnson, 1987; R�chardson et al., 1999). Ljungblad et al. (1988) d�d not �nvest�gate behav�oral react�ons over such ranges. Dur�ng the summer, feed�ng bowheads exh�b�ted subtle behav�oral responses but not act�ve avo�dance at d�stances beyond 6 km from a�rgun sources (R�chardson et al., 1986; see also M�ller et al., 2005).

R�chardson et al. (1999) stud�ed autumn-m�grat�ng bowhead whale and found avo�dance by most �nd�v�dual whales at d�stances up to 20 km and some avo�dance at 20 to 30 km. Se�sm�c surveys us�ng a�rgun arrays w�th 6 to 16 guns and total volumes of 560 to 1,500 �n3 were conducted �n shallow (generally < 20 m) water of the Alaskan

Beaufort Sea. Whales �n the�r westward autumn m�grat�on over three seasons (1996 to 1998) were detected w�th aer�al surveys on days w�th and w�thout se�sm�c survey act�v�ty. Us�ng the obser-vat�ons of dozens of m�grat�ng whales dur�ng per�-ods when a�rguns were not act�ve, we were able to calculate the percentage of observed whales dur�ng se�sm�c surveys that demonstrated avo�d-ance behav�or at var�ous RLs (see Table 7). These results �nd�cate that m�grat�ng bowhead whales �n the R�chardson et al. (1999) study often avo�ded areas where RLs exceeded 120 to 130 dB re: 1 µPa (RMS over pulse durat�on).

In contrast, R�chardson et al. (1986) observed qu�te d�fferent movement patterns of bowhead whales exposed to se�sm�c a�rgun sounds on the�r summer feed�ng grounds �n the Canad�an Beaufort Sea. Rece�ved levels from a s�ngle se�s-m�c a�rgun (0.66-L) were measured in situ near �nd�v�dual whales be�ng observed 3 to 5 km from the sound source, and ranged from 118 to 133 dB re: 1 µPa. V�sual or�entat�on by groups of whales dur�ng a�rgun exposure was observed on two of f�ve occas�ons; only m�nor changes �n sw�m-m�ng and resp�rat�on patterns were observed. R�chardson et al. (1986) also made opportun�st�c observat�ons of groups of bowhead whales near a se�sm�c vessel operat�ng an a�rgun array. At the h�ghest RLs, some measurements exceeded the dynam�c range of the record�ng equ�pment and are cons�dered exposure m�n�ma, although th�s was not the case for most measurements relevant to the behav�oral observat�ons. From these observa-t�ons and the controlled exposure to sounds from a s�ngle a�rgun, R�chardson et al. (1986) concluded that some whales responded subtly by chang�ng d�v�ng and breath�ng patterns at relat�vely low RLs (ca. 120 to 140 dB re: 1 µPa), but that avo�d-ance and other more profound behav�oral changes were generally not observed unless the RL was ≥ 160 dB re: 1 µPa.

Ljungblad et al. (1988) conducted a ser�es of acoust�c exper�ments on behav�oral react�ons of bowhead whales exposed to sounds from sh�ps w�th operat�ng a�rgun(s). Exper�ment 1 was con-ducted on a group of e�ght whales. When a se�s-m�c vessel approached to w�th�n 3.5 km (max. RL near observed �nd�v�duals was 142 dB re: 1 µPa), the bowhead whales coalesced and moved �n a t�ght group away from the approach�ng vessel.



Exper�ment 2 �nvolved a group of three bowhead whales that demonstrated startle responses at the onset of sounds from an a�rgun 7 km away (max. measured RL was 165 dB re: 1 µPa). Behav�or returned to pre-exposure values shortly after the operat�on was term�nated. Exper�ment 3 �nvolved a group of seven bowhead whales that demonstrated avo�dance behav�or at ranges of ~3.5 km (max. measured RL of 178 dB re: 1 µPa). Exper�ment 4 �nvolved a group of 50 bowhead whales. Behav�oral react�ons were f�rst observed at ranges of about 8 km (max. measured RLs of 157 dB re: 1 µPa) and avo�dance behav�or was noted at ~3 km (RLs ~165 dB re: 1 µPa). Avo�dance behav�or �n th�s �nstance s�m�larly abated shortly follow�ng cessat�on of exposure (and was thus ass�gned a behav�oral score of 6).

Recent work on summer�ng bowhead whales by M�ller et al. (2005) also found that avo�dance responses were l�m�ted to d�stances of at most a few k�lometers and RLs exceed�ng 160 dB re: 1 µPa. M�ller et al. conducted a mon�tor�ng program over two summers for var�ous mar�ne mammals offshore of the Mackenz�e Delta �n the Southeast Beaufort Sea before and dur�ng se�sm�c surveys. They presented observat�onal data from both vessel-based and aer�al observat�ons of bowhead whales, belugas, and several p�nn�ped spec�es. The general methodology �s br�efly d�scussed here as well as data on behav�oral responses by low-frequency cetaceans (bowhead whales) and the correspond�ng rank on the sever�ty scale. The a�rgun operat�ons �nvolved 3-D se�sm�c prof�l�ng from a 67-m vessel us�ng two �dent�-cal 2,250 �n3 sleevegun arrays, each w�th 24 a�r-guns. Shots were at 8-s �ntervals and at a depth of 5 m below the surface of the water. Surveys were conducted �n very shallow water (13 m average). Acoust�c mon�tor�ng w�th cal�brated hydrophones across the 10 Hz to 24 kHz bandw�dth was con-ducted wh�le se�sm�c operat�ons were underway. Phys�cal propert�es of the operat�onal env�ron-ment, and hence sound propagat�on �n the shal-low water env�ronments, were h�ghly var�able, but RLs as a funct�on of range from act�ve a�rgun arrays were measured. Vessel-based observers and aer�al surveyors used l�ne-transect methods to mon�tor mar�ne mammals �n and adjacent to se�sm�c operat�onal areas, both before and dur�ng shoot�ng. Bowhead whales observed dur�ng the per�ods co�nc�dent w�th se�sm�c operat�ons were presumed to be feed�ng (�.e., not m�grat�ng). Many bowheads (355 �nd�v�duals �n 232 groups) were seen by mar�ne mammal observers aboard the se�s-m�c vessel. S�ght�ng rates were lower and mean s�ght�ng d�stances were somewhat larger dur�ng se�sm�c operat�ons than at t�mes when the a�rguns were not operat�ng, but the zone of avo�dance

around act�ve a�rguns was very l�m�ted. The approx�mate d�fference �n mean s�ght�ng d�stance was ~600 m. S�m�larly, the aer�al surveyors d�d not detect any large-scale avo�dance of the a�rgun operat�ons by bowheads. These observat�ons were generally cons�stent for both years �n wh�ch mea-surements were made and are generally cons�stent w�th the observat�ons of R�chardson et al. (1986) �n the same reg�on and season (summer). An�mals not exh�b�t�ng observable behav�oral react�ons (response score: 0) were cons�stently s�ghted �n areas where RLs very l�kely ranged from 130 to 180 dB re: 1 µPa. The general lack of s�ght�ngs w�th�n a small area around the se�sm�c vessel sug-gests behav�oral avo�dance (response score: 6) at RLs exceed�ng 180 dB re: 1 µPa. Exposures were not est�mated to exceed 190 dB re: 1 µPa. The ent�re study was treated as a s�ngle observat�on for the purposes of the behav�oral analys�s. Half of the “observat�on” was scored as avo�dance behav-�or and half as no response, w�th exposure RL b�ns from 130 to 190 dB re: 1 µPa (Table 6).

The comb�ned data for bowhead whale avo�d-ance of a�rgun sounds (R�chardson et al., 1986, 1999; Ljungblad et al., 1988; M�ller et al., 2005) �nd�cated that, when m�grat�ng, these an�mals can be part�cularly prone to behav�oral d�sturbance, w�th the onset of s�gn�f�cant responses occur-r�ng at approx�mately 120 dB re: 1 µPa (RMS over pulse durat�on) (Table 6). In contrast, when feed�ng, they may show subtle effects at low RLs but only tend to d�splay act�ve avo�dance at RLs exceed�ng 160 dB re: 1 µPa.

Low-frequency cetaceans, other than m�grat�ng bowhead whales, appear to be much more toler-ant of exposure to mult�ple pulses, although data are l�m�ted to a few spec�es and (pr�mar�ly) a�rgun sources. Ava�lable data for spec�es other than bow-heads �nclude react�ons to opportun�st�c and �nten-t�onal exposures of humpback whales (Malme et al., 1985; Todd et al., 1996; McCauley et al., 1998, 2000) and gray whales (Malme et al., 1983, 1984, 1986, 1988; also see rev�ew by Moore & Clarke, 2002). Todd et al. (1996), Malme et al. (1983, 1984), and McCauley et al. (1998) are �ncluded �n the behav�oral scor�ng analys�s here because they conta�n suff�c�ent �nformat�on on exposures and �nd�v�dual responses of low-fre-quency cetaceans other than bowhead whales.

Todd et al. (1996) analyzed the �mpact of con-struct�on act�v�ty (explos�ons and dr�ll�ng) on the entanglement of three forag�ng humpback whales off Newfoundland. They conducted observat�ons of whale behav�or dur�ng and follow�ng explo-s�ons and obta�ned acoust�c measurements of underwater sound s�gnatures. The data suggest few short-term changes �n movement and behav-�or patterns �n response to d�screte exposures;

504 Southalletal.

however, repeated exposures to h�gh levels may have resulted �n sensory �mpa�rment �n whales and perhaps greater suscept�b�l�ty to entanglement �n f�sh�ng gear.

Malme et al. (1983, 1984) documented behav-�oral react�ons of m�grat�ng gray whales to se�sm�c pulses from both s�ngle a�rguns and an array. Only land-based observers were used, wh�ch meant that the observers could not have affected the whales’ behav�or. Both phases of the �nvest�gat�on y�elded the general conclus�on that RLs exceed�ng 160 dB re: 1 µPa (on an approx�mate RMS bas�s) were requ�red to cause m�grat�ng gray whales to avo�d a�rgun sounds, although stat�st�cally s�gn�f�cant react�ons that were less profound occurred at much larger ranges and lower levels. From the�r emp�r�cal phase II results, Malme et al. (1984) calculated 10, 50, and 90% probab�l�t�es of gray whale avo�dance react�ons �n these cond�t�ons to be 164, 170, and 180 dB re: 1 µPa, respect�vely.

McCauley et al. (1998) made behav�oral obser-vat�ons of m�grat�ng humpback whales off western Austral�a dur�ng se�sm�c operat�ons w�th a s�ngle a�rgun and several a�rgun array conf�gurat�ons. Se�sm�c track l�nes were or�ented perpend�cular to the m�grat�on paths of humpback whales mov�ng through the area. Aer�al surveys were conducted to determ�ne the presence of humpback whales mov�ng through the survey area. Deta�led obser-vat�onal data were presented for �nd�v�duals and groups of whales; RLs were measured at var�-able ranges. The se�sm�c survey d�d not appear to grossly affect the m�grat�on of humpback whales through the area; however, avo�dance behav-�or was observed to beg�n at ranges from 5 to 8 km and to be almost un�versal at ranges of 1 to 4 km. Exposures to a s�ngle a�rgun (20 �n3) were extrapolated to equ�valent ranges for exposure to full arrays based on emp�r�cal measurements. The data �nd�cated an onset of behav�oral avo�dance at ~159 dB re: 1 µPa (peak-to-peak), roughly equ�va-lent to the full array at 5 km. General behav�oral avo�dance (most �nd�v�duals) occurred at a range of about 1 km for the s�ngle gun (~168 dB re: 1 µPa [peak-to-peak]), equ�valent to the full array at about 3 km. Some �nd�v�dual whales d�d approach closer than the typ�cal 3-km stand-off range; these may have been males �nvest�gat�ng the presence of the low-frequency source.

In add�t�on to present�ng aga�n the results g�ven �n the McCauley et al. (1998) paper, McCauley et al. (2000) prov�de add�t�onal behav�oral observa-t�ons of 16 humpback whale pods that approached as a s�ngle a�rgun (Bolt PAR 600b 20-�n3) was operated. These whales were also observed after term�nat�on of a�rgun operat�ons. These tr�als were conducted �n a large embayment (Exmouth Gulf) as the an�mals were engaged �n a var�ety of rest�ng

and soc�al behav�ors. F�ve tr�als were excluded from cons�derat�on �n our analys�s, but behav�oral observat�ons were reported for the rema�n�ng 11. Of these, ten �ncluded cow pods of var�ous s�zes, and one was a lone male. S�nce the cow pods were not m�grat�ng and were not �nd�v�dually �dent�-f�ed, a s�ngle behav�oral observat�on �s �ncluded �n Table 7 for the ten observat�ons. The results for the cow pods were very cons�stent, �nd�cat�ng clear avo�dance (sever�ty score = 6) of the a�rgun at exposures �n the 140 to 150 dB re: 1 µPa range (RMS over pulse durat�on). The lone male essen-t�ally �gnored the a�rgun unt�l w�th�n ca. 100 m, when the rece�ved level approached 180 dB re: 1 µPa (RMS); th�s response may have had as much or more to do w�th the presence of the vessel than exposure to the a�rgun sound. Not�ng th�s con-textual complex�ty here, a s�ngle observat�on for th�s �nd�v�dual �s reported �n the 170 to 180 dB re: 1 µPa exposure b�n �n Table 7 as general avo�d-ance (sever�ty score = 6).

