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ECOLOGY AiID BIOLOGY OF THE ROI.'GH-TOOTHED DOLPHI>
S TELO BRED.JIVE.%'SIS!
A DISSERTATION Sl'Bil ITTE D TO TH F. GRADL ATE Dli'ISIO> OF TH F l:~IYERSITW OF HA~IAI'I l> PARTIAL FI;I.FILL~IE>T OF THF REQl'IREilE>TS FOR THE DEGRFE OF
DOCTOR OF PHILOSOPHY
BIOIIF.DICAI. SCIF.. IiCES PHYS IOI.OGY!
DECEilBF.R 2002
By christi L. ll'est
Dissertation Committee:
G. Causey %'hitto», Chairperson Claude Payri, Co-chairperson! David Lally Alemandre Gannier John Claybaugh Jay Sweeney James Carpenter James ~lead referee! Yu-Chong Lin l'incent Ridouv referee! UMI Number: 3070732
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ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 ECOLOGIE ET BIOLOGIE DU DAUPHIN A BEC ETROIT
STENO BREDA NENES'IS
DISSERTATION CONJOINTEMENT PRESENTEE A L'UN[VFRSITE DE HAWAI'I ET L'UNIVERSITE DE I-A POLYNESIE FRANCAISE EN VUE DE L'OBTENTION DU
DOCTO RAT
F.N
SCIENCF BIOMEDICALE ET FCOI OGIE MARINE
DECEMBRE 2002
paf Kristi L. West
Membresdu Jury:
Causey G. Whittow, Co-Directeur Claude Payri, Co-Directrice David Lally, examinateur Alexandre Gannier, tuteur John Claybaugh,examinateur Jay Sweeney,examinatew James Carpenter, examinateur James Mead rapporteur! Yu-Chong Lin, examinateur Vincent Ridoux rapporteur! UNIVMQvt 0%LA University of Hawai'i at Manoa ~mksts rauocruss
University of Hawaii at Manoa Universithde la Polynhsiefranqaise
Associate Dean, Graduate Division La prbsidente The graduateChair of Departtnent of Physio ogy
Consideringthe generalagreemcnt signed in 1994by the presidentofboth Universityde la PoIynbsic franchise ex University~isc du Pacifique!and The Universityof Hawaii at Manoa Consideringthe spo:ific letter of agreementsignod m I 997between the two Universities concerning the joint Ph.D dissertation for Ms Kristi WEST
The two institutionsagree upoa the foilowiag committeel'or tbe Pb.D. viva voce czatlllnatlon:
Article I The viva voce examination for thc PhD dissertation of Ms Kristi WEST will bc held Scptcmber30, 200' st the Vnivetsity of Hawat at Maooa ln the Pbysiology Coo fcrence room room T408 ln the Biomedical ScieaccsBuildiag!.
ice dissertation title is: Ecol Biolo f the rou h-ooth d I hn rcno !~rrrlantnsi
Article 2- Thc viva voce committee includes:
David Lally, Professor,UH, reader Yu-Cbong Lia, Professor, UH. reader J nhaClaybaugh, Professor,UH, reader James Carpenter, Professor, UH, reader Causey Whittow, Professor,co-advisor Claude Payri, professor oo-advisor Alexaodre Gaaaicr, PhD, reader Jay Sweeney,Dr VeterinarianDolphin }vest, reader ViaceatR!BOUX, ProfessorUniversity of La RochclleFrance, referee JamesMEAD, MarineMammal Curator, Smithsonian Institution Washington DC, referee
Article3 The universitiesinvolved arc responsible for the application of thisde:ision.
For Universityof ldawaii For Universityof FrenchPolynesia
The Associate Dean, Gmluntc Division
Peter V. GARROO III DUAL PH.D. PROGRAM BETWEEN THE UMVERSITY OF HAWAI'I AND LVNIVERSITE DE LA POLYNESIE FRANQAISE
This dissertationis part of a dual Ph.D. program under a joint agreementbetween the
University of Hawaii at Manoa and LVniversite de la Polynksie Franqaise.The dissertationcommittee is composedof an equal number of membersto representboth
Universities. Although the format of the dissertationdocument is not traditional,each of the threechapters follows similar formatting for journal submission. An overall abstract.
introduction and discussion are also included in the dissertation document that follows more traditional formatting. 9'e certify that we haveread this thesisand that. in our opinion.it is satisfactoryin scopeand quality as a dissertationfor thedegree of Doctorof
Philosophyin BiomedicalScience Physiology!.
DISSERTATION COMMI I I I I: ~Ne certiti tnat ice haie reai thi' tl esis and tiiat. in our opinion. it sat,stactor in scopeand quality zs a dissertationtor th" degreeot Doctor
DIS>ER I A Tl Ct'iliXIITTEE Greater knowledge of the rough-toothed dolphin..S'Ieno bredanensis, is needed to effectively contribute to conservationand managementefforts for this species. 1he primarypurpose of this researchwas to describeecological and biological parameters for
X bredanensis that will be useful in future assessmentsof population stress. Several approacheswere usedto studyX bfedanensis,including investigations of free-ranging populations.dead specimens,and captive individuals. Free-rangingrough-toothed dolphinsdistributed near small oceanicisland environmentswere found to be more commonly sightedin-shore than off-shore. fn the Windwardislands of FrenchPolynesia, this speciespreferred water depths of 1000to 2000m anda distanceof 1.8to 5.5 km from the barrier reef. Group sizesof rough-tootheddolphins sighted in FrenchPolynesia rangebetween 1 and35 individualswith a meansize of 12.1. Fndocrinologydata for 5 bredanensiswas establishedin captive healthy and strandedindividuals. Rangesand means were provided for progesterone,testosterone, cortisol and thyroid hormones.
Changesin thyroid hormone concentrationswere reflective of health status and testosteroneappeared to be suppressedin ill individuals.Reproduction in X bredanensis wasinvestigated by determiningthe size and age range that this species attains sexual and physicalmaturity. Femalerough-toothed dolphins attain sexual maturity by 9 to 10years of ageand malesbetween 5 and 10 yearsat a similarlength of approximately216 cm.
Physicalmaturity is generallyreached at an olderage and larger size for bothmales and females. Ecologically healthy and unhealthypopulations of S. bredanensiswere describedin this investigationand these finding will beuseful in assessingfuture threats to this species. Une meilleure connaissancedu dauphin a bec etroit. S en' bredanenvis.semble cruciale pow
ameliorer1'impact des efTorts de conservationet de protectionde cetteespece. Le but principalde cette etude est de decrire les parametres ecologiques et biologiques du dauphin Steno
bredanensis, afin d'avoir dans le futur une meilleure evaluation du niveau de stress de cette
population.Plusieurs approches ont et' utiliseesdans cette etudedu dauphin..S.bredanensis,
incluant des observationsen mer, desechantillons prelevessur animauxdecedes et des animaux
vivant en captivite.Les populationssauvages etudiees dans un environnementinsulaire ont ete
plus &equemmentobservees pres des cotes qu'au large.Dans les Iles du Vent en Polynesie
franqaise, cette espece semble se situer preferentiellementdans des eaux presentant une
profondeurde 1000a 2000metres et dansune zone distante de I.S i 5,5 kilometresde la barriere
de corail. La taille des groupesde dauphinsa becetroit observesen Polynesic fran>;aiseva de 1 a
35 individus avec une moyennede 12,1par groupe. Desmesures de taux d' hormonespour Steno
bredanensisont ete etablies a partir de prdlevementsfaits sur dauphins en bonne santeen captivite et sur dauphinsechoues. Les valeurs et leurs moyennessont donneespour la
progesterone,la testosterone,le cortisolet les hormonesthyroidiennes. Les variationsdes taux d'honmnesthyroYdiennes sont correlees avec 1'etat de sante de I'animal; la testosteroneapparait
ge&ralement bassechez les animaux malades.La physiologic reproductricedes .Cteno
bredanensisa eteetude: en detertnittantla taille et 1'age moyena laquellecette ence atteintsa
maturitesexuelle et morphologique.Les femelles atteignent la maturitesexuelle entre 9 et 10ans,
lesmiles entre5 et 10ans, leur longueurcorporeHe ayant alors ete evaluee a approximativement
216 cm. La maturitephysique est logiquementatteinte plus tardivement, la taille desanimaux
etant alors superieure,aussi bien chez les malesque chez les femelles. La comparaisonde I'ecologic des populationsde Stenobredanensis en bonne ou mauvaisesante, decrite dans cette etude.sera tres utile pour evaluerles menacesfutures qui pesentsur cetteespece. TABLE OF CONTENTS
Abstract. .Vl Resume. List of Tables...... List of Figures Xt Introduction. .1 Chapter I: Distribution of the rough-tootheddolphin Steno bredanen»i»!around the Windward Islands French Polynesia! Abstract. 73 Introduction. 74 Methods. ~6 Results. 30 Discussion 33 References 37 Chapter2: Reproductionin the rough-tootheddolphin. Stenohredanen»i»: Attainment ot sexualand physical maturity. Abstract. 50 Introduction. 51 Methods. 5'7 Results. 58 Discussion 66 References. 71 Chapter3: flormone concentrationsduring rehabilitationand in healthy rough-tootheddolphins, Stenobreclanensis .84 Abstract. .85 Introduction. .86 Methods. ..88 Results 93 Discussion 96 References.. 104 Synthesis. Re ferences. 145 LIST OF TABLES
1.1. SurveyEffort and Sighting Conditions 40
1.2 Mean Sighting Ratesfor Different Strata.
2.1 TheAge, Body Length and Body Weightof S. bredanensisfor PhysicallyMature and Immature Males and Females. 7'7
2.2 TheAge, Body Lengthand Body Weightof X bredunensisfor SexuallyMature and Immature Males and Females. 73
2.3 UterineTissue Measurements Among ReproductiveStates.
2.4 Mammary TissueComposition and StructureMeasurements Among Reproductive States. 75
Appendix I: Male reproductivedata for X bredanensis. .80
Appendix 2: Femalereproductive data for S. bredanensis. .81. 82
3.1 CortisoL Total T~, FreeT~, Total T3, FreeT3, Progesteroneand Testosteronein S bredunensis. 108 LIST OF FIGURES
1.1. Map of Study Location in the Windward Islands.French Polynesia.. 4'7
1.2 Study RegionsSub-divided According to Area.
1.3 SurveyEffort Correctedby Season:September - November
1.4 SurveyEffort Correctedby Season:December - February.
1.5 Survey Effort Corrected by Season: March - May
1.6 Grcup sizesof.S. hredanensis...
2.1 Age VersusTotal Body Lengthin X hredanensis. 76
2.2 Weight VersusTotal Body Lengthin X bredanensis. .77
2.3 TestisLength and Weight VersusTotal Body Lengthin.S'. bredanensis..
2.4 Ovary Length and Weight VersusTotal Body Lengthin.S. bredanensis...... 79
3.1 Cortisol ConcentrationsProfiled Against Time in Rehabilitation. .109
3.2 Thyroid HormoneConcentrations Profiled Against Time in Rehabilitation for Dolphin F- l. .110
3.3 ThyroidHormone Concentrations Profiled Against Time in Rehabilitation for Dolphin F-2
3.4 Thyroid HormoneConcentrations Profiled Against Time in Rehabilitation for Dolphin F-3. 112 3.5 Thyroid HormoneConcentrations Profiled Against Time in Rehabilitation for Dolphin F-4.
3.6 Thyroid HormoneConcentrations Profiled Against Time for Dolphin P...
3.7 Thyroid HormoneConcentrations Profiled Against Time for Dolphin M...
3.8 Thyroid HormoneConcentrations Profiled Against Time for Dolphin T...
3.9 Testosteroneand ProgesteroneConcentrations Profiled Against Time in Rehabilitationfor 4 StrandedDolphins.
3.10 TestosteroneConcentration Profiled Against Time for Dolphin M...
3.11 ProgesteroneConcentration Profiled Against Time for Dolphin P andT... INTRODUCTlON
Background
Marine ecosystemsare being impactedby naturaland anthropogenicsources on a world-wide scale. Thesechanges are likely to causestresses to cetaceanpopulations and have the potential to harm individuals and lead to reductionsin population sizes. The definition of stressdeveloped in the early 1900's describesthe biological responsein three stages:I! alarm and adaptation,2! hormonalevents. and 3! resistance.exlmustion and death.which are independentot the natureof the damagingagent Neyan. 1998in St.
Aubin and Dierauf. 2001!. The adaptationresponse apparent during this first stage is
likely to retlcct populationlevel changes. For example,shiAs in habitat preferencemay signify a first sign ot impactas the sourceof knownpotential stressors all involvethe
immediatesurroundings of theseanimals. As the biological stressresponse proceeds to the secondand third stage,detectable physiological changes are likely to becomeevident on an individual level.
In a few of the relatively well-known speciesof cetacean,such as the bottlenose dolphin, beluga whale, and spinnerdolphin. immunologicaland molecularbiology markingtechniques are currentlybeing developed to studystress due to anthropogenic
factors Aldridgeet al., 2001;De Guiseet al., 1998;Romano et al., 1992;Romano et al.,
1994; Southern,2000; St. Aubin and Dierauf. 2001!. In thesespecies research is now
focusingon defining precisebiological perturbations on an individuallevel. Cetacean
work in this area has included the developmentof specific monoclonalantibodies for a
few species Aldridge et al., 2001;De Guiseet al., 1998!and molecular studies initiated with the bottlenosedolphin are now being extended to beluga whales Romano et aL,
1992; 1999!. Recentefforts to identify stressactivated proteinsby molecularanalyses of tissuessuggest promise for studying the effects of coastalpollution on individual beluga whalesand tuna fishery stresseson individual spinner dolphins Southern,2000!.
The effects of environmentalimpacts on wild populationsof the cetaceanspecies
Stenobredanensis are unknown. It is undoubtablethat changingmarine ecosystems have someimpact on dolphinspecies such as S. bredanensis.However, basic information and quantitativedata for assessingimpacts on eithera populationor individuallevel for this speciesis lacking. Defined distributional patterns for S. Aredanensiswoukl provide a startingpoint for investigatingpopulation level changes.Means to sensethe adaptation ot populationsand eventuallyphysiological responds to stresson an individuallevel wouldbe a significantcontribution to the futureconservation of thisdolphin species.
lsepactsAffecting Sonre Small DolphinSpecks
Very little is knownabout the rough-tootheddolphin when compared with other tropical and sub-tropicalsmall dolphinswith similar world-widedistributions. In the tropical Pacific ocean, speciesof the genus Stenella have been relatively well documented, and dec ides of research focusing on this genus provides a very comprehensiveoverview comparedto the Steno genus. Most likely the only other speciesof dolphin where more informationis availableis the bottlenosedolphin, T. truncatus, which is the best known of all cetaceans Reynolds et al., 2000; Wells and
Scott, 1999!. Direct catch of small dolphins is one of severalthreats to populationsthroughout the world. andhigh numbersot' take for humanfood consumptionor otherproducts can result in reducedpopulation sizes. Direct catchof rough-tootheddolphins have been reported.but far moreinformation on theextent of this impactis availablefor othersmall dolphin species. The tropical and subtropicalspinner dolphin, Slenellalongirostris, appearsto inhabitsimilar waters to X bredanensis.The distribution of X longirostrisis primarily pelagic but this speciesalso occurs near islands throughoutits range
Klinowska.1991!. Althoughthe primarythreat to this speciesis incidentalby-catch in the tuna fishery,some direct catchof spinnerdolphins does occur, and reportedareas includethe SolomonIslands, Japan and the l.esserAntilles Klinowska. 1991!. The pantropicalspotted dolphin..Slenella aaenuata is anothersmall dolphin species tound in the samewater temperature range as .'i. bredunenvis,and in both coastaland off-shore habitats Klinowska, 1991!. Similar to spinnerdolphins, pantropicalspotted dolphins are consideredto be the most threatenedby incidentalcatch but this dolphin is taken in direct fisheriesin Japan,the Caribbean, Sir l~ andthe SolomonIslands Klinowska, 1991!.
The stripeddolphin, Ãlenella coeruleoalba is an exampleof anotherspecies tound in a similar distributionalrange to X bredanensis,but strjied dolphinsare also found in temperatewaters and are morecommon in the MediterraneanSea Leatherwoodand
Reeves,1983!. A directJapanese fishery for this speciesdates back centuries, and in the
1960'sannual catches were estimatedto be as high as 20,000animals in this area. Direct fisheriesare also presentin PapuaNew Guineaand the SolomonIslands, and striped dolphinswere harpooned in the EasternAtlantic from fishingboats to providecrew with meat Leatherwoodand Reeves.1983!. T. truncatus,have a world-widedistribution and are found in all tropical and temperateenvironments, absent only &om cold waters
Leatherwoodand Reeves1983; Klinowska, 1991:Reynolds et al., 2000; Wells and
Scott, 1999!. The ~~e of S. hredanensisis covered within that of T. truncatus. and thereis concernregarding the effects of environmentalimpacts on inshorepopulations of
T. truncatus as the nearshorehabitat is especially suseptibleto disturbances Klinowska.
1991!. Direct catch of bottlenosedolphins also posesa significant threat to this sanies and has resulted in populationdeclines severe enough to close a Turkish fishery in 1983
Klinowska, 1991!. In the past,direct fisheries for bottlenosedolphin were common in small localuM areasand in severalcountries including Russia,Bulgaria, the USSR.and
Japan.Today. Japan and L'wopean countries remain the primaryareas where bottlenose dolphins are taken to providemeat for humanconsumption Klinowska, 1991!. A relatively small numberot T. truncatusare also taken for public display purposesin some partsof the world as this speciestends to do well undercaptive conditions Klinowska,
1991!. Ikowever,no significantnumber of wild caughtindividuals have Ixwn brought into captivitysince 1989 in theUnited States. and animals are not takenfor publicdisplay from all regions Andrews,1999!. Thereare a few selectedareas where significant numbersof bottlenosedolphins are still takenfor publicdisplay, for examplehundrcxh have beenremoved from Cubanand Mexican waters Krames,personal comm.!.
Direct fisheriesfor thespecies S. bredanensishave been identified lrom the West
Indiesand WestAfrica, and specimenshave beeninvestigated from drive fisheriesin
Japanand in the SolomonIslands Klinowska. 1991; Miyazaki, 1980!. Numberstaken to supply food for human consumptionare small from all areas, but the limited distributional information available for this speciesindicates that populations to draw &om are not especiallylarge in any regionidentified to date Klinowska,1991!. lt is unknown what atTectthese direct fisherieshave on the current populationstatus of rough- tootheddolphins and in order to assessthese potential effects. increasedspecies knowledgeis required Young et al., 1993!. Baselinedistributional data for S. hredanensiswould provide a meansto determineaberrant distribution and eventual populationdecline resulting from potentialthreats to this speciessuch as excessive direct catch.
incidentaldeath through fishery interactions poses a significantthreat to the future of manydolphin populations.Perhaps the most well knownexample of this problem comestrom largenumbers of delphinidby-catch in the f'.asternTropical Pacific '.TP! tunafishery. Rough-tootheddolphins are sometimes associated with tunain the ETPand fishermen accounts indicate that this association occurs elsewhere as well .'arwardine et al., 1998;l~therwood and Reeves,1983!. 1lowever,the total numberof S. hredanensis individuals documentedas incidental deathsin the 1'.TPis not nearlyas extensiveas for speciesin the SIenellagenus Klinowska, 1991;f~herwood andReeves, 1983; Wade and Gerrodctte, 1993!. Tuna fisheries in the 1:TP annually reported hundreds of thousandsof spinnerand spotted dolphins as by-catchduing the 1980's Klirmwska,
1991!. As a resultof intenseexploitation pressure on spinnerdolphins, populations in this area are well studiedand informationon distributionalpatterns over a largeopen oceanregion is available.1 nthe deep FTP waters,S. longirostrisis o Aensighted in pods numberingin the hundredsor thousatids,much greatergroup si7~ than for S bredanensiswhen found in this region Perrinet al., 1987;Wade and Gerodette, 1993!.
Theexploitation of S. atIenuatain thetuna purse seine f sheryhas led to detailedstudy of thisspecies in theETP. Podsizes of thepantropical spotted dolphin range from only a few individuals to thousands,and the smaller pod sizes are similar to that of 8, bredanensis found in the FTP Wade and Gerodette. 1993!. X aaenuala is also incidentiallylost in the hook-likefishery off of Japanwhere this speciesis believedto be in competitionwith fishermenand is blamedfor interference Perrin and flohn, 1994!.
The stripeddolphin experiences some incidental mortaility in thc F.'I'Ptuna fisheryas well Leatherwoodand Reeves,1983!. T. truncatusis lost incidentially in fishery operationswhich includegill nets,purse seines, and beachnetting tor sharksin some regions I.eatherwood and Rcevcs, 1983; Klinowska. 1991!. The bottlenose dolphin also hasa reputationof beingdamaging to tishcryprotits in someI'.uropcan areas and this specieshas beenknown to be killed off of Japanduc to apparentcompetition with tishermen Lcathcrwoodand Reeves,1983; Klinowska. 199I!.
In the 1970'sby-catch information from thc I'.TP indicatedthat althoughS. hredanensiswas taken, numbers were not high when comparedto the Steno lugenus
Perrinand flenderson,1984!. At leastsome rough-toothed dolphins were killed in the purse-seineindustry Miywaki and Perrin.1994!, and assessmentot the deadspecimen collection at the SmithsonianInstitution in 2000 indicatesa significant contributionof specimensfrom incidental catch in the Pacificduring the 1980'sand 1990's personal observation!.Tuna fishery interactions likely affect rough-toothed dolphin popoulations in otherregions in additionto the I'.TP. In theearly 1990's,although the total incidental takeof S. bredanensisfor the Indo-Pacificwas not reported, the effect on theIndo-Pacilic populationof rough-tootheddolphins is believedto be insigniticant Young et al., 1993!.
No estimateof incidentalcatch is availablefor theAtlantic, and the potentialeffect on the X bredanensis population in the Western North Atlantic and Gulf of Mexico is consideredunknown Young et al., 1993!. In the Indianocean, a small numberof rough- toothed dolphins are also lost in gillnets in Sir Lanka Klinowska. 1991!. On a world- wide scale,loss of this speciesin pelagicdriAnets is unknown Kiinowska, 1991!.
Environmental change can result in distributional shiIIs of small cetacean populations. For the speciesS. bredanensis,very limited distributional information is available,and not enoughis currentlyknown to accesspotential changes in distribution due to impact effects. Oceanographicconditions during Fl Nino years indicatechanging distributional patterns of spotted dolphins as well as other species of small cet'~ans
Fielder and Reilly, 1994;Reilly and Fielder, 1994!. Since the 1982/83 El Nino event, a northwardrange extension of T. trunca ushas also beenapparent off ot the coastof
California Klinowska, 1991; Wells, 1990!. The effec ot either natural or unnatural environmental variations on X hredanensis populations have not been previously investigated.
Ilabitat degredationis recognizedas yet anotherexample of a potential threat to small cetacean populations. Vhe near-shore habitat is especially vulnerable to anthropogeniceffects such as humanencroachment, pollution and other disturbances.
For spinnerdolphin populationsusing near-shorewaters as a resting area, human disturhux:eswithin the preferredhabitat are believedto haveresulted in distributional patternshiAs as the populationadapts to thedisturbance Klinowska, 1991; Perrin, 1989!.
Changesin thedistribution of bottlenosedolphin populations off of boththe Eastand
West coastsof the USA havebeen attributed to pollution, pollution linked decline in food availability, and increased boat traffic as likely causes Klinowska, 1991!. For the speciesS. bredanensisit would be useful to establishexpected distributional patternsin near-shoreenvironments for future assessmentof thesetypes of threats to populations which are relatedto quality of habitat.
Impacton ReprodnctiveParameters
Extreme exploitation cf dolphins can result in severe population stress when numbers experiencegreat declines. A density dependentresponse may occur on a population leveL where reproductiveparaineters of individuals shiR in an attempt at compensation. this phenomenonprovides another example of the biological stress response,and in this casethe reproductivephysiology is altered on an individual basisas part of the population adaptationalphase. Age ot sexual maturity attainment is an especially important reproductive parameter as it is believed to vary in individuals accordingto the degreeof populationexploitation Pcrrin and Reilly, 1984;Smith, 1983!.
Other reproductivemeasures may also vary accordingly. Pressuresdue to low population numberswould be expectedto result in younger ageand smaller size of sexualmaturity attainment in individuals, a higher rate of pregnancy.and shorter lactations Perrin and
Reilly, 1984!.
Exploitation effects on reproductiveparameters in populationsof small delphinids have been investigated in Stenella populations from the ETP and Western Tropical
Pacific WTP! where heavy exploitation has occurred. Tuna fisheries in the eastern tropical pacific ETP! annually reported hundredsof thou~s of spinner and spotted dolphins as by-catchduring the 1980's Klinowska, 1991!. Over a twenty year period, the spinnerdolphin population in the ETP region was estimatedto have beenreduced to only 20'/oof pre-exploitationabundances Klinowska. 1991!. This extremeexploitation is evident in the reproductive parametersof ETP spinner dolphins, believed to be responsiveto the loss of huge numbers from this population Perrin and Henderson,
1984!. Attainmentof sexualmaturity in the E I P spinnerdolphins were comparedwith an unexploitedpopulation in the Gulf of Mexicowhere both males and females reach sexualmaturity at a longerand heaviersize Perrin and Henderson.1984!. Female spinnerdolphins in theeastern tropical pacific reach sexual maturity at anaverage of 5.5 growth layergroups GLG's! and at an averageof 7-10 GLG s in the Gulf of Mexico
Klinowska, 1991; Perrin and Henderson,1984!. Striped dolphins off of the coast of
Japanhave beentaken in high numbersas direct catch for centuries,and tens of thousandshave been estimated as kill in this region on an annualbasis Leatherwoodand
Reeves,1983!. A shorter calving interval, a decreasein both the length of lactationand in the resting period were apparentin the exploited Japanesestriped dolphins Kasuya.
1984!. Over 3000 individual striped dolphins were investigatedin one of thesestudies, and over 4000 spinner dolphins in another Miyazaki, 1984; Perrin and Henderson,
1984!.
When thousandsof individuals are available for reproductivestudies and the level of exploitation is known, it is possibleto comparereproductive parameters among populationsof the samedolphin species. For the speciesS. bredanensis,reproductive information is lacking and it is not evenknown for any region at what ageand size range theseanimals attain sexualmaturity. A baseline to assessreproductive pirameter shifts resulting from exploitation pressures into the future is needed for the species X bredanensis. Is~ diets oe HonaowalEvents
Adversely impacted cetaceanpopulations are likely to reflect biological and physiologicalchanges at the individual level. Hormonalevents representstage two of the biological stress response,directly following the alarm and adaptation responseof populations. Hornmnal change in relation to stressful events can be investigatedby obtaining serum samplesfrom individual dolphins to determine the circulating hormone concentrations Hadley, 1994; St. Aubin, 2001!. In order to be able to detect hormonal changes signifying that a species is experiencing significant stress, baseline endocrinologydata from healthyanimals is first requiredfor comparativeanalyses.
Cortisol is a primary glucocorticoid secretedby the adrenal gland, and is oflen considered as a stress hormone. Glucocorticoids affect the metabolism of gluclose, protein, and fat and the speedof theseprocesses increase when the body is under strum. ln the bottlenosedolphin, cortisol concentrationshave been found to rise to more than three times baselinewhen the animal undergoescapture and handling stress I hompson and Geraci. 1986!. Thyroid hormoneconcentrations are likely to be affected by various factors in cetaceans,and the stress of captureand release in bottlenosedolphins and belugawhales has resulted in decreasedthyroid hormonalconcentrations St. Aubin and
Geraci, 1988; St. Aubin and Geraci, 1992; Schroeder and Keller, 1989!. In beluga whales, studies of the stress responseto capture and handling identified an interplay betweenchanges in both cortisol and thyroid hormonesand this has been suggestedto define part of the biological mechanismsassociated with stressfor this species St. Aubin and Geraci, 1992!. Hormonalconcentrations are also effected by envirommntal surroundingsand the topic of endocrinedisruption has recently received a great deal of attention. Pollution levels are believed to be reflected in thyroid hormone values in marine mammals St.
Aubin, 2001!. ln the gray sealthyroid hormonesact as biomarkersand in the common seal a thyroid deficiency has been found to be associated with environmental contamination, specifically polychlorinated biphenyls PCB s! Brouwer et al., 1989;
Hall et aL, l998!. Evaluationof thyroid glands from dead harbor sealsin the North Sea are thought to be morphologicallydefective due to pollution in this area Schumacheret aL, l993!. Abnormal histological findings from beluga whale thyroid glands also correlate with high organochlorinecontamination in the St. l.awrenceestuary !c Guise et aL, 1994!. To be able to accuratelyassess the effects of environmentalstressors such as contaminateson hormonalevents, baseline concentrations from healthy populationson a species specific basis are first needed. No published values for any hormone are available for the rough-tootheddolphin, 3'.hredanensiv.
Limitr4iefonmtfioefor stcaobnrduaeasis
Although it becomesclear that unprecedentedchange on marine ecosystemswill ultimately affect 6ee-rangingcetacian populations, information is lacking to assessthe effects of environmental impactson some species. In the relatively unknown rough- tootheddolphin, no immurmlogicalor molecularresearch has beenundertaken, and there remainsa needto obtain baselineinformation to aid in determining the potential impact of environmentalchanges on wild populationsof this species. There is so little known about S. bredanensisthat it is indeterminatewhether this speciesis even endangeredor threatenedor experiencingsignifcant population stresses Klinowska, 1991!. For X bredanensisthere are no distributional or preferred habitat usagestudies conductedto date in near-shorewaters. 'I here is almost no knowldegeon reproductiveparameters in this species,nor areany hormonalvalues available for 8'.bredanensis. 1 hisinformation is necessaryto providea baseto aid in assessinglarge-scale population changes and individual perturbationsthat may be causedby environmentalimpacts. 1'herough- toothed dolphin is a diAicult to accessspecies, and opportunisticstudies of both controlled confmed populationsand natural wild populationsare neededto obtain this type of information.
Historyof Stenobredanensis
'I he speciesX bredanensiswas first identifiedfrom skulls in the Parismuseum andoriginally namedLe Dauphina Ixwmince which translates to thedolphin with a thin beak. In the early 1800'sthis specieswas classified as Delphinusfrontatus along with severalother types of smalldolphins Cuvier, 1817!. In 1823,an importantaddition was publishedindicating that this previouslyidentified animal was in fact a new species
Cuvier, 1823!. Lesson 828! lists this specieswith a newname, Delphinus bredanensis and this is the first indication of a name change &om frontatus in historical literature.
This specieswas includedin the broaderDelphinus genus until Gray 846! divided
Delphinusand established the Steno genus. Accordingto Gray 846! the Stenogenus included: The Steno,Steno rostratus, I he Malay Dolphin, Stenomalayanus, the Fronted
Dolphin, Stenofrontatus, the Compressed-BeakedDolphin, Steno eompressus,the
Attenuated-BeakedDolphin, Stenoattenuatus, and the CubanSteno, Steno fuscus. 1 his
12 genuswas originallynamed after a Danishnaturalist and anatomist,Dr. NikoiasSteno
Gotch, 1995!. In 1934Steno rostratus was being used for this species,incorporating both the original nameand the new Stenogenus Richards, 1934!. In 1955 Muller and
Kellog introductedthe scientific nameSteno bredanensis and Fraserand Purvcs 960! classified the family Stenidae which included the Steno, Sousa and Sotalia genera
Today the rough-tootheddolphin, X bredanensis,is classified in the Subfamily Stenidae of the Family Delphinidae.S. bredanensisis the only speciesin the Stenogenus. The common namefor S. bredanensis,the rough-tootheddolphin. is associatedwith wrinkled enamel found on the teeth of this species Harrison and Bryden, 1988!. S. bredanensis skulls are part of museumcollections in many locations including Marseille, I'lorence,
London, WashingtonD.C. and Honolulu.
Status of Nild Populations
'I'hestatus of the speciesS. bredanensisis describedas insufficientlyknown, and there is no estimateof worldwidepopulation numbers Klinowska, 1991; Leatherwood and Reeves, 1983!. Only one true abundance estimate is available from extensive cetaceansurveys in the easterntropical Pacific. In this region,approximately 150,000 rough-tootheddolphins are present,with confidencelimits ranging between 100,000 and
250,000 individuals Wade and Gerrodette,1993!. A summaryof the populationstatus of S. bredanensisin otherareas, including the NorthPacific, Western North Atlantic, and
Gulf of Mexicostates that populations are unknown Young et al., 1993!.
S. bredanensisis describedas a widely distributedspecies throughout warm watersof the worldsoceans. Although isolated sightings of rough-tootheddolphins have beenreported from severalregions, distribution of this speciesis centeredin tropical and sub-tropicalareas. Live, free-ranginganimals are believedto generally inhabit seaswith a water temperaturegreater than 25'C Klinowska, 1991; Leatherwood et al.. 1982;
Leatherwood and Reeves, 1983; Miyazaki and Perrin, 1994!. However, in the Canary
Islandsrough-toothed dolphins are quite commonly sighted where summertemperatures only range between 22 and 24'C and reach as low as 17-19'C in the winter Ritter,
2002!. Other than the presenceof this species around the Canary Islands, a ~e extension has typically been described when sighted in cooler waters Miya7Mi and
Perrin. 1994!. For example,a few strandedrough-toothed dolphins have beenreported off the Washington and Oregon coasts in the North Pacific, and a range extension documented in the South Atlantic off Brazil Ferrero et al., 1994; Ott and Danielwitz
1996!. '1'he rough-toothed dolphin is found throughout the eastern tropical Pacific, although at low densities,as indicated from cetaceansurvey work in this area Au and
Perryman, 1985; Hewitt, 1985; Wade and Gerrodette, 1993!. S. bredunensis is also presentaround at least someisland groups in the Pacific, such as llawaii Mazuccaet al.,
1999; Miyazaki and Perrin, 1994; Mobley et al., 2000!. Iwatherwood et al. 982! may have been the first authors to recognize and draw attention to the presenceof S. bredanensisspecifically in Polynesia. Study by Gannierand Gannier 998! has further indicated that Frerx:h Polynesia representsan area where S. bredanensisis found in relatively high concentrationcompared to other cetaceanspecies. Surveysof cetaceans in this region have ranked S bredanensisas the second most common speciesto be sighted in these waters Gannier, 2000!.
14 Slmwdiags of Qrao brefuacase
1lxre are certainly records of both massand individual rough-tootheddolphin strandingsIrom severalareas Chantrapornsylet al., 1996;Ferrero et al., 1994;Gaspar et al., 2000; Mazuccaet al., 1999; Miyazaki, 1989; Parsons,1998; Smith and Whitehead,
1999;Stolen et aL, 1999!. However,this cetus> speciesis usually describedas one that only occasionally strands,or where there are relatively few records of S. bredanensis strandingscompared to that of other cetaceanspecies Ellis, 1982; Leatherwoodand
Reeves,1983!. It has beensuggested that this may be due to the pelagic natureof rough- tootheddolphins, as off-shore speciesare less likely to be found washedashore Baker,
1983; Bruyus, 1971!. Mass strandingsof S. bredunensishave occurred, primarily in tropical or sub-tropicalregions which is in agreementwith the world-wide distributional information that is available for this species. Severalevents have beendocumented from the Florida area, dating back to 1965, and specimensinvestigated from three separate eventsduring the 1990's Stolen et al., 1999!. In 1976,two massstrandings of rough- tootheddolphins occurred,one off of Hawaii and the other in Virginia. Rough-toothed dolphin skulls also indicate a smaller-scaleevent that either occurred in the Indonesian archipelagoor Irom Senegalat somepoint in the past Rudolph et aL, 1997!. From more temperateregions, generally only a single individual or very few animals have been documentedto strand. For example, Irom the MediterrammtScL skulls are included in museumcollections in France,England, and Italy note by Schevill cited in Watkins et aL, 1987!. Along the Washingtonand Oregoncoast, Balcomb 980! reporteda single individual found in Washington, and Ferrero et al. 994! described three separate animals found in this area. Other regionswhere individual strandingshave beenknown to occurinclude Brazil, the Galapagos, Hong Kong, and Thailand Chantrapornsylet aL,
1996; Hetzel and Lodi, 1998; Palacios,1995; Parsons, 1998; Smith and Whitehead,
1999!. FromFrench Polynesia, there are accounts of rough-tootheddolphin strandings from the Windward Islands Gasparet J~.,2000!.
Biologyof Stc'aobmfaacase
The physicalappearance of S. bredanensisis distinct from all other cetacean species.The rough-tootheddolphin has a long and slenderbeak, a uniquehead shape where the beak blends with the forehead and o Benthe white coloration is apparent on the tip of the beak Ellis, 1982;Leatherwood et aI., 1976!. I hisspecies tends to havelarge eyes,a dark gray coloration,and a high numberof scars,marks and lighter colored splotches.External markings appear to increasewith age Leatherwoodet aL, 1982!.
Adult S. bredanensisrange from approximately210 to 240 cm in length,and weigh around100 kg Leatherwoodet aL, 1976!. The Sinu hasa leanbody shapecompared with other cetaceansof a similar size. Previousstudies focusing on the physiologyof S. hredanensis include documentation of internal body temperature, where the core temperatureof the rough-tootheddolphin was found to be lowerthan that of thespinner dolphin Whittow et al., 1978!.
In termsof thereproductive biology of S. bredanensis,very few publishedreports are available. This presentsa ckar lackof necessaryinformation for effectivespecies conservationefforts, as detmitionof reproductiveparatneters is requiredfor population modeling. The needfor knowledgeon reproductivebiology has beenemphasized as paramountfor conservationmeasures aimed at the rough-tootheddolphin Klinowska, 1991!. Only one study has addressedreproduction in S. bredanensisto date. Miyazaki