nearshore distribution and an abundance estimate for green sea · 509 nearshore distribution and an...

509

Nearshore Distribution and an Abundance Estimate for Green SeaTurtles, Chelonia mydas, at Rota Island, Commonwealth

of the Northern Mariana Islands1

Steven P. Kolinski,2 Ronald K. Hoeke,3 Stephani R. Holzwarth,3 Larry I. Ilo,4 Evelyn F. Cox,2

Robert C. O’Conner,2 and Peter S. Vroom3

Abstract: Seventy-three green turtles, Chelonia mydas (Linnaeus, 1758), wereobserved in 84 sightings along 28 transects covering 67% of Rota’s shorelineand outer reef perimeter in the Commonwealth of the Northern Mariana Is-lands. No other sea turtle species were encountered. Juvenile turtles of varioussizes dominated in all surveyed environments, and observations of turtles withestimated straight carapace lengths a 40 cm suggested recent and continuingrecruitment at Rota. Distribution of turtles appeared temporally stable whencompared with previously reported observations and data, with turtle concentra-tions highest along northeast, east, and southeast coasts of the island. Approxi-mately 118 turtles were projected to inhabit nearshore habitats at Rota.Although this population may appear minor and indistinct compared with thoseat nearby Tinian and Saipan, continued monitoring would be useful for compar-ison of Mariana Islands trends. Thirty-five species of cyanophytes, algae, and asea grass noted as green turtle forage in other world regions were identified atRota in this and previous surveys.

The green turtle, Chelonia mydas (Lin-naeus, 1758), has been reported as the princi-pal sea turtle species in the Commonwealthof the Northern Mariana Islands (CNMI)(Wiles et al. 1989, 1990, McCoy 1997, Pultzet al. 1999, Kolinski et al. 2001, 2004, 2005).Anecdotal observations and intermittent sur-veys suggest that nesting greens make up arelatively small proportion of the local seaturtle population, with known numbers of

annual nests ranging to the low tens through-out the commonwealth (Pritchard 1982,Wiles et al. 1989, 1990, McCoy 1997, Pultzet al. 1999, Ilo and Manglona 2001, Kolinskiet al. 2001). The preponderance of turtles inthe region are found residing in nearshorereef areas of the southern arc islands (Figure1), where identification of distributions andabundance has become critical to ascertainingturtle population status and dynamics, partic-ularly in relation to human activities that in-clude efforts at resource management andrecovery (National Marine Fisheries Serviceand U.S. Fish and Wildlife Service 1998, Ko-linski et al. 2001, 2004, 2005; S.P.K., unpubl.data).

In 2003, surveys of reefs throughout theMariana Archipelago off the NOAA ship R/V Oscar Elton Sette included a rapid yet com-prehensive assessment for turtles in nearshoremarine habitats of the southernmost CNMIisland, Rota. Few assessments for sea turtlesin nearshore waters at Rota have been made(Wiles et al. 1990, Ilo and Manglona 2001),and published observations on turtle distribu-tions and abundance for the island are limited(Wiles et al. 1990, Kolinski et al. 2004). Con-

Pacific Science (2006), vol. 60, no. 4:509–522: 2006 by University of Hawai‘i PressAll rights reserved

1 Manuscript accepted 20 December 2005.2 Joint Institute for Marine and Atmospheric Re-

search, National Marine Fisheries Service, Pacific IslandsRegional Office, 1601 Kapiolani Boulevard, Suite 1110,Honolulu, Hawai‘i 96814-0047 (e-mail: [email protected]).

3 Joint Institute for Marine and Atmospheric Re-search, National Marine Fisheries Service, Coral ReefEcosystem Division, 1125B Ala Moana Boulevard, Ho-nolulu, Hawai‘i 96814.

4 Division of Fish and Wildlife, Department of Landsand Natural Resources, P.O. Box 10007, Lower BaseArea, Saipan, MP 96950.

Fig

ur

e1.

Th

eM

aria

na

Isla

nd

san

dth

e20

03d

istr

ibu

tio

no

ftr

anse

cts

and

turt

les

atR

ota

Isla

nd

.

sistent with recommendations of the recoveryplan for U.S. Pacific green turtle populations(National Marine Fisheries Service and U.S.Fish and Wildlife Service 1998), in this paperwe present detailed information on turtledistributions, estimated size classes, projectedabundance, and likely food resources forgreen turtles in marine habitats surroundingRota Island.

Study Area

Rota (14� 9 0 N, 145� 12 0 E) is an 85-km2 is-land located northeast of Guam (60 km) andsouthwest of Aguijan (71 km) in the southernarc of the Mariana Archipelago (Figure 1).The island consists of terraced limestone pla-teaus bordering two small volcanic outcropsand reaches 491 m in height (Eldredge 1983,Wells and Jenkins 1988, Wiles et al. 1990).Steep limestone cliffs, rocky shores, andintermittent benches characterize much ofthe eastern and southern coasts as well as thesouthern portion of the western peninsula.Coarse calcareous sand beaches are inter-spersed among rock along northern, south-ern, and western shores (Eldredge andRandall 1980), where sea turtle nesting hasbeen reported as infrequent (Wiles et al.1990, Grout 1997, McCoy 1997, Ilo andManglona 2001). Marine habitats are di-verse and include fringing reefs, shallow reefslopes, spur and groove zones, extensive pave-ment, boulder fields, ledges, and steep cliffs.Human development is concentrated mainlyin the southwest of the island at Songsong(Figure 1). The 2000 census identified 3,283residents (Evans et al. 2002), approximately5% of the CNMI population. Fisheries re-sources at Rota are exploited by local andneighboring island residents.

