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{{#Wiki_filter:APPLIEDBI0L'06Y,INC.AB-610I'LORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTALOPERATINGREPORTVOLUMEI1990I2968ANORTHDECATURROAD9105070294910025PDRADOCK05000389RPDR~ATLANTA,GEORGIA30033~404-296-3900 AB-610FLORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTALOPERATINGREPORT1990VOLUME1APRIL1991FLORIDAPOWER&LIGHTCOMPANYJUNOBEACH,FLORIDAAPPLIEDBIOLOGY,INC.ATLANTA,GEORGIA IIIIII ENVIRONMENTALOPERATINGREPORTTABLEOFCONTENTSTABLEOFCONVERSIONFACTORSFORMETRICUNITSEXECUTIVESUMMARYIntroductionTurtleNestingSurveyIntakeCanalMonitoringOtherRelatedActivitiesINTRODUCTIONBackgroundAreaDescriptionPlantDescriptionTURTLESIntroductionMaterialsandMethodsNestingSurveyIntakeCanalMonitoringStudiestoEvaluateand/orMitigateIntakeEntrapmentResultsandDiscussionNestingSurveyDistributionofLoggerheadNestsAlongHutchinsonIslandEstimatesofTotalLoggerheadNestingonHutchinsonIslandTemporalLoggerheadNestingPatternsPredationonLoggerheadTurtleNestsGreenandLeatherbackTurtleNestingIntakeCanalMonitoringRelativeAbundanceandTemporalDistributionSize-ClassDistributionsSexRatiosCaptureEfficienciesRelativeConditionMortalitiesRecaptureIncidentsSummaryLITERATURECITEDFIGURESTABLESIVIV10101415151518192021232326.28.3031333436404870 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+273.183.937x103.281x103.281x101.0x102.205x103.527x102.4711.0x102.20463.5274x106.214x101.0x101.0x102.642x103.2813.937x101.0941.0x101.01.0x103.937x103.281x101.550x101.076x101.55x10Toobtainfahrenheit(degrees)kelvin(degrees)inchesfeetfeetpersecondliterspoundsounces(avoirdupois)acresgramspoundsounces(avoirdupois)miles(statute)millimetcrscubiccentimeters(cm)gallons(USliquid)feetinchesJJardsgramspartspermillionliters(USliquid)inchesfeetsquareinchessquarefeetsquareinches IIIrIe,t EXECUTlVESUMMARYINTRODUCTIONTheSt.LuciePlantisanelectricgeneratingstationonHutchinsonIslandinSt.LucieCounty,Florida.Theplantconsistsoftwonuclear-fueled850-MWunits;Unit1wasplacedon-lineinMarch1976andUnit2inMay1983.Thisdocumenthasbeenpreparedtosatisfy.therequirementscontainedintheUnitedStatesNuclearRegulatoryCommission'sAppendixBEnvironmentalProtectionPlan(EPP)toSt.LucieUnit2FacilityOperatingLicenseNo.NPF-16.ThisreportdiscussesenvironmentalprotectionactivitiesrelatedtoseaturtlesasrequiredbySubsection4.2oftheEPP.OtherroutineannualreportingrequirementsareaddressedinVolume2,alsoentitled"St.LucieUnit2AnnualEnvironmentalOperatingReport".TURTLENESTINGSURVEYTherehavebeenconsiderableyear-to-yearfluctuationsinseaturtlenestingactivityonHutchinsonIslandsincemonitoringbeganin1971.Lownestingactivityin1975and1981-1983inthevicinityofthepowerplantwasattributedtoconstructionofplantin-takeanddischargestructures.Nestingreturnedtonormalorabovenormallevelsfol-lowingbothperiodsofconstruction.Powerplantoperationexclusiveofconstructionhashadnosignificanteffectonnestingneartheplant.Datacollectedthrough1990haveshownnolong-termreductionsintotalnesting,totalemergencesornestingsuc-cessontheisland.Formalrequirementstoconductthisprogramexpiredin1986butwerevoluntarilycontinuedin1990withagreementfromfederalandstateagencies.
{{#Wiki_filter:APPLIEDBI0L'06Y,INC.AB-610I'LORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORTVOLUMEI1990I2968ANORTHDECATURROAD9105070294 910025PDRADOCK05000389RPDR~ATLANTA,GEORGIA30033~404-296-3900 AB-610FLORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORT1990VOLUME1APRIL1991FLORIDAPOWER&LIGHTCOMPANYJUNOBEACH,FLORIDAAPPLIEDBIOLOGY,INC.ATLANTA,GEORGIA IIIIII ENVIRONMENTAL OPERATING REPORTTABLEOFCONTENTSTABLEOFCONVERSION FACTORSFORMETRICUNITSEXECUTIVE SUMMARYIntroduction TurtleNestingSurveyIntakeCanalMonitoring OtherRelatedActivities INTRODUCTION
INTAKECANALMONITORINGSinceplantoperationbeganin1976,2,193seaturtles(including100recaptures)representingfivedifferentspecieshavebeenremovedfromtheintakecanal.Eighty-fourpercentofthesewereloggerheads.Differencesinthenumbersofturtlesfoundduringdifferentmonthsandyearswereattributedtonaturalvariationintheoccurren-cesofturtlesinthevicinityoftheplant,ratherthantoanyinfluenceoftheplantitself.Themajorityofturtlesremovedfromtheintakecanal(about93percent)werecapturedaliveandreleasedbackintotheocean.TurtlesconfinedbetweentheA1Abarriernetandintakeheadwallsusuallyresidedinthecanalforarelativelyshortperiodoftime,andmostwereingoodtoexcellentconditionwhencaught.OTHERRELATEDACTIVITIESStudiestoevaluatevariousintakedeterrentsystems,asrequiredbytheNRC'sUnit2EnvironmentalProtectionPlan,wereconductedduring1982and1983.Resultsandevaluationsofthosestudieswerepresentedtoregulatoryagenciesduring1984,andtherequirementisnowconsideredcompleted.
INTRODUCTIONBACKGROUNDThisdocumenthasbeenpreparedtosatisfytherequirementscontainedintheUnitedStatesNuclearRegulatoryCommission's(NRC)AppendixBEnvironmentalProtectionPlantoSt.LucieUnit2FacilityOperatingLicenseNo.NPF-16.In1970,FloridaPower8LightCompany(FPL)wasissuedPermitNo.CPPR-74bytheUnitedStatesAtomicEnergyCommission,nowtheNuclearRegulatoryCommis-sion,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, 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.Previousresultsdealingexclusivelywithseaturtlestudiesarecontainedinsevenenvironmen-taloperatingreports(ABI,1984b,1985b,1986,1987,1988,1989,1990).Thisreportdescribesthe1990environmentalprotectionactivitiesrelatedtoseaturtles,asrequiredbySubsection4.2oftheSt.LuciePlantUnit2EnvironmentalProtectionPlan.AREADESCRIPTIONTheSt.LuciePlantislocatedona457-hasiteonHutchinsonIslandonFlorida'seastcoast(Figures1and2).TheplantisapproximatelymidwaybetweentheFt.PierceandSt.LucieInlets.ItisboundedonitseastsidebytheAtlanticOceanandonitswestsidebytheIndianRiverLagoon.
IIIII HutchinsonIslandisabarrierislandthatextends36kmbetweeninletsandobtainsitsmaximumwidthof2kmattheplantsite.Elevationsapproach5matopdunesbor-deringthebeachanddecreasetosealevelinthemarigroveswampsthatarecommononmuchofthewesternside.IslandvegetationistypicalofsoutheasternFloridacoas-talareas;densestandsofAustralianpine,palmetto,seagrapeandSpanishbayonetarepresentatthehigherelevations,andmangrovesaboundatthelowerelevations.Largestandsofblackmangroves,includingsomeontheplantsite,havebeenkilledbyfloodingformosquitocontroloverpastdecades.TheAtlanticshorelineofHutchinsonIslandiscomposedofsandandshellhashwithintermittentrockypromontoriesprotrudingthroughthebeachfacealongthesouthernendoftheisland.Submergedcoquinoidrockformationsparallelmuchoftheislandofftheoceanbeaches.Theoceanbottomimmediatelyoffshorefromtheplantsitecon-sistsprimarilyofsandandshellsediments.Theunstablesubstratelimitstheestab-lishmentofrootedmacrophytes.TheFloridaCurrent,whichflowsparalleltothecontinentalshelfmargin,beginstodivergefromthecoastlineatWestPalmBeach.AtHutchinsonIsland,thecurrentisapproximately33kmoffshore.Oceanicwaterassociatedwiththewesternboundaryofthecurrentperiodicallymeandersovertheinnershelf,especiallyduringsummermonths.PLANTDESCRIPTIONTheSt.LuciePlantconsistsoftwo850-MWnuclear-fueledelectricgeneratingunitsthatusenearshoreoceanwatersfortheplant'sonce-throughcondensercoolingwater system.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-faceoftheoceanundertheinfluenceofwindandcurrentsandtheheatdissipatestotheatmosphere.
>tIIIIII 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.AIInewnestsandfalsecrawlswillbecountedandrecordedineacharea.Aftercounting,allcrawltrackswillbeobliteratedtoavoidrecounting.Predationonnestsbyraccoonsorotherpredatorswillberecordedasitoccurs.Recordswillbekeptofanyseasonalchangesinbeachtopographythatmayaffectthesuitabilityofthebeachfornesting.4.2.2Aprogramthatemployslightand/orsoundtodeterturtlesfromtheintakestructurewillbeconducted.Thestudywilldeterminewithlaboratoryandfieldexperimentsifsoundand/orlightwillresultinareductionoftotalturtleentrapmentrate.
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,ofthecaptul'Bdevice(s)willbemadebyaqualifiedindividualwhenthedevice(s)aredeployed.Theturtleswillbeidentifiedtospecies,measured,weighed(ifappropriate),taggedandreleasedbackintotheocean.Recordsofwounds,freshorold,andasubjectivejudgementontheconditionoftheturtle(e.g.,barnaclecoverage,underweight)willbemaintained.Methodsofobtainingadditionalbiological/physiologi-caldata,suchasbloodanalysesandparasiteloads,fromcaptured IIIIII seaturtleswillbepursued.Deadseaturtleswillbesubjectedtoagrossnecropsy,iffoundinfreshcondition.INTRODUCTIONHutchinsonIsland,Florida,isanimportantrookeryfortheloggerheadturtle,Caret-tacarettaandalsosupportssomenestingofthegreenturtle,Chelonia~mdasandthIth5kttl.~OIII1915IIt1.,1959;5t,1995;9I-lagheretal.,1972;WorthandSmith,1976;Williams-Wallsetal.,1983).Allthreespeciesareprotectedbystateandfederalstatutes.Thefederalgovernmentclassifiedthelog-gerheadturtleasathreatenedspecies.TheleatherbackturtleandtheFloridanestingpopulationofthegreenturtlearelistedbythefederalgovernmentasendangeredspecies.Becauseofreductionsinworldpopulationsofmarineturtlesresultingfromcoastaldevelopmentandfishingpressure(NMFS,1978),maintainingthevitalityoftheHutchinsonIslandrookeryisimportant.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 IIIIII installedduringthatyear.Installationofthesestructuresincludedconstructionactivitiesconductedoffshorefromandperpendiculartothebeach.Constructionhadbeencom-pletedandtheplantwasinfulloperationduringthe1977and1979surveys.Amodifieddaytimenestingsurveywasconductedin1980duringthepreliminaryconstructionoftheoceandischargestructureforSt.LuciePlantUnit2.Duringthisstudy,fourofthepreviouslyestablished1.25-km-longsurveyareasweremonitored.Additionally,eggsfromturtlenestspotentiallyendangeredbyconstructionactivitieswererelocated.Everyyearfrom1981through1990,361-km-longsurveyareascomprisingtheen-tireislandweremonitoredsevendaysaweekduringthenestingseason(Figure3).TheSt.LuciePlantUnit2dischargestructurewasinstalledduringthe1981nestingseason.OffshoreandbeachconstructionoftheUnit2intakestructureproceededthroughoutthe1982nestingseasonandwascompletedneartheendofthe1983lseason.ConstructionactivitiesassociatedwithinstallationofbothstructuresweresimilartothoseconductedwhenUnit1intakeanddischargestructureswereinstalled.Eggsfromturtlenestspotentiallyendangeredbyconstructionactivitieswererelocatedduringallthreeyears.Requirement4.2.1oftheNRC'sSt.LucieUnit2AppendixBEnvironmentalProtec-tionPlanwascompletedwithsubmissionofthe1986nestingsurveydata(ABI,1987).Thenestingsurveywascontinuedvoluntarilythrough1990withagreementfromfederalandstateagencies.Resultsarepresentedinthisreportanddiscussedinrelationtopreviousfindings.
I~pIIIIIII,)ClII Inadditiontomonitoringseaturtlenestingactivitiesandrelocatingnestsawayfromplantconstructionareas,removalofturtlesfromtheintakecanalhasbeenanintegralpartoftheSt.LuciePlantenvironmentalmonitoringprogram.Turtlesenteringtheoceanintakestructuresareentrainedwithcoolingwaterandrapidlytransportedthroughtheintakepipesintoanenclosedcanalsystemwheretheymustbemanuallycapturedandreturnedtotheocean.Sincetheplantbecameoperationalin1976,turtlesentrappedintheintakecanalhavebeensystematicallycaptured,measured,weighed,taggedandreleased.Previouspublicationsandtechnicalreportshavepresentedfindingsofthenestingsurveys,nestrelocationactivitiesandcanalcaptureprogram(Gallagheretal.,1972;WorthandSmith,1976;ABI,1978,1980a,1981a,1982,1983,1984b,1985b,1986,1987,1988,1989,1990;Williams-Wallsetal.,1983;Proffittetal.,1986;Ernestetal.,1988,1989;Martinetal.,1989a,1989b).Resultsofstudiestoassesstheeffectsofther-maldischargesonhatchlingswimmingspeedhavealsobeenreported(ABI,1978;O'ara,1980).Thepurposeofthisreportisto1)present1990seaturtlenestingsur-veydataandsummarizeobservedspatialandtemporalnestingpatternssince1971,2)documentandsummarizepredationonturtlenestssince1971,and3)present1990canalcapturedataandsummarizecomparabledatacollectedsince1976.
IIIIIII MATERIALSANDMETHODSNestinSurveMethodologiesusedduringpreviousturtlenestingsurveysonHutchinsonIslandweredescribedbyGallagheretal.(1972),WorthandSmith(1976)andABI(1978,1981a,1982,1987,1988,1989).Methodsusedduringthe1990surveyweredesignedtoallowcomparisonswiththesepreviousstudies.On11and13April1990,preliminarynestsurveyswereconductedalongHutchin-sonIslandfromtheFt.PierceInletsouthtotheSt.LucieInlet.From16Aprilthrough7September,nestsurveyswereconductedonadailybasis.After7September,severaladditionalsurveyswereconductedtoconfirmthatnestinghadceased,thelastsurveybeingconductedon14September.Biologistsusedsmalloff-roadmotorcyclestosur-veytheislandeachmorning.Newnests,non-nestingemergences(falsecrawls),andnestsdestroyedbypredatorswererecordedforeachofthe361-km-longsurveyareascomprisingtheentireisland(Figure3).Thenine1.25-km-longsurveyareasestablishedbyGallagheretal.(1972)alsoweremonitoredsocomparisonscouldbemadewithpreviousstudies.Duringthedailynestmonitoring,anymajorchangesintopographythatmayhaveaffectedthebeach'ssuitabilityfornestingwererecorded.Inaddition,eachofthe361-km-longsurveyareashasbeensystematicallyanalyzedandcategorizedbasedonbeachslope(steep,moderate,etc.),widthfromhightidelinetothedune,presenceofbenches(areasofabruptverticalrelief)andmiscellaneouscharacteristics(packed10
'lI sand,scatteredrock,vegetationonthebeach,exposedrootsontheprimarydune,etc.).Inacooperativeeffort,datafromstrandedturtlesfoundduringbeachsurveyswereroutinelyprovidedtotheNationalMaiineFisheriesService(NMFS)throughtheSeaTurtleStrandingandSalvageNetwork.IntakeCanalMonitorinMostturtlesentrappedintheSt.LuciePlantintakecanalwereremovedbymeansoflarge-meshtanglenetsfishedbetweentheintakeheadwallsandabarriernetlocatedattheHighwayA1Abridge(Figure2).Netsusedduring1990werefrom30to40minlength,3to4mdeepandcomposedof40cmstretchmeshnylontwine.Largefloatswereattachedtothesurface,andunweightedlinesusedalongthebottom.Turtlesen-tangledinthenetsgenerallyremainedatthewater'ssurfaceuntilremoved.Sinceitsinceptionin1976,ABI'scanalcaptureprogramhasbeenundercontinualreviewandrefinementinanattempttominimizebothentrapmenttimesandin-juries/mortalitiestoentrappedseaturtles.PriortoApril1990,turtlenetswereusuallydeployedonMondaymorningsandretrievedonFridayafternoons.Duringperiodsofdeployment,thenetswereinspectedforcapturesbyABIpersonnelatleasttwiceeachday(morningsandafternoons).Additionally,St.LuciePlantpersonnelcheckedthenetsperiodically,andABIwasnotifiedimmediatelyifacapturewasobserved.ABI'sseaturtlespecialistswereoncall24hoursadaytoretrievecapturedturtlesfromtheplant.11 I
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.Inthepast,theintegrityofthebarriernetwasoccassionallycompromised,andturtleswereabletomovewestofA1A.Theseturtleswerefurtherconstraineddownstreambyanunderwaterintrusiondetectionsystem(UIDS)consisting,inpart,ofalargebarrierpositionedperpendiculartothenorth-southarmofthecanal(Figure2).TheUIDSsecuritybarrieralsoconsistsof30.5cmx30.5cmmesh,butthenetisconstructedofheavychainlinksratherthanrope.12 III PriortocompletionoftheUIDSinDecember1986,turtlesuncontainedbytheA1AbarriernetwereusuallyremovedfromthecanalattheintakewellsofUnits1and2(Figure2).Theretheywereretrievedbymeansoflargemechanicalrakesorspeciallydesignednets.FollowingconstructionoftheUIDSbarrier,individualswithcarapacewidthslargerthan30.5cmwereunabletoreachtheintakewells.Thus,asrequired,tanglenetswerealsodeployedwestofA1A.ImprovementsmadetotheA1Abarriernetduring1990shouldproveeffectiveinconfiningallturtleslargerthan30.5cmtotheeasternendofthecanal.Formaldailyinspectionsoftheintakecanalweremadetodeterminethenumbers,locationsandspeciesofturtlespresent.SurfaceobservationswereaugmentedwithperiodicunderwaterinspectionsusingSCUBA,particularlyinandaroundtheA1Abar-riernetandUIDSbarrier.Becauseofthereductionintotalnettinghoursduring1990,increasedeffortwasdirectedtowardhandcaptureofturtles.Thiswasaccomplishedbydivinganduseofdipnets,anditprovedveryeffectivewhengoodwaterclaritycon-ditionsprevailed.Regardlessofcapturemethod,allturtlesremovedfromthecanalwereidentifiedtospecies,measured,weighed,tagged,andexaminedforoverallcondition(wounds,abnormalities,parasites,etc.).Healthyturtleswerereleasedintotheoceanthesamedayofcapture.Sickorinjuredturtlesweretreatedandoccasionallyheldforobserva-tionpriortorelease.Whentreatmentwaswarranted,injectionsofantibioticsandvitaminswereadministeredbyalocalveterinarian.Resuscitationtechniqueswereusedifaturtlewasfoundthatappearedtohavediedrecently.Beginningin1982,necrop-13 Ili~l sieswereconductedondeadturtlesfoundinfreshcondition;onenecropsywasper-formedduring1990.Since1982,bloodsampleshavebeencollectedandanalyzedtodeterminethesexofimmatureturtles.Bloodwasremovedfromthepaireddorsalcervicalsinusesofsub-jectturtlesusingthetechniquedescribedbyOwensandRuiz(1980).Thesamplesweremaintainedoniceandlatercentrifugedfor15minutestoseparatecellsandserum.SexdeterminationsweresubsequentlymadebyresearchersatTexasA8MUniver-sityusingradioimmunoassayforserumtestosterone(Owensetal.,1978).FloridaPower8LightCompanyandAppliedBiology,Inc.continuedtoassistotherseaturtleresearchersin1990.Data,specimensand/orassistancehavebeengiventotheFloridaDepartmentofNaturalResources,NationalMarineFisheriesService,USFishandWildlifeService,USArmyCorpsofEngineers,SmithsonianInstitution;SouthCarolinaWildlifeandMarineResourcesDivision,CenterforSeaTurtleResearch(UniversityofFlorida),TexasA&MUniversity,UniversityofRhodeIsland,UniversityofSouthCarolina,UniversityofIllinois,UniversityofCentralFlorida,UniversityofGeor-gia,VirginiaInstituteofMarineScienceandtheWesternAtlanticTurtleSymposium.StudiestoEvaluateandorMitiateIntakeEntramentAprogramthatassessedthefeasibilityofusinglightand/orsoundtodeterturtlesfromenteringtheSt.LuciePlantintakestructureswasconductedin1982and1983andcompletedinJanuary1984.Asrequired,testresultsandevaluationswerewrittenupandapresentationwasmadetotheNRC,NationalMarineFisheriesServiceandtheFloridaDepartmentofNaturalResourceson11April1984.Requirement4.2.2of Il1lI theNRC'sSt.LucieUnit2AppendixBEnvironmentalProtectionPlanisconsideredcompletedwithsubmissionofdeterrentstudyfindings.RESULTSANDDISCUSSIONNestinSurveDistributionofLoerheadNestsAlonHutchinsonIslandWhenseaturtlenestingsurveysbeganonHutchinsonIsland,nine1.25-km-longsurveyareaswereusedtoestimateloggerheadnestingactivityfortheentireisland.Since1981,all361-km-longsegmentscomprisingtheisland'scoastlinehavebeensurveyed.Regardlessoftechnique,loggerheadnestdensitieshaveshowncon-siderableannualvariationwithinindividualsurveyareas(Figures4and5).Yet,theannualspatialdistributionofthosenestsamongsurveyareashasproducedaratheruniformgradient,nestdensitiesconsistentlyincreasingfromnorthtosouth(ABI,1987).Thegradientappearstobelinearwhenonlythenine1.25-km-longsurveyareasareused(Figure4),butbecomesnon-linearwhenall361-km-longsurveyareasarein-cludedintheanalysis(Figure5).During1990thedistributionofloggerheadnestsalongtheislandwascharacterizedbyrecordhighnestingalongthenorthernandcentralpor-tionsoftheisland(Figure5).Inthepast,thepronouncedgradientobservedonthenorthernendoftheislandwasoccasionallyinfluencedbyphysicalprocessesoccurringthere;periodsofheavyaccretionreducedthegradient,whileperiodsoferosionaccentuatedit(WorthandSmith,1976;Williams-Wallsetal.,1983).However,duringrecentyearsnoconsistent IIlI relationshipwasapparentwhenfieldobservationsofbeachwidthswerecomparedtothespatialdistributionofnestsalongtheisland(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-cesorunsatisfactorynestingbeachcharacteristics.Therefore,certainfactorsmayaf-fectaturtle'spreferencetoemergeonabeach,whileotherfactorsmayaffectaturtle'tendencytonestafterithasemerged.Anindexwhichrelatesthenumberofneststothenumberoffalsecrawlsinanareais.usefulinestimatingthepost-emergencesuitabilityofabeachfornesting.Inthepresentstudythisindexistermed"nestingsuc-cess"andisdefinedasthepercentageoftotalemergencesthatresultinnests.
loHistorically,thepatternofloggerheademergencesontheislandhasgenerallyparal-leledthedistributionofnests(ABI,1987,1988),andthissametrendwasapparentin1990(Figure6).Incontrast,nestingsuccessbyloggerheadsalongtheislandhastypi-Pcallylackedgradients(Figure7).Thus,therelativelyhighnumbersofloggerheadnestsobservedincertainareasareusuallyaresultofmoreturtlescomingashoreinthoseareasratherthanofmorepreferablenestingconditionsbeingencounteredbytheturtlesaftertheyemerged.Loggerheadnestingdensitiesduring1990weregenerallyhighwhencomparedwithpreviouslyrecordedvalues(Figures4and5).Recordhighnestingwasrecordedin21ofthe36one-kilometer-longsurveyareasandwasmostnotableonthenorthernhalfoftheisland.Therewerenoapparentchangesinthephysicalcharacteristicsofthebeachthatwouldaccountforthisincreaseinnesting.Ingeneral,recordhighnestingwasduetorecordhighemergencerates,andthismayreflectanincreaseinthenum-berofnestingfemalesintheHutchinsonIslandarea.NestingsurveysonHutchinsonIslandwereinitiatedinresponsetoconcernsthattheoperationoftheSt.LuciePlantmightnegativelyimpactthelocalseaturtlerookery.Previousanalysis,usinglog-likelihoodtestsofindependence(G-test;SokalandRohlf,1981)demonstratedthattheconstructionoftheplant'soffshoreintakeanddischargestructuressignificantlyreducednestingattheplantsiteduringconstructionyears-1975,1981,1982and1983(Proffittetal.,1986;ABI,1987).However,nestingattheplantconsistentlyreturnedtolevelssimilartoorgreaterthanthoseatacontrolsiteinyearsfollowingconstruction.Thistrendcontinuedduring1990(Figure8).Thus,power plantoperationexclusiveofintake/dischargeconstructionhashadnoapparenteffectonnesting.Datacollectedthrough1990haveshownnolong-termreductioninloggerheadnestdensities,totalemergencesornestingsuccessineitherthenine1.25-km-longsurveyareasorthe361-km-longsurveyareas(Table1;Figure9).EstimatesofTotaILoerheadNestinonHutchinsonlslandVariousmethodswereusedduringsurveyspriorto1981toestimatethetotalnum-berofloggerheadnestsonHutchinsonIslandbasedonthenumberofnestsfoundinthenine1.25-km-longsurveyareas(Gallagheretal.,1972;WorthandSmith,1976;ABI,1980a).Eachofthesemethodsweresubsequentlyfoundtoconsistentlyoveres-timateislandtotals(ABI,1987).Sincewhole-islandsurveysbeganin1981,ithasbeenpossibletodeterminetheactualproportionoftotalnestsdepositedinthenineareas.Thishasthenallowedextrapolationfromtheninesurveyareastotheentireislandforyearspriorto1981.From1981through1990thetotalnumberofnestsinthenineareasvariedfrom32.5to35.6percentofthetotalnumberofnestsontheisland(Table1).Thisisslight-lyhigherthanthe31.3percentwhichwouldbeexpectedbasedstrictlyonthepropor-tionoflinearcoastlinecomprisedbythenineareas.Usingtheten-yearmeanof33.8percent,estimatesofthetotalnumberofnestsonHutchinsonIslandcanbecalculatedbymultiplyingthenumberofnestsinthenineareasby2.96.Thistechnique,whenap-pliedtotheninesurveyareasduringthetenyearsinwhichtheentireislandwassur-veyed,producedwhole-islandestimateswithin5.3percentoftheactualnumberof18 IIl nestscounted.Becausetheproportionofnestsrecordedintheninesurveyareasremainedrelativelyconstantoverthelasttenyears,thisextrapolationprocedureshouldprovideafairlyaccurateestimateoftotalloggerheadnestingforyearspriorto1981.ItisclearthatloggerheadnestingactivityonHutchinsonIslandfluctuatescon-siderablyfromyeartoyear(Table1).Annualvariationsinnestdensitiesalsoarecom-monatotherrookeries(Hughes,1976;DavisandWhiting,1977;Ehrhart,1980)andmayresultfromtheoverlappingofnon-annualbreedingpopulations.Nonetheless,datacollectedthrough1990suggestanoverallincreaseinnestingonHutchinsonIs-landsincesurveysbeganin1971.Totalnestingactivitywasgreatestduring1990when6,700loggerheadnestswererecorded.Norelationshipsbetweentotalnestingactivityandpowerplantoperationorintake/dischargeconstructionwereindicatedbyyear-to-yearvariationsintotalnestingonHutchinsonIsland.TemoralLoerheadNestinPatternsTheloggerheadturtlenestingseasonusuallybeginsbetweenmid-AprilandearlyMay,attainsamaximumduringJuneorJuly,andendsbylateAugustorearlySep-tember(ABI,1987).Nestingactivityduring1990followedthissamepattern(Figure10).CoolwaterintrusionsfrequentlyoccuroverthecontinentalshelfofsoutheastFloridaduringthesummer(TaylorandStewart,1958;Smith,1982).WorthandSmith(1976),Williams-Wallsetal.(1983)andABI(1982,1983,1984b,1985b,1986,1987,1988,1989,1990)suggestedthattheseintrusionsmayhavebeenresponsibleforthetemporarydeclinesinloggerheadturtlenestingactivitypreviouslyobservedonHutchinsonIs-19 IIIIII land.Similarly,asubstantialdecreaseinnestingduringmid-July1990wasapparentlyduetoanintrusionofcoolwater(Figure10).Thoughnaturalfluctuationsintemperaturehavebeenshowntoaffecttemporalnest-ingpatternsonHutchinsonIsland,therehasbeennoindicationthatpowerplantopera-tionhasaffectedthesetemporalpatterns(ABI,1988)~PredationonLoerheadTurtleNestsSincenestsurveysbeganin1971,raccoonpredationprobablyhasