ML17227A398
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| Site: | Saint Lucie  |
| Issue date: | 12/31/1991 |
| From: | APPLIED BIOLOGY, INC. |
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APPLIEDBIOLOGY,INC.IAB-617FLORIDAPOWER&LIGHTCOMPANYST.I.UCIEUNIT2ANNUALENVIRONMENTALOPERATINGREPORTItItVOLUMEI19912968ANORTHDECATURROAO~ATLANTA,GEORGIA30033~404-296-390092042'70199920423PDRADOCK05000389'PDR ILIIII)I AB-617FLORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTALOPERATINGREPORT1991VOLUME1APRIL1992FLORIDAPOWER8,LIGHTCOMPANYJUNOBEACH,FLORIDAAPPLIEDBIOLOGY,INC.ATLANTA,GEORGIA
'IIIi1)I iISIIENVIRONMENTALOPERATINGREPORTTABLEOFCONTENTSTABLEOFCONVERSIONFACTORSFORMETRICUNITSEXECUTIVESUMMARYIntroductionTurtleNestingSurveyIntakeCanalMonitoringOtherRelatedActivitiesINTRODUCTIONBackgroundAreaDescriptionPlantDescriptionTURTLESIntroductionMaterialsandMethodsNestingSurveyIntakeCanalMonitoringStudiestoEvaluateand/orMitigateIntakeEntrapmentResultsandDiscussionNestingSurveyDistributionofLoggerheadNestsAlongHutchlnsonIslandEstimatesofTotalLoggerheadNestingonHutchinsonIslandTemporalLoggerheadNestingPatternsPredationonLoggerheadTurtleNestsGreenandLeatherbackTurtleNestingIntakeCanalMonitoringRelativeAbundanceandTemporalDistributionSize-ClassDistributionsSexRatiosCaptureEfficienciesRelativeConditionMortalitiesRecaptureIncidentsSummaryLITERATURECITEDFIGURESTABLESIVIV1010151515151920212224242729.31323437414971 l~.lgI TABLEOFCONVERSIONFACTORSFORMETRICUNITSToconvertcentigrade(degrees)centigrade(degrees)centimeters(cm)centimeters(cm)centimeters/second(cm/sec)cubiccentimeters(cm)grams(g)grams(g)hectares(ha)kilograms(kg)kilograms(kg)kilograms(kg)kilometers(km)kilometers(km)liters(I)liters(I)meters(m)meters(m)meters(m)milligrams(mg)milligrams/liters(mg/I)milliliters(ml)millimeters(mm)millimeters(mm)squarecentimeters(cm)squaremeters(m)squaremillimeters(mm)MultiIb(Cx1.8)+32C+273.183.937x103.281x103.281x101.0x102.205x103.527x102.4711.0x102.20463.5274x106.214x101.0x101.0x102.642x103.2813.937x101.0941.0x101.01.0x103.937x-103.281x101.550x101.076x101.55x10Toobtainfahrenheit(degrees)kelvin(degrees)inchesfeetfeetpersecondliterspoundsounces(avoirdupois)acresgramspoundsounces(avoirdupois)miles(statute)millimeterscubiccentimeters(cm)gallons(USliquid)feetinchesyardsgramspartspermillion.liters(USliquid)inchesfeetsquareinchessquarefeetsquareinches
EXECUTlVESUMMARYINTRODUCTIONTheSt.LuciePlantisanelectricgeneratingstationonHutchinsonIslandinSt.LucieCounty,Florida.Theplantconsistsoftwonuclear-fueled850-MWunits;Unit1wasplacedon-lineinMarch1976andUnit2inMay1983.ThisdocumenthasbeenpreparedtosatisfytherequirementscontainedintheUnitedStatesNuclearRegulatoryCommission'sAppendixBEnvironmentalProtectionPlan(EPP)toSt.LucieUnit2FacilityOperatingLicenseNo.NPF-16.ThisreportdiscussesenvironmentalprotectionactivitiesrelatedtoseaturtlesasrequiredbySubsection4.2oftheEPP.OtherroutineannualreportingrequirementsareaddressedinVolume2,alsoentitled"St.LucieUnit2AnnualEnvironmentalOperatingReport".TURTLENESTINGSURVEYSincemonitoringbeganin1971,therehavebeenconsiderableyear-to-yearfluc-tuationsinseaturtlenestingactivityonHutchinsonIsland.However,datacollectedthrough1991haveshownnolong-termreductionsintotalnesting,totalemergencesornestingsuccessontheisland.Relativelyhighnestingduringrecentyearsmayac-tuallyreflectanincreaseinthenumberofnestingfemalesinthestudyarea.Onasmallerscale,powerplantoperationhashadnosignificanteffectonnestingneartheplant.Lownestingactivityin1975andagainin1981-1983inthevicinityoftheplantwasat-tributedtonighttimeconstructionactivitiesassociatedwithinstallationofplantintakeanddischargestructures.Nestingreturnedtonormalorabovenormallevelsfollowing III bothperiodsofconstruction.During1991,daytimecons:tructionactivitiesassociatedwithvelocitycaprepairshadnoapparenteffectonnesting.Formalrequirementstoconductnestingsurveysexpiredin1986butthisprogramwasvoluntarilycontinuedthrough1991withagreementfromfederalandstateagencies.INTAKECANALMONITORINGSinceplantoperationbeganin1976,2,314seaturtles(including108recaptures)representingfivedifferentspecieshavebeenremovedfromtheintakecanal.Eighty-fivepercentofthesewereloggerheads.Differencesinthenumbersofturtlesfoundduringdifferentmonthsandyearshavebeenattributedprimarilytonaturalvariationintheoccurrencesofturtlesinthevicinityoftheplant,ratherthantooperationalinfluen-cesoftheplantitself.Themajorityofturtlesremovedfromtheintakecanal(about93percent)werecapturedaliveandreleasedbackintotheocean.Ongoingevaluationsandimprovementstothecanalcaptureprogramhavesubstantiallyreducedmortalitiesofentrappedseaturtlesduringrecentyears.TurtlesconfinedbetweentheA1Abarriernetandintakeheadwallstypicallyresideinthecanalforarelativelyshortperiodpriortocapture,andmostareingoodtoexcellentconditionwhencaught.OTHERRELATEDACTIVITIESStudiestoevaluatevariousintakedeterrentsystems,asrequiredbytheNRC'sUnit2EnvironmentalProtectionPlan,wereconductedduring1982and1983.Resultsandevaluationsofthosestudieswerepresentedtoregulatoryagenciesduring1984,andtherequirementisnowconsideredcompleted.
'EIIIIII INTRODUCTIONBACKGROUNDThisdocumenthasbeenpreparedtosatisfytherequirementscontainedintheUnitedStatesNuclearRegulatoryCommission's(NRC)AppendixBEnvironmentalProtectionPlantoSt.LucieUnit2FacilityOperatingLicenseNo.NPF-16.In1970,FloridaPower8LightCompany(FPL)wasissuedPermitNo.CPPR-74bytheUnitedStatesAtomicEnergyCommission,nowtheNuclearRegulatoryCom-mission,thatallowedconstructionofUnit1oftheSt.LuciePlant,an850-MWnuclear-poweredelectricgeneratingstationonHutchinsonIslandinSt.LucieCounty,Florida.StLuciePlantUnit1wasplacedon-lineinMarch1976.InMay1977,FPLwasissuedPermitNo.CPPR-144bytheNRCfortheconstructionofasecond850-MWnuclear-poweredunit.Unit2wasplacedon-lineinMay1983andbegancommercialoperationinAugustofthatyear.St.LuciePlantUnits1and2usetheAtlanticOceanasasourceofwaterforonce-throughcondensercooling.Since1971,thepotentialenvironmentaleffectsresultingfromtheintakeanddischargeofthiswaterhavebeenthesubjectofFPL-sponsoredbioticstudiesatthesite.BaselineenvironmentalstudiesofthemarineenvironmentadjacenttotheSt.LuciePlantweredescribedinaseriesofreportspublishedbytheFloridaDepartmentofNaturalResources(Campetal.,1977;FutchandDwinell,1977;Gallagher,1977;Gal-lagherandHollinger,1977;WorthandHollinger,1977;MofflerandVanBreedveld, IIII 1979;TesterandSteidinger,1979;Walker,1979;Walkeretal.,1979;WalkerandSteidinger,1979;Lyons,1989).TheresultsofUnit1operationalandUnit2preopera-tionalbioticmonitoringattheSt.LuciePlantwerepresentedinsixannualreports(ABI,1977,1978,1979,1980a,1981b,1982).InJanuary1982,aNationalPollutantDischargeEliminationSystem(NPDES)permitwasissuedtoFPLbytheUSEnvironmentalProtec-tionAgency(EPA).TheEPAguidelinesfortheSt.Luciesitebiologicalstudieswerebasedonthedocumententitled"ProposedSt.LuciePlantPreoperationalandOpera-tionalBiologicalMonitoringProgram-August1981"(ABI,1981c).Findingsfromthesestudieswerereportedinthreeannualreports(ABI,1983,1984a,1985a).TheEPAbioticmonitoringrequirementsweredeletedfromtheNPDESpermitin1985.JurisdictionforseaturtlestudiesiswiththeNRC,whichisconsideredtobetheleadfederalagencyrelativetoconsultationundertheEndangeredSpeciesAct.Previousresultsdealingexclusivelywithseaturtlestudiesarecontainedineightan-nualenvironmentaloperatingreportscoveringtheperiodfrom1983through1990(ABI1984b,1985b,1986,1987,1988,1989,1990,1991).Thisreportdescribesthe1991environmentalprotectionactivitiesrelatedtoseaturtles,asrequiredbySubsection4.2oftheSt.LuciePlantUnit2EnvironmentalProtectionPlan.AREADESCRIPTIONTheSt.LuciePlantislocatedona457-hasiteonHutchinsonIslandonFlorida'seastcoast(Figures1and2).TheplantisapproximatelymidwaybetweentheFt.PierceandSt.LucieInlets.ItisboundedonitseastsidebytheAtlanticOceanandonitswestsidebytheIndianRiverLagoon.
g HutchinsonIslandisabarrierislandthatextends36kmbetweeninletsandob-tainsitsmaximumwidthof2kmattheplantsite.Elevationsapproach5matopdunesborderingthebeachanddecreasetosealevelinthemangroveswampsthatarecom-mononmuchofthewesternside.IslandvegetationistypicalofsoutheasternFloridacoastalareas;densestandsofAustralianpine,palmetto,seagrapeandSpanishbayonetarepresentatthehigherelevations,andmangrovesaboundatthelowereleva-tions.Largestandsofblackmangroves,includingsomeontheplantsite,havebeenkilledbyfloodingformosquitocontroloverpastdecades.TheAtlanticshorelineofHutchinsonIslandiscomposedofsandandshellhashwithintermittentrockypromontoriesprotrudingthroughthebeachfacealongthesouthernendoftheisland.Submergedcoquinoidrockformationsparallelmuchoftheislandofftheoceanbeaches.Theoceanbottomimmediatelyoffshorefromtheplantsiteconsistsprimarilyofsandandshellsediments.Theunstablesubstratelimitstheestablishmentofrootedmacrophytes.TheFloridaCurrent,whichflowsparalleltothecontinentalshelfmargin,beginstodivergefromthecoastlineatWestPalmBeach.AtHutchinsonIsland,thecurrentisapproximately33kmoffshore.Oceanicwaterassociatedwiththewesternboundaryofthecurrentperiodicallymeandersovertheinnershelf,especiallyduringsummermonths.PLANTDESCRIPTIONTheSt.LuciePlantconsistsoftwo850-MWnuclear-fueledelectricgeneratingunitsthatusenearshoreoceanwatersfortheplant'sonce-throughcondensercooling
'IIIt)IIii)I watersystem.Waterfortheplantentersthroughthreesubmergedintakestructureslocatedabout365moffshore(Figure2).Eachoftheintakestructuresisequippedwithavelocitycaptominimizefishentrainment.Horizontalintakevelocitiesarelessthan30cm/sec.Fromtheintakestructures,thewaterpassesthroughsubmergedpipes(two3.7mandone4.9mindiameter)underthebeachanddunesthatleadtoa1,500-mlongintakecanal.Thiscanaltransportsthewatertotheplant.Afterpassingthroughtheplant,theheatedwaterisdischargedintoa670-mlongcanalthatleadstotwoburieddischargepipelines.Thesepassunderneaththedunesandbeachandalongtheoceanfloortothesubmergeddischarges,thefirstofwhichisapproximately365moffshoreand730mnorthoftheintake.HeatedwaterleavesthefirstdischargelinefromaY-shapednozzle(diffuser)atadesignvelocityof396cm/sec.Thishigh-momentumjetentrainsambientwater,result-inginrapidheatdissipation.Theoceandepthintheareaofthefirstdischargeisabout6m.Heatedwaterleavestheseconddischargelinethroughaseriesof48equallyspacedhighvelocityjetsalonga323-mmanifold(multiportdiffuser).Thisdiffuserstarts168mbeyondthefirstdischargeandterminates856mfromshore.Theoceandepthatdischargealongthisdiffuserisfromabout10to12m.Aswiththefirstdiffuser,thepurposeoftheseconddiffuseristoentrainambientwaterandrapidlydissipateheat.Fromthepointsofdischargeatbothdiffusers,thewarmerwaterrisestothesurfaceandformsasurfaceplumeofheatedwater.Theplumethenspreadsoutonthesur-faceoftheoceanundertheinfluenceofwindandcurrentsandtheheatdissipatesto'heatmosphel'B.
TURTLESTheNRC'sSt.LucieUnit2AppendixBEnvironmentalProtectionPlanissuedApril1983containsthefollowingtechnicalspecifications:4.2TerrestrialAuaticIssuesIssuesonendangeredorthreatenedseaturtlesraisedintheUnit2FES-OL[NRC,1982]andintheEndangeredSpeciesBiologicalAs-sessment(March1982)[Bellmundetal~,1982]willbeaddressedbyprogramsasfollows:Beachnestingsurveysforallspeciesofseaturtleswillbeconductedonayearlybasisfortheperiodof1982through1986.Thesesur-veyswillbeconductedduringthenestingseasonfromap-proximatelymid-AprilthroughAugust.TheHutchinsonIslandbeachwillbedividedinto36one-km-longsurveyareas.Inaddition,thenine1.25-km-longsurveyareasusedinpreviousstudies(1971-1979)willbemaintainedforcomparisonpurposes.Surveyareaswillbemarkedwithnumberedwoodenpla-quesand/orexistinglandmarks.Theentirebeachwillbesurveyedsevendaysaweek.Allnewnestsandfalsecrawlswillbecountedandrecordedineacharea.Aftercounting,allcrawltrackswillbeobliteratedtoavoidrecounting.Predationonnestsbyraccoonsorotherpredatorswillberecordedasitoccurs.Recordswillbekeptofanyseasonalchangesinbeachtopographythatmayaffectthesuitabilityofthebeachfornesting.4.2.2Aprogramthatemployslightand/orsoundtodeterturtlesfromtheintakestructurewillbeconducted.Thestudywilldeterminewithlaboratoryandfieldexperimentsifsoundand/orlightwillresultinareductionoftotalturtleentrapmentrate.
IIIIIII Thestudyshallbeimplementednolaterthanafterthefinalremovalfromtheoceanofequipmentandstructuresassociatedwithcon-structionofthethirdintakestructureandtheexperimentsshallter-minate18monthslater.Fourmonthsaftertheconclusionoftheexperimentalperiod,areportontheresultsofthestudywillbesub-mittedtoNRC,EPA,NationalMarineFisheriesService(NMFS),andtheUSFishandWildlifeService(USFWS)fortheirevaluation.Ifastatisticallysignificantreductioninannualtotalturtleentrapmentrateof80percentorgreatercanbedemonstrated,usingthedevelopedtechnologyanduponFPLreceivingwrittenconcurrencebyNRC,EPA,NMFS,andUSFWSthenpermanentinstallationofthedeterrentsystemshallbecompletedandfunctioningnolaterthan18monthsaftertheagencies'oncurrence.Thedesignofthisstudyneedstotakeintoaccountthesignificantannualvariationinturtleentrapmentobservedinthepast.Ifan80percentreductionofturtleentrapmentcannotbeprojectedtoallthreeintakestructures,thenaninteragencytaskforcecom-posedofNRC,EPA,NMFS,USFWS,andFPLshallconvene18monthsaftercompletionofthethirdintakeanddetermineifothercoursesofactiontomitigateand/orreduceturtleentrapmentarewarranted(suchasphysicalbarrier,emergenceofnewtechnologyormethodstodeterturtles).4.2.3Alternativemethodsorproceduresforthecaptureofseaturtlesentrappedintheintakecanalwillbeevaluated.Ifamethodorpro-cedureisconsideredfeasibleandcosteffectiveandmayreducecapturemortalityrates,itwillbefieldtestedintheintakecanal.4.2.5CatureandReleaseProramSeaturtleremovalfromtheintakecanalwillbeconductedonacon-tinuingbasis.Theturtleswillbecapturedwithlargemeshnets,orothersuitablenondestructivedevice(s),ifdeemedappropriate.Aformalizeddailyinspection,fromtheshoreline,ofthecapturedevice(s)willbemadebyaqualifiedindividualwhenthedevice(s)aredeployed.Theturtleswillbeidentifiedtospecies,measured,weighed(ifappropriate),taggedandreleasedbackintotheocean.Recordsofwounds,freshorold,andasubjectivejudgementontheconditionoftheturtle(e.g.,barnaclecoverage,underweight)willbemaintained.Methodsofobtainingadditionalbiological/physiologi-caldata,suchasbloodanalysesandparasiteloads,fromcaptured 1IIIIII seaturtleswillbepursued.Deadseaturtleswillbesubjectedtoagrossnecropsy,iffoundinfreshcondition.INTRODUCTIONHutchinsonIsland,Florida,isanimportantrookeryfortheloggerheadturtle,Caret-ta~carettandalsosupportssomenestingofthegreenturtle,~Chionia~mdasand59tt~I.~DhI9imatdIdII1.,1959;9t,1999;91-lagheretal.,1972;WorthandSmith,1976;Williams-Wallsetal.,1983).Allthreespeciesareprotectedbystateandfederalstatutes.Thefederalgovernmentclassifiedthelog-gerheadturtleasathreatenedspecies.TheleatherbackturtleandtheFloridanestingpopulationofthegreenturtlearelistedbythefederalgovernmentasendangeredspecies.Becauseofreductionsinworldpopulationsofmarineturtlesresultingfromcoastaldevelopmentandfishingpressure(NMFS,1978),maintainingthevitalityofthe5HutchinsonIslandrookeryisimportant.IthasbeenaprimeconcernofFPLthattheconstructionandsubsequentopera-tionoftheSt.LuciePlantwouldnotadverselyaffecttheHutchinsonIslandrookery.Becauseofthisconcern,FPLhassponsoredmonitoringofmarineturtlenestingac-tivityontheislandsince1971~Daytimesurveystoquantifynesting,aswellasnighttimeturtletaggingprograms,wereconductedinoddnumberedyearsfrom1971through1979.Duringdaytimenest-ingsurveys,nine1.25-km-longsurveyareasweremonitoredfivedaysperweek(Figure3).TheSt.LuciePlantbeganoperationin1976;therefore,thefirstthreesurveyyears(1971,1973and1975)werepreoperational~Thoughthepowerplantwasnotoperat-ingduring1975,St.LuciePlantUnitNo.1oceanintakeanddischargestructureswere IIIII installedduringthatyear.Installationofthesestructuresincludednighttimeconstruc-tionactivitiesconductedoffshorefromandperpendiculartothebeach.Constructionhadbeencompletedandtheplantwasinfulloperationduringthe1977and1979sur-veys.Amodifieddaytimenestingsurveywasconductedin1980duringthepreliminaryconstructionoftheoceandischargestructureforSt.LuciePlantUnit2.'Duringthisstudy,fourofthepreviouslyestablished1.25-km-longsurveyareasweremonitored.Additionally,eggsfromturtlenestspotentiallyendangeredbyconstructionactivitieswererelocated.Everyyearfrom1981through1991,361-km-longsurveyareascomprisingtheentireislandweremonitoredsevendaysaweekduringthenestingseason(Figure3).TheSt.LuciePlantUnit2dischargestructurewasinstalledduringthe1981nestingseason.OffshoreandbeachconstructionoftheUnit2intakestructureproceededthroughoutthe1982nestingseasonandwascompletedneartheendofthe1983season.ConstructionactivitiesassociatedwithinstallationofbothstructuresweresimilartothoseconductedwhenUnit1intakeanddischargestructureswereinstalled.Eggsfromturtlenestspotentiallyendangeredbyconstructionactivitieswererelocatedduringallthreeyears.During1991,anothermajoroffshoreconstructionprojectwasundertakentoreplacedamagedvelocitycapsonthethreeintakestructures.Alargeelevatedplat-form,fromwhichrepairactivitieswereconducted,waserectedaroundthethreestruc-tures.Constructionoccurredthroughoutthenestingseason.However,incontrastto 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previousoffshoreprojects,workwasrestrictedalmostentirelytodaylighthours,nighttimelightingoftheworkareawasminimal,andnoequipmentormaterialswereusedonthebeach.Aseaturtleprotectionplanimplementedinsupportoftheprojectincludedcagingofnestsalonga1,500msectionofbeachwestoftheplatformandreleaseofhatchlingstounaffectedareastothenorthandsouth.Thisplanwasintendedtomitigateanynegativeeffectspotentiallyresultingfromrequiredsafetyandnaviga-tionallightingonandneartheplatform.Requirement4.2.1oftheNRC'sSt.LucieUnit2AppendixBEnvironmentalProtec-tionPlanwascompletedwithsubmissionofthe1986nestingsurveydata(ABI,1987).Thenestingsurveywascontinuedvoluntarilythrough1991withagreementfromfederalandstateagencies.Resultsarepresentedinthisreportanddiscussedinrelationtopreviousfindings.Inadditiontomonitoringseaturtlenestingactivitiesandrelocatingnestsawayfromplantconstructionareas,removalofturtlesfromtheintakecanalhasbeenanin-tegralpartoftheSt.LuciePlantenvironmentalmonitoringprogram.Turtlesenteringtheoceanintakestructuresareentrainedwithcoolingwaterandrapidlytransportedthroughtheintakepipesintoanenclosedcanalsystemwheretheymustbemanuallycapturedandreturnedtotheocean.Sincetheplantbecameoperationalin1976,turtlesentrappedintheintakecanalhavebeensystematicallycaptured,measured,weighed,taggedandreleased.Previouspublicationsandtechnicalreportshavepresentedfindingsofthenest-ingsurveys,nestrelocationactivitiesandcanalcaptureprogram(Gallagheretal.,1972; IIIILIOtt WorthandSmith,1976;ABI,1978,1980a,1981a,1982,1983,1984b,1985b,1986,1987,1988,1989,1990,1991;Williams-Wallsetal.,1983;Proffittetal.,1986;Ernestetal.,1988,1989;Martinetal.,1989a,1989b).Resultsofstudiestoassesstheeffectsofthermaldischargesonhatchlingswimmingspeedhavealsobeenreported(ABI,1978;O'ara,1980).Thepurposeofthisreportisto1)present1991seaturtlenestingsur-veydataandsummarizeobservedspatialandtemporalnestingpatternssince1971,2)documentandsummarizepredationonturtlenestssince1971,and3)present1991canalcapturedataandsummarizecomparabledatacollectedsince1976.MATERIALSANDMETHODSNestinSurveMethodologiesusedduringpreviousturtlenestingsurveysonHutchinsonIslandweredescribedbyGallagheretal.(1972),WorthandSmith(1976)andABI(1978,1981a,1982,1987,1988,1989).Methodsusedduringthe1991surveyweredesignedtoallowcomparisonswiththesepreviousstudies.On10and12April1991,preliminarynestsurveyswereconductedalongHutchin-sonIslandfromtheFt.PierceInletsouthtotheSt.LucieInlet.From15Aprilthrough6September,nestsurveyswereconductedonadailybasis.Toconfirmthatnestinghadceased,afinalsurveywasconductedon9September.Biologistsusedsmalloff-roadmotorcyclestosurveytheislandeachmorning.Newnests,non-nestingemer-gences(falsecrawls),andnestsdestroyedbypredatorswererecordedforeachofthe361-km-longsurveyareascomprisingtheentireisland(Figure3).Thenine1.25-km-10 IIIII longsurveyareasestablishedbyGallagheretal.(1972)alsoweremonitoredsocom-parisonscouldbemadewithpreviousstudies.Duringthedailynestmonitoring,anymajorchangesintopographythatmayhaveaffectedthebeach'ssuitabilityfornestingwererecorded.In,addition,eachofthe361-km-longsurveyareashasbeensystematicallyanalyzedandcategorizedbasedonbeachslope(steep,moderate,etc.),widthfromhightidelinetothedune,presenceofbenches(areasofabruptverticalrelief)andmiscellaneouscharacteristics(packedsand,scatteredrock,vegetationonthebeach,exposedrootsontheprimarydune,etc.).Inacooperativeeffort,datafromstrandedturtlesfoundduringbeachsurveyswereroutinelyprovidedtotheNationalMarineFisheriesService(NMFS)throughtheSeaTurtleStrandingandSalvageNetwork.IntakeCanalMonitorinMostturtlesentrappedintheSt.LuciePlantintakecanalwereremovedbymeansoflarge-meshtanglenetsfishedbetweentheintakeheadwallsandabarriernetlocatedattheHighwayA1Abridge(Figure2).Netsusedduring1991werefrom30to40minlength,3to4mdeepandcomposedof40cmstretchmeshnylontwine.Largefloatswereattachedtothesurface,andunweightedlinesusedalongthebottom.Turtlesen-tangledinthenetsgenerallyremainedatthewater'ssurfaceuntilremoved.Sinceitsinceptionin1976,ABI'scanalcaptureprogramhasbeenundercontinualreviewandrefinementinanattempttominimizebothentrapmenttimesandin-11
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juries/mortalitiestoentrappedseaturtles.PriortoApril1990,turtlenetswereusuallydeployedonMondaymorningsandretrievedonFridayafternoons.Duringperiodsofdeployment,thenetswereinspectedforcapturesbyABIpersonnelatleasttwiceeachday(morningsandafternoons).Additionally,St.LuciePlantpersonnelcheckedthenetsperiodically,andABIwasnotifiedimmediatelyifacapturewasobserved.ABI'sseaturtlespecialistswereoncall24hoursadaytoretrievecapturedturtlesfromtheplant.BeginningApril1990,afterconsultationwithNMFS,netdeploymentwasscaledbacktodaylighthoursonly.Concurrently,surveillanceoftheintakecanalwasin-creasedandABIpersonnelremainedonsiteforthedurationofeachday'snettingac-tivities.Thismeasuredecreasedresponsetimeforremovalofentangledturtlesfromnetsandprovidedanopportunitytoimprovedailyassessmentsofturtlelevelswithinthecanal.Recordsofdailycanalobservationswerecomparedwithcapturedatatoas-sesscaptureefficiencies.TheA1Abarriernetisusedtoconfineturtlestotheeasternmostsectionofthein-takecanal,wherecapturetechniqueshavebeenmosteffective.Thisnetisconstructedoflargediameterpolypropyleneropeandhasameshsizeof30.5cmx30.5cm.Acableandseriesoflargefloatsareusedtokeepthetopofthenetabovethewater'surface,andthebottomisanchoredbyaseriesofheavyblocks.Thenetisinclinedataslopeof3:1,withthebottompositionedupstreamofthesurfacecable.Thisreducesbowinginthecenterandminimizestheriskofaweakorinjuredturtlebeingpinnedun-derwaterbystrongcurrents.12 IIIIIII Inthepast,theintegrityofthebarriernetwasoccasionallycompromised,andturtleswereabletomovewestofA1A.Theseturtleswerefurtherconstraineddownstreambyanunderwaterintrusiondetectionsystem(UIDS)consisting,inpart,ofalargebarrierpositionedperpendiculartothenorth-southarmofthecanal(Figure2).TheUIDSsecuritybarrieralsoconsistsof30.5cmx30.5cmmesh.PriortocompletionoftheUIDSinDecember1986,turtlesuncontainedbytheA1AbarriernetwereusuallyremovedfromthecanalattheintakewellsofUnits1and2(Figure2)~Theretheywereretrievedbymeansoflargemechanicalrakesorspeciallydesignednets.FollowingconstructionoftheUIDSbarrier,individualswithcarapacewidthslargerthan30.5cmwereunabletoreachtheintakewells.Thus,asrequired,tanglenetswerealsodeployedwestofA1A.ImprovementsmadetotheA1Abarriernetduring1990haveeffectivelyconfinedallturtleslargerthan30.5cmtotheeasternendofthecanal.Formaldailyinspectionsoftheintakecanalweremadetodeterminethenumbers,locationsandspeciesofturtlespresent.SurfaceobservationswereaugmentedwithperiodicunderwaterinspectionsusingSCUBA,particularlyinandaroundtheA1Abar-riernet.BecauseofthereductionintotalnettinghourssinceApril1990,increasedef-forthasbeendirectedtowardhandcaptureofturtles.Thiseffort,accomplishedbydivinganduseofdipnets,hasprovedveryeffectiveduringperiodsofgoodwaterclarity.Regardlessofcapturemethod,allturtlesremovedfromthecanalwereidentifiedtospecies,measured,weighed,tagged,andexaminedforoverallcondition(wounds,13 IIII abnormalities,parasites,etc.).Healthyturtleswerereleasedintotheoceanthesamedayofcapture.Sickorinjuredturtlesweretreatedandoccasionallyheldforobserva-tionpriortorelease.Whentreatmentwaswarranted,injectionsofantibioticsandvitaminswereadministeredbypermittedveterinarians.Resuscitationtechniqueswereusedifaturtlewasfoundthatappearedtohavediedrecently.Beginningin1982,necropsieswereconductedondeadturtlesfoundinfreshcondition;nonecropsieswereperformedduring1991.Since1982,bloodsampleshavebeencollectedandanalyzedtodeterminethesexofimmatureturtles.BloodwasremovedfromthepaireddorsalcervicalsinusesofsubjectturtlesusingthetechniquedescribedbyOwensandRuiz(1980).Thesamplesweremaintainedoniceandlatercentrifugedfor15minutestoseparatecellsandserum.SexdeterminationsweresubsequentlymadebyresearchersatTexasA8MUniver-sityusingradioimmunoassayforserumtestosterone(Owensetal.,1978).FloridaPower8LightCompanyandAppliedBiology,Inc.continuedtoassistotherseaturtleresearchersin1991.Sincetheprogrambegan,data,specimensand/orassistancehavebeengiventotheFloridaDepartmentofNaturalResources,NationalMarineFisheriesService,USFishandWildlifeService,USArmyCorpsofEngineers,SmithsonianInstitution,SouthCarolinaWildlifeandMarineResourcesDivision,CenterforSeaTurtleResearch(UniversityofFlorida),FloridaAtlanticUniversity,UniversityofCentralFlorida,TexasA8MUniversity,UniversityofRhodeIsland,UniversityofSouthCarolina,UniversityofIllinois,UniversityofGeorgia,VirginiaInstituteofMarineScienceandtheWesternAtlanticTurtleSymposium.14 IIIIIII StudiestoEvaluateandorMitiateIntakeEntramentAprogramthatasses'sedthefeasibilityofusinglightand/orsoundtodeterturtlesfromenteringtheSt.LuciePlantintakestructureswasconductedin1982and1983andcompletedinJanuary1984.Asrequired,testresultsandevaluationswerewrittenupandapresentationwasmadetotheNRC,NationalMarineFisheriesServiceandtheFloridaDepartmentofNaturalResourceson11April1984.Requirement4.2.2oftheNRC'sSt.LucieUnit2AppendixBEnvironmentalProtectionPlanisconsideredcompletedwithsubmissionofdeterrentstudyfindings.RESULTSANDDISCUSSIONNestinSurveDistributionofLoerheadNestsAlonHutchinsonIslandWhenseaturtlenestingsurveysbeganonHutchinsonIsland,nine1.25-km-longsurveyareaswereusedtoestimateloggerheadnestingactivityfortheentireisland.From1971through1988,thedistributionofnestsamongthesenineareasindicatedagradientofincreasednestingfromnorthtosouth(ABI,1989).Thegradienthasbe-comelesspronouncedduringthelastthreeyearsandduring1991nogradientwasapparent(Figure4).Thischangeinthespatialdistributionofnestswasapparentlyduetoadisproportionateincreaseinnestinginnorthernversussouthernsurveyareas.Since1981,all361-km-longsegmentscomprisingtheisland'scoastlinehavebeensurveyed.Thedistributionofnestsamongthese36surveyareashasshownanincreaseinnestingfromnorthtosouthonlyalongthenorthernhalfoftheisland(Figure15 Ii~i) 5).Alongthesouthernhalfoftheislandtherehasbeenagradientofdecreasingnest-ingfromnorthtosouth.Aswiththenineareas,therehasbeenadisproportionatein-creaseinnestinginnorthernversussouthernsurveyareasduringthelastthreeyears.Inthepast,thepronouncedgradientobservedonthenorthernendoftheislandwasoccasionallyinfluencedbyphysicalprocessesoccurringthere;periodsofheavyaccretionreducedthegradient,whileperiodsoferosionaccentuatedit(WorthandSmith,1976;Williams-Wallsetal.,1983).However,duringrecentyearsnoconsistentrelationshipwasapparentwhenfieldobservationsofbeachwidthswerecomparedtothespatialdistributionofnestsalongtheisland(ABI,1987).Thus,eventhoughbeachdynamicsmaysometimesaffecttheselectionofnestingsitesbyloggerheadturtles,otherfactorsmustalsocontributetotheselectionprocess.Offshorebottomcontours,spatialdistributionofnearshorereefs,typeandextentofdunevegetation,anddegreeofhumanactivityonthebeachatnighthavebeenidentifiedassomeofthefactorsaf-fectingnesting(Caldwell,1962;HendricksonandBalasingam,1966;Bustard,1968;BustardandGreenham,1968;Hughes,1974;DavisandWhiting,1977;Mortimer,1982).Relationshipsbetweenspatialnestingpatternsandspecificenvironmentalcon-ditionsareoftendifficulttoestablishbecauseoftheinterrelationshipofthefactorsin-volved.Notallventuresontothebeachbyafemaleturtleculminateinsuccessfulnests.These"falsecrawls"(non-nestingemergences)mayoccurformanyreasonsandarecommonlyencounteredatotherrookeries(BaldwinandLofton,1959;Schulz,1975;DavisandWhiting,1977;Talbertetal.,1980;Raymond,1984).DavisandWhiting(1977)suggestedthatrelativelyhighpercentagesoffalsecrawlsmayreflectdisturban-16 IIIII cesorunsatisfactorynestingbeachcharacteristics.Therefore,certainfactorsmayaf-fectaturtle'spreferencetoemergeonabeach,whileotherfactorsmayaffectaturtle'tendencytonestafterithasemerged.Anindexwhichrelatesthenumberofneststothenumberoffalsecrawlsinanareaisusefulinestimatingthepost-emergencesuitabilityofabeachfornesting.Inthepresentstudythisindexistermed"nestingsuc-cess"andisdefinedasthepercentageoftotalemergencesthatresultinnests.Historically,thepatternofloggerheademergencesontheislandhasgenerallyparalleledthedistributionofnests(ABI,1987,1988),andthissametrendwasapparentin1991(Figure6).Incontrast,nestingsuccessbyloggerheadsalongtheislandhastypicallylackedgradients(Figure7).Thus,therelativelyhighnumbersofloggerheadnestsobservedincertainareasareusuallyaresultofmoreturtlescomingashoreinthoseareasratherthanofmorepreferablenestingconditionsbeingencounteredbytheturtlesaftertheyemerged.Loggerheadnestingdensitiesduring1991weregenerallyhighwhencomparedwithpreviouslyrecordedvalues(Figures4and5).Recordhighnestingwasrecordedin12ofthe36one-kilometer-longsurveyareasandwasmostnotableonthenorthernhalfoftheisland.Therewerenoapparentchangesinthephysicalcharacteristicsofthebeachthatwouldaccountforthisincreaseinnesting.Ingeneral,recordhighnest-ingwasduetorecordhighemergencerates,andthismayreflectanincreaseinthenumberofnestingfemalesintheHutchinsonIslandarea'.NestingsurveysonHutchinsonIslandwereinitiatedinresponsetoconcernsthattheoperationoftheSt.LuciePlantmightnegativelyimpactthelocalseaturtlerookery.17 IIIIIIIIItI)i Previousanalysis,usinglog-likelihoodtestsofindependence(G-test;SokalandRohlf,1981)demonstratedthattheconstructionoftheplant'soffshoreintakeanddischargestructuressignificantlyreducednestingattheplantsiteduringconstructionyears-1975,1981,1982and1983(Proffittetal.,1986;ABI,1987).However,nestingattheplantconsistentlyreturnedtolevelssimilartoorgreaterthanthoseatacontrolsiteinyearsfollowingconstruction(Figure8).Powerplantoperationexclusiveofintake/dis-chargeconstructionhashadnoapparenteffectonnesting.During1991,nestingatthepowerplantsiteremainedhigherthanatthecontrolsitedespiteconstructionactivities(velocitycaprepairs)ontheintakestructures.Thoughtheseconstructionactivitiesproceededthroughoutthesummer,includedtheconstructionofalargeoffshoreplatform,andinvolvedtheuseofheavyequipment,therewasnoapparenteffectonseaturtlenestinginthevicinityoftheconstruction.Severalaspectsoftheconstructionprojectminimizedpotentialeffectsonnestingseaturtles.Constructionactivitiestookplacealmostexclusivelyduringtheday,thusmini-mizinginterferencewiththenocturnalnestingbehaviorofturtles.Also,safetyandnavigationallightingontheplatformandsupportvesselswasdesignedtominimizeef-fectstoseaturtles.Furthermore,nostructuresormaterialswereplacedonthebeach,therebyavoidinginterferencewiththenestingbehaviorofemergentturtles.Datacollectedthrough1991haveshownnolong-termreductioninloggerheadnestdensities,totalemergencesornestingsuccessineitherthenine1.25-km-longsurveyareasorthe361-km-longsurveyareas(Table1;Figure9).Tothecontrary,datacollectedfrombothsetsofsurveyareasindicatealong-termincreaseinlogger-18 1IIIII EstimatsofTotalLrheNestinnHuthinsonIslandVariousmethodsw'ereusedduringsurveyspriorto1981toestimatethetotalnumberofloggerheadnestsonHutchinsonIslandbasedonthenumberofnestsfoundinthenine1.25-km-longsurveyareas(Gallagheretal.,1972;WorthandSmith,1976;ABI,1980a).Eachofthesemethodsweresubsequentlyfoundtoconsistentlyoveres-Itimateislandtotals(ABI,1987).Sincewhole-islandsurveysbeganin1981,ithasbeenpossibletodeterminetheactualproportionoftotalnestsdepositedinthenineareas.Thishasthenallowedextrapolationfromtheninesurveyareastotheentireislandforyearspriorto1981.From1981through1991thetotalnumberofnestsinthenineareasvariedfrom32.5to35.6percentofthetotalnumberofnestsontheisland(Table1).Thisisslight-lyhigherthanthe31.3percentwhichwouldbeexpectedbasedstrictlyonthepropor-tionoflinearcoastlinecomprisedbythenineareas.Usingtheeleven-yearmeanof33.97percent,estimatesofthetotalnumberofnestsonHutchinsonIslandcanbecal-culatedbymultiplyingthenumberofnestsinthenineareasby2.944.Thistechnique,whenappliedtotheninesurveyareasduringtheelevenyearsinwhichtheentireis-landwassurveyed,producedwhole-islandestimateswithin5.0percentoftheactualnumberofnestscounted.Becausetheproportionofnestsrecordedintheninesur-veyareasremainedrelativelyconstantoverthelastelevenyears,thisextrapolationprocedureshouldprovideafairlyaccurateestimateoftotalloggerheadnestingforyearspriorto1981~19 IIII ItisclearthatloggerheadnestingactivityonHutchinsonIslandfluctuatescon-siderablyfromyeartoyear(Table1).Annualvariationsinnestdensitiesalsoarecom-monatotherrookeries(Hughes,1976;DavisandWhiting,1977;Ehrhart,1980)andmayresultfromnon-annualreproductivebehavior(Frazer,1989).Nonetheless,datacollectedthrough1991suggestanoverallincreaseinnestingonHutchinsonIslandsincesurveysbeganin1971.Totalnestingactivitywasgreatestduring1991when6,812loggerheadnestswererecorded.Norelationshipsbetweentotalnestingactivityandpowerplantoperationorintake/dischargeconstructionwereindicatedbyyear-to-yearvariationsintotalnestingonHutchinsonIsland.TemoralLoerheadNestinPatternsTheloggerheadturtlenestingseasonusuallybeginsbetweenmid-AprilandearlyMay,attainsamaximumduringJuneorJuly,andendsbylateAugustorearlySep-tember(ABI,1987).Nestingactivityduring1991followedthissamepattern(Figure10).CoolwaterintrusionsfrequentlyoccuroverthecontinentalshelfofsoutheastFloridaduringthesummer(TaylorandStewart,1958;Smith,1982).WorthandSmith(1976),Williams-Wallsetal.(1983)andABI(1982,1983,1984b,1985b,1986,1987,1988,1989,1990,1991)suggestedthattheseintrusionsmayhavebeenresponsibleforthetemporarydeclinesinloggerheadturtlenestingactivitypreviouslyobservedonHutchinsonIsland.Similarly,anintrusionofcoolwaterduringlateJuly1991mayhavecontributedtothesubstantialdecreaseinnestingbetweenlateJulyandearlyAugust(Figure10).20 IIiIII ThoughnaturalfluctuationsintemperaturehavebeenshowntoaffecttemporalnestingpatternsonHutchinsonIsland,therehasbeennoindicationthatpowerplantoperationhasaffectedthesetemporalpatterns(ABI,1988).PredationnLoerheadTurtleNestsSincenestsurveysbeganin1971,raccoonpredationhasbeenamajorcauseofturtlenestdestructiononHutchinsonIsland.Researchersatotherlocationshavereportedraccoonpredationlevelsashighas70tonearly100percent(DavisandWhit-ing,1977;Ehrhart,1979;Hopkinsetal.,1979;Talbertetal.,1980).RaccoonpredationofloggerheadturtlenestsonHutchinsonIslandhasnotapproachedthislevelduringanystudyyear,thoughlevelsforindividual1.25-km-longareashavebeenashighas80percent.Overallpredationratesforsurveyyears1971through1977werebetween21and44percent,withahighof44percentrecordedin1973.Apronounceddecreaseinraccoonpredationoccurredafter1977,andoverallpredationratesforthenineareashavenotexceeded10percentsince1979.AdeclineinpredationratesonHutchinsonIslandhasbeenvariouslyattributedtotrappingprograms,constructionactivities,habitatlossanddisease(Williams-Wallsetal.,1983;ABI,1987)~During1991,fourpercent(301)oftheloggerheadnests(n=6,812)ontheislandweredepredatedbyraccoons.Asinpreviousyears(ABI,1991),predationofturtlenestswasprimarilyrestrictedtothemostundevelopedportionoftheisland(i.e.,AreasEthroughS;Figure11).However,predationratesinAreas0andPduring1991wereconsiderablylowerthanduringpreviousyears.Thisreductionisattributedtothefactthatmostofthenestsinthesetwoareaswerecoveredwithwirecages.Thesecages,21 IIIII originallyinstalledtoretainhatchlingsduringvelocitycaprepairs,werealsoeffectiveinexcludingraccoons.Ghostcrabshavebeenreportedbynumerousresearchersasimportantpredatorsofseaturtlenests(BaldwinandLofton,1959;Schulz,1975;Diamond,1976;Fowler,1979;Hopkinsetal.,1979;Stancyk,1982).ThoughturtlenestsonHutchinsonIslandprobablyhavebeendepredatedbyghostcrabssincenestingsurveysbeganin1971,thissourceofnestdestructiondidnotbecomeapparentuntil1983.Quantificationofghostcrabpredationwasinitiatedthesameyear.Overallpredationratesbyghostcrabshavevariedfrom0.1to2.1percentfrom1983-1990(ABI,1991).During1991,0.5percent(31)oftheloggerheadnests(n=6,812)ontheislandweredepredatedbyghostcrabs(Figure11).Nestsdestroyedbyacombinationofraccoonandghostcrabpredationhavebeenincludedasraccoonpredationsinpreviousdiscussions.Whenthesecombinationpredationsareincludedascrabpredations,theoverallpredationratesbyghostcrabsrangefromOAto3.2percent.During1991,1.3percent(90nests)weredestroyedbyeitherghostcrabsoracombinationofghostcrabsandraccoons.GreenandLeatherbackTurtleNestinGreenandleatherbackturtlesalsonestonHutchinsonIsland,butinfewernum-bersthanloggerheadturtles.Priorto1981,bothsurvey(nine1.25-km-longsections)andinter-surveyareasweremonitoredforthepresenceofgreenandleatherbacknests.Thirty-onekilometersofbeachfromArea1southtotheSt.LucieInletwerein-cludedinthateffort.Duringwhole-islandsurveysfrom1981through1991,onlysixof22 IIII 226leatherbacknestsandonlyeightof648greennestswererecordedonthefivekilometersofbeachnorthofArea1.Therefore,previouscountsofgreenandleather-backnestswithinthe31kilometerssurveyedwereprobablynotappreciablydifferentfromtotaldensitiesfortheentireisland.Basedonthisassumption,greenandleather-backnestdensitiesmaybecomparedamongallsurveyyears,except1980,whenlessthan15kilometersofbeachweresurveyed.Priorto1991,thenumberofnestsobservedontheislandrangedfrom5to132forgreenturtlesandfrom1to36forleatherbacks(Figure12).Duringthe1991survey,47greenturtleand44leatherbackturtlenestswererecordedonHutchinsonIsland.Temporalnestingpatternsforthesespeciesdifferfromthepatternforloggerheadturtles.GreenturtlestypicallynestonHutchinsonIslandfrommid-JunethroughthefirstorsecondweekofSeptember.During1991,greenturtlesnestedfrom2Junethrough1September.Leatherbackturtlesusuallynestontheislandfrommid-Aprilthroughearlytomid-July.During1991thisspeciesnestedfrom5Aprilthrough18July.Considerablefluctuationsingreenturtlenestingontheislandhaveoccurredamongsurveyyears(Figure12).Thisisnotunusualsincetherearedrasticyear-to-yearfluctuationsinthenumbersofgreenturtlesnestingatotherbreedinggrounds(Carretal.,1982).Despitethesefluctuations,datacollectedthrough1991suggestanoverallincreaseinnestingsince1971andmayreflectanincreaseinthenumberofnestingfemalesintheHutchinsonIslandarea.During1991,greenturtlesnestedmostfrequentlyalongthesouthernhalfoftheisland.Thisisconsistentwithresultsofpre-vioussurveys.23 IIIII~II LeatherbackturtlenestdensitieshaveremainedlowonHutchinsonIsland;however,increasednestingduringrecentyears(Figure12)mayreflectanoverallin-creaseinthenumberofnestingfemalesintheHutchinsonIslandarea.During1991,leatherbackturtlesprimarilynestedonthesouthernhalfoftheisland.IntakeCanalMonitorinEntrainmentofseaturtlesattheSt.LuciePlanthasbeenattributedtothepresumedphysicalattractivenessoftheoffshorestructureshousingtheintakepipesratherthantoplantoperatingcharacteristics(ABI,1980band1986).Thevelocitycapssupportedabovetheopeningstoeachintakepipeeliminateverticalwaterentrainmentandsubstantiallyreducecurrentvelocitiesnearthestructuresbyspreadinghorizontaldrawoveranarcof360.Thus,evenwhenbothunitsareoperatingatfullcapacity,turtlesmustactivelyswimintothemouthofoneoftheintakepipesbeforetheyen-countercurrentvelocitiessufficientlystrongtoeffectentrainment.Consequently,aturtle'sentrapmentrelatesprimarilytotheprobabilitythatitwilldetectandsubsequentlyenteroneoftheintakestructures.Assumingthatdetectiondistancesdonotvaryap-preciablyovertimeandthatallturtles(oraconstantproportion)areequallyattractedtothestructures,capturerateswillvaryproportionallytothenumberofturtlesoccur-ringinthevicinityofthestructures.RelativeAbundanceandTemoralDistributionDuring1991,121seaturtlecapturestookplaceintheintakecanaloftheSt.LuciePlant:107loggerheads,12greenturtles,1hawksbilland1Kemp'sridley(Table2).Allbutoneofthefivespeciesofseaturtlesinhabitingcoastalwatersofthesoutheastern24
~3'll1'II~III UnitedStateswerepresent.SinceintakecanalmonitoringbeganinMay1976,1,960loggerhead(including107recaptures),318green(including1recapture),9leather-back,9hawksbilland18Kemp'sridleycaptureshavetakenplaceattheSt.LuciePlant.Annualcatchesofloggerheadsincreasedsteadilyfromalowof33in1976(par-tialyearofplantoperationandmonitoring)to172in1979(Figure13).Afterdecliningbetween1979and1981,yearlycatchesofloggerheadsagainrosesteadily,reachingahighof195during1986.Captureshavebeenindeclinesince1986,decreasingabout45percentoverthelastfiveyears.TwooffshoreintakestructureswereinplacepriortoUnit1start-upin1976;thethirdandlargeststructurewasinstalledduring1982-1983.Eventhoughallthreestruc-turesareinrelativelycloseproximity,theadditionofanotherpipemayhaveincreasedtheprobabilityofaturtlebeingentrained.Becausethischangecannotbequantified,datacollectedpriorto1982maynotbecomparablewiththatcollectedafter1983.Ad-ditionally,theinfluenceoftheconstructionitselfonseaturtleentrainmentduring1982and1983isunknown.Similarly,damagetothecenterportionsoftwoofthethreevelocitycapswasobservedin1989.Thisdamageaddedastrongverticalcomponenttowaterentrainment.Followingathoroughevaluationoftheextentandcause(s)ofthedamage,amajorrepairoperationwasundertakenduring1991.Thedegreetowhichashiftinentrainmentcharacteristicsandsubsequentrepairoperationsaffectedseaturtleentrapmentisalsounknown.Withtheseconsiderationsinmind,neitheralong-termincreasenordecreaseinthenumberofloggerheadscapturedattheSt.LuciePlantcanbeinferredfromthedata.25 IIIrig During1991,themonthlycatchofloggerheadsrangedfrom1(NovemberandDecember)to20(March),withamonthlymeanof8.9(+7.0;Table3).ThenumberofcapturesduringMarch,AprilandMaywereconsiderablyaboveaverage,whilecap-turesthroughouttheremainderoftheyearwereslightlytoconsiderablylowerthanaverage(Figure14).Overtheentiremonitoringperiod,monthlycatcheshaverangedfrom0to39;thegreatestnumberofcapturesoccurredduringJanuary1983.Whendatafromallfullyearsofmonitoring(1977-1991)werecombined,thehighestnumberofloggerheadcapturesoccurredinJanuary;fewestcaptureswererecordedinNovemberandDecember(Table3).However,monthlycatcheshaveshownconsiderableannualvariability.Monthshavingrelativelylowcatchesoneyearoftenhavehadrelativelyhighcatchesinanother.Catchesofgreenturtlesalsohavevariedwidelyamongyears,rangingfrom0in1976(partialyearofsampling)to69in1984(Figure13;Table4).During1991,12in-dividualswerecaptured.Theaverageannualcatchofgreenturtles,excluding1976,was21.2(+17.5).Asforloggerheads,nolong-termtrendscanbeinferredfromthedata.Greenturtleshavebeencaughtduringeverymonthoftheyear,withaveragemonthlycatchesforallyearscombinedrangingfrom0.4inSeptemberto6.7inJanuary(Table4).Seasonalabundancepatternsofgreenturtlesweremuchmorepronouncedthanforloggerheads,nearly60percentofallcapturesoccurringduringthethreemonthperiodbetweenJanuaryandMarch.During1991,thelargestnumberofgreenturtles26 lIIlII (4)werecapturedinFebruary.Themostevercaughtinonemonthwas37inJanuary1984.Catchesofleatherbacks,hawksbillsandKemp'sridleyshavebeeninfrequentandscatteredthroughoutthe16yearstudyperiod(Table2).Eachspecieshasshownratherpronouncedseasonaloccurrences;allbuttwoofthenineleatherbackswerecollectedbetweenFebruaryandMay,sevenoftheninehawksbillswerecollectedbe-tweenJuneandSeptember,andallbuttwoofthe18Kemp'sridleyswerecaughtbe-tweenNovemberandApril.Size-ClassDistributionsAlthoughseveralstraight-lineandcurvedmeasurementswererecordedforturtlesremovedfromtheintakecanal,onlyonestraight-linemeasurementhasbeenusedinanalysespresentedhere.Straight-linecarapacelength(SLCL)wasmeasuredfromtheprecentralscutetothenotchbetweenthepostcentralscutes(minimumcarapacelengthofPritchardetal.,1983).Todate,loggerheadsremovedfromtheintakecanalhaverangedinlength(SLCL)from40.2to112.0cm(x=66.8+13.7cm)andinweightfrom10.7kgto169.6kg(x=49.3+31.1kg;Figures15and16).Acarapacelengthof70cmapproximatesthesmallestsizeofnestingloggerheadfemalesobservedalongtheAtlanticeastcoast(Hirth,1980).However,adultscanonlybereliablysexedonexternalmorphologicalcharacteristics(i.e.,relativetaillength)afterattainingasomewhatlargersize.Inearlierannualreports,80.0cmwasusedasthelowerlimitforadultturtles.However,recentdatasuggestthatsomemalesmaynotmature,andthusmightnot-bedistinguishablefromfemales,untiltheyareabout85.027 cmlong.Basedonthesedivisions,dataweresegregatedintothreegroups:Juveniles((70cm),adults()85cm)andtransitional(71-85cm)~Thelattergroupprobablyin-cludesbothmatureandimmatureindividuals.Ofthe1,848loggerheadcapturesbetween1977and1991forwhichlengthdatawererecorded,69.3percentwerejuveniles,themajorityofthesemeasuringbetween50and70cmSLCL(Table5).Theremainingindividualswerenearlyequallydividedbetweenadultsandanimalsinthetransitionalsizeclass.Similarsize-frequencydis-tributions,indicatingapreponderanceofjuveniles,havebeenreportedforloggerheadsinhabitingtheMosquito/IndianRiverLagoon(MendoncaandEhrhart,1982),theCanaveralshipchannel(Henwood,1987),andGeorgiaandSouthCarolina(Hillestadetal.,1982).ThesedatasuggestthatcoastalwatersofthesoutheasternUnitedStatesconstituteanimportantdevelopmentalhabitatforloggerheadseaturtles.Seasonalpatternsofabundanceforvarioussizeclassesindicatedthatjuvenileloggerheadswereslightlymoreabundantduringthewinterthanatothertimesoftheyear(Table5).About47percentofthejuvenileswer'ecapturedbetweenJanuaryandApril.AbundancesdecreasedinspringandremainedrelativelyconstantduringthesummerandearlyfallbeforedecreasingagaintolowestlevelsinNovemberandDecember.Theseasonaldistributionofadultloggerheadswasmuchmorepronounced,76percentofallcapturesoccurringbetweenMayandAugust.Thisrep-resentsthemajorportionofthenestingseasononHutchinsonIsland.Greenturtlesremovedfromtheintakecanalovertheentirestudyperiodrangedinsizefrom20.0to108.0cmSLCL(x=35.8+14.0cm)and0.9kgto177.8kg(x=28 lIttg 9.3+19.9kg;Figures17and18).Nearlyall(98percent)werejuveniles.About80per-centwere40cmorlessinlength,and65percentweighed5kilogramsorless.Al-thoughtheseimmatureturtlesexhibiteddistinctwinterpulses,somesmallindividualswerecapturedthroughouttheyear(Table4).Todate,onlyeightadultgreenturtles(SLCL)83cm;WitheringtonandEhrhart,1989)havebeenremovedfromthecanal;allwerecapturedduringorshortlyafterthenestingseason.Theninehawksbillsremovedfromthecanalrangedinsizefrom34.0to83.4cmSLCL(x=50.3+17.3cm)andinweightfrom6.4to86.6kg(x=25.0+27.8kg).Allbuttwowerejuveniles(SLCL<63cm;Witzell,1983).Similarly,allbutoneofthe18Kemp'sridleyscapturedattheSt.LuciePlantwerejuveniles(SLCL<60.0cm;Hirth,1980).Carapacelengthsfortheridleysrangedfrom27.0to62.0cmSLCL(x=37.0+10.1cm)andweightsfrom3.1to31.8kg(x=8.6+8.2kg).Thenineleather-backsremovedfromthecanalrangedinlengthfrom112.5to150.0cm,andatleastsevenwereadults(SLCL)121cm;Hirth,1980).Thelargestleatherbackforwhichanaccurateweightwasobtained,afemalewithacurvedcarapacelengthof158.5cm,'eighed334.8kg.SexRatiosSinceintakecanalmonitoringbeganin1976,282adultloggerheads(SLCL>85.0cm)havebeensexed.Femalespredominatedmalesbyaratioof5.3:1.0,whichsig-nificantlydepartsfroma1:1ratio(X,P<0.05).Consequently,temporalpatternsinthenumberofadultloggerheadcaptureswereheavilyinfluencedbythenumbersoffemalespresent.Whensexeswereseparated,itwasevidentthatmaleswererelative-29 lyevenlydistributedamongmonths,whereasalmost90percentofthefemalesweretakenduringthenestingseason(MaythroughSeptember;Figure19).ThenumberofadultfemaleloggerheadscapturedattheSt.LuciePlanthasin-creasednoticeablysince1983.From1977(firstfullyearofplantoperation)through1983,anaverageof4.4adultfemales(+3.2;range=1-10)wereentrappedeachyear,whereassincethen,anaverageof25.3femalesperyearwerecaptured(+6.9;range=16-35).Thisincreasecorrespondstoageneralriseinloggerheadnestingac-tivityneartheplant(Figure20).Increasednearshoremovementassociatedwithnest-ingincreasestheprobabilityofaturtledetectingoneoftheintakestructuresandhencetheprobabilityofentrainment.Thesharpdeclineincapturesduring1991isprobablyrelatedtothevelocitycaprepairproject.Constructionoftheoffshoreplatformandsub-sequentdaytimerepairactivitiesmayhavereducedtheattractivenessoftheintakestructuresasarestingorstagingareaforadultfemalesbetweensuccessivenestingforays.Reducedassociationwiththestructureswoulddecreasethelikelihoodofentrainment.Despitetherecentdeclineincaptures,theoveralltrendsince1983sug-gestsagenuineincreaseinthenumberoffemaleloggerheadsoccurringinthevicinityoftheplant.BetweenSeptember1982andDecember1986,267individualjuvenileandsub-adultloggerheadturtlescapturedinthecanalweresexedbyTexasA8MUniversityresearchersusingabioimmunoassaytechniqueforbloodserumtestosterone.Aspre-viouslyreported,femalesoutnumberedmalesbyaratioof2.3:1.0(ABI,1989).ThesefindingsareconsistentwiththosereportedforsamplestakenfromtheCapeCanaveralshipchannel(1.7:1.0)andtheIndianRiverLagoon(1.4:1.0),wheresexratiosarealso30 I1III significantlyskewedinfavoroffemales(WibbeIsetal.,1984).Bloodsamplescollectedsince1986arecurrentlybeinganalyzedandtheseresultswillprovideavaluabletoolforassessingtemporalvariabilityinthesexratiosofthelocalloggerheadpopulation.Oftheeightadultgreenturtlescapturedsincemonitoringbegan,sixweremalesandtwowerefemales.Siximmaturegreenturtleshavebeensexedthroughbloodwork;allhavebeenfemales.Ofthesixadultleatherbackturtlesforwhichsexwasrecorded,threewerefemalesandthreeweremales.ThetwoadulthawksbillsandoneKemp'sridleywereallfemales.Nosexinformationexistsforjuvenilesofanyofthesespecies.CatureEfficienciesCapturemethodologieshavebeenundercontinualreviewandrefinementasnetmaterials,configurationsandplacementwerevariedinanefforttominimizeseaturtleentrapmenttimes.Concurrently,alternativecapturetechniqueswereevaluatedandpotentialdeterrentsystemstestedinthelaboratory.Duringthisperiod,captureefficien-ciesvariedinrelationtonettingeffortandtheeffectivenessofthesystemsdeployed:Acapture/recapturestudyconductedintheintakecanalbetweenOctober1980andJanuary1981indicatedthatmostturtlesconfinedbetweentheA1Abridgeandtheintakeheadwallswerecapturedwithintwoweeksoftheirentrainment(ABI,1983).Basedonmorerecentformaldailyinspections,itappearsthatcaptureefficiencieshavefurtherimproved.Nearly50percentoftheturtlesenteringthecanalarenowcaughtwithin24hoursoffirstsighting,and90percentarecapturedduringtheirfirstweekofentrapment(Figure21).Averagecaptureefficiency,expressedaselapseddaysbe-tweenfirstsightingandcapture,duringtheperiodfromApril1990throughDecember IIIII 1991was3.8days(+5.9days;range=1-50days).Betterutilizationofcurrentsandeddies,adjustmentstotetheringlines,multi-netdeploymentsandincreasedeffortstohandcaptureturtleshavecontributedtoreducedentrapmenttimes.EntrapmenttimesmaybeextendedforturtlesswimmingpasttheA1Abarriernet(ABI,1987).Priortobarriernetrepairsin1990,thetopofthenetwasoccasionallysub-mergedortheanchorcablepulledfreefromthebottom,allowingturtleswiderthan30.5cmtopass.BecausecaptureeffortswestoftheA1Abridgeweregenerallylesseffectivethanthoseneartheintakeheadwalls,mostturtlesbreachingthebarriernetwerenotcaughtuntiltheyenteredtheintakewellsofUnits1and2.PriortoinstallationoftheUIDSbarrierin1986,about15percentofallturtlesentrappedinthecanalwereremovedfromtheintakewells.Becauseoftheirrelativelysmallsizes,amuchlargerproportionofgreens(51.6percent)reachedtheplantthanloggerheads(10.1percent).Since1986,thepercentageofgreenscaughtattheintakewellshasdecreasedto33.3percent,whileallloggerheadshavebeenpreventedfromreachingtheplant.During1991,onlytwoofthe12greenturtlecapturesoccurredattheintakewells.During1991,98percentofallturtlesentrappedinthecanalwerecapturedeastoftheA1Abridge,71bynettingand48byhand.TheeffectiveconfinementofturtleseastofA1Ahasbeenamajorcontributortothehighcaptureefficiencyachievedduringrecentyears.RelativeConditionTurtlescapturedaliveintheintakecanaloftheSt.LuciePlantwereassignedarelativeconditionbasedonweight,activity,parasiteinfestation,barnaclecoverage,32 IIy~IIIIIIII wounds,injuriesandanyotherabnormalitieswhichmighthaveaffectedoverallvitality.During1991,88.8percent(95)ofallloggerheadsfoundinthecanalwerealiveandingoodtoexcellentcondition.Only10.3percent(11)ofloggerheadcapturesinvolvedindividualsinfairorpoorcondition;oneloggerheadwasdeadwhenremovedfromthecanal.Ofthe12greenturtlesremovedfromtheintakecanalduring1991,allbuttwowereingoodtoexcellentcondition(oneinfairconditionandoneinpoorcondition).Overtheentiremonitoringperiod,about77and78percent,respectively,ofallloggerheadandgreencaptureshaveinvolvedturtlesingoodtoexcellentcondition(Table6).Capturesofindividualsinfairtopoorconditionhaveoccurredabout15per-centofthetimeforloggerheadsand14percentofthetimeforgreens.Allofthehawksbills'andleatherbackshavebeenremovedfromthecanalingoodtoexcellentcondition,whilehalfoftheKemp'sridleyshavefallenintothesecategories.Relativeconditionratingscanbeinfluencedbyanumberoffactors,somerelatedandothersunrelatedtoentrainmentand/orentrapmentintheintakecanal.Ratingsofgoodtoexcellentindicatethatturtleshavenotbeennegativelyimpactedbytheirentrap-mentinthecanal,atleastasevidencedbyphysicalappearance.Althoughratingsoffairorpoorimplyreducedvitality,theextenttowhichentrainment/entrapmentisresponsibleisoftenindeterminable.Insomeinstances,conditionsresponsibleforlowerratings,suchasinjuries,obviouslyweresustainedpriortoentrainment.During1991,onlyfourofthe107loggerheadcaptures(3.7percent)involvedin-dividualswithnoticeableinjuries,suchasmissingappendages,brokenormissingpiecesofcarapaceanddeeplacerations.Mostofthesewereold,well-healedwounds,33 andnonewereseriousenoughtorequiremedicalattention.Noneofthegreenturtlescapturedduring1991hadmajorinjuries.Themajorityofloggerheadsratedasfairorpoorduring1991didnotsufferfromphysicaldisabilitiesbutratherappearedlethargic.Mostwereunderweightandheavi-lyinfestedwithbarnaclesandleeches.Thiscondition,referredtoas"diseasedturtlesyndrome"(Ehrhart,1987)hasbeenreportedfromseveralotherlocalesandisunre-latedtoaturtle'sentrapmentinthecanal~Intwocases,theinfirmitywassoextremethattheanimalsweretransferredtoSeaWorldofFloridafortreatmentandrehabilita-tion.Onewassubsequentlyreleased,theotherdiedincaptivity.MortalitiesSeaturtlemortalitieshavebeencloselymonitoredthroughoutthelifeofthecanalcaptureprograminanattempttoassignprobablecausesandtakeappropriateremedialactiontominimizefutureoccurrences.Previousanalysesofcapturedataiden-tifieddrowninginnets(A1Abarriernet,UIDSbarrier,andtanglenets),drowningintheintakepipesduringperiodsofreducedintakeflow,injuriessustainedfromdredgingoperationsandinjuriessustainedfromthemechanicalrakesusedintheintakewellsasprobablemortalityfactors(ABI,1987).Althoughdifficulttoquantify,theentrapmentandsubsequentdemiseofinjuredorsickturtleshasprobablyaccountedforaportionofobservedmortalities.Overtheentire16yearmonitoringperiod,128(6.5percent)ofthe1,960logger-headsand21(6.6percent)ofthe318greenturtlesentrappedinthecanalwerefounddead(Table6).Mortalitiesspannedtherangeofsizeclassesforloggerheads(SLCL34
=47.5-103cm),whileallgreenturtlemortalitiesinvolvedjuvenileslessthan42cminlength.ThefourKemp'sridleymortalitiesdocumentedattheplantduring1987and1988weretheonlydeathsforthisspeciestodate;noleatherbackorhawksbillmor-talitieshaveoccurredattheSt.LuciePlant.Modificationstocaptureprocedures,improvementstotheA1Abarriernetandvirtualeliminationoflowflowconditionswithinthecanalhaveresultedinasubstantialreductioninseaturtlemortalitiesoverthelifeofthecanalcaptureprogram.Mortalityrate,expressedasthepercentageoftotalcapturesinvolvingdeadanimals,declinednearly50percentbetweenthefirst(1976-1983)andsecond(1984-1991)halvesoftheprogram(Table2).During1991,onlyonemortality,aloggerhead,wasdocumented.Thisrepresentsthelowestannualmortalityrate(<1.0percentoftotalcaptures)sincethecanalcaptureprogrambeganandcontinuesthedecliningtrendreferencedabove.Thedeadloggerheadremovedfromthecanalin1991wasfoundfloatingattheA1Abarriernet.Noapparentphysicalinjurieswerenoted.Becauseofitsadvancedstageofdecomposition,nonecropsywasperformed,andcauseofdeathcouldnotbedetermined.RecatureIncidentsSincetheSt.LuciePlantcaptureprogrambegan,mostturtlesremovedfromtheintakecanalhavebeentaggedandreleasedintotheoceanatvariouslocationsalongHutchinsonIsland.Consequently,individualturtlescanbeidentifiedaslongastheyretaintheirtags.Overthe16yearhistoryofturtleentrapmentattheSt.LuciePlant,64individuals(63loggerheadsand1green)havebeenremovedfromthecanalmorethan35 III~II once.Severalotherturtleswithtagscarshavealsobeenrecovered,indicatingthattheactualnumberofrecapturesmaybehigher.Ofthe63individualloggerheadsknowntohavebeencaughtmorethanonce,43werecaughttwice,10werecaughtthreetimes,4werecaughtfourtimes,2werecap-turedfivetimes,2werecapturedsixtimes,1wascaughtseventimesand1wascaughtonnineseparateoccasions,yieldingatotalof107recaptureincidents.Releasesitedidnotappeartohaveanyeffectonaturtle'sprobabilityofbeingrecaptured.Turtlesreleasedbothnorthandsouthoftheplantreturned.Recapturesalsodidnotappeartoberelatedtosize,asbothjuvenilesandadultswerecapturedmorethanonce(rangeofSLCL=47-89cm).Asforoverallcaptures,themajorityofrecaptureincidentsin-volvedjuveniles(SLCL<70cm).Recaptureintervalsforloggerheadsrangedfromfourto858days,withameanof149days(+169.4days).TheonlygreenturtlecaughtmorethanoncewascapturedIontwooccasions,returningtothecanal59daysafterfirstbeingreleasedintotheocean.About57percentofallloggerheadrecaptureincidentsoccurredwithin90daysofpreviouscaptureand90percentwithinoneyear(Figure22).Theaverageintervalbetweenfirstandlastcapturewas257days(+325.2days).Thelongestperiodbe-tweenfirstandlastcapturewas5.3years.ThesedatasuggestthatresidencytimesofloggerheadswithinthenearshorehabitatadjacenttotheSt.LuciePlantarerelativelyshort.SimilarfindingshavebeenreportedforloggerheadsinhabitingtheMosquito/In-dianRiverLagoonsofeast-centralFlorida(MendoncaandEhrhart,1982).36 lII~>II SUMMARYAgradientofincreasingloggerheadturtlenestdensitiesfromnorthtosouthalongthenorthernhalfofHutchinsonIslandhasbeenshownduringmostsurveyyears.Thisgradientmayresultfromvariationsinbeachtopography,offshoredepthcontours,dis-tributionofnearshorereefs,onshoreartificiallightingandhumanactivityonthebeachatnight.Lownestingactivityinthevicinityofthepowerplantduring1975andfrom1981through1983wasattributedtonighttimeconstructionactivitiesassociatedwithinstallationofpowerplantintakeanddischargestructures.Nestingreturnedtonormalorabovenormallevelsfollowingbothperiodsofconstruction.During1991,daytimeconstructionactivitiesassociatedwithvelocitycaprepairshadnoapparenteffectonnesting.Statisticalanalysesindicatethatpowerplantoperation,exclusiveofnighttimeconstruction,hashadnosignificanteffectonnestdensitiesneartheplant.Therehavebeenconsiderableyear-to-yearfluctuationsinloggerheadnestingac-tivityonHutchinsonIslandfrom1971through1991.Fluctuationsarecommonatotherrookeriesandmayresultfromnon-annualre'productivebehavior.Despitethesefluc-tuations,loggerheadnestingactivityhasremainedhighduringrecentyearsandmayreflectanoverallincreaseinthenumberofnestingfemalesintheHutchinsonIslandarea.Norelationshipbetweentotalnestingontheislandandpowerplantoperationorintake/dischargeconstructionwasindicated.TemporarydeclinesinloggerheadnestingactivityhavebeenattributedtocoolwaterintrusionsthatfrequentlyoccuroverthecontinentalshelfofsoutheastFlorida.ThoughtemporalnestingpatternsoftheHutchinsonIslandpopulationmaybein-37 fluencedbynaturalfluctuationsinwatertemperature,nosignificanteffectsduetopowerplantoperationhavebeenindicated.Sincenestingsurveysbeganin1971,raccoonpredationwasconsideredthemajorcauseofturtlenestdestructiononHutchinsonIsland.From1971through1977,overallpredationratesintheninesurveyareaswerebetween21and44percent.However,apronounceddecreaseinraccoonpredationoccurredafter1977,andover-allpredationratesintheninesurveyareashavenotexceededtenpercentsince1979.Decreasedpredationbyraccoonsprobablyreflectsadeclineintheraccoonpopula-tion.During1991,47greenturtleand44leatherbackturtlenestswererecordedonHutchinsonIsland.Nestingactivitybythesetwospeciesexhibitedconsiderableannualfluctuations,ashasbeenrecordedatotherrookeries,buthasremainedrelativelyhighduringrecentyears.ThismayreflectanoverallincreaseinthenumberofnestinggreenandleatherbackturtlesintheHutchinsonIslandarea.During1991,107loggerheads,12greenturtles,1hawksbilland1Kemp'sridleywereremovedfromtheSt.LuciePlantintakecanal.SincemonitoringbeganinMay1976,1,960loggerhead,318green,9leatherback,9hawksbilland18Kemp'sridleyturtleshavebeencaptured.Overthelifeofthemonitoringprogram,annualcatchesforloggerheadturtleshaverangedfrom33in1976(partialyearofplantoperationandmonitoring)toahighof195in1986.Yearlycatchesofgreenturtleshaverangedfrom0in1976to69in1984.Differencesinthenumberofturtlesentrappedduringdifferentyearsandmonthsareattributedprimarilytonaturalvariationintheoccurrenceofturtles38 IIOglII inthevicinityoftheoffshoreintakestructures,ratherthantoplantoperatingcharac-teristics.Size-classdistributionsofloggerheadturtlesremovedeachyearfromthecanalhaveconsistentlybeenpredominatedbyjuvenilesbetween50and70cminstraightlinecarapacelength.Mostgreenturtlesentrappedinthecanal(about80percent)werejuveniles40cmorlessinlength.Forbothspecies,thelargestnumberofcapturesforallyearscombinedoccurredduringthewinter,buttheseseasonalpeaksweremuchmorepronouncedforgreenturtles.Sexratiosofbothadultandimmatureloggerheadscaughtinthecanalcontinuedtobebiasedtowardsfemales.During1991,about93and80percent,respectively,ofallloggerheadsandgreenturtlesremovedfromthecanalwerecategorizedbyphysicalappearanceasbeingingoodtoexcellentcondition.Overtheentire16yearmonitoringperiod,77and78per-cent,respectively,ofallloggerheadandgreenturtlecaptureshaveinvolvedindividualsinthesecategories;15percentoftheloggerheadsand14percentofthegreenturtlesremovedfromthecanalhavebeeninfairorpoorcondition.Onlyfourpercentoftheturtlesremovedfromtheintakecanalduring1991hadsubstantialinjuries,andmostofthosewereapparentlysustainedpriortoentrapment.Onceinthecanal,turtlesconfinedeastofA1Atypicallyhadverybriefresidencytimes.Thustherelativeconditionofmostturtleswasnotaffectedbytheirentrapment.During1991,oneloggerheadmortalityoccurredintheintakecanal.Causeofdeathcouldnotbedetermined.Programmodifications,includingcontinualsurveillanceoftanglenetsduringperiodsofdeployment,improvementstotheintegrityoftheA1A39 barriernetandgreaterefforttohandcaptureturtleshavecontributedtoasubstantialdeclineinseaturtlemortalitiesduringrecentyears.40 CIIII 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III Mendonca,M.T.andL.M.Ehrhart.1982.Activity,populationsizeandstructureoftheimma-ture~h~lni~m~d.qand~CrettagarettainMosquitoLagoon,Florida.Copeis1982:(1)161-167.Moffler,M.D.andJ.F.VanBreedveld.1979.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.X.Benthicalgaespecieslist.FloridaMarineResearchPublications34:118-122.Mortimer,J.A.1982.Factorsinfluencingbeachselectionbynestingseaturtles.Pages45-51inBjorndal,K.A.,ed.BiologyandConservationofSeaTurtles.SmithsonianInstitutionPress.Washington,D.C.NMFS(NationalMarineFisheriesService).1978.FinalEISlistingandprotectingthegreenseaturtle(Chelonia~mdas,loggerheadseaturtle(Caretta~carettaandthePacificRidley~LiII~lid<<hEdgdSpiAt1973N.alMarineFisheriesService,Dept.ofCommerce,Washington,D.C.NRC(USNuclearRegulatoryCommission).1982.FinalenvironmentalstatementrelatedtotheoperationofSt.LuciePlantUnit2.DocketNo.50-389.O'ara,J.1980.Thermalinfluencesontheswimmingspeedofloggerheadturtlehatchlings.Copeia1980(4):779-780.~~~Owens,D.W.,J.R.Hendrickson,V.LanceandI.P.Callard.1978.Atechniquefordetermin-ingsexofimmatureChelonia~mdasusingaradioimmunoassay.Herpetologica34:270-273.Owens,D.W.andG.J.Ruiz.1980.Newmethodsofobtainingbloodandcerebrospinalfluidfrommarineturtles.Herpetologica36:17-20.Pritchard,P.C.,P.R.Bacon,F.H.Berry,A.F.Carr,J.Fletemeyer,R.M.Gallagher,S.R.Hop-kins,R.R.Lankford,R.MarquesM.,L.H.Ogren,W.G.Pringle,Jr.,H.A.ReichartandR.Witham.1983.IVlanuaiofseaturtleresearchandconservationtechniques.PreparedfortheWesternAtlanticTurtleSymposium,SanJose,CostaRica,July1983.126pp.Proffitt,C.E.,R.E.Martin,R.G.Ernest,B.J.Graunke,S.E.LeCroy,K.A.Muldoon,B.D.Peery,J.R.WilcoxandN.Williams-Walls.1986.Effectsofpowerplantconstructionandopera-tiononthenestingoftheloggerheadseaturtle(Caretta~caretta:1971-1984.Copeia1986(3):813-816.Raymond,P.W.1984.TheeffectsofbeachrestorationonmarineturtlesnestinginsouthBrevardCounty,Florida.M.S.thesis,UniversityofCentralFlorida.
IIIII Routa,R.A.1968.SeaturtlenestsurveyofHutchinsonIsland,Florida.QuarterlyJournalFloridaAcademyofSciences30(4):287-294.Schulz,J.P.1975.SeaturtlesnestinginSurinam.ZoologischeVerhandelingen,uitgegevendoorhetRijksmuseumvanNatuurlijkeHistoricteLeiden,No.143:1-144.Smith,N.P.1982.UpwellinginAtlanticshelfwatersofsouthFlorida.FloridaScientist45(2):125-138.Sokal,R.R.andF.J.Rohlf.1981.Biometry.Theprinciplesandpracticeofstatisticsinbiologi-calresearch.W.H.FreemanandCompany,SanFrancisco.859pp.Stancyk,S.E.1982.Non-humanpredatorsofseaturtlesandtheircontrol.Pages139-152inBjorndal,K.A.,ed.BiologyandConservationofSeaTurtles.SmithsonianInstitutionPress.Washington,D.C.Talbert,O.R.,S.E.Stancyk,J.M.DeanandJ.M.Will.1980.Nestingactivityoftheloggerheadturtle(Caretta~carettainSouthCarolina.I:Arookeryintransition.Copeia1980:(4)709-718.Taylor,C.B.,andH.B.Stewart.1958.SummerupwellingalongtheeastcoastofFlorida.Jour-nalofGeophysicalResearch64(1):33-40.Tester,L.A.andK.A.Steidinger.1979.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.Vll.Phytoplankton,1971-1973.FloridaMarineResearchPublica-tions34:16-61.Walker,L.M.1979.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.IX.Dielplankton,1973-1974.FloridaMarineResearchPublications34:99-117.Walker,L.M.,B.M.GlassandB.S.Roberts.1979.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.Vill.Zooplankton,1971-1973.FloridaMarineResearchPublications34:62-98.Walker,L.M.andK.A.Steidinger.1979.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.VI.Planktondynamics,1971-1973.FloridaMarineResearchPublications34:1-15.Wibbels,T.,D.Owens,Y.MorrisandM.Amass.1984.SexratiosofimmatureloggerheadseaturtlescapturedalongtheAtlanticcoastoftheUnitedStates.FinalReporttotheNa-tionalMarineFisheriesService.ContractNo.NA81-GA-C-0039.47pp.47 IIIIIItiII Williams-Walls,N.,J.O'ara,R.M.Gallagher,D.F.Worth,B.D.PeeryandJ.R.Wilcox.1983.SpatialandtemporaltrendsofseaturtlenestingonHutchinsonIsland,Florida,1971-1979.BulletinofMarineScience33(1):55-66.Witherington,B.E.andL.M.Ehrhart.1989.Statusandreproductivecharacteristicsofgreenturtles(Qhel~oni~mdasnestinginFlorida.Pages35t-352inOgren,L.,F.Berry,K.Bjorndal,H.Kumpf,R.Mast,G.Medina,H.ReichartandR.Witham,editors.Proceed-ingsoftheSecondWesternAtlanticTurtleSymposium.Mayaguez,PuertoRico,12-16October1987.NOAATechnicalMemorandumNMFS-SEFC-226.WitIIWN1993939IitiIpiIdtk33tillI~EhI(Linnaeus,1766).FAOFisheriesSynopsis,137:1-78.Worth,D.F.andM.L.Hollinger.1977.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.III.Physicalandchemicalenvironment.FloridaMarineResearchPublica-tions23:25-85.Worth,D.F.,andJ.B.Smith.1976.MarineturtlenestingonHutchinsonIsland,Florida,in1973.rFloridaMarineResearchPublications18:1-17.I48 GULFOFMEXICO0C)IYAROSKILOMETERSSCALE~~C~CT-N-yiOI't.LuclePlantFigurei.LocationoftheSt.LuciePlant.
IIII
~,'l'r7~~V~0<2G00.r';~~~I/~.:,::HUTCHINSONISLAND.'SI7J'~g~@X~~ye0'IQ~o,...,-.:::::'"""INTAKEWELLSUIDSBARRIER0Ph1jI4<t0250500METERS~~rTgI'"8,PrI@Gas'DISCHARGE~gG+'.:PIPES~i::INTAKE'I:HEADWALL'.INTAKE~-.",STRUCTURESA1A'::.:.BARRIER,.NET;%.,'vINTAKECANALFigure2.St.LuciePlantcoolingwaterintakeanddischargesystem.
,I~l~~)
Ft.PierceInletoA((s\~(EPStateHwyA0'pi'('(~(AlgQ(bb,tOF1GH2F+p+3I.MN40FPLFSTLUCIEPLANTQ~"U.S.Hwy1$6v0SkrnR)VER'0e'(BBCCDDEE8FFGGoa((HH0aPin~~St.I.ucleInletFigure3.Designationandlocationofnine1.25-kmsegmentsandthirty-six1-kmsegmentssurveyedforseaturtlenesting.HutchinsonIsland,1971-1991.
350300250zg200DZ1501005012NORTH450POWERPLANT9SOUTHFigure4.Meanannualnumberofloggerheadturtlenestsineachofthenine1.25-km-longsurveyareas,KutchinsonIsland,1971-1990,comparedwithnumberofnestsduring1991.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1991values(1980datawereexcludedbecausenotallareasweresurveyed).
II) 350300z250200Z150100ABCDEFGHIJKLMN0PQRSTUVWXYZABCDEFGHIJABCDEFGHIJ.NORTH0POWERPLANTSOUTHFigure5.Meanannualnumberofloggerheadturtlenestsineachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1990,comparedwithnumberofnestsduring1991.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1991values.
lI 700600(o500Oz400Dz300200100~A8CDEFGHIJKLMN0PQRSTUVWXYZA8CDEFGHIJA8CDEFGHIJNORTHPOWERPLANTSOUTHFigure6.Meanannualnumberofloggerheadturtleemergencesineachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1990,comparedwiththenumberofemergencesduring1991.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1991values.
,IIIIIII 10080KMMillOOg60C9ZI-MZ4020ABCDEFGHIJKLMN0PQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure7.Meanannualloggerheadturtlenestingsuccess(percentageofemergencesthatresultedinnests)foreachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1990,comparedwithnestingsuccessduring1991.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1991values.
300250Area4(PowerPlantSite)~----0Area5(ControlSite)IIIIIIII200//zO150DZ10050197119721973197419751976197719781979198019811982198319841985198619871988198919901991Figure8.NumberofloggerheadturtlenestsinAreas4and5,1971-1991.Arrowsdenoteyearsduringwhichintake/dischargeconstructionoccurredinArea4.
,I 6000I-COz0CLDz50004000300020001000COOz(9KDz12000100008000600040002000gCOCOIllOODCOC9zI-COLUz8060402019811982198319841985198619871988198919901991Figure9.Annualnumberofnests,annualnumberofemergencesandannualnestingsuccessforloggerheadturtles,HutchinsonIsland,1981-1991.
.I 3130O29o2827P262524232212090z60Dz3015.30515APRMAY30515JUN30515JUL30515AUG30515SEPFigure10.Dailyloggerheadturtlenestingactivityandwatertemperature,HutchinsonIsland,1991.
,III 605018'/oDestroyedbyghostcrabsgDestroyedbyraccoonsandghostcrabsQg-,'estroyedbyraccoonsOO40OzO30z2016'/o.:'/o1g/o10:::6'/o4o/o3'/o2%1%1%(1%1o/o(1%ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure11.Numberofloggerheadturtlenestsdestroyedbyraccoons.andghostcrabsandpercentageofnestsdestroyedineach1-km-longsurveyarea,HutchinsonIsland,1991.
lItItt(I 120100I-(0zO80z604020~---wGreen(Cheloniamydas)~Leatherback(Oermochetyacoriacea)r~rII)IIIIp--$lI>IIy/II'lg~IIIIII1971197319751977197919811982198319841985198619871988198919901991Figure12.Annualnumbersofgreenturtleandleatherbackturtlenests,HutchinsonIsland,1971-1991.
,I 200~-eLOGGERHEAD(Carettacaretta)o---oGREEN(Chelcniam~das)80(0KDQ.OCIzCCG(900Kz175150125100755025I1III'IIp'iIPLp/h//P-0o1976197719781979198019811982198319841985198619871988198919901991706050z403020D10Figure13.Numberofloggerheadandgreenturtlesremovedeachyearfromtheintakecanal,St.LuciePlant,1976-1991.
,I mmmmmmmmm4040m3020z30201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure14.Meannumberofloggerheadscapturedeachmonth,St.LuciePlantintakecanal,1977-1990,comparedwithnumberofmonthlycapturesduring1991.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1%Ivalues.
I 400400CODo300oz0Kg200DZ300200100100+4041-4546-5051-5556-6061-6566-7071-7576-8081-8586-9091-9596-STRAIGHTLINECARAPACELENGTH(cm)100101-106->110105110Figure15.Lengthdistribution(SLCL)ofloggerheadturtles(N=1,771)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-199I.Nodatacollectedfor82individuals.
400400MDQ300CIz0Kg200Dz300200100100~1011-2021-3031-4041-5051-6061-7071-8081-9091-100101-111-121-131-141-<<150WEIGHT(kg)110120130140150Figure1LWeightdistributionofloggerheadturtles(¹1,584)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1991.Nodatacollectedfor269individuals.
120120-10010080COO0Z600KQ)408060402020-1516-21-26-31-36-41-46-51-56-61-66-71-76-81-86-91-96-101-106->11020253035404550556065707580859095100105110STRAIGHTLINECARAPACELENGTH(cm)Figure17.Lengthdistribution(SLCL)ofgreenturtles(N=307)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1%I.Nodatacollectedfor10individuals.
,I 200200180180160160m140D0)120Zrt-10080140120100806060404020201-56-1011-1516-2021-2526-3031-3536-4041-4546-5051-101-151-)200WEIGHT(kg)100150200Figure18.Weightdistributionofgreenturtles(N=303)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-199I.Nodatacollectedfor14individuals.
.II 8080MDO60DZ0KLlj40Z60402020JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure19.Numbersofadultloggerheads(SLCL>85.0cm),includingrecaptures,removedeachmonthfromtheintakecanal,St.LuciePlant,1976-1991(N=278;sexnotrecordedfor4individuals>85.0cm).
,IIIIII
~CANALCAPTURES0lZI-Ol~D00KQlzzz5040302010o---oEMERGENCESp~]///o~P//I0////~op/500400300200100ILJKz(0OzUJGCCUl0zzz197719781979198019811982198319841985198619871988198919901991Figure20.Comparisonofcapturesofadultfemaleloggerheads(SLCL>85.0cm)intheintakecanal,St.LuciePlant,19774991,andnumbersofloggerheademergencesinarea4adjacenttotheplant.Nestingactivitywasnotmonitoredin1978.
II ILJKI-CLO(090Z0I-ZUJOKUJ0UjI-O1OO806040201008060402010203040DAYSBETWEENFIRSTSIGHTINGANDCAPTURE50Figure21.Captureefficiency,expressedasdaysbetweenfirstsightingandcapture,forloggerheadturtlesentrappedintheintakecanal,St.LuciePlant,April,1990-December,1991.(N=119).
.IIIl 100100tu80(9Z~60DD>40200vr'o~I0//9IPIIII0IIIIIIntervalbetweenfirstandlastcapture0---0Intervalbetweensuccessivecaptures8060402025050075010001250RECAPTUREINTERVAL(days)15001750Figure22.Cumulativepercentageofallloggerheadrecapturesoccurringwithinvarioustimeintervalsbetweensuccessivecaptures(N=105)andfirstandlastcapture(N=61),St.LuciePlantintakecanal1976-1991.
,IIIIIIIII TABLE1ESTIMATESOFTHENUMBERSOFLOGGERHEADTURTLENESTSONHUTCHINSONISLANDBASEDONSURVEYSOFNINE1.25-KM-LONGSURVEYAREAS,1971-1991,COMPAREDTOTHEACTUALNUMBEROFNESTSONTHEISLAND,1981-1991NumberofnestsinthenineExtrapolationfromtheninesurveyareastotheActualnumberofnestsonthe19711973197519771979198119821983198419851986198719881989199114201260149393214491031163415921439162318391645170117742177240941803709439527444266303548104687423647785414484350085223640970923115474342774877548346234990519367006812 TABLE2TOTALNUMBEROFSEATURTLECAPTURESAND(NUMBEROFDEAD)TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-19911976197719781979198019811982198319841985198619871988198919901991TotalAnnualMean~33(4)80(5)138(19)172(13)116(5)62(5)101(16)119(4)148(3)157(4)195(27)175(11)134(6)111(4)112(1)107(1)1960(128)128.55(2)6(1)3(1)10(3)32(2)823(4)69(2)1422(1)3542(2)17(1)20(2)12318(21)21.29(0)0.619(0)0.616(2)5(2)2118(4)1.233(4)86(7)148(20)175(14)126(8)97(7)110(16)142(8)220(5)172(4)220(28)218(13)181(10)133(5)132(3)121(1)2314(153)152.1Excludes1976(partialyearofplantoperation).
,IIIII TABLE3TOTALNUMBEROF(ANDNUMBEROFDEAD)LOGGERHEADTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-199119761977197819791980138(1)75(2)11911(2)27(2)19(5)3(1)24(3)29(1)111701621(2)-14103(1)8(3)7(1)2175(3)9315(1)9(1)5512117(2)15(7)41027(2)16(2)8(1)15(3)12121933(4)80(5)138(19)172(13)116(5)198111(1)11(3)6106162(1)0062(5)19826(2)141417(4)772(1)9(1)9(5)4(2)101(16)198319843913(1)104131162(1)77(1)768(2)17528(1)12(1)261610912119(4)148(3)198511152013161720(3)19(1)1473157(4)198615(2)16(4)14(4)20(2)1220(1)26(2)34(6)9(4)11(2)810195(27)198726(3)118(1)24(3)23(1)26(1)19(1)17(1)435175(11)198819891310(3)1113(2)284(2)111330165311(1)2521(1)15235(1)134(6)111(4)199099232516.7(1)112(1)1991131220191511632(1)4107(1)Total232(11)190(17)172(9)176(15)177(6)219(8)178(11)180(11)128(13)125(13)87(13)96(1)1960(128)MonthlyMean15.5%TotalCatch12.012.79.98.99.19.111.48.99.26.611.511.711.113.711.111.38.07.8~6.15.46.04.34.5Excludes1976(partialyearofplantoperation).
TABLE4TOTALNUMBEROF(ANDNUMBEROFDEAD)GREENTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-1991197619771978197919801981198219831984198522(1)120105(1)20(1)7108(1)437(1)104(1)3(2)2(1)4(1)4(1)5(2)6(1)3(1)10(3)32(2)23(4)69(2)19866(1)22(1)198719884112113342319891991Total3(1)06316(1)3(1)31114210100(5)52(3)35(4)20(2)9(1)MonthlyMean6.73.32.31.30.6%TotalCatch31.416.411.06.32.8316(2)10100018(3)81.10.55.72.59(1)0.62.8041.9150.94.75110202211121(2)251.31.66.67.93542(2)17(1)20(2)12318(21)
TABLE5NUMBEROFMONTHLYCAPTURESBYSIZECLASSFORLOGGERHEADTURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1977-1991Sizeclasses(SLCLincm)January16February12March8April15May12June12JulyAugust7September4October7453585050355357403548383515213512511010698927814.811.910.59.88.68.36.57.67.26.1262120301729293616289.27.47.010.66.010.210.212.75.69.92216261528442723301919585110745739153.51.43.22.815.626.220.213.85.32.5November4December4Total106%ofTotal213424265404912823.85.069.31967134615.412913815102823.22.115.3Excludes1976(partialyearofdata).Nodatawerecollectedfor79individuals.
WWWWTABLE6RELATIVECONDITIONOFSEATURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPIANT,1976-1991Relative43122.054928.052226.623111.8723.71286.5271.413442.16119.25316.73611.382.5216.651.6111.1111.1777.8316.7316.7316.7316.7211.1422.2777.8222.257624.961626.658525.327011.7823.51536.6321.4Total3181823141Excellent:normalorabovenormalweight,active,veryfewornobarnaclesorleeches,nowounds.2Verygood:intermediategoodtoexcellent.3Good:normalweight,active,lighttomediumcoverageofbarnaclesand/orleeches,woundsabsent,healedordonotappeartodebilitatetheanimal.4Fair:intermediatepoortogood.5Poor:emaciated,sloworinactive,heavybarnaclecoverageand/orleechinfestation,debilitatingwoundsormissingappendages.6Dead7Alivebutothenviseconditionnotrecorded.