materials and methods

Assessments for turtles at Rota were con-ducted on 19 and 20 September 2003, off theNOAA ship R/V Oscar Elton Sette. Two sur-vey methods were employed. Towed-diversurveys (Kenyon et al. in press) consisted oftwo scuba divers per boat being towed paral-lel to shore by each of two boats at depths

ranging from 3 to approximately 30 m. Onone of the boats, when a turtle was sightedits approximate position was signaled to boatpersonnel via a magnetic-switch telegraph andrecorded on a geographic positioning system(GPS) (Garmin 76S). On the other boat tur-tle positions were estimated by matching ob-servation times with points collected every 5sec on a GPS set to record tow tracks. Obser-vation time, species, size (visually estimatedstraight carapace length [SCL] made in com-parison with 1-m-wide tow-boards delineatedwith 10-cm markings), sex (when discern-able), activity, and habitat characteristics wererecorded by underwater observers. Individualtows typically lasted 1 hr and occurred at spa-tial intervals that allowed for characterizationof all major (i.e., north, east, south, and west)coastlines (Figure 1). The second methodconsisted of dive surveys made betweendepths of 12 and 22 m by eight scientificdivers who collected data on turtles while as-sessing fish, invertebrate, and algal commu-nities along three 25-m transects at each ofsix locations around the island. The dive sur-vey data are presented to reflect consistencyin observations of turtle distributions. How-ever, they were not included in abundance es-timates because most likely were resightingsof turtles counted in tow surveys that over-lapped these short transects. In all surveys,benthic habitats and the water column wereassessed for turtles within ranges of visibility(typically 15 to >40 m). Surface waters alsowere searched by support boat personnel,with pertinent information on turtle sightings(as previously described) being recorded.

Turtle maturity status was not directlymeasured for any individual. Visual SCL esti-mates were used to grossly categorize turtlesas juveniles (a70 cm), juvenile/adults (>70and a90 cm), and presumed adults (>90cm). The range for ‘‘presumed adults’’ mayappear liberal but was based on the averageof mean SCL nesting sizes presented for Pa-cific turtles by Hirth (1997), rounded to thenearest decimeter. Estimated turtle numberswere adjusted for each transect by removingresightings of the same individual based onsize, distinguishing features, time, and specificlocations and/or routes. Such methods are

Sea Turtles at Rota Island . Kolinski et al. 511

TA

BL

E1

Ob

serv

atio

ns

of

Gre

enT

urt

les

atR

ota

Isla

nd

,C

NM

I,in

2003

Est

imat

edN

o.

of

Tu

rtle

sO

bse

rved

Sit

eD

ate

Max

.T

ime

(hr:

min

)M

eth

od

Tra

nse

ctL

engt

h(k

m)

To

tal

No

.o

fO

bse

rvat

ion

sJu

ven

ile

Juve

nil

e/A

du

ltP

resu

med

Ad

ult

To

tal

Tu

rtle

sp

erkm

No

rth

Ro

taP

un

tan

Sai

liga

ito

Tat

ach

ok

9/20

0:15

Sin

gle

tow

0.67

00

00

00.

0

Tat

ach

ok

toT

etet

o9/

201:

00S

ingl

eto

w2.

580

00

00

0.0

Say

anG

igan

i9/

201:

35D

ive

surv

ey*0

.08

00

00

0*0

.0S

ayan

Gig

ani

toA

gusa

n9/

201:

00S

ingl

eto

w2.

620

00

00

0.0

IB

atko

toL

alay

ak9/

200:

33S

ingl

eto

w0.

822

20

02

2.4

Lal

ayak

toM

och

on

g9/

200:

27D

ou

ble

tow

1.05

63

20

54.

8

Mo

cho

ng

toM

aya

9/20

0:32

Sin

gle

tow

1.12

21

10

21.

8

Mo

cho

ng

9/20

1:19

Div

esu

rvey

*0.0

85

*1*2

0*3

*37.

5

Su

bto

tal

6:41

8.86

156

30

9(M

eanG

SE

)1.

5G

0.8

Eas

tR

ota

Pu

nta

nF

ina

Atk

os

9/19

0:28

Sin

gle

tow

0.99

41

21

44.

0

Pu

nta

nF

ina

Atk

os

toA

sD

ud

o

9/19

0:29

Do

ub

leto

w0.

993

20

13

3.0

As

Du

do

9/19

1:36

Div

esu

rvey

*0.0

80

00

00

*0.0

As

Du

do

toP

un

tan

As

Fan

i9/

190:

36S

ingl

eto

w1.

349

61

07

5.2

IC

hiu

gai

toP

un

tan

Sag

uag

ahga

9/19

0:54

Do

ub

leto

w1.

8627

148

426

14.0

Su

bto

tal

4:03

5.18

4323

116

40(M

eanG

SE

)6.

6G

2.5

So

uth

Ro

taP

un

tan

Sag

uag

ahga

toT

aksu

no

k

9/19

0:28

Sin

gle

tow

1.21

41

30

43.

3

Tak

sun

ok

9/19

1:25

Div

esu

rvey

*0.0

80

00

00

*0.0

Ala

guan

toP

ayap

ai9/

190:

56S

ingl

eto

w2.

316

13

26

2.6

Aga

tasi

toG

aon

an9/

191:

00S

ingl

eto

w2.

962

20

02

0.7

Gu

aato

Gag

ani

9/19

1:00

Sin

gle

tow

2.30

11

00

10.

4S

ou

thP

un

tan

Po

na

9/20

0:30

Sin

gle

tow

*0.8

71

*10

0*1

*1.1

Wes

tP

un

tan

Po

na

9/19

1:26

Div

esu

rvey

*0.0

80

00

00

*0.0

Pu

nta

nP

on

ato

Po

dd

on

g9/

191:

01S

ingl

eto

w**

2.78

10

10

10.

4

Ail

ato

Pu

nta

nT

aip

ingo

t9/

200:

58S

ingl

eto

w2.

793

30

03

1.1

Tai

pin

got

toP

un

tan

Tai

pin

got

9/19

0:23

Sin

gle

tow

*1.2

33

20

02

1.6

Su

bto

tal

9:07

14.2

121

107

219

(Mea

nG

SE

)1.

4G

0.4

Wes

tR

ota

Pu

nta

nT

aip

ingo

tto

Liy

o9/

190:

38S

ingl

eto

w*1

.38

21

10

21.

4

Pu

nta

nT

aip

ingo

tto

Fal

ago

n9/

200:

51S

ingl

eto

w2.

110

00

00

0.0

So

ngs

on

gto

Sai

liga

iP

apa

9/20

1:01

Sin

gle

tow

**2.

951

10

01

0.3

Eso

ng

9/20

1:35

Div

esu

rvey

*0.0

80

00

00

*0.0

Sai

liga

iP

apa

toP

un

tan

Sal

igai

9/20

0:44

Sin

gle

tow

1.41

22

00

21.

4

Su

bto

tal

4:49

6.06

54

10

5(M

eanG

SE

)0.

8G

0.4

To

tals

24:4

034

.31

8443

228

73(G

ran

dm

eanG

SE

)2.

3G

0.7

*,N

um

ber

no

tin

clu

ded

into

tal

bec

ause

like

lyn

ote

din

rep

etit

ive

area

surv

eys;

**,

tran

sect

len

gth

ove

rlap

no

tin

clu

ded

into

tals

.

open, however, to potentially counting someindividuals twice, particularly those observedat distance and lacking distinguishing fea-tures. Regional turtle abundance in Rota’snearshore waters was projected by multiply-ing the mean number of turtles per kilometerfrom surveyed transects by total kilometersin each region. Total abundance was deter-mined using the mean of islandwide samples.No correction factor for single tows was usedbecause the mean percentage increase in tur-tle numbers with double tows was zero (Ko-linski et al. 2004). Upper boundaries of 95%confidence intervals were calculated for eachregion as well as islandwide using t distribu-tions.

Field identifications of algal and sea-grassspecies were conducted by P.S.V. using thealgal sampling protocol described by Preskittet al. (2004). The results were collated withthose reported in the literature, and a specieslist of potential green turtle forage for Rotawas compiled along with locations and refer-ences. Hirth (1997) and additional sources(Agastheesapillai and Thiagarajan 1979, Ba-lazs 1980, 1985, Mortimer 1981, Mendonca1983, Balazs et al. 1987, 1995, 2005, Burkeet al. 1991, Limpus et al. 1994, 2005, Forbes1996, Russell and Balazs 2000, Read andLimpus 2002, Seminoff et al. 2002, Calvoet al. 2003, Ferreira et al. 2003, Lopez-Mendilaharsu et al. 2003, 2005, Russellet al. 2003, Searle 2003, Andre et al. 2005,Holloway-Adkins and Ehrhart 2005, Sanchezand Quiroga 2005, Sara et al. 2005, Uzcateguiet al. 2005, Makowski et al. 2006) were usedfor guidance in listing only those speciesidentified as turtle forage in other parts ofthe world.

results

Seventy-three individual green turtles wereobserved via 84 sightings along 28 transectscovering 67% of Rota’s 51 km of outer reefperimeter (Table 1, Figure 1). No other tur-tle species were encountered. Fifty-nine per-cent (43 turtles) of the turtles were juveniles,30% (22 turtles) were classified as juvenile/adult, and 11% (8 turtles) were categorizedas presumed adults. Juveniles were the domi-

nant size class on all coastlines. Presumedadults were observed in east- and south-coasthabitats (Figure 2) and included four proba-ble females (SCL b 100 cm) and three males.Four turtles had estimated SCLs a 40 cm,suggesting relatively recent recruitment tothe resident population.

Twelve percent (9 turtles) of the turtleswere observed in habitats on the north sideof the island, 55% (40 turtles) on the east,26% (19 turtles) at south-coast sites, and 7%(5 turtles) along the west coast. Projectednumbers and average densities of turtles forthe entire perimeter of each coastal regionare shown in Table 2. The average projecteddensity of turtles on the east coast was 4.4and 4.7 times that of the north and southcoasts, respectively, and 8.3 times that of thewest coast. Turtle concentrations were high-est along northeastern, eastern, and south-eastern shorelines from Lalayak to Alaguan(Figure 1). The total number of green turtlesinhabiting Rota’s nearshore environmentswas projected to be approximately 118, withan upper estimate of 191 (95% confidence in-terval) (Table 2).

The compilation of data from marineplant and algae surveys indicated the presenceof at least 35 species of cyanophytes, algae,and a sea grass identified as green turtle for-age in other parts of the world (Table 3).Three (9%) of the species were cyanophytes,11 (31%) were chlorophytes, 8 (23%) werephaeophytes, 12 (34%) were rhodophytes,and one (3%) was an anthophyte. Twenty-five (71%) of the species were located atnorth-coast sites, 5 (14%) along the east coast(only one site surveyed), 24 (69%) on thesouth coast, and 25 (71%) at west-coast sites.Additional Rota genera (Tsuda 2003, thisstudy) that may be utilized by turtles includeCalothrix, Microcystis, Avrainvillea, Chaetomor-pha, Microdictyon, Udotea, Valonia, Dictyopteris,Rosenvingia, Amphiroa, Ceramium, Galaxaura,Gelidium, Hypoglossum, Laurencia, Liagora, andPolysiphonia.

discussion

The distribution of sea turtles at Rota wassimilar to that described in Wiles et al.

514 PACIFIC SCIENCE . October 2006

(1990), with concentrations highest along thenortheastern, eastern, and southeastern coastsof the island. Similarly, the distribution ap-peared consistent with observations and dataprovided by Ilo and Manglona (2001) in areaswhere survey overlap occurred. Temporal

consistency in the general distribution sug-gests stability in Rota’s habitat availabilityand utilization by turtles but also may reflectillegal harvesting pressure, with limited accessfor poaching along trade-wind coasts. Similardistributions favoring east-coast habitats have

Figure 2. Estimated number of green turtles observed at Rota Island categorized by size and location.

TABLE 2

Projected Green Turtle Abundance by Region and Islandwide for Rota

Region

TotalPerimeter

(km)

PerimeterSurveyed

(%)

Average No.Turtles/km

(GSE)

ProjectedNo. ofTurtles

Upper 95%Confidence

Interval Boundary

North 15.2 58.4 1.5G 0.8 23 54East 6.3 82.7 6.6G 2.5 41 92South 22.1 64.3 1.4G 0.4 32 55West 7.7 78.7 0.8G 0.4 6 15Islandwide 51.3 67.0 2.3G 0.7 118 191


TABLE 3

Rota Marine Algae Listed by Hirth (1997) and Additional Sources (See Text) as Green Turtle Forage

Classification Location and Reference

CyanophytaHormothamnium entermorphoides Grunow Uyulan9, North Rota; Gaonan1, Apanon, Gagani8, South Rota;

Puntan Sailigai, Falagon1, West RotaMicrocoleus lyngbyaceus (Kutzing)

Anagnostidis & KomarekTeteto area1, North Rota; Gaonan, Sasanhaya Bay1, Apanon8,

South Rota; Puntan Sailigai1, Falagon1, West RotaSchizothrix calcicola (C. Agardh) Gomont Teteto area, Tatachok1, Mochon-As Matmos area6, North Rota;

Gaonan, Sasanhaya Bay1, Apanon, Gagani8, South Rota;Puntan Sailigai1, West Rota

ChlorophytaBryopsis pennata Lamouroux Uyulan9, Teteto area1, Mochong-As Matmos area6, North Rota;

West Punton Pona12, South Rota; Puntan Sailigai1, West RotaCaulerpa cupressoides (West) C. Agassiz Uyulan9, North Rota; Gagani8, South Rota; Falagon1, Puntan

Sailigai1, West RotaCaulerpa racemosa (Forsskal) J. Agassiz Tatachok1,4, Uyulan9, Teteto area1, Mochong-As Matmos area6,

North Rota; Apanon, Gagani8, Sasanhaya Bay10, South Rota;Falagon1,2, Puntan Sailigai1, West Rota

Caulerpa serrulata (Forsskal) J. Agardh Teteto area1, Mochong-As Matmos area5, North Rota;Puntan Sailigai1, West Rota

Caulerpa urvilliana Montagne Sayan Gigani, Mochong12, North Rota; As Dudo12, East Rota;Falagon, Songsong1, West Rota

Chlorodesmis fastigiata (C. Agardh) Ducker Mochong-As Matmos area6, North RotaCladophorposis sundanensis Reinbold Tatachok1, North Rota; Puntan Sailigai1, West RotaDictyosphaeria cavernosa (Forsskal) Børgesen Tatachok, Teteto area1, Mochong12, Mochong-As Matmos area6,

North Rota; As Dudo12, East Rota; Taksunok12, Gaonan1,Apanon8, Sasanhaya Bay1, South Rota; Puntan Sailigai1,West Rota

Dictyosphaeria versluysii Weber van Bosse Teteto area1, Sayan Gigani, Mochong12, North Rota; AsDudo12, East Rota; Taksunok, West Punton Pona12, SouthRota; Falagon1, Esong12, West Rota

Halimeda opuntia (L.) Lamouroux Tatachok, Tetoto area1, Mochong, Sayan Gigani12, Mochong-AsMatmos6, North Rota; As Dudo12, East Rota; Sasanhaya Bay1,Apanon8, South Rota

Ulva lactuca L. Sasanhaya Bay10, South RotaPhaeophyta

Chnoospora implexa Hering Falagon1, West RotaDictyota bartayresiana Lamouroux Teteto area1, North Rota; Falagon1, West RotaDictyota friabilis Setchel Tatachok1, North RotaLobophora variegata (Lamouroux) Womersley

ex OliveiraTatachok1, North Rota; Sasanhaya Bay1, South Rota; Falagon,

Songsong, Puntan Sailigai1, West RotaPadina minor Yamada Tatachok1, Mochong-As Matmos area6, North Rota; Gaonan1,

South Rota; Falagon1,2, West RotaSargassum cristaefolium C. Agardh

(formerly S. duplicatum)Sasanhaya Bay1, South Rota; Songsong7, West Rota

Sphacelaria tribuloides Meneghini Tatachok1, North Rota; Sasanhaya Bay1, South Rota; Falagon1,Apanon8, West Rota

Turbinaria ornata (Turner) J. Agassiz Tatachok1,4, Uyulan9, Sayan Gigani12, Mochong-As Matmosarea6, North Rota; As Dudo12, East Rota; Apanon8,West Punton Pona12, Gagani8, Sasanhaya Bay1,10, South Rota;Esong12, Puntan Sailigai1, West Rota

RhodophytaAcanthophora spicifera (Vahl) Børgesen Uyulan9, North Rota; Gaonan1, Apanon8, South RotaBotryocladia skottsbergii ( J. Agardh) Kylin Mochong12, North RotaCentroceras clavulatum (C. Agassiz)

MontagneTatachok1, North Rota; Gaonan1, Apanon8, Sasanhaya Bay1,

South RotaChampia parvula (Agassiz) Harvey Puntan Sailigai1, West RotaGelidiella acerosa (Forsskal) Feldmann &

HamelUyulan9, Mochong-As Matmos area6, North Rota; Apanon8,

South Rota; Puntan Sailigai1, West Rota

been reported for other human-inhabitedCNMI southern arc islands (Kolinski et al.2001, 2004), all of which are large in size.Long-term fidelity to nearby resting and for-aging areas is known for green turtles in thePacific (Balazs 1980, Balazs et al. 1987, Lim-pus et al. 1994, Musick and Limpus 1997).Although potential food resources appear onall major coasts (Table 3), food abundanceand its proximity to resting habitats at Rotaremain unknown. Additional studies exam-ining habitat specificity and usage in highturtle density areas may be warranted, be-cause identification and protection of impor-tant marine habitats is considered critical tothe maintenance and recovery of sea turtlepopulations (National Marine Fisheries Ser-vice and U.S. Fish and Wildlife Service1998).

The projection of 118 turtles for Rota’snearshore reefs was similar to the estimate of92 turtles generated for 2001 (Kolinski et al.2004) using snorkel-tow and land-basedsurvey data (Ilo and Manglona 2001). Thecloseness of the estimates over the 3-yr pe-riod suggests general consistency among themethodologies as well as short-term stabilityin turtle abundance at Rota. Frequent long-term monitoring and estimates of uncertaintywill be needed to fully elucidate stability ortrends in population status (see Bjorndal et al.2005). Confidence intervals on future abun-dance estimates may be gained through in-corporation of distance sampling (Bucklandet al. 1993) in the towed-diver monitor-

ing protocol. However, additional nearshoremapping of CNMI benthic depths will benecessary because accurate estimates on habi-tat area are lacking and will influence distancesampling analysis results.

United States recovery criteria for regionalgreen turtle stocks require demonstration ofstatistically significant population increasesin key foraging areas (National MarineFisheries Service and U.S. Fish and WildlifeService 1998). Although stock identificationshave yet to be made for turtles foraging inRota and other CNMI waters, there is somequestion as to whether Rota is ‘‘key’’ withregard to turtle utilization of regionalnearshore habitats. Between 1,000 and 2,000green turtles are believed to inhabit islandreef areas in the southern arc of the CNMI.Approximately 92% of these turtles are lo-cated along the coasts of Tinian (54%) andSaipan (38%). Rota habitats appear to sup-port 6% of turtles in CNMI southern arcwaters (Kolinski et al. 2004), despite an is-land-reef perimeter similar in size to that ofneighboring Tinian. There is no conspicuousdistribution differentiation based on turtlesize or maturity between Rota, Tinian, andSaipan (Kolinski et al. 2004, this study). Al-though observations of turtles a40 cm SCLindicate relatively recent and perhaps directrecruitment of pelagic transitioning juvenilesat Rota (Hirth 1997, Musick and Limpus1997, but see Limpus and Chaloupka 1997,Zug et al. 2002, Balazs and Chaloupka 2004,Chaloupka et al. 2004), Rota’s relative contri-

TABLE 3 (continued)

Classification Location and Reference

Gracilaria crassa Harvey Gaonan1, South RotaGracillaria salicornia (C. Agardh) Dawson Gaonan5, South RotaHypnea musciformis (Wulfin) Lamouroux Teteto1,11, North Rota; Sasanhaya Bay1,11, South Rota;

Songsong, Puntan Sailigai1,11, West RotaHypnea pannosa J. Agardh Puntan Sailigai1, West RotaHypnea spinella (C. Agardh) Kutzing Esong12, West RotaJania capillacea Harvey Mochon-As Matmos area6, North Rota; Apanon8, South RotaTolypiocladia glomerulata (Agassiz) Schmitz Gaonan1, South Rota; Falagon1, West Rota

AnthophytaEnhalus acoroides (L.f ) Royle Apanon8, South Rota; Falagon3, West Rota

References for locations: 1, Tsuda 1969; 2, U.S. Fish and Wildlife Service 1980; 3, Eldredge and Randall 1980; 4, Ellis-Neill andNeill 1985; 5, Meneses and Abbott 1987; 6, Randall and Smith 1988; 7, Tsuda 1988; 8, Wylie 1989; 9, Randall 1997; 10, Winzler andKelly Consulting Engineers 2002; 11, Tsuda 2003; 12, this study.


bution to supporting regional foraging turtlescurrently appears minor and indistinct.

The relevance of Rota to regional turtlemonitoring may be in comparing MarianaIslands trends, because the capacity for in-creasing turtle numbers may be great wherethey are least abundant, assuming that appro-priate habitat is available. Poaching in theMariana Islands occurs (Wiles et al. 1990,McCoy 1997; Jay Gutierrez, Guam Divisionof Aquatic and Wildlife Resources, pers.comm.), but its influence on turtle popula-tions remains unknown, highlighting a needfor investigation and analysis. Future researchshould also focus on the genetic identificationof green turtle stocks and the geographic ex-tent of their dispersal (FitzSimmons et al.1999, Kinan 2002), because foraging popula-tion demographics in the Marianas may de-pend primarily on impacts and processes thatoccur across international boundaries (Kolin-ski 1995, Gutierrez 2004).

acknowledgments

Thanks to Ken Barton and the crew of theNOAA ship R/V Oscar Elton Sette for thevoyage and survey support. Data on turtleswere collected by Rusty Brainard, Fran Cas-tro, R.K.H., S.R.H., Peter Houk, S.P.K., JoeLaughlin, Trina Leberer, Machel Malay, KateMoots, Doug Roberts, Robert Schroeder,Molly Timmers, Mike Trianni, and BrianZgliczynski. Richard Seman, Ray Clarke, andCharles Karnella were instrumental in priori-tizing turtle surveys as a cruise objective. JohnNaughton, Alan Everson, and Gerry Davisprovided program support. Thanks to JayGutierrez at the Guam Division of Aquaticand Wildlife Resources, and the CNMIDivision of Fish and Wildlife for informationand local support. Gerry Davis, Ray Clarke,Charles Karnella, and two anonymous re-viewers provided suggestions that improvedthe manuscript.

Literature Cited

Agastheesapillai, A., and R. Thiagarajan.1979. Biology of the green turtle Cheloniamydas (Linnaeus) in the Gulf of Mannar

and Palk Bay. J. Mar. Biol. Assoc. India21:45–60.

Andre, J., E. Gyuris, and I. R. Lawler. 2005.Comparison of the diets of sympatric du-gongs and green turtles on the OrmanReefs, Torres Strait, Australia. Wildl. Res.32:53–62.

Balazs, G. H. 1980. Synopsis of biologicaldata on the green turtle in the HawaiianIslands. NOAA Tech. Mem. NOAA-TM-NMFS-SWFSC-7.

———. 1985. Status and ecology of marineturtles at Johnston Atoll. Atoll Res. Bull.285:1–46.

Balazs, G. H., and M. Chaloupka. 2004. Spa-tial and temporal variability in somaticgrowth of green sea turtles (Chelonia my-das) resident in the Hawaiian Archipelago.Mar. Biol. (Berl.) 145:1043–1059.

Balazs, G. H., R. G. Forsyth, and A. K. H.Kam. 1987. Preliminary assessment ofhabitat utilization by Hawaiian green tur-tles in the resident foraging pastures.NOAA Tech. Mem. NOAA-TM-NMFS-SWFC-71.

Balazs, G. H., M. R. Rice, N. Hoffman, S. K.K. Murakawa, D. M. Parker, and R. J.Shallenberger. 2005. Green turtle foragingand resting habitats at Midway Atoll:Significant findings over 25 years, 1975–2000. NOAA Tech. Mem. NOAA-TM-NMFS-SEFSC-528:102–103.

Balazs, G. H., P. Siu, and J.-P. Landret. 1995.Ecological aspects of green turtles nestingat Scilly Atoll in French Polynesia. NOAATech. Mem. NOAA-TM-NMFS-SEFSC-361:7–10.

Bjorndal, K. A., A. B. Bolton, and M. Y. Cha-loupka. 2005. Evaluating trends in abun-dance of immature green turtles, Cheloniamydas, in the greater Caribbean. Ecol.Appl. 15:304–314.

Buckland, S. T., D. R. Anderson, K. P. Burn-ham, and J. L. Laake. 1993. Distance sam-pling: Estimating abundance of biologicalpopulations. Chapman and Hall, London.

Burke, V. J., S. J. Morreale, P. Logan, andE. A. Standora. 1991. Diet of green turtles(Chelonia mydas) in the waters of Long Is-land, N.Y. NOAA Tech. Mem. NOAA-TM-NMFS-SEFSC-301:140–143.


Calvo, M. V., C. Lezama, M. Lopez-Mendilaharsu, A. Fallabrino, and J.Coll. 2003. Stomach content analysis ofstranded juvenile green turtles in Uruguay.NOAA Tech. Mem. NOAA-TM-NMFS-503:203–204.

Chaloupka, M., C. Limpus, and J. Miller.2004. Green turtle somatic growthdynamics in a spatially disjunct GreatBarrier Reef metapopulation. Coral Reefs23:325–335.

Eldredge, L. G. 1983. Summary of environ-mental and fishing information on Guamand the Commonwealth of the NorthernMariana Islands: Historical background,description of the islands, and review ofthe climate, oceanography, and submarinetopography. NOAA Tech. Mem. NOAA-TM-NMFS-SWFC-40.

Eldredge, L. G., and R. H. Randall. 1980.Atlas of the reefs and beaches of Saipan,Tinian and Rota. Office of Coastal Re-sources Management of the Common-wealth of the Northern Marianas.

Ellis-Neill, L., and J. B. Neill. 1985. Envi-ronmental assessment of the reef-flat plat-form habitat in the Tatachog Park area,Rota, CNMI. Unpublished Report for theCoastal Resources Management Office,Saipan, CNMI. University of Guam Ma-rine Laboratory, Guam. (Available fromCoastal Resources Management Office,Saipan.)

Evans, D. L., K. B. Cooper, and W. G. Bar-ron Jr. 2002. 2000 census of populationand housing: The Commonwealth of theNorthern Mariana Islands. Populationand Housing Profiles, 2000. U.S. CensusBureau, Department of Commerce.

Ferreira, M. B., M. Garcia, B. Jupp, and A.Al-Kiyumi. 2003. Feeding ecology of thegreen turtle, Chelonia mydas, at Ra’s AlHadd, Arabian Sea, Sultanate of Oman.NOAA Tech. Mem. NOAA-TM-NMFS-SEFSC-503:205–206.

FitzSimmons, N., C. Moritz, and B. W. Bo-wen. 1999. Population identification.Pages 72–79 in K. L. Eckert, K. A. Bjorn-dal, F. A. Abreu-Grobois, and M. Don-nelly, eds. Research and managementtechniques for the conservation of sea tur-

tles. IUCN/SSC Marine Turtle SpecialistGroup Publication No. 4.

Forbes, G. A. 1996. The diet of the green turtlein an algal-based coral reef community—Heron Island, Australia. Ph.D. diss., JamesCook University, Townsville, Australia.

Grout, D. 1997. Summary of USFWS Rotasea turtle nesting surveys. Unpublishednotes, U.S. Fish and Wildlife Service, Ho-nolulu, Hawai‘i. (Available from U.S. Fishand Wildlife Service, Honolulu.)

Gutierrez, J. 2004. Guam sea turtle recoveryannual progress report. Unpublishedreport. Division of Aquatic and WildlifeResources, Guam. (Available from Divi-sion of Aquatic and Wildlife Resources,Guam.)

Hirth, H. F. 1997. Synopsis of the biologicaldata on the green turtle Chelonia mydas(Linnaeus 1758). U.S. Fish Wildl. Serv.Biol. Rep. 97 (1).

Holloway-Adkins, K. G., and L. M. Ehrhart.2005. A comparison of habitat, foragingecology and the biotoxin okadaic acid infive Florida populations of Chelonia mydas.NOAA Tech. Mem. NOAA-TM-NMFS-SEFSC-528:61–63.

Ilo, L. I., and J. M. Manglona. 2001. Rotaturtle assessment report. Unpublishedreport. Division of Fish and Wildlife,Commonwealth of the Northern MarianaIslands, Saipan. (Available from Divisionof Fish and Wildlife, CNMI, Saipan.)

Kenyon, J. C., R. E. Brainard, R. K. Hoeke,F. A. Parrish, and C. B. Wilkinson. Inpress. Towed-diver surveys, a method formesoscale spatial assessment of benthicreef habitat: A case study at Midway Atollin the Hawaiian Archipelago. CoastalManage.

Kinan, I., ed. 2002. Proceedings of the west-ern Pacific sea turtle cooperative researchand management workshop, 5–8 February2002, Honolulu, Hawai‘i, USA. WesternPacific Regional Fishery ManagementCouncil, Honolulu, Hawai‘i.

Kolinski, S. P. 1995. Migrations of the greenturtle, Chelonia mydas, breeding in YapState, Federated States of Micronesia. Mi-cronesica 28:1–8.

Kolinski, S. P., R. K. Hoeke, S. R. Holz-


warth, and P. S. Vroom. 2005. Sea turtleabundance at isolated reefs of the MarianaArchipelago. Micronesica 37:287–296.

Kolinski, S. P., L. I. Ilo, and J. M. Manglona.2004. Green turtles and their marine habi-tats at Tinian and Aguijan, with projec-tions of resident turtle demographics inthe southern arc of the Commonwealthof the Northern Mariana Islands. Micro-nesica 37:95–116.

Kolinski, S. P., D. M. Parker, L. I. Ilo, andJ. K. Ruak. 2001. An assessment of seaturtles and their marine and terrestrialhabitats at Saipan, Commonwealth of theNorthern Mariana Islands. Micronesica34:55–72.

Limpus, C., and M. Chaloupka. 1997. Non-parametric regression modeling of greensea turtle growth rates (southern GreatBarrier Reef ). Mar. Ecol. Prog. Ser.149:23–34.

Limpus, C. J., P. J. Couper, and M. A. Reed.1994. The green turtle Chelonia mydasin Queensland: Population structure in awarm temperate feeding area. Mem.Queensl. Mus. 35:139–154.

Limpus, C. J., D. J. Limpus, K. E. Arthur,and C. J. Parmenter. 2005. Monitoringgreen turtle population dynamics in Shoal-water Bay: 2000–2004. Great Barrier ReefMarine Park Authority Res. Publ. 83.

Lopez-Mendilaharsu, M., S. C. Gardner, andJ. A. Seminoff. 2003. Feeding ecology ofthe East Pacific green turtle (Chelonia my-das agassizii) in Bahia Magdalena, B.C.S.,Mexico. NOAA Tech. Mem. NOAA-TM-NMFS-SEFCS-503:213–214.

Lopez-Mendilaharsu, M., S. C. Gardner, J. A.Seminoff, and R. Riosmena-Rodriguez.2005. Identifying critical foraging habitatsof the green turtle (Chelonia mydas) alongthe Pacific coast of the Baja Californiapeninsula, Mexico. Aquatic Conserv: Mar.Freshwater Ecosyst. 15:259–269.

Makowski, C., J. A. Seminoff, and M.Salmon. 2006. Home range and habitatuse of juvenile Atlantic green turtles (Che-lonia mydas L.) on shallow reef habitatsin Palm Beach, Florida, USA. Mar. Biol.(Berl.) 148:1167–1179.

McCoy, M. A. 1997. The traditional and cer-

emonial use of the green turtle (Cheloniamydas) in the Northern Mariana Islandswith recommendations for its use in cul-tural events and education. Unpublishedreport prepared for the Western PacificRegional Fishery Management Counciland the University of Hawai‘i Sea GrantCollege Program, Honolulu, Hawai‘i.(Available from the Western Pacific Re-gional Fishery Management Council.)

Mendonca, M. T. 1983. Movements andfeeding ecology of immature green turtles(Chelonia mydas) in a Florida lagoon. Co-peia 1983:1013–1023.

Meneses, I., and I. A. Abbott. 1987. Gracilariaand Polycavernosa (Rhodophyta) from Mi-cronesia. Micronesica 20:187–200.

Mortimer, J. A. 1981. The feeding ecology ofthe West Caribbean green turtle (Cheloniamydas) in Nicaragua. Biotropica 13:49–58.

Musick, J. A., and C. J. Limpus. 1997. Habitatutilization and migration in juvenile seaturtles. Pages 137–163 in P. L. Lutz andJ. A. Musick, eds. The biology of sea tur-tles. CRC Press, Boca Raton, Florida.

National Marine Fisheries Service and U.S.Fish and Wildlife Service. 1998. Recoveryplan for U.S. Pacific populations of thegreen turtle (Chelonia mydas). NationalMarine Fisheries Service, Silver Spring,Maryland.

Preskitt, L. B., P. S. Vroom, and C. M.Smith. 2004. A rapid ecological assessment(REA) quantitative survey method for ben-thic algae using photoquadrats with scuba.Pac. Sci. 58:201–209.

Pritchard, P. C. H. 1982. Marine turtles ofMicronesia. Pages 263–272 in K. A. Bjorn-dal, ed. Biology and conservation of seaturtles. Proceedings of the world confer-ence on sea turtles. Smithsonian Institu-tion Press, Washington, D.C.

Pultz, S., D. O’Daniel, S. Krueger, H.McSharry, and G. Balazs. 1999. Marineturtle survey on Tinian, Mariana Islands.Micronesica 32:85–94.

Randall, R. H. 1997. A biological and geolog-ical assessment of the Holocene and mod-ern fringing reef system developed alongUyulan Beach, Rota, Mariana Islands. Un-published report prepared for IOTA Part-


ners, Bellevue, Washington. (Availablethrough the U.S. Army Corps of Engi-neers, Honolulu District.)

Randall, R. H., and B. D. Smith. 1988. Areconnaissance marine survey of theMochong-As Matmos coastal area of Rotain the Mariana Islands. Univ. Guam Mar.Lab. Environ. Surv. Rep. No. 21.

Read, M. A., and C. J. Limpus. 2002. Thegreen turtle, Chelonia mydas, in Queens-land: Feeding ecology of immature turtlesin Moreton Bay, southeastern Queensland.Mem. Queensl. Mus. 48:207–214.

Russell, D. J., and G. H. Balazs. 2000. Identi-fication manual for dietary vegetation ofthe Hawaiian green turtle Chelonia mydas.NOAA Tech. Mem. NOAA-TM-NMFS-SWFSC-294.

Russell, D. J., G. H. Balazs, R. C. Phillips,and A. K. H. Kam. 2003. Discovery ofthe sea grass Halophila decipiens (Hydro-charitaceae) in the diet of the Hawaiiangreen turtle, Chelonia mydas. Pac. Sci.57:393–397.

Sanchez, F. A., and D. D. Quiroga. 2005. De-termination of feeding habits and behaviorof the Pacific black turtle (Chelonia mydasagassizii) in Gorgona National Park, De-partamento del Cauca, Columbia. NOAATech. Mem. NOAA-TM-NMFS-SEFSC-528:303–305.

Sara, S. K., C. M. Bravo, X. Velez-Zuazo,and M. W. de Castro. 2005. Green turtle(Chelonia mydas agassizii) diet differencesin two Peruvian coastal localities. NOAATech. Mem. NOAA-TM-NMFS-SEFSC-528:305–307.

Searle, L. 2003. Diet of green turtles(Chelonia mydas) captured in the RobinsonPoint foraging ground, Belize. NOAATech. Mem. NOAA-TM-NMFS-SEFSC-503:228–229.

Seminoff, J. A., A. Resendiz, and W. J. Nich-ols. 2002. Diet of East Pacific green turtles(Chelonia mydas) in the central Gulf ofCalifornia, Mexico. J. Herpetol. 36:447–453.

Tsuda, R. T. 1969. Biological results of anexpedition to Rota, Mariana Islands. Misc.Rep., Univ. Guam, Div. Biosci. Mar. Stud.,Guam.

———. 1988. Sargassum from Micronesia.Pages 59–63 in I. A. Abbott, ed. Taxon-omy of economic seaweeds with referenceto some Pacific and Caribbean species.Vol. 2. California Sea Grant College Pro-gram Report No. T-CSGCP-018.

———. 2003. Checklist and bibliography ofthe marine benthic algae from the MarianaIslands (Guam and CNMI). Univ. GuamMar. Lab. Tech. Rep. No. 107.

U.S. Fish and Wildlife Service. 1980. RotaHarbor project, Commonwealth of theNorthern Mariana Islands. Unpublishedreport, U.S. Fish and Wildlife Service, Di-vision of Ecological Services, Honolulu,Hawai‘i. (Available from U.S. Fish andWildlife Service, Honolulu.)

Uzcategui, R. F., H. B. Garrido, T. L. Fuen-mayor, and J. R. Hernandez 2005.Stomach content analysis of a greenturtle (Chelonia mydas) found in Porshoure,Zulia State, Venezuela. NOAA Tech.Mem. NOAA-TM-NMFS-SEFSC-528:346–347.

Wells, S. M., and M. D. Jenkins. 1988.Northern Mariana Islands. Pages 241–246in S. M. Wells and M. D. Jenkins, eds.Coral reefs of the world. Vol. 3. Centraland western Pacific. IUCN ConservationMonitoring Center and the United Na-tions Environmental Programme.

Wiles, G. J., A. B. Amerson Jr., and R. E.Beck Jr. 1989. Notes on the herpetofaunaof Tinian, Mariana Islands. Micronesica22:107–118.

Wiles, G. J., G. H. Rodda, R. H. Fritts, andE. M. Taisacan. 1990. Abundance andhabitat use of reptiles on Rota, Mariana Is-lands. Micronesica 23:153–166.

Winzler and Kelly Consulting Engineers.2002. Permit application package for RotaEast Harbor rehabilitation project. Appli-cation prepared for the CNMI Depart-ment of Public Works, Saipan. (Availablethrough the U.S. Army Corps of Engi-neers, Honolulu District.)

Wylie, C. R. 1989. A quantitative assessmentof macroalgae. Pages 28–34 in B. D.Smith, R. H. Randall, S. S. Amesbury,E. E. Irish, and C. R. Wylie, A marinesurvey of the Apanon coastal environment,


Talakhaya area, Rota, Mariana Islands.Univ. Guam Mar. Lab. Environ. Surv.Rep. No. 22.

Zug, G. R., G. H. Balazs, J. A. Wetherall, and

D. M. Parker. 2002. Age and growth ofHawaiian green sea turtles (Chelonia my-das): An analysis based on skeletochronol-ogy. Fish. Bull. 100:117–127.


nearshore distribution and an abundance estimate for green sea · 509 nearshore distribution and an...

Documents