Mid-Frequency Cetaceans/Multiple Pulses (Cell 5)

A l�m�ted number of behav�oral observat�ons have been made of m�d-frequency cetaceans exposed to mult�ple pulses. F�eld observat�ons have �nvolved sperm whales and a few other odontocete spec�es exposed to se�sm�c a�rguns and small explos�ves (Madsen & Møhl, 2000; Madsen et al., 2002; M�ller et al., 2005). Laboratory �nvest�gat�ons have cons�dered behav�oral responses to var�ous k�nds of mult�ple pulse sources (Akamatsu et al., 1993). As �n most cr�ter�a cells, a number of reported observat�ons were not scored and reported here due to lack of relevant �nformat�on and d�ff�cult�es �n account�ng for var�ous contextual var�ables. A summary of those stud�es used and others cons�d-ered �s g�ven �n Table 8; the sever�ty scal�ng analy-s�s for Cell 5 �s shown �n Table 9.

The comb�ned data for m�d-frequency ceta-ceans exposed to mult�ple pulses do not �nd�cate a clear pattern of �ncreas�ng probab�l�ty and sever-�ty of response w�th �ncreas�ng RLs. In certa�n cond�t�ons, mult�ple pulses at relat�vely low RLs (~80 to 90 dB re: 1 µPa) temporar�ly s�lence �nd�-v�dual acoust�c behav�or for one spec�es (sperm whales). In other cases w�th sl�ghtly d�fferent st�mul�, RLs �n the 120 to 180 dB re: 1 µPa range fa�led to el�c�t observable react�ons from a s�gn�f�-cant percentage of �nd�v�duals of the same spec�es, both �n the f�eld and �n the laboratory.

FieldObservations(Cell5)Madsen & Møhl (2000) �nvest�gated sperm whale responses to small underwater detonators that �ncluded 1-g TNT charges, produc�ng a 1-ms


broadband (300 Hz to 15 kHz) pulse; several charges were tr�ggered per day. Echolocat�on cl�ck behav�or was mon�tored, and one whale was local-�zed acoust�cally. Th�s �nd�v�dual demonstrated no modulat�on of vocal behav�or when exposed to an RMS-equ�valent RL of ~173 dB re: 1 µPa. There was also one observat�on of a whale exposed to 179 dB re: 1 µPa; �t cont�nued breath�ng normally w�th no v�s�ble response.

Madsen et al. (2002) stud�ed responses of sperm whales �n Norway to sounds assoc�ated w�th d�s-tant se�sm�c survey operat�ons. Cal�brated RLs for �nd�v�duals and correlated acoust�c behav�or are reported for three d�screte s�ght�ngs over a 5-d per�od. The f�rst observat�on �nvolved three sperm whales tracked by acoust�c local�zat�on w�th�n a d�spersed array of cal�brated hydrophones, wh�ch also recorded a�rgun sounds from an array operat-�ng 40 km away. RL at the pos�t�on of the whale was est�mated to be 123 dB re: 1 µPa. The second observat�on (3 d later) �nvolved a s�ngle sperm whale recorded before, dur�ng, and after a�rgun exposure at a range of 86 km; measured RL was 130 dB re: 1 µPa. The th�rd observat�on (2 d later) �nvolved three �nd�v�duals; the survey vessel was 94 km away and measured RL was 130 dB re: 1 µPa. No change �n sperm whale acoust�c behav-�or was noted �n any of these cases. The authors also played art�f�c�al codas and not�ced that two whales d�rected the�r sonar beams at the speaker, but �nsuff�c�ent �nformat�on �s g�ven to assoc�ate th�s response w�th a part�cular RL.

M�ller et al. (2005) documented behav�oral reac-t�ons of var�ous mar�ne mammal spec�es, �nclud-�ng belugas, to a�rgun operat�ons. The general methodology �s deta�led above (see the “Cell 2” sect�on). Ow�ng to the�r normal seasonal patterns �n the Beaufort Sea, belugas were most abundant �n the M�ller et al. (2005) study area pr�or to the start of se�sm�c operat�ons. There were relat�vely few vessel-based s�ght�ngs, most of wh�ch were made when a�rguns were not act�ve. Many belugas were observed dur�ng aer�al surveys, however, and these data were used to compare beluga s�ght�ngs w�th�n concentr�c 10-km bands around the act�ve se�sm�c source w�th s�ght�ng rates �n non-a�rgun cond�t�ons. Dur�ng a�rgun operat�ons, M�ller et al. detected s�gn�f�cantly fewer an�mals 10 to 20 km from se�sm�c operat�ons and an unexpectedly h�gh number of s�ght�ngs �n the 20- to 30-km zone. Th�s was suggest�ve of behav�oral avo�dance of se�sm�c operat�ons at d�stances up to 20 km. These observa-t�ons may �n part expla�n why so few an�mals were observed by sh�pboard mar�ne mammal observers. M�ller et al. noted that the apparent avo�dance of se�sm�c operat�ons was much greater than expected �f the whales were respond�ng to non-a�rgun sounds assoc�ated w�th vessel operat�on. For the

purposes of our behav�oral analyses, the comb�ned beluga results were treated as a s�ngle observa-t�on that was subd�v�ded equally �nto e�ther avo�d-ance behav�or or no observable response. Belugas exposed to RLs of 100 to 120 dB re: 1 µPa (RMS over pulse durat�on) were determ�ned to have had no observable react�on (response score: 0) to se�s-m�c exposures. RLs between 120 and 150 dB re: 1 µPa were determ�ned to have �nduced temporary avo�dance behav�or (response score: 6) �n belugas, based on the vessel-based and aer�al observat�ons. Based on both the vessel-based and aer�al surveys, exposures apparently d�d not exceed 150 dB re: 1 µPa. We�ghted behav�oral response scores for each of these f�ve exposure RL b�ns are g�ven �n Table 7.

Several stud�es �nvolved behav�oral react�ons of free-rang�ng, m�d-frequency cetaceans but lacked spec�f�c measures to be �ncluded d�rectly �n our analyses. André et al. (1997) exposed sperm whales to var�ous st�mul�, �nclud�ng two pulse sounds (recorded coda playbacks and a 10-kHz pulse). A s�gn�f�cant number of exposed whales exh�b�ted vocal modulat�ons and mod�f�ed d�v�ng behav�or, but �nsuff�c�ent �nformat�on �s ava�lable on rece�ved exposures of �nd�v�dual whales. Stone (2003) comp�led a large database of s�ght�ng data of several m�d-frequency cetacean spec�es observed from se�sm�c survey vessels. S�ght�ng rates of small odontocetes were s�gn�f�cantly lower when a�rguns were f�r�ng, and they were s�ghted at greater d�stances from vessels, �nd�cat�ng avo�d-ance behav�or. The study sponsors (JNCC) k�ndly prov�ded raw data for use �n our quant�tat�ve avo�dance analyses, but they are not �ncluded due to d�ff�cult�es �n est�mat�ng exposure RL for �nd�-v�dual s�ght�ngs. (See also Stone & Tasker, 2006, for a recently publ�shed account.)

LaboratoryObservations(Cell5)Akamatsu et al. (1993) �nvest�gated avo�d-ance behav�or �n two capt�ve false k�ller whales exposed to 15 d�fferent k�nds of sounds, �nclud�ng pulse sequences (manual str�kes on a metal p�pe once every 2 s) �n the 24 to 115 kHz range. For th�s st�mulus, no avo�dance was seen follow�ng the f�rst exposure (174 dB re: 1 µPa), but tempo-rary avo�dance behav�or (response score: 6) was observed for success�ve exposures at 174 and 178 dB re: 1 µPa.

F�nneran et al. (2000) observed behav�oral responses of two capt�ve bottlenose dolph�ns and a beluga whale dur�ng TTS exper�ments �nvolv�ng a ser�es of �mpuls�ve exposures des�gned to rep-l�cate d�stant explos�ons. Each an�mal exh�b�ted alterat�ons of nom�nal tra�ned behav�ors (reluc-tance to return to exper�mental stat�ons) dur�ng the exper�ment; the onset of behav�oral d�sturbance

506 Southalletal.

occurred �n the beluga at 220 dB re: 1 µPa (peak-to-peak) and �n the two bottlenose dolph�ns at 196 and 209 dB re: 1 µPa (peak-to-peak), respect�vely. In a related study, F�nneran et al. (2002b) observed behav�oral responses of a bottlenose dolph�n and a beluga whale after exposure to �mpuls�ve sounds produced by a water gun. Both �nd�v�duals showed a s�m�lar reluctance to return to exper�mental sta-t�ons (beluga at 202 dB re: 1 µPa (peak-to-peak); bottlenose dolph�n at 229 dB re: 1 µPa [peak-to-peak]). Romano et al. (2004) stud�ed phys�olog�-cal responses to these exposures �n these same an�mals. They observed clear neuro-�mmune responses �n the beluga at exposures above 222 dB re: 1 µPa (peak-to-peak) and s�gn�f�cant d�ffer-ences �n aldosterone and monocyte counts �n the dolph�n for exposures exceed�ng 225 dB re: 1 µPa (peak-to-peak).

High-Frequency Cetaceans/Multiple Pulses (Cell 8)

Based on our source type d�st�nct�on (see Chapter 2), v�rtually all sound sources used �n behav�oral stud�es of h�gh-frequency cetaceans (e.g., acoust�c harassment dev�ces [AHDs] and acoust�c deterrent dev�ces [ADDs]) would be character�zed as non-pulses. Wh�le �nd�v�dual elements produced by some of these sources would be character�zed as pulses, and sequences of them as mult�ple pulses, they are generally em�tted �n such rap�d fash�on that mammal�an aud�tory systems are l�kely to perce�ve them as nonpulses. Further, some AHDs, ADDs, and all other sources used �n behav�oral stud�es w�th h�gh-frequency cetaceans lack the character�st�cs of pulses. Due to the lack of data, �t �s not poss�ble to present any behav�oral response data on mult�ple pulses for h�gh-frequency ceta-ceans; ava�lable data for nonpulse sounds are cons�dered elsewhere (see the “H�gh-Frequency Cetaceans/Nonpulses [Cell 9]” sect�ons of Chapter 4 and Append�x C). We note the need for behav�oral research on these an�mals us�ng sound sources unequ�vocally class�f�ed as pulses.

Pinnipeds in Water/Multiple Pulses (Cell 11)

Informat�on on behav�oral react�ons of p�nn�peds �n water to mult�ple pulses �s der�ved from stud�es us�ng small explos�ves s�m�lar to those used �n f�sh-er�es �nteract�ons, construct�on act�v�ty, and se�s-m�c surveys. Several stud�es lacked matched data on acoust�c exposures and behav�oral responses by �nd�v�duals. As a result, the quant�tat�ve �nforma-t�on on react�ons of p�nn�peds �n water to mult�ple pulses �s very l�m�ted. Our general f�nd�ng �s that exposures �n the ~150 to 180 dB re: 1 µPa range (RMS over pulse durat�on) generally have l�m�ted

potent�al to �nduce avo�dance behav�or �n p�nn�-peds, whereas RLs exceed�ng 190 dB re: 1 µPa are l�kely to el�c�t responses, at least �n some r�nged seals (Harr�s et al., 2001; Blackwell et al., 2004b; M�ller et al., 2005).

Harr�s et al. (2001) documented responses of p�nn�peds (pr�mar�ly r�nged seals, but a few bearded and spotted seals) and obta�ned cal�brated measures of RLs w�th�n def�ned spat�al zones dur�ng operat�on of a s�ngle a�rgun, an 11-a�rgun array total�ng 1,320 �n3, and dur�ng control per�-ods. V�sual observat�ons from the se�sm�c vessel were l�m�ted to the area w�th�n a few hundred meters, and 79% of the seals observed were w�th�n 250 m of the vessel. Dur�ng dayl�ght, seals were observed at nearly �dent�cal rates w�th no a�rguns, one a�rgun, or when a full a�rgun array was f�r�ng. Seals were s�gn�f�cantly further away dur�ng full array operat�ons compared to the other two con-d�t�ons. Also, there was some avo�dance w�th�n 150 m of the vessel �n these cond�t�ons (0.37 seals seen per hour �n control per�ods compared to 0.21 seals/h dur�ng full array operat�ons). Se�sm�c operat�ons were not bel�eved to cause many, �f any, seals to desert the operat�onal area.

Blackwell et al. (2004b) �nvest�gated behav-�oral react�ons of r�nged seals to �mpact sounds assoc�ated w�th the dr�v�ng of steel p�pes �n the construct�on of an o�l product�on fac�l�ty. Mult�ple str�kes were recorded under water at d�stances up to 3 km from the source. Unwe�ghted peak pres-sure level, SPL, and SEL measurements were made at var�ous d�stances. At the closest po�nt (63 m), RLs were 151 dB re: 1 µPa (RMS), 157 dB re: 1 µPa (peak), and 145 dB re: 1 µPa2-s (SEL). Pulses had measurable components extend�ng to over 10 kHz, although more than 95% of the energy �n the s�gnals was below 225 Hz. A frequency-we�ght-�ng metr�c somewhat s�m�lar to that proposed here was appl�ed to the recorded s�gnals �n est�mat�ng aud�b�l�ty ranges. Ind�v�duals demonstrated no or low-level behav�oral responses to p�le-dr�v�ng sounds, but were somewhat respons�ve to hel�cop-ter overfl�ghts. Blackwell et al. noted, however, that the�r data were collected after a prolonged per�od of �ntens�ve construct�on act�v�ty and may reflect the least respons�ve part of the or�g�nal populat�on of seals that may have already hab�tu-ated to the no�se source. Ind�v�dual observat�ons �n wh�ch hel�copters were not present are cons�d-ered �n our behav�oral analys�s, we�ghted by the total number of relevant observat�ons (Table 11). Aer�al measurements of mult�ple pulse exposures were also obta�ned �n th�s study and are cons�d-ered �n the relevant cond�t�on below.

M�ller et al. (2005) documented behav�oral react�ons of var�ous mar�ne mammal spec�es, �nclud�ng p�nn�peds �n water, to se�sm�c a�rgun


operat�ons. The general methodology �s deta�led above (see the “Cell 2” sect�on). The vast major-�ty (> 90%) of the seals were r�nged seals and the rema�nder were bearded seals. Vessel-based observers saw seals around the vessel, and often qu�te close to �t, throughout the per�od of se�s-m�c operat�ons. Seals were observed s�gn�f�cantly further away dur�ng a�rgun operat�ons �n the f�rst summer, whereas the reverse pattern was actu-ally the case �n the second season. Comb�ned, the results suggest essent�ally no observable behav-�oral response �n p�nn�peds exposed to se�sm�c s�gnals �n these spec�f�c cond�t�ons. Based on the acoust�c measurements that were conducted and the areas �n wh�ch these p�nn�peds were observed, RLs were l�kely 170 to 200 dB re: 1 µPa (RMS over pulse durat�on). A s�ngle observat�on of no react�on (response score: 0) for p�nn�peds �n water �s reported for th�s study and �s we�ghted equally across these exposure RL b�ns (Table 8).

Several other stud�es were deleted from our analys�s due to a lack of certa�n �nformat�on. Two stud�es �nvest�gated small f�recracker-l�ke explos�ves (called “seal bombs”) and the�r effect on the underwater behav�or of p�nn�peds around f�sh�ng gear (Shaughnessy et al., 1981; Mate & Harvey, 1987). In�t�ally, these explos�ves tend to �nduce the des�red avo�dance behav�or, but th�s response fades qu�ckly due to hab�tuat�on (see R�chardson et al., 1995). Mate & Harvey (1987) reported fa�rly extens�ve descr�pt�ons of startle and temporary avo�dance data as well as some �nformat�on on exposure cond�t�ons. Bes�des the challeng�ng matter of �nterpret�ng the apparently rap�d hab�tuat�on to th�s sound source, however, data are lack�ng that relate d�screte exposures w�th def�ned behav�oral responses of spec�f�c �nd�v�dual p�nn�peds. For these reasons, we excluded data on responses to seal bombs from our analys�s. Moulton et al. (2003, 2005) conducted surveys of r�nged seal d�str�but�on before and dur�ng the construct�on and operat�on of the same o�l produc-t�on fac�l�ty descr�bed by Blackwell et al. (2004a, 2004b). Sound sources �ncluded nonpulse as well as mult�ple pulse sources (�nclud�ng �mpact p�le-dr�v�ng). The�r observat�ons across mult�ple sea-sons �nd�cated l�ttle or no behav�oral avo�dance of the area �n response to var�ous �ndustr�al act�v�-t�es. Due to d�ff�cult�es w�th control observat�ons across seasons and the lack of �nformat�on about d�screte exposures and �nd�v�dual react�ons, how-ever, we excluded the Moulton et al. (2003, 2005) data from our analys�s. A f�nal study for wh�ch ava�lable data were �nsuff�c�ent for �nclus�on here �s Thompson et al. (1998). That telemetry study seemed to show much h�gher respons�veness of gray and harbor seals to a�rgun sounds than has been demonstrated �n other stud�es, wh�ch rel�ed

on v�sual observat�ons. Thus, future stud�es may show some seals to be more respons�ve to mult�ple pulses than Table 11 would suggest.

Pinnipeds in Air/Multiple Pulses (Cell 11)

The effects of mult�ple aer�al pulses on p�nn�peds are among the least well-documented of the cond�-t�ons we cons�dered. Most of the ava�lable data on responses to pulses are from s�ngle-pulse events (e.g., rocket launches) over populat�ons of p�n-n�peds exposed to such s�gnals repeatedly (e.g., Thorson et al., 1998, 1999, 2000a, 2000b; Berg et al., 2001, 2002, 2004). These launches are not repeated so frequently that the exposure can be cons�dered as �nvolv�ng mult�ple pulses, and many of the exposures �nclude nonpulse components. However, they are d�scussed �n some deta�l �n th�s append�x (as well as �n Append�x C for nonpulses w�th�n these stud�es) along w�th several other stud-�es potent�ally relevant to Cell 14 but ult�mately not used �n the analys�s here. Consequently, the quant�tat�ve �nformat�on analyzed for react�ons of p�nn�peds �n a�r exposed to mult�ple pulses (see Table 12 for summary and Table 13 for sever�ty scal�ng analys�s) focuses on the aer�al data of Blackwell et al. (2004b). These extremely l�m�ted data suggest very m�nor, �f any, observable behav-�oral responses for exposures rang�ng from 60 to 80 dB re: 20 µPa.

Blackwell et al. (2004b) reported behav�oral react�ons of r�nged seals to aer�al �mpact sounds from p�le-dr�v�ng (descr�bed above). Mult�ple str�kes were recorded �n a�r at d�stances up to 500 m from the source. Unwe�ghted SPL, peak sound pressure levels, and SEL measurements were made at var�ous d�stances. At the closest po�nt (63 m) average RLs were 93 dB re: 20 µPa (RMS), 111 dB re: 20 µPa (peak), and 87 dB re: (20 µPa)2-s (SEL). Mean pulse durat�ons were between 0.17 and 0.63 s, w�th measurable energy to over 10 kHz, but w�th 95% of the energy occurr�ng between 89 and 3,534 Hz. A frequency-we�ght-�ng metr�c somewhat s�m�lar to that proposed here was appl�ed to the recorded s�gnals �n est�mat-�ng aud�b�l�ty ranges. Ind�v�duals demonstrated very l�m�ted behav�oral responses to p�le-dr�v�ng sounds �n some cond�t�ons (most appeared e�ther “�nd�fferent or cur�ous”) but were more respon-s�ve to hel�copter overfl�ghts. Data were collected after prolonged construct�on act�v�t�es, and some hab�tuat�on probably had taken place already. Ind�v�dual observat�ons for wh�ch hel�copters were not present are cons�dered �n the behav�oral analys�s here and we�ghted by the total number of relevant observat�ons (Table 13) to equal a s�ngle observat�on for the study.

508 Southalletal.

Perry et al. (2002) measured the effects of repeated (0 to 5/d) son�c booms from Concorde a�rcraft on harbor and gray seals on Sable Island, Nova Scot�a. They measured the number of an�-mals on shore before and after booms as well as the frequency of var�ous behav�ors. Add�t�onally, they compared heart rates �n exposure and control cond�t�ons us�ng record�ng dev�ces deployed on the an�mals. They reported rece�ved sound over-pressure of booms on the breed�ng beaches of both p�nn�ped spec�es. Observed effects on an�mal presence, behav�or, and heart rate were generally m�nor and not stat�st�cally s�gn�f�cant; an�mals were largely tolerant of the sounds but became somewhat more alert follow�ng them. However, Perry et al. (2002) note that there �s a long h�s-tory of son�c booms from a�rcraft �n the area and the an�mals are l�kely hab�tuated to the�r presence. Due to th�s compl�cat�on and the lack of expl�c�t rece�ved SPL measures at exposed �nd�v�duals, we d�d not score the results of Perry et al. (2002) here.

Appendix C. Studies Involving Marine Mammal Behavioral Responses to Nonpulses

Low-Frequency Cetaceans/Nonpulses (Cell 3)

Wh�le there are clearly major areas of uncerta�nty rema�n�ng, there has been relat�vely extens�ve behav�oral observat�on of low-frequency ceta-ceans exposed to nonpulse sources. As sum-mar�zed �n Table 14, these f�eld observat�ons �nvolve the major�ty of low-frequency cetacean spec�es exposed to a w�de range of �ndustr�al, act�ve sonar, and tomograph�c research act�ve sources (Baker et al., 1982; Malme et al., 1983, 1984, 1986; R�chardson et al., 1990b; McCauley et al., 1996; Frankel & Clark, 1998; Borggaard et al., 1999; B�asson� et al., 2000; Croll et al., 2001; Palka & Hammond, 2001; Nowacek et al., 2004). Observat�ons from several related stud�es (Dahlhe�m, 1987; Frankel & Clark, 2000, 2002; Sch�ck & Urban, 2000; Moore & Clarke, 2002; Jahoda et al., 2003; Mobley, 2005) were rev�ewed br�efly but not analyzed here because key �nfor-mat�on was lack�ng.

These papers generally �nd�cate no (or very l�m�ted) responses at RLs 90 to 120 dB re: 1 µPa and an �ncreas�ng probab�l�ty of avo�dance and other behav�oral effects �n the 120 to 160 dB re: 1 µPa range (Table 14). However, the data also �nd�cate cons�derable var�ab�l�ty �n RLs assoc�-ated w�th behav�oral responses. Contextual var�-ables (e.g., source prox�m�ty, novelty, operat�onal features) appear to have been at least as �mportant as exposure level �n pred�ct�ng response type and magn�tude.

Baker et al. (1982) �nvest�gated behav�oral responses of �nd�v�dual humpback whales to vessel traff�c �n southeast Alaska. Ind�v�dual RLs were not reported, but suff�c�ent �nformat�on regard�ng �nd�v�dual ranges was obta�ned to approx�mate exposures g�ven that the acoust�c character�st�cs of �dent�cal classes of vessel classes �nvolved were measured �n s�m�lar cond�t�ons by M�les & Malme (1983). Results �nd�cate some behav�oral avo�dance when RL was �n the 110 to 120 dB re: 1 µPa range and clear avo�dance at 120 to 140 dB re: 1 µPa.

Malme et al. (1983, 1984) used playback meth-ods to document behav�oral react�ons of m�grat-�ng gray whales to �nterm�ttent sounds of hel�-copter overfl�ghts and cont�nuous sounds from dr�ll�ng r�gs and platforms. Both phases of the

�nvest�gat�on y�elded the general conclus�on that RLs exceed�ng 120 dB re: 1 µPa �nduced demon-strable behav�oral react�ons (avo�dance). Malme et al. (1984) calculated 10%, 50%, and 90% probab�l�t�es of gray whale avo�dance react�ons �n these cond�t�ons as 110, 120, and 130 dB re: 1 µPa. Malme et al. (1986) observed the behav�or of feed�ng gray whales dur�ng four exper�mental playbacks of dr�ll�ng sounds (50 to 315 Hz; 21-m�n overall durat�on and 10% duty cycle; source levels 156 to 162 dB re: 1 µPa-m). In two cases for RLs 100 to 110 dB re: 1 µPa, there was no observed behav�oral react�on. Avo�dance behav�or was observed �n two cases where RLs were 110 to 120 dB re: 1 µPa.

R�chardson et al. (1990b) performed 12 play-back exper�ments �n wh�ch bowhead whales �n the Alaskan Arct�c were exposed to dr�ll�ng sounds. Low-frequency source character�st�cs and trans-m�ss�on loss were well-character�zed, enabl�ng RL est�mates to be made for �nd�v�dual cases. Whales generally d�d not respond to exposures �n the 100 to 130 dB re: 1 µPa range, although there was some �nd�cat�on of m�nor behav�oral changes �n several �nstances.

Us�ng d�fferent detect�on and sampl�ng tech-n�ques, McCauley et al. (1996) reported several cases of humpback whales respond�ng to vessels �n Hervey Bay, Austral�a, along w�th measure-ments of no�se RL. Not all cases reported prov�ded suff�c�ent �nformat�on to assoc�ate a response or lack of response w�th exposure, but �n three cases, �nd�v�dual responses and no�se RL were reported. Results �nd�cated clear avo�dance at RLs between 118 to 124 dB re: 1 µPa.

Palka & Hammond (2001) analyzed l�ne transect census data �n wh�ch the or�entat�on and d�stance off transect l�ne were reported for large numbers of m�nke whales. General add�t�ve models were used to est�mate the range at wh�ch cetaceans respond to the no�se of the research vessel by approach or avo�dance. The typ�cal avo�dance d�stance for 272 m�nke whales �n the Gulf of Ma�ne was 717 m; for 352 m�nke whales �n the North Sea, �t was 563 m; and for 493 m�nke whales �n the Northeastern Atlant�c, �t was 695 m. Rece�ved levels were est�-mated based on a nom�nal source level for that class of research vessel (ca. 170 to 175 dB re: 1 µPa-m) and an assumpt�on of spher�cal (20 log R) spread�ng loss (54 dB loss @ 500 m; l�kely


510 Southalletal.

reasonable for these cond�t�ons). These data are represented �n Table 14 by the 110 to 120 dB re: 1 µPa exposures and a relat�vely low (less severe) behav�oral response score of three (�.e., m�nor changes �n locomot�on speed, d�rect�on, and/or d�v�ng prof�le).

Several add�t�onal stud�es have used playback exper�ments w�th act�ve sound sources to �nvest�-gate the behav�oral react�ons of low-frequency ceta-ceans to nonpulse sources. B�asson� et al. (2000) and M�ller et al. (2000) report behav�oral observat�ons for humpback whales exposed to a low-frequency sonar st�mulus (160- to 330-Hz frequency band; 42-s tonal s�gnal repeated every 6 m�n; source levels 170 to 200 dB re: 1 µPa-m). Measured RLs ranged from 120 to 150 dB re: 1 µPa. In n�ne cases, �nd�-v�dual whales cont�nued s�ng�ng throughout expo-sures, wh�le �n four �nstances, �nd�v�duals ceased call�ng when they jo�ned another whale. The cessa-t�on of song and jo�n�ng another �nd�v�dual �s typ�-cal of normal myst�cete soc�al �nteract�ons (Tyack, 1981). Consequently, these events were not scored as a vocal response to the playback but as a mod-erate or�ent�ng behav�or (sever�ty score = 2). For the rema�n�ng f�ve playbacks, �nd�v�dual whales stopped s�ng�ng dur�ng exposure w�thout jo�n�ng other whales (sever�ty scale = 4). Although s�ngers also stop spontaneously under control cond�t�ons, the latter f�ve exper�mental tr�als were cons�dered vocal cessat�on result�ng from sound exposure (B�asson� et al., 2000). However, there are �nsuf-f�c�ent data to compare control and exper�mental cases for spontaneous rates of cessat�on. Analys�s of all s�ngers �nd�cated an �ncrease �n song dura-t�on dur�ng exposure due to �ncreased repet�t�on of elements of the song. S�nce �t was poss�ble that some �nd�v�dual whales were represented mult�ple t�mes w�th�n the playbacks, the B�asson� et al. (2000) and M�ller et al. (2000) data were scored as a s�ngle behav�oral observat�on. The 18 �nd�v�dual observat�ons were we�ghed �nversely by the total number (1/18) �n Table 15.

Croll et al. (2001) �nvest�gated responses of for-ag�ng f�n and blue whales to the same LFA sonar st�mulus off southern Cal�forn�a. Unl�ke the pre-v�ous two stud�es, where �nd�v�dual exper�mental subjects were tracked on a behav�oral scale, th�s study used s�ght�ng data on an ecolog�cal scale. Playbacks and control �ntervals w�th no trans-m�ss�on were used to �nvest�gate behav�or and d�str�but�on on t�me scales of several weeks and spat�al scales of tens of k�lometers. S�ght�ngs and whale d�v�ng behav�or were not random but were related to env�ronmental features such as the con-t�nental shelf break and �ts effects on prey abun-dance rather than operat�on and locat�on of the nonpulse sonar source. The general conclus�on was that whales rema�ned feed�ng w�th�n a reg�on

for wh�ch 12 to 30% of exposures exceeded 140 dB re: 1 µPa. A s�ngle observat�on was scored for th�s study because �nd�v�dual responses were not reported.

Frankel & Clark (1998) conducted playback exper�ments w�th w�nter�ng humpback whales around the B�g Island of Hawa�’�. The sound source was a s�ngle speaker produc�ng a low-frequency “M-sequence” (s�ne wave w�th mult�ple-phase reversals) s�gnal �n the 60 to 90 Hz band. Th�s was s�m�lar �n bandw�dth to the ATOC source, but had a much lower output level (172 dB re: 1 µPa @ 1 m). A vert�cal l�ne array of cal�brated hydrophones was deployed from a spar buoy to measure rece�ved s�gnals in situ. Deta�led observat�ons of many behav�oral patterns (�nclud�ng resp�rat�on, d�v�ng, and general movements) were recorded before, dur�ng, and after playback (n = 50) and control (n = 34) sequences. A s�ngle tr�al also �nvolved playback of humpback forag�ng sounds. Most of the playback sequences �nvolved very low-level RLs, ca. 90 to 120 dB re: 1 µPa, though not spec�-f�ed �n suff�c�ent deta�l to �nclude �n the analys�s here. For 11 playbacks, exposures were between 120 and 130 dB re: 1 µPa and �ncluded suff�-c�ent �nformat�on regard�ng �nd�v�dual responses. Dur�ng e�ght of the tr�als, there were no measur-able d�fferences �n tracks or bear�ngs relat�ve to control cond�t�ons, whereas on three occas�ons, whales e�ther moved sl�ghtly away from (n = 1) or towards (n = 2) the playback speaker dur�ng expo-sure. Because �t was not poss�ble to determ�ne whether the same �nd�v�dual whales were repre-sented more than once �n the playback sequences, a s�ngle observat�on was recorded for Frankel & Clark (1998), w�th 0.73 of th�s observat�on (8/11) scored as a 0 (no response) and 0.27 (3/11) scored as a 3 (m�nor changes �n locomot�on speed, d�rec-t�on, and/or d�v�ng). A f�nal �mportant observat�on from the deta�led stat�st�cal analys�s by Frankel & Clark was that the presence of the source vessel �tself had a greater effect than d�d the M-sequence playback.

F�nally, Nowacek et al. (2004) used controlled exposures to demonstrate behav�oral react�ons of northern r�ght whales to var�ous nonpulse sounds. Playback st�mul� �ncluded sh�p no�se; soc�al sounds of conspec�f�cs; and a complex, 18-m�n “alert” sound cons�st�ng of repet�t�ons of three d�fferent art�f�c�al s�gnals (alternat�ng 1-s pure tones [500 and 850 Hz]; a 2-s, tonal, frequency downsweep [4,500 to 500 Hz]; and a pa�r of 1-s pure tones [1,500 Hz and 2,000 Hz] ampl�tude modulated at 120 Hz). A total of ten whales were tagged w�th cal�brated �nstruments that measured rece�ved sound character�st�cs and concurrent an�mal movements �n three d�mens�ons. F�ve out of s�x exposed whales reacted strongly to alert


s�gnals at measured RLs between 130 and 150 dB re: 1 µPa (�.e., ceased forag�ng and swam rap�dly to the surface; sever�ty scale = 7). Two of these �nd�v�duals were not exposed to sh�p no�se and are g�ven as a d�screte observat�on �n Table 15, whereas the other four were exposed to both st�m-ul� and thus we�ghted as 0.5 (1/2) observat�ons for the respect�ve RL and sever�ty score. These whales reacted m�ldly to conspec�f�c s�gnals (not scored here because of b�olog�cal s�gnals). Seven whales, �nclud�ng the four exposed to the alert st�mulus, had no measurable response to e�ther sh�p sounds or actual vessel no�se. Th�s study by Nowacek et al. �ncluded the careful exper�mental des�gn, controls, and deta�led �nformat�on on exposure and �nd�v�dual behav�oral response that were requ�red for behav�oral analys�s. More stud�es of th�s type and r�gor are urgently needed (see Chapter 5).

We rev�ewed add�t�onal stud�es concern�ng low-frequency cetaceans and nonpulse sounds but d�d not �nclude them �n the analys�s here, generally due to the absence of key �nformat�on. Dahlhe�m (1987) exposed gray whales to playbacks of outboard no�se, gray whale calls, and tonal sounds. Whales s�gn�f�cantly �ncreased call�ng rate and mod�f�ed call structure for sources other than the test tone (the latter caused all vocal�zat�on to cease). Dur�ng and follow�ng longer durat�on playbacks of o�l dr�ll�ng and k�ller whale sounds w�th more prec�se track�ng of gray whale locat�ons, �nd�v�duals spent more t�me m�ll�ng, and whales rema�ned farther off-shore dur�ng k�ller whale playbacks. Unfortunately, �nsuff�c�ent �nformat�on �s presented to assoc�ate changes w�th spec�f�c RLs. Borggaard et al. (1999) measured the effects of �ndustr�al act�v�ty on several myst�cete spec�es �n Newfoundland, but �nsuff�c�ent �nformat�on �s reported on �nd�v�dually d�scern�ble responses. Sch�ck & Urban (2000) appl�ed stat�st�-cal methods to assess spat�al avo�dance of act�ve dr�ll�ng r�gs by bowhead whales, but no acoust�c data are reported. Moore & Clarke (2002) synthe-s�zed prev�ously publ�shed data (all cons�dered separately above) on numerous nonpulse sources, �n order to assess the avo�dance probab�l�ty of gray whales for var�ous exposure RLs. Jahoda et al. (2003) stud�ed �nd�v�dual responses of f�n whales (n = 25) to close rap�d approaches of small vessels; 18 observat�ons �ncluded control and exper�mental data. Clear behav�oral responses were observed, but ne�ther RL nor range from source to �nd�v�du-als were g�ven. Results are further compl�cated by whale tagg�ng attempts from the vessel. Frankel & Clark (2000) and Mobley (2005) �nvest�gated the d�str�but�on of humpback whales �n Hawa�’� �n relat�on to the operat�on of a low-frequency tomo-graph�c source (ca. 75 Hz; 37.5-Hz nom�nal band-w�dth; 20-m�n durat�on every 2 h dur�ng dayl�ght hours; source level: 195 dB re: 1 µPa-m). Frankel

& Clark (2000) observed whales from a land stat�on and determ�ned that the average d�stance between the sound source and the whale groups s�ghted was s�gn�f�cantly greater dur�ng source operat�on. These and other data were also cons�dered �n the context of other factors affect�ng humpback whale d�str�bu-t�on off the �sland of Kaua’�. Mobley (2005) con-ducted aer�al surveys �n each of three years (2001, source off; 2002 & 2003, source on) dur�ng the peak season of humpback res�dency. Abundance and d�str�but�on of whales were very s�m�lar �n the area surround�ng the source over all three years; small d�fferences �n s�ght�ng rates, s�ght�ng loca-t�on depth, and d�stances from the source and shore were not stat�st�cally s�gn�f�cant. Frankel & Clark (2002) and Mobley (2005) lack expl�c�t data on RLs assoc�ated w�th �nd�v�dual behav�oral observa-t�ons, wh�ch precludes the�r �nclus�on here.

Mid-FrequencyCetaceans/Nonpulses(Cell6)A relat�vely large number of m�d-frequency cetaceans have been observed �n the f�eld and �n the laboratory respond�ng to nonpulse sounds, �nclud�ng vessels and watercraft (LGL & Greener�dge, 1986; Gordon et al., 1992; Palka & Hammond, 2001; Buckstaff, 2004; Mor�saka et al., 2005), pulsed p�ngers and ADD/AHDs (Watk�ns & Schev�ll, 1975; Morton & Symonds, 2002; Monte�ro-Neto et al., 2004), �ndustr�al act�v�t�es (Awbrey & Stewart, 1983; R�chardson et al., 1990b), m�d-frequency act�ve m�l�tary sonar (NRL, 2004a, 2004b; NMFS, 2005), and tones or bands of no�se �n laboratory cond�t�ons (Nacht�gall et al., 2003; F�nneran & Schlundt, 2004). Summary �nformat�on on these stud-�es �s g�ven �n Table 16. As �n other cond�t�ons, a number of potent�ally relevant f�eld stud�es are not �ncluded �n the sever�ty scal�ng analys�s due to lack of suff�c�ently deta�led �nformat�on.

An add�t�onal challenge �n �nterpret�ng many of the f�eld data for th�s cond�t�on �s �solat�ng the effect of RL from the effects of mere source presence (as poss�bly �nd�cated by v�sual st�mul� or other aspects of acoust�c exposure such as the presence of h�gh-frequency components) and other contextual var�-ables. For th�s reason, several stud�es were cons�d-ered but not �ntegrated �nto the analys�s.

The laboratory observat�ons are of capt�ve ceta-ceans exposed to prec�sely controlled and known no�se exposures �n the context of hear�ng and TTS exper�ments. The relevance of behav�oral reac-t�ons of tra�ned, food-re�nforced capt�ve an�mals exposed to no�se �n assess�ng react�ons of free-rang-�ng mar�ne mammals �s not well-known, however (d�scussed below).

The comb�ned f�eld and laboratory data for m�d-frequency cetaceans exposed to nonpulse sounds do not lead us to a clear conclus�on about

512 Southalletal.

RLs co�nc�dent w�th var�ous behav�oral responses (see sever�ty scal�ng, Table 17). In some sett�ngs, �nd�v�duals �n the f�eld showed profound (and what we regard here as s�gn�f�cant) behav�oral responses to exposures from 90 to 120 dB re: 1 µPa, wh�le others fa�led to exh�b�t such responses for exposure RLs from 120 to 150 dB re: 1 µPa. Contextual var�ables other than exposure RL, and probable spec�es d�fferences, are the l�kely reasons for th�s var�ab�l�ty. Context, �nclud�ng the fact that capt�ve subjects were often d�rectly re�nforced w�th food for tolerat�ng no�se exposure, may also expla�n why there �s great d�spar�ty �n results from f�eld and laboratory cond�t�ons—exposures �n capt�ve sett�ngs generally exceeded 170 dB re: 1 µPa before �nduc�ng behav�oral responses.

FieldObservations(Cell6)The most extens�ve ser�es of observat�ons regard-�ng vessels and watercraft �s from LGL and Greener�dge (1986) and F�nley et al. (1990), who documented belugas and narwhals (Monodonmonoceros) congregated near �ce edges react�ng to the approach and passage of �ce-break�ng sh�ps. Over a 3-y per�od (1982 to 1984), they used both �ce-based local observat�ons of whales and aer�al surveys, and also made deta�led acoust�c measure-ments. The survey method made �t d�ff�cult to assess �ndependent groups of an�mals. Some large-scale group�ngs could be �dent�f�ed for several d�f-ferent “d�sturbance” per�ods, however. Pre-d�s-turbance group s�ze was ~3; we d�v�ded reported numbers of d�sturbed “herds” by three to est�mate the number of �ndependent groups. Aer�al surveys �n 1984 lumped s�ght�ngs by m�nute, wh�ch cor-responded to about 3.4 km �n d�stance. We cons�d-ered th�s d�stance suff�c�ent to treat each m�nute as an �ndependent un�t for avo�dance analys�s. The responses of both spec�es over a 3-y per�od were generally s�m�lar to responses they make to preda-tors as descr�bed by Inu�t hunters.

Beluga whales responded to oncom�ng ves-sels by (1) flee�ng at speeds of up 20 km/h from d�stances of 20 to 80 km, (2) abandon�ng normal pod structure, and (3) mod�fy�ng vocal behav�or and/or em�tt�ng alarm calls. Narwhals, �n contrast, generally demonstrated a “freeze” response, ly�ng mot�onless or sw�mm�ng slowly away (as far as 37 km down the �ce edge), huddl�ng �n groups, and ceas�ng sound product�on. There was some ev�dence of hab�tuat�on and reduced avo�dance 2 to 3 d after onset. Due to the deta�led and exten-s�ve nature of these observat�ons, data from each season, and how they are �nterpreted here, are g�ven �n deta�l.

The 1982 season observat�ons by LGL & Greener�dge (1986) �nvolved a s�ngle passage of an �cebreaker w�th both �ce-based and aer�al

measurements on 28 June 1982. Four groups of narwhals (n = 9 to 10, 7, 7, and 6) responded when the sh�p was 6.4 km away (exposure RLs of ~100 dB re: 1 µPa �n the 150- to 1,150-Hz band). At a later po�nt, observers s�ghted belugas mov�ng away from the source at > 20 km (exposure RLs of ~90 dB re: 1 µPa �n the 150- to 1,150-Hz band). The total number of an�mals observed flee�ng was about 300, suggest�ng approx�mately 100 �nde-pendent groups (of three �nd�v�duals each), wh�ch �s the sample s�ze used here. No whales were s�ghted the follow�ng day, but some were s�ghted on 30 June, w�th sh�p no�se aud�ble at spectrum levels of approx�mately 55 dB re 1 µPa/Hz (up to 4 kHz).

Observat�ons dur�ng 1983 (LGL & Greener�dge, 1986) �nvolved two �ce-break�ng sh�ps w�th aer�al survey and �ce-based observat�ons dur�ng seven sampl�ng per�ods. As the f�rst vessel approached at a d�stance of about 65 km, �ce-based observ-ers noted react�ons from both narwhals (seven groups) and belugas (e�ght groups) (exposure RLs of ~101 to 105 dB re: 1 µPa �n the 20- to 1,000-Hz band). After 22 h w�thout operat�on, the vessel commenced �ce-break�ng, and a second �cebreaker approached (exposure RLs of ~120 dB re: 1 µPa �n the 20- to 1,000-Hz band). Th�s resulted �n the rap�d movement of > 225 belugas (est�mated as a sample s�ze of 75 for th�s analy-s�s); belugas were ne�ther seen nor heard for the rema�nder of the second observat�on per�od. Behav�oral responses were also observed for 10 groups of narwhals. A total of 73 narwhals were seen and/or heard, but the�r react�ons are not clearly reported and are thus excluded from analys�s here. At the onset of the th�rd sampl�ng per�od, follow�ng a 4.5-h s�lent �nterval, four narwhal groups were observed �n nom�nal soc�al behav�or (d�v�ng and vocal�z�ng). An �ce-break�ng vessel operated �nterm�ttently, but no change was observed �n narwhal behav�or. Belugas �n the area d�d mod�fy vocal�zat�on parameters dur�ng opera-t�ons (exposure RLs of ~116 dB re: 1 µPa �n the 20- to 1,000-Hz band). A 6-h qu�et �nterval was followed by 10.5 h of �ce-break�ng operat�on, but bad weather precluded an�mal observat�ons. After an add�t�onal 9-h h�atus, �ce-break�ng commenced aga�n by both vessels (exposure RLs of ~121 dB re: 1 µPa �n the 20- to 1,000-Hz band). Ice-based observers documented 14 narwhals and 11 belu-gas leav�ng the area, and aer�al surveys �nd�cated 80% of 673 belugas mov�ng away from sound sources (est�mated number of groups calculated as [.8]*[673/3] = 179.5). As no�se levels from �ce-break�ng operat�ons d�m�n�shed, a total of 45 nar-whals returned to the area and engaged �n d�v�ng and forag�ng behav�or. The s�xth observat�on per�od followed 6.5 h w�thout a vessel �n the area,


dur�ng wh�ch 30 belugas (est�mated as 10 groups) and 15 narwhals (est�mated as f�ve groups) were observed d�v�ng �n the area (exposure RLs of ~105 dB re: 1 µPa �n the 20- to 1,000-Hz band). A s�ngle beluga vocal response was noted at RL = 116 dB re: 1 µPa �n the 20- to 1,000-Hz band. Aer�al surveys �nd�cated dense concentrat�ons of narwhals (n = 50) and belugas (n = 400) appar-ently forag�ng well away from the d�sturbance s�te. Dur�ng the f�nal sampl�ng per�od, follow�ng an 8-h qu�et �nterval, no react�ons were seen from 28 narwhals and 17 belugas (exposure RLs rang�ng up to 115 dB re: 1 µPa).

The f�nal season (1984) reported �n LGL & Greener�dge (1986) �nvolved aer�al surveys before, dur�ng, and after the passage of two �ce-break�ng sh�ps. The lack of �ce camps precluded acoust�c measurements as well as behav�oral observat�ons. A prel�m�nary survey was conducted the day before operat�ons, and an add�t�onal aer�al survey was conducted as both sh�ps commenced operat-�ng. Dur�ng operat�ons, no belugas and few nar-whals were observed �n an area approx�mately 27 km ahead of the vessels, and all whales s�ghted over 20 to 80 km from the sh�ps were sw�mm�ng strongly away. Add�t�onal observat�ons conf�rm the remarkable spat�al extent of avo�dance reac-t�ons to th�s sound source �n th�s context. In the absence of acoust�c measurements, however, �t was necessary to est�mate RLs from the deta�led data from the same �ce-break�ng vessel dur�ng the prev�ous season.

Behav�oral responses at fa�rly low exposure RLs are suggested by stud�es of some other m�d-frequency cetaceans as well. Gordon et al. (1992) conducted opportun�st�c v�sual and acoust�c mon�-tor�ng of sperm whales �n New Zealand exposed to nearby whale-watch�ng boats (w�th�n 450 m). Ind�v�duals could not be used as the un�ts of analys�s because �t was d�ff�cult to re-s�ght spe-c�f�c �nd�v�duals dur�ng both exposure and control cond�t�ons. Sperm whales resp�red s�gn�f�cantly less frequently, had shorter surface �ntervals, and took longer to start cl�ck�ng at the start of a d�ve descent when boats were nearby than when they were absent. No�se spectrum levels of whale-watch�ng boats ranged from 109 to 129 dB re: 1 µPa/Hz. Over a bandw�dth of 100 to 6,000 Hz, equ�valent broadband source levels are ~157 dB re: 1 µPa-m; RLs at a range of 450 m are ~104 dB re: 1 µPa.

Palka & Hammond (2001) appl�ed a General Add�t�ve Model to l�ne transect data to est�mate the range at wh�ch m�d-frequency cetaceans typ�-cally responded to the no�se of research vessels. The subjects were Atlant�c wh�te-s�ded dolph�ns �n the Gulf of Ma�ne and wh�te-beaked dolph�ns (Lagenorhynchus albirostris) �n the North Sea.

The wh�te-s�ded dolph�ns exh�b�ted s�mple avo�d-ance behav�or (as �nd�cated by the�r or�entat�ons) out to an est�mated range of 592 m based on 85 group s�ght�ngs (n > 1). Wh�te-beaked dolph�ns actually approached vessels between 150 and 300 m away, but demonstrated avo�dance at d�stances of 300 to 700 m. Typ�cal avo�dance d�stance was est�mated as 716 m based on 48 groups s�ghted.

Buckstaff (2004), us�ng repeated samples of the behav�or of 14 �nd�v�dual bottlenose dol-ph�ns, observed 1,233 vessel approaches (w�th�n 400 m) near Sarasota, Flor�da. Dolph�n wh�stle rates became elevated before vessel no�se was detectable to the researcher l�sten�ng v�a towed hydrophones. Vessel RLs measured near dolph�n subjects ranged from 113 to 138 dB re: 1 µPa. Dolph�n vocal responses were observed before vessel sounds were aud�ble, and apparently occurred w�th RLs �n the 110 to < 120 dB re: 1 µPa category.

Mor�saka et al. (2005) compared wh�stles from three populat�ons of Indo-Pac�f�c bottlenose dol-ph�ns (Tursiops aduncus). One populat�on was exposed to vessel no�se w�th spectrum levels of ~85 dB re: 1 µPa/Hz �n the 1- to 22-kHz band (broadband RL ~128 dB re: 1 µPa) as opposed to ~65 dB re: 1 µPa/Hz �n the same band (broadband RL ~108 dB re: 1 µPa) for the other two s�tes. Dolph�n wh�stles �n the no�s�er env�ronment had lower fundamental frequenc�es and less frequency modulat�on, suggest�ng a sh�ft �n sound param-eters as a result of �ncreased amb�ent no�se.

Morton & Symonds (2002) used census data on k�ller whales �n Br�t�sh Columb�a to evaluate avo�dance of nonpulse AHD sources. They con-s�dered unusually long t�me scales, compar�ng pre-exposure data from 1985 to 1992, exposure from 1993 to 1998, and post-exposure from 1999 to 2000. The response data were s�mply pres-ence or absence, mak�ng �t d�ff�cult to assess RLs. Us�ng some mon�tor�ng and reasonable assump-t�ons, however, they est�mated aud�b�l�ty ranges throughout the complex study area. Avo�dance ranges were ca. 4 km. Also, there was a dramat�c reduct�on �n the number of days “res�dent” k�ller whales were s�ghted dur�ng AHD-act�ve per�ods compared to pre- and post-exposure per�ods and a nearby control s�te. Morton & Symonds d�d not �nd�cate how many pods were �nvolved �n the�r analys�s. Consequently, we assume a s�ngle �nde-pendent group �n our analys�s.

Monte�ro-Neto et al. (2004) stud�ed avo�dance responses of tucux� (Sotaliafluviatilis) to Dukane® Netmark ADDs. Source character�st�cs are not g�ven, but �dent�cal dev�ces were used by Cul�k et al. (2001), and acoust�c parameters are reported �n deta�l there (and �n the “Cell 9” sect�on). In a total of 30 exposure tr�als, ~5 groups each demonstrated

514 Southalletal.

s�gn�f�cant avo�dance compared to 20 p�nger off and 55 no-p�nger control tr�als over two quad-rats of about 0.5 km2. Ne�ther avo�dance range nor RLs are g�ven, but based upon a central d�s-tance from the quadrat of 10 m, and assum�ng 15 log R transm�ss�on loss �n th�s shallow env�ron-ment (water depth 1 to 5 m), est�mated exposure RLs were ~115 dB re: 1 µPa.

The only spec�f�c s�tuat�on �nvolv�ng exposure of w�ld mar�ne mammals to act�ve m�d-frequency m�l�tary sonar for wh�ch exposure cond�t�ons are known w�th any degree of spec�f�c�ty �nvolved �nc�dental exposure of k�ller whales to sounds from the naval vessel USS Shoup (NRL, 2004a, 2004b; NMFS, 2005). A group (J-pod) of south-ern res�dent k�ller whales �n the eastern Stra�t of Juan de Fuca and Haro Stra�t, Wash�ngton, was observed by researchers before, dur�ng, and after the approach�ng USSShoup transm�tted sonar s�g-nals from �ts 53C sonar at a source level of ca. 235 dB re: 1 µPa-m once every ca. 28 s for several hours. At �ts po�nt of closest approach, the mean d�rect-path RL w�th�n a spec�f�ed area around the an�mals was ca. 169 dB re: 1 µPa (NRL, 2004a, 2004b). As �nd�cated by NMFS (2005), there �s some d�screpancy �n �nterpretat�on of the behav-�oral responses among researchers who were e�ther on the water or who observed v�deo record-�ngs of behav�oral responses. The lead researcher follow�ng and observ�ng the an�mals dur�ng the event �nd�cated that �nd�v�duals �n the group dem-onstrated abnormal avo�dance behav�or, most dramat�cally at the po�nt of closest approach. However, the behav�or of the whales apparently returned to normal w�th�n a short per�od follow�ng cessat�on of sonar transm�ss�ons. A sever�ty score of 6 (m�ld/moderate avo�dance) �s subsequently reported �n the 160 to 170 dB re: 1 µPa b�n for th�s s�ngle observat�on of the group.

Awbrey & Stewart (1983) played back sem�-sub-mers�ble dr�llsh�p sounds (source level: 163 dB re: 1 µPa-m) to belugas �n Alaska. They reported avo�d-ance react�ons at 300 and 1,500 m and approach by groups at a d�stance of 3,500 m (RLs ~110 to 145 dB re: 1 µPa over these ranges assum�ng a 15 log R transm�ss�on loss). S�m�larly, R�chardson et al. (1990b) played back dr�ll�ng platform sounds (source level: 163 dB re: 1 µPa-m) to belu-gas �n Alaska. They conducted aer�al observat�ons of e�ght �nd�v�duals among ~100 spread over an area several hundred meters to several k�lometers from the sound source and found no obv�ous reac-t�ons. Moderate changes �n movement were noted for three groups sw�mm�ng w�th�n 200 m of the sound projector.

A number of add�t�onal stud�es (Rendell & Gordon, 1999; Ch�lvers & Corkeron, 2001; Bord�no et al., 2002; W�ll�ams et al., 2002; Cox et

al., 2003; Hast�e et al., 2003; Lusseau, 2003; Foote et al., 2004; Sche�fele et al., 2005) were rev�ewed �n deta�l. The results were excluded from Table 17 due to l�m�ted or no �nformat�on on an�mal num-bers and/or locat�on relat�ve to the source, acous-t�c propert�es of sources, propagat�on var�ables, or rece�ved exposure cond�t�ons. The general obser-vat�ons of each study are g�ven here br�efly. Hast�e et al. (2003) documented �ncreased sw�mm�ng and d�v�ng synchrony of bottlenose dolph�ns off northern Scotland �n the presence of vessel traf-f�c. Lusseau (2003) observed effects on behav�or of New Zealand bottlenose dolph�ns w�th�n 400 m of boats. Ch�lvers & Corkeron (2001) cons�dered d�fferences �n behav�or of bottlenose dolph�ns that do and do not forage around trawlers. W�ll�ams et al. (2002) observed that some k�ller whales adopt errat�c movement patterns, suggest�ve of avo�d-ance, when whale-watch�ng vessels accelerate to �ntersect the whale’s course. RLs of vessel sound �ncreased approx�mately 14 dB w�th �ncreased speed assoc�ated w�th leapfrogg�ng. Bord�no et al. (2002) determ�ned that ADDs were �n�t�ally effec-t�ve at reduc�ng by-catch of Franc�scana dolph�ns �n Argent�ne subs�stence g�llnet f�sher�es. Cox et al. (2003) �nvest�gated react�ons of bottle-nose dolph�ns to Dukane® NetMark 1000 ADDs attached to commerc�al g�llnets and found very l�m�ted to no behav�oral avo�dance. A group of long-f�nned p�lot whales (Globicephala melas) demonstrated s�gn�f�cant elevat�ons of wh�stle rates follow�ng each exposure to m�d-frequency m�l�tary sonar reported to be at a “h�gh” level (Rendell & Gordon, 1999).

F�nally, two recent papers deal w�th �mportant �ssues relat�ng to changes �n mar�ne mammal vocal behav�or as a funct�on of var�able background no�se levels. Foote et al. (2004) found �ncreases �n the durat�on of k�ller whale calls over the per�od 1977 to 2003, dur�ng wh�ch t�me vessel traff�c �n Puget Sound, and part�cularly whale-watch�ng boats around the an�mals, �ncreased dramat�cally. Sche�fele et al. (2005) demonstrated that belugas �n the St. Lawrence R�ver �ncreased the levels of the�r vocal�zat�ons as a funct�on of the background no�se level (the “Lombard Effect”). (See also Parks et al., 2007, for a related new paper on mys-t�cetes.) These papers demonstrate some degree of plast�c�ty �n the vocal s�gnal parameters of mar�ne mammals �n response to the amb�ent cond�t�on (l�kely affected by the presence of human sound sources). These stud�es were not part�cularly amenable to the k�nd of analys�s conducted �n the sever�ty scal�ng. We note the part�cular �mpor-tance of d�rect measurements of no�se �mpacts on mar�ne mammal vocal�zat�on and commun�cat�on systems.


LaboratoryObservations(Cell6)Several researchers conduct�ng laboratory exper�-ments on hear�ng and the effects of nonpulse sounds on hear�ng �n m�d-frequency cetaceans have reported concurrent behav�oral responses. Nacht�gall et al. (2003) reported that no�se expo-sures up to 179 dB re: 1 µPa and 55-m�n durat�on affected the tra�ned behav�ors of a bottlenose dol-ph�n part�c�pat�ng �n a TTS exper�ment. F�nneran & Schlundt (2004) prov�ded a deta�led, compre-hens�ve analys�s of the behav�oral responses of belugas and bottlenose dolph�ns to 1-s tones (RLs 160 to 202 dB re: 1 µPa) �n the context of TTS exper�ments. Romano et al. (2004) �nvest�gated the phys�olog�cal responses of a bottlenose dolph�n and a beluga exposed to these tonal exposures and demonstrated a decrease �n blood cort�sol levels dur�ng a ser�es of exposures between 130 and 201 dB re: 1 µPa. Collect�vely, the laboratory observa-t�ons suggested the onset of behav�oral response at h�gher RLs than d�d f�eld stud�es (see Table 16). The d�fferences were l�kely related to the very d�f-ferent cond�t�ons and contextual var�ables between untra�ned, free-rang�ng �nd�v�duals vs laboratory subjects that were rewarded w�th food for tolerat-�ng no�se exposure.

High-Frequency Cetaceans/Nonpulses (Cell 9)

Numerous controlled stud�es have been con-ducted recently on the behav�oral reac-t�ons of h�gh-frequency cetaceans to var�-ous nonpulse sound sources both �n the f�eld (Cul�k et al., 2001; Johnston, 2002; Oles�uk et al., 2002) and �n laboratory sett�ngs (Kastele�n et al., 1997, 2000, 2005, 2006a). However, only one h�gh-frequency spec�es (harbor porpo�se) has been extens�vely stud�ed. For that spec�es, suf-f�c�ent data are ava�lable to est�mate behav�oral response magn�tude vs rece�ved exposure cond�-t�ons. The or�g�nal stud�es were attempts to reduce harbor porpo�se by-catch by attach�ng warn�ng p�ngers to f�sh�ng gear. More recent stud�es con-s�der whether ADDs and AHDs also exclude harbor porpo�ses from cr�t�cal hab�tat areas and whether these dev�ces affect harbor porpo�se behav�or �n controlled laboratory cond�t�ons.

The comb�ned w�ld and capt�ve an�mal data (summar�zed �n Table 18) clearly support the observat�on that harbor porpo�ses are qu�te sens�-t�ve to a w�de range of human sounds at very low exposure RLs (~90 to 120 dB re: 1 µPa), at least for �n�t�al exposures. Th�s observat�on �s also ev�dent �n the sever�ty scal�ng analys�s for Cell 9 (Table 19). All recorded exposures exceed�ng 140 dB re: 1 µPa �nduced profound and susta�ned avo�d-ance behav�or �n w�ld harbor porpo�ses. Harbor porpo�ses also tend to avo�d boats, although

Dall’s porpo�ses do not (R�chardson et al., 1995). Whether th�s apparently h�gh degree of behav�oral sens�t�v�ty by harbor porpo�ses to anthropogen�c sounds extends to other h�gh-frequency cetacean spec�es (or to nonpulse sources other than ADDs, AHDs, and boats) �s unknown. However, g�ven the lack of �nformat�on to the contrary, such a relat�onsh�p should be assumed as a precaut�onary measure.

Hab�tuat�on to sound exposure was noted �n some but not all stud�es. In certa�n f�eld cond�-t�ons, strong �n�t�al react�ons of h�gh-frequency cetaceans at relat�vely low RLs appeared to wane rather rap�dly w�th repeated exposure (Cox et al., 2001). In contrast, several laboratory observat�ons showed l�ttle or no �nd�cat�on of reduced behav-�oral sens�t�v�ty as a funct�on of exposure exper�-ence (Kastele�n et al., 1997, 2005).

FieldObservations(Cell9)Kraus et al. (1997) found (and Barlow & Cameron, 2003, later conf�rmed) that ADDs can affect by-catch rates of harbor porpo�ses �n commerc�al f�sh�ng appl�cat�ons. Kraus et al. (1997) found that nets w�th Dukane® p�ngers (10-kHz fundamental frequency, 300-ms durat�on, 132 dB re: 1 µPa source level) were suff�c�ently avo�ded that s�g-n�f�cantly fewer porpo�ses were entangled than �n nets lack�ng p�ngers. The�r observat�ons suggest an ADD avo�dance range of at least 10 m (expo-sure RL ~110 dB re: 1 µPa) but are not expl�c�t enough �n document�ng exposure cond�t�ons or �nd�v�dual responses to �nclude �n the behav�oral scor�ng analys�s here.

Cul�k et al. (2001) conducted behav�oral observat�ons of groups of harbor porpo�ses near Vancouver Island before, dur�ng, and after the removal of a PICE p�nger (e�ght d�fferent w�de-band swept frequency s�gnals between 20 and 160 kHz; 300-ms durat�on at random �ntervals [5 to 30 s]; max. broadband SL = 145 dB re: 1 µPa @ 1 m). Source character�st�cs of the alarm were known, but propagat�on measurements were not made insitu. Exposure RLs are est�mated here based on source character�st�cs and assumpt�ons regard�ng propagat�on, allow�ng for measures of s�m�lar sources �n s�m�lar cond�t�ons. A large exclus�on zone of approx�mately 530-m rad�us surround�ng act�ve acoust�c alarms was observed (correspond�ng to exposure RLs of ~90 to 100 dB re: 1 µPa). Ind�v�dual s�ght�ng and avo�dance data dur�ng CEE act�ve and control cond�t�ons were scored for �nd�v�duals w�th�n and outs�de th�s exclus�on zone (see Table 18).

Johnston & Woodley (1998) conducted an exten-s�ve survey of AHDs used �n the Bay of Fundy to exclude p�nn�peds from salmon aquaculture s�tes. Based on the behav�oral observat�ons of Oles�uk

516 Southalletal.

et al. (1996), Johnston & Woodley (1998) deter-m�ned that harbor porpo�ses were l�kely be�ng excluded from extens�ve areas of �mportant hab�tat as a result of overlapp�ng AHD deployments. Th�s study lacked the d�screte observat�onal data neces-sary for analys�s here, but two subsequent stud�es conta�ned such measurements for harbor porpo�ses exposed to AHDs.

Oles�uk et al. (2002) conducted a controlled exposure �n wh�ch they deact�vated an array of four A�rmar® AHDs for 3 wk and then act�vated the array for three 3-wk �ntervals over an 18-wk per�od. Source character�st�cs are known (10-kHz fundamental frequency; 194 dB re: 1 µPa-m (peak-to-peak) source level; ser�es of 1.8-ms pulses, repeated at 40-ms �ntervals grouped �nto 2.3-s tra�ns separated by 2.1-s qu�et per�ods). However, no emp�r�cal acoust�c measurements were obta�ned. Exposure RLs were est�mated here based on source character�st�cs and s�mple assumpt�ons about the propagat�on of h�gh-frequency sounds �n shallow-water env�ronments. Act�ve AHDs resulted �n clear avo�dance behav�or by �nd�v�duals and groups of harbor porpo�ses. The s�ght�ng rate dur�ng act�ve per�ods as a percent of that dur�ng control per�ods was only 1.4% at ranges from 400 to 599 m, 2.5 to 3.3% at 600 to 2,499 m, and 8.1% at 2.5 to 3.5 km. RLs at 3.5 km were est�mated to be ~123 dB re: 1 µPa. Avo�dance data dur�ng act�ve and control per�ods were scored here for �nd�v�duals w�th�n the var�ous exposure zones (Table 18).

Johnston (2002) observed s�m�lar harbor por-po�se behav�oral avo�dance of act�ve AHDs. They used an A�rmar® dB II Plus AHD System (10-kHz fundamental frequency; 180 dB re: 1 µPa-m source level, produc�ng a short tra�n of 2.5-ms s�gnals repeated every 17 s) deployed from a small boat. They s�ghted fewer an�mals when the AHD was act�ve, and these an�mals were s�gn�f�cantly fur-ther away than dur�ng control phases. Approx�mate exposure RLs at the po�nt of closest approach were est�mated here as ~128 dB re: 1 µPa; mean clos-est approach d�stance was cons�stent w�th exposure RLs of ~125 dB re: 1 µPa.

Add�t�onal f�eld observat�ons of harbor por-po�ses suggest that the�r apparently h�gh degree of behav�oral sens�t�v�ty extends to sources other than ADDs and AHDs. Kosch�nsk� et al. (2003) observed behav�oral responses of harbor porpo�ses to s�mulated w�nd turb�ne no�se (max. energy between 30 and 800 Hz; spectral dens�ty source levels of 128 dB re: 1 µPa/Hz at 80 and 160 Hz). They s�ghted harbor porpo�ses at greater ranges dur�ng playbacks of s�mulated w�nd turb�ne no�se and observed that an�mals more frequently used echolocat�on s�gnals dur�ng �ndustr�al act�v�ty. These data are not scored here, however, due to

l�m�ted ava�lable �nformat�on about no�se exposure cond�t�ons and �nd�v�dual behav�oral responses.

F�nally, wh�le the�r study was not cons�dered �n the sever�ty scal�ng here, we note the �mportance of the Cox et al. (2001) observat�ons regard�ng harbor porpo�se hab�tuat�on. They found that w�ld porpo�ses were �n�t�ally d�splaced by approx�-mately 208 m from act�ve ADDs, but th�s d�splace-ment decreased by 50% �n 4 d, and reached control levels �n 10 to 11 d. Because of the potent�al for hab�tuat�on, �t should be noted that many or most of the f�eld observat�ons reported here, other than those that �nvolve long-durat�on deployments, are l�kely most relevant for naïve �nd�v�duals.

LaboratoryObservations(Cell9)Relat�vely extens�ve laboratory data are ava�lable on capt�ve, �nd�v�dual h�gh-frequency cetaceans exposed to some of the same acoust�c alarms (ADDs and AHDs) and scar�ng dev�ces deployed �n f�eld appl�cat�ons. We appl�ed our behav�oral scor�ng parad�gm to data from each of the capt�ve stud�es conducted by Kastele�n and colleagues, wh�ch �ncluded relat�vely deta�led �nformat�on on �nd�v�dual responses and d�rectly measured expo-sure RLs.

Kastele�n et al. (1997) recorded behav�oral responses (locat�on, sw�mm�ng speed, and resp�rat�on patterns) of a naïve, capt�ve harbor porpo�se exposed to a var�ety of cl�cks, tones, and frequency sweeps. All of the relat�vely low expo-sure RLs (~90 to 115 dB re: 1 µPa) resulted �n strong behav�oral avo�dance (subjects bas�cally swam rap�dly as far from the dev�ces as pos-s�ble w�th�n the enclosure) as well as changes �n sw�mm�ng speed and breath�ng patterns. Although th�s response qu�ckly abated follow�ng no�se cessa-t�on, no hab�tuat�on was observed across mult�ple exposure events. Data from �nd�v�dual exposure tr�als were presented by Kastele�n et al. and are analyzed here. To avo�d pseudorepl�cat�on, these data are �nversely we�ghted by the total number of tr�als to approx�mate a s�ngle exposure for the �nd�v�dual. Based on harbor porpo�se hear�ng mea-surements (Andersen, 1970) and the Kastele�n et al. (1997) data on behav�oral react�ons, Taylor et al. (1997) est�mated zones of no�se �nfluence (aud�b�l�ty, behav�oral d�sturbance, and hear�ng damage) for free-rang�ng harbor porpo�ses.

Subsequently, Kastele�n et al. (2000) exposed two naïve subjects to three d�fferent nonpulse sources and observed generally s�m�lar behav�oral avo�dance �n all cond�t�ons. Pooled data for each subject were scored and reported here; pooled data for each alarm �n the dose-response analys�s were we�ghted to equate w�th a s�ngle exposure event for each �nd�v�dual. Kastele�n et al. (2001) later measured s�m�lar behav�oral responses of


the same two �nd�v�dual harbor porpo�ses to three d�fferent acoust�c alarms, but these data were not �ncluded �n th�s analys�s because subjects were no longer naïve to controlled no�se exposures.

Kastele�n et al. (2005) exposed two add�t�onal naïve harbor porpo�ses to var�ous sounds assoc�-ated w�th underwater data transm�ss�on systems (cl�cks, tones, sweeps, and �mpuls�ve d�stance sensors w�th a range of source character�st�cs). They d�rectly measured source levels of each sound type and RLs at numerous pos�t�ons w�th�n the exper�mental pool. Observed behav�oral responses (avo�dance and changes �n sw�mm�ng and resp�rat�on patterns) were very s�m�lar to those dur�ng the prev�ous Kastele�n et al. (1997, 2000, 2001) stud�es. Pooled data for each �nd�-v�dual response and source type were analyzed here �n the same manner as we appl�ed to the Kastele�n et al. (2000) measurements. Kastele�n et al. (2006a) exposed yet another naïve �nd�v�dual harbor porpo�se and reported very s�m�lar f�nd-�ngs, wh�ch we �ncorporated as a s�ngle pooled result, w�th all exposures equally we�ghted.

Pinnipeds in Water/Nonpulses (Cell 12)

The effects of nonpulse exposures on p�nn�-peds �n water are poorly understood. Stud�es for wh�ch enough �nformat�on was ava�lable for our analys�s �nclude f�eld exposures of harbor seals to AHDs (Jacobs & Terhune, 2002) and of translo-cated d�v�ng northern elephant seals to a research tomography source (Costa et al., 2003), as well as responses of capt�ve harbor seals to underwa-ter data commun�cat�on sources (Kastele�n et al., 2006b). These l�m�ted data (see Table 20) suggest that exposures between ~90 and 140 dB re: 1 µPa generally do not appear to �nduce strong behav-�oral responses �n p�nn�peds exposed to nonpulse sounds �n water; no data ex�st regard�ng exposures at h�gher levels. The sever�ty scal�ng for Cell 12 �s g�ven �n Table 21.

It �s �mportant to note that among these stud-�es of p�nn�peds respond�ng to nonpulse exposures �n water, there are some apparent d�fferences �n responses between f�eld and laboratory cond�t�ons. In contrast to the m�d-frequency odontocetes, cap-t�ve p�nn�peds responded more strongly at lower levels than d�d an�mals �n the f�eld. Aga�n, contex-tual �ssues are the l�kely cause of th�s d�fference. Capt�ve subjects �n the Kastele�n et al. (2006b) study were not re�nforced w�th food for rema�n�ng �n no�se f�elds, whereas free-rang�ng subjects may have been more tolerant of exposures because of mot�vat�on to return to a safe locat�on (Costa et al., 2003) or to approach enclosures hold�ng prey �tems (Jacobs & Terhune, 2002).

FieldObservations(Cell12)Jacobs & Terhune (2002) observed harbor seal react�ons to A�rmar® dB plus II AHDs (general source character�st�cs g�ven �n the “Cell 9” sect�on above; source level �n th�s study was 172 dB re: 1 µPa-m) deployed around aquaculture s�tes. From 1 to 10 AHDs were deployed around n�ne d�ffer-ent s�tes. Jacobs & Terhune measured rece�ved SPLs around the AHDs and measured the behav-�or of seals �n the surround�ng area. Seals �n th�s study were generally unrespons�ve to sounds from the AHDs. Dur�ng two spec�f�c events, �nd�v�du-als came w�th�n 43 and 44 m of act�ve AHDs and fa�led to demonstrate any measurable behav�oral response; est�mated exposure RLs based on the measures g�ven were ~120 to 130 dB re: 1 µPa. These �nd�v�dual observat�ons are we�ghted to rep-resent a s�ngle observat�on for th�s study, scored (as 0), and reported �n Table 21.

Costa et al. (2003) measured rece�ved no�se levels from an ATOC sound source off north-ern Cal�forn�a us�ng acoust�c data loggers placed on translocated elephant seals. Subjects were captured on land, transported to sea, �nstrumented w�th arch�val acoust�c tags, and released such that the�r trans�t would lead them near an act�ve ATOC source (at 939-m depth; 75-Hz s�gnal w�th 37.5- Hz bandw�dth; 195 dB re: 1 µPa-m max. source level, ramped up from 165 dB re: 1 µPa-m over 20 m�n) on the�r return to a haulout s�te. Costa et al. prov�ded a w�de range of deta�led quant�tat�ve measures of �nd�v�dual d�v�ng behav�or, responses, and exposure RLs �n well-character�zed contexts; th�s k�nd of �nformat�on was �deal for the present purposes. D�ve depth and durat�on, descent/ascent veloc�ty, surface �nterval, and exposure RL were recorded from a total of 14 seals. An add�t�onal three seals were exposed to the ATOC source dur�ng translocat�ons and behav�oral observat�ons were made, but exposure RLs were unava�lable. Seven control seals were �nstrumented s�m�larly and released when the ATOC source was not act�ve. Rece�ved exposure levels of the ATOC source for exper�mental subjects averaged 128 dB re: 1 µPa (range 118 to 137) �n the 60- to 90-Hz band. None of the �nstrumented an�mals term�nated d�ves or rad�cally altered behav�or upon exposure, but some stat�st�cally s�gn�f�cant changes �n d�v�ng parameters were documented �n n�ne �nd�v�duals. The behav�oral scores ass�gned here for stat�st�-cally s�gn�f�cant responses were e�ther three or four depend�ng on the change �n d�v�ng behav�or dur�ng exposure relat�ve to mean values for the same �nd�-v�duals before and after exposure (< 50% change scored 3; > 50% change scored 4). Translocated northern elephant seals exposed to th�s part�cular nonpulse source (ATOC) began to demonstrate

518 Southalletal.

subtle behav�oral changes at ~120 to 140 dB re: 1 µPa exposure RLs (Table 21).

Several other f�eld stud�es (d�scussed br�efly below) were cons�dered but not �ncluded �n the behav�oral analyses due to l�m�ted �nformat�on about source and/or propagat�on character�st�cs, �nd�v�dual responses dur�ng and/or �n the absence of exposure, or both. Wh�le study�ng cetaceans, R�chardson et al. (1990b, 1991) made some observat�on of r�nged and bearded seal responses to playbacks of underwater dr�ll�ng sounds. The�r f�nd�ngs generally suggested a fa�rly h�gh degree of tolerance by exposed p�nn�peds to these sounds. Th�s contrasts to some extent w�th the results of Frost & Lowry (1988) who found some reduct�on �n r�nged seal dens�t�es around �slands on wh�ch dr�ll�ng was occurr�ng. Norberg & Ba�n (1994) made deta�led acoust�c measurements of several arrays of Cascade Appl�ed Sc�ences® AHDs (11.9- to 14.7-kHz frequency sweeps; 195 dB re: 1 µPa-m source level; 1-ms pulse produced �n 57 to 58 d�screte pulse ch�rps of 2.3-s total durat�on). These dev�ces were placed on the Ch�ttenden Locks �n Puget Sound, Wash�ngton, �n an effort to d�ssuade predat�on of w�ld steelhead trout by Cal�forn�a sea l�ons. Behav�oral responses of �nd�v�dual an�-mals, however, were not reported. Norberg (2000) evaluated the behav�oral responses of Cal�forn�a sea l�ons to A�rmar® AHDs (10-kHz fundamen-tal frequency; 195 dB re: 1 µPa-m source level; short tra�n of 2.5-ms s�gnals repeated every 17 s) �ntended to reduce predat�on on salmon�ds �n aquaculture fac�l�t�es. Behav�oral observat�ons suggested l�m�ted behav�oral deterrence by the dev�ces (predat�on rates were s�m�lar �n exper�-mental and control cond�t�ons), but measures of RLs and �nd�v�dual response behav�or are absent. Yurk (2000) also observed p�nn�peds exposed to AHDs �n the context of f�sher�es �nteract�ons. He determ�ned that act�ve AHDs were more effec-t�ve than a mechan�cal barr�er or altered l�ght�ng cond�t�ons �n d�ssuad�ng harbor seals from prey-�ng on f�sh under br�dges. Aga�n, however, �nsuf-f�c�ent �nformat�on regard�ng rece�ved sounds and �nd�v�dual responses �s ava�lable to cons�der these observat�ons expl�c�tly here. Kosch�nsk� et al. (2003) observed harbor seals dur�ng under-water playbacks of s�mulated w�nd turb�ne no�se (max�mum energy between 30 and 800 Hz; spec-tral dens�ty source levels of 128 dB re: 1 µPa/Hz at 80 and 160 Hz). Harbor seals were s�ghted at greater d�stances dur�ng playbacks than dur�ng control cond�t�ons. However, l�m�ted �nformat�on on rece�ved exposures and �nd�v�dual behav�oral responses precluded �nclus�on �n our analys�s. Moulton et al. (2003, 2005) stud�ed r�nged seals before and dur�ng the construct�on and operat�on of an o�l product�on fac�l�ty. They found l�ttle or

no avo�dance of the area around the var�ous �ndus-tr�al sources, most of wh�ch em�tted nonpulses. Because of the cont�nuous exposure to mult�ple sound sources at vary�ng d�stances, th�s study d�d not produce data on d�screte exposures and responses.

LaboratoryObservations(Cell12)Kastele�n et al. (2006b) exposed n�ne capt�ve harbor seals �n a ~25 × 30 m enclosure to non-pulse sounds used �n underwater data commun�-cat�on systems (s�m�lar to acoust�c modems). Test s�gnals were �dent�cal to those used by Kastele�n et al. (2005) �n harbor porpo�se exposure stud�es (frequency modulated tones, sweeps, and bands of no�se w�th fundamental frequenc�es between 8 and 16 kHz; 128 to 130 [± 3] dB re: 1 µPa-m source levels; 1- to 2-s durat�on [60-80% duty cycle]; or 100% duty cycle). They recorded seal pos�t�ons and the mean number of �nd�v�dual surfac�ng behav�ors dur�ng control per�ods (no exposure), before exposure, and �n 15-m�n exper�-mental sess�ons (n = 7 exposures for each sound type). Background no�se and exposure RLs (�n terms of Leq; 32-s total t�me) were measured at numerous pos�t�ons around the enclosure for each acoust�c source. Acoust�c d�scomfort was recogn�zed based on movement out of areas that an�mals used dur�ng control per�ods. An acoust�c d�scomfort threshold was calculated for the group of seals for each source type, and for each sound source th�s was ca. 107 dB re: 1 µPa. Seals gener-ally swam away from each source, avo�d�ng �t by ~5 m, although they d�d not haul out of the water or change surfac�ng behav�or. Seal react�ons d�d not appear to wane over repeated exposure (�.e., there was no obv�ous hab�tuat�on), and the colony of seals generally returned to basel�ne cond�t�ons follow�ng exposure.

For the behav�oral analys�s conducted here, the Kastele�n et al. (2006b) results were �nterpreted as follows. Because the behav�or of �nd�v�duals w�th�n the same pool at the same t�me cannot be cons�d-ered �ndependent, the group of n�ne harbor seals was cons�dered a s�ngle observat�on. Because of s�m�lar�ty of sources and exposure cond�t�ons and the close temporal t�m�ng of exposures, we com-b�ned observat�ons across the four sound types and �nclude a s�ngle observat�on w�th�n each appropr�-ate 10-dB b�n. Exposures between ~80 and 107 dB re: 1 µPa seemed �nsuff�c�ent to �nduce behav�oral avo�dance �n the colony of seals, but h�gher expo-sures were cons�dered suff�c�ent. Consequently, s�ngle observat�ons �nd�cat�ng no response (0) appear �n the 80 to 90 and �n the 90 to 100 dB re: 1 µPa exposure b�ns, and a s�ngle observat�on �nd�cat�ng avo�dance behav�or (6) �s shown �n the 100 to 110 dB re: 1 µPa cond�t�on (Table 21).


Pinnipeds in Air/Nonpulses (Cell 15)

There has been cons�derable effort to study the effects of aer�al nonpulse sounds on p�nn�ped behav�or, pr�mar�ly �nvolv�ng rocket launches, a�r-craft overfl�ghts, power-boat approaches, and con-struct�on no�se. Unfortunately, many of the stud�es are d�ff�cult to �nterpret �n terms of exposure RL and �nd�v�dual or group behav�oral responses. In many cases, �t was d�ff�cult or �mposs�ble to d�s-cern whether the reported behav�oral response was �nduced by the no�se from a spec�f�c operat�on or some correlated var�able such as �ts v�sual presence. For these reasons, most of the observat�onal stud�es of behav�oral d�sturbance are not appropr�ate for quant�tat�ve analyses relat�ng exposure level and scored behav�oral response. However, a number of the techn�cal reports and analyses of rocket launches are relevant for th�s cell and conta�n suf-f�c�ently deta�led �nformat�on regard�ng est�mated RLs. These observat�ons are compl�cated, how-ever, by the fact that all stud�es were conducted �n the same general area w�th subjects l�kely hab�tu-ated to the presence of launch no�se. Further, �n many cases, exposures conta�ned both a nonpulse component and a pulse component (descr�bed below). Only those observat�ons for wh�ch there was clearly just nonpulse exposure were con-s�dered �n the sever�ty scal�ng analys�s (Thorson et al., 1999, 2000b; Berg et al., 2002).

The l�m�tat�ons of these and other potent�ally appl�cable stud�es resulted �n a very l�m�ted data set for use �n th�s analys�s (see summary �n Table 22 and sever�ty scal�ng analys�s �n Table 23). As a general statement from the ava�lable �nformat�on, p�nn�peds exposed to �ntense (~110 to 120 dB re: 20 µPa) nonpulse sounds often leave haulout areas and seek refuge temporar�ly (m�nutes to a few hours) �n the water. In contrast, p�nn�peds exposed to d�stant launches at RLs ~60 to 70 dB re: 20 µPa tend to �gnore the no�se. It �s d�ff�cult to assess the relevance of e�ther of these observat�ons to naïve �nd�v�duals, however, g�ven the repeated exposure of colon�es stud�ed to such no�se events. Also, there are strong spec�es d�fferences, w�th harbor seals be�ng much more respons�ve than northern elephant seals (e.g., Holst et al., 2005a, 2005b). Due to the l�m�tat�ons of the ava�lable data, �t �s not currently poss�ble to make any further general character�zat�ons regard�ng th�s cond�t�on.

A ser�es of h�ghly deta�led, quant�tat�ve analy-ses on the behav�or of p�nn�peds exposed to the sounds of var�ous large m�ss�le launches were rev�ewed. These sources generally produce sus-ta�ned, generally low-frequency (l�ttle energy above 1,000 Hz) “rumbl�ng” sounds last�ng tens of seconds (nonpulse) assoc�ated w�th launch boosters, as well as a son�c boom (pulse) �n fl�ght

as the rocket goes superson�c. Extens�ve research has been conducted on the effects of both sound types on p�nn�peds. Nonpulse exposures are cons�dered �n th�s sect�on, whereas behav�oral responses to the pulse component of some of the same launches are cons�dered �n Append�x B. Because many measurements were made on the same few colon�es of p�nn�peds that were exposed to mult�ple launches, �t �s l�kely that some of the same �nd�v�duals were resampled. Therefore, we we�ghted the comb�ned results across stud�es for each spec�es and breed�ng locat�on �nto a s�ngle observat�on for the behav�oral analys�s here. That �s, we cons�dered each spec�es �n an �nd�v�dual breed�ng colony a s�ngle un�t of observat�on across stud�es. The results were pooled accord-�ngly �n Table 22, but the stud�es are d�scussed long�tud�nally below. The stud�es d�scussed below reported exposure cond�t�ons on or near p�nn�ped breed�ng rooker�es dur�ng launches of d�fferent types of rockets us�ng a var�ety of metr�cs, �nclud-�ng A-we�ghted values and a frequency-we�ght�ng funct�on der�ved from the harbor seal aud�ogram; we used unwe�ghted SPL values for the analys�s here.

Thorson et al. (1998) measured harbor seal responses and conducted AEP measurements on seals exposed to a T�tan IV A-18 launch from Vandenberg A�r Force Base (VAFB), Cal�forn�a. They stud�ed colon�es both on the ma�nland at VAFB and on nearby Santa Cruz Island. Unfortunately, the launch occurred at n�ght and dur�ng a per�od of relat�vely h�gh t�de, l�m�t�ng both the number of seals present on the rooker�es and the observat�on of �nd�v�duals. However, behav�oral mon�tor�ng over several days after the launch d�d not �nd�cate any abandonment of the breed�ng rooker�es at e�ther s�te. Hear�ng measures (AEP) on �nd�v�duals tested before and several hours after the launch d�d not �nd�cate any loss of sens�t�v�ty.

Thorson et al. (1999) conducted s�m�lar observa-t�ons of harbor seals at VAFB and also observed northern elephant seals, Cal�forn�a sea l�ons, and northern fur seals at nearby San M�guel Island. Follow�ng the launch (of an Athena 2 IKONOS-1 m�ss�le), 33 harbor seals (�nclud�ng s�x pups) at the VAFB rookery entered the water. They began to return to the beach beg�nn�ng 16 m�n after the launch, and no pups were observed to have d�ed as a result of the event. Th�s behav�or was cons�dered to represent both m�nor avo�dance and a br�ef/m�nor potent�al or actual separat�on of females and dependent off-spr�ng (scored 6 here). The max�mum unwe�ghted SPL value was 119 dB re: 20 µPa. Ind�v�duals of the three p�nn�ped spec�es mon�tored on San M�guel Island reacted s�m�larly. However, the�r responses were to the son�c boom generated by the rocket once a�rborne rather than to the nonpulse

520 Southalletal.

sounds assoc�ated w�th the launch per se, and thus are not scored here.

Thorson et al. (2000a) conducted observat�ons of harbor seal abundance, d�str�but�on, and haulout patterns at VAFB for several days before and after the launch of a T�tan II G-13 m�ss�le from VAFB. Th�s launch occurred dur�ng the m�ddle of the n�ght, preclud�ng d�rect observat�on of seal react�ons (and behav�oral scor�ng here), although observat�ons on subsequent days �nd�cated generally nom�nal harbor seal presence and d�str�but�on �n the area.

Thorson et al. (2000b) measured behav�oral and aud�tory responses of harbor seals at VAFB and behav�oral responses of northern elephant seals and Cal�forn�a sea l�ons on San M�guel Island to the launch of a T�tan IV B-28 m�ss�le from VAFB. They observed all 54 harbor seals at the VAFB s�te mov�ng from the breed�ng rookery �nto the water w�th�n 2 m�n of the onset of the launch (47 entered the water �mmed�ately). The max�mum unwe�ghted SPL value near the rookery was 116 dB re: 20 µPa; th�s exposure was cons�dered here to be cons�stent w�th a behav�oral score of 6 for th�s group of seals. The sound pers�sted for several m�nutes, and the unwe�ghted SEL value was 127 dB re: (20 µPa)2-s. There was no d�fference �n the hear�ng capab�l�-t�es of three young seals tested us�ng AEP meth-ods before and after the m�ss�le launch. Ne�ther the Cal�forn�a sea l�ons nor elephant seals on San M�guel Island were observed to respond at all to the “fa�nt” no�se assoc�ated w�th the launch, cor-respond�ng to a sever�ty scal�ng score of 0 (Table 23). These sounds were from the launch boosters (nonpulses) rather than son�c booms and were est�-mated here as ~60 to 70 dB re: 20 µPa based on the measurements and descr�pt�ons g�ven.

Berg et al. (2001) obta�ned s�m�lar measure-ments of behav�oral responses of harbor seals at VAFB and Cal�forn�a sea l�ons and northern ele-phant seals at San M�guel Island to a Delta II EO-1 m�ss�le launch from VAFB. Observat�ons were also made of southern sea otter (Enhydralutrisnereis) and Cal�forn�a brown pel�can (Pelecanusocciden-taliscalifornicus) responses. No harbor seals were hauled out on the VAFB rookery dur�ng th�s launch. Berg et al. note that subsequent harbor seal abun-dance and d�str�but�on �n the days after the launch were w�th�n normal var�ab�l�ty, and there appeared to be no last�ng behav�oral react�ons. Elephant seals and Cal�forn�a sea l�ons at San M�guel Island d�d not not�ceably respond to sounds assoc�ated w�th the launch, wh�ch �n th�s case were predom�nantly the son�c boom (pulse) component.

Berg et al. (2002) measured behav�oral responses of harbor seals on VAFB rooker�es to the launch of a T�tan IV B-34 m�ss�le from a launch pad at VAFB ~8.6 km away. At the t�me of the launch, 38 seals were present at two haulout s�tes, all of wh�ch

entered the water �mmed�ately follow�ng the onset of launch no�se. More seals (n = 56) were present at the locat�ons 90 m�n after the launch event, �nd�-cat�ng the temporary and m�nor nature of the d�s-turbance, and no �njured an�mals were located. The avo�dance behav�or was co�nc�dent w�th a max�-mum unwe�ghted SPL value near the rooker�es of 119 dB re: 20 µPa (unwe�ghted aer�al SEL value was 130 dB re: [20 µPa]2-s).

F�nally, Berg et al. (2004) observed behav�oral responses of Cal�forn�a sea l�ons, northern elephant seals, and northern fur seals on San M�guel Island to the launch of an Atlas IIAS MLV-14 m�ss�le from VAFB. Rece�ved s�gnals were son�c booms wh�ch had l�ttle to no effect on the behav�or of the p�nn�peds, other than m�nor or�ent�ng behav�ors and movements �n some of the Cal�forn�a sea l�ons. These results are not scored here, �n part because the sounds �ncluded pulses.

Other researchers have �nvest�gated the effects of other k�nds of human act�v�t�es (e.g., a�rcraft, motorboats, general human presence) as well as rocket launches on the haulout behav�or, �nclud�ng avo�dance, of p�nn�peds (Allen et al., 1984; Suryan & Harvey, 1998; Born et al., 1999; Moulton et al., 2002). The comb�ned results �nd�cated that hauled-out p�nn�peds �n certa�n cond�t�ons can be d�sturbed, s�gn�f�cantly �n some cases, by the presence of var�-ous human act�v�t�es. However, these stud�es lack e�ther spec�f�c est�mates of rece�ved no�se expo-sure cond�t�ons or �nd�v�dual-spec�f�c behav�oral responses or both. Add�t�onally, mult�ple st�mul� were generally s�multaneously present, �nclud�ng the v�sual presence of sources, wh�ch preclude the�r �nclus�on here. Gentry et al. (1990) determ�ned that northern fur seals were generally tolerant of under-ground explos�ons and other quarry�ng operat�ons �n relat�vely close prox�m�ty; only a few or�ent�ng behav�ors were observed �n response to the largest blasts. Some acoust�c measurements were made, but �nd�v�dual behav�ors or group responses and rece�ved exposure levels were not reported and were thus not scored here.

Holst et al. (2005a, 2005b) observed behav�oral responses �n three spec�es of p�nn�peds—harbor seal, Cal�forn�a sea l�on, and northern elephant seal—on San N�colas Island to 47 small- and m�d-s�zed m�s-s�le launches over a 4-y per�od. They observed an�mal presence and d�str�but�on before launches and behav�or dur�ng and follow�ng launches. Some of the m�ss�les generated son�c booms, but the major�ty of the exposures were relat�vely low-fre-quency, long-durat�on rumbl�ng sounds that would be categor�zed as nonpulses. Dur�ng many launches, acoust�c measurements were made near the an�mals whose behav�or was v�deotaped. Peak, SPL, and SEL exposures were reported. Th�s dataset has not been �ncorporated �nto the present analys�s. However,


results indicated that California sea lions had mixed reactions to rocket launches, with some individuals exhibiting startle responses and increased vigilance and others showing virtually no reaction. Northern elephant seal reactions were minimal, consisting only of minor movements and orienting responses that rapidly subsided. Conversely, harbor seals were by far the most responsive of the pinnipeds observed, with many individuals entering the water from haulout sites following rocket launches and failing to return for periods of hours. No cases of long-term pup separation or of injury were documented. If those phenomena had occurred, they would be considered relatively severe in terms of the behav-ioral scoring paradigm given here and should also be

considered as they relate to injury criteria. In California sea lions and northern elephant seals, there were significant correlations between behav-ioral responses and both the missile’s closest dis-tance and the RL of the launch sound near the pinnipeds (SEL). Corresponding relationships for harbor seals were weaker. Holst et al. (2005b) con-cluded that the temporary behavioral responses, even the relatively severe ones observed in harbor seals, do not appear to have substantial adverse effects on pinniped populations. This conclusion is based on the decades-long occurrence of missile launches and the presence of increasing numbers of pinnipeds of all three species in the area.

(LefttoRight): David Kastak, Roger Gentry, Peter Tyack, Brandon Southall, Darlene Ketten, W. John Richardson, Jeanette Thomas, James Miller, Ann Bowles, James Finneran, Charles Greene, Jr., Paul Nachtigall, and William Ellison

Thismanuscriptisrespectfullydedicatedtoourco-author,DavidKastak.

Davewasabrilliantscientist,butevenmoreimportantly,hewasamanwithgreatsincerity,integrity,andasharpwit.Hewasaninspirationandmentortomany,

andhissignificant,incisiveresearchonmarinemammalcognitionandsensorysystemsoverthepasttwodecadesprovidedadvancesthatshapedandwill

continuetoguidethefutureofthesefields.Davewasavaluedcolleagueandtreasuredfriendtoallofus.Hewillbemissedbutneverforgotten.

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