semiochemicals as shark repellents: identification and behavioral response eric m. stroud michael m....

Semiochemicals as Shark Repellents: Identification and

Behavioral Response

Eric M. Stroud

Michael M. Herrmann

Dr. Samuel G. Gruber

Semiochemical Mixture

• Semiochemicals are messengers or “clues” – Shark-specificity– Non-lethal – Action is suspected to be olfactory (mouth

dose is not required)– Not based on Cu+, surfactants, acid, or

dye– Safe to handle and store

Discovery of the Mixture

• Shark carcass – Not decayed, no Cu+, no ammonium acetate

• Production– Multi-phase extraction process– Deproteinization– Filtration– Neutralization

• Modern analytical instrumentation• Mixture of nucleotides

Analytical Tools

• Visible / IR Spectrophotometry

• Fluorimetry

• Derivatization and HPLC

• Flash Chromatography and TLC

• GC-MS

GC-MS Total Ion Chromatograph

Field Tests

• Find a suitable wild shark population

• Construct a delivery apparatus

• Test a behavioral control

• Test a variety of fractions of the semiochemical mixture

• Quantify results

Testing Locations

• BBFS – South Bimini– Blacknose, Caribbean Reef, Lemon, Bull

sharks

• Ordinance Dump – Montauk, NY– Blue sharks

Delivery Apparatus

• Based on Donald Nelson’s design

• Pressurized delivery of liquid through a tube to a fish head suspended on a pole

• Pressures ranges from 5- 20 psig

• Delivery volumes ranges from 100mL to 500mL

Controls and Repellents

• Control is introduced while sharks are actively feeding– Seawater with or without FD&C Red 3 & 40, at the

same pressure and dose size for the repellent

• Repellent is introduced while sharks are actively feeding– Observations are made on the size of the feeding

population before and after dosing– Observations are made on changes in feeding

behavior

Results

• Controls– Feeding shark populations were not

diminished for control deliveries of up to 20 psig

– Plain seawater nor FD&C Red 3 &40 and seawater did not deter feeding

– Sharks are not afraid to feed from and near the delivery apparatus

Results• Repellents

– 100mL to 250mL doses of the semiochemical mixture dramatically reduce the feeding population size

– Nearby fish are unaffected and continue feeding– In six separate field tests, feeding populations of 2 to

12 Blacknose and Caribbean Reef sharks are reduced to 0 within 120 seconds of a subsurface dose

– Visual behavior changes occur within 20 seconds of the subsurface dose

– 4 fl oz is the optimal dose size for large populations, but response has been observed with as little as 25mL

Species and Populations

• Blacknose / Caribbean Reef Sharks – Up to 12

• Blue Sharks – 2

• Bull Sharks – 2

• Lemon Sharks – 2

• Nurse Sharks - 2

Cloud Test: Population = 12

Tonic Immobility Test

0.1ppm Criteria

• Test for a behavioral response at with 0.1 ppm of the chemical repellent

• Johnson-Baldridge proposed that a 100mL/hr release of a chemical repellent into a 6m3 boundary of water under steady-state conditions for 3.5 hours represents 0.1 ppm.

0.1ppm Criteria

• Use a tall plastic tripod with wireless camera to observe a 6m3 boundary of water, with a fish head suspended in the 6m3 boundary

• Chum to attract sharks into the boundary area, let them take the fish head

• Begin metered dosing of the repellent using a precision peristaltic pump into the boundary once a population is established, using a new fish head

• New fish head must remain protected for 3.5 hours

Johnson-Baldridge Apparatus

0.1ppm Results

• September 2003– Fish head was protected for 1.5 hours from two

lemon sharks, until medical pump battery died

• March 2004– Fish head was protected for 2 hours from two

Caribbean reef sharks, until pump failed

• May 2004– Successfully performed and video’d a control

Next Steps

• More field testing:– Tiger, Great White, Hammerhead, Oceanic

Whitetip

• More validation:– Bull, blue

• Perfect synthesis pathway for commercialization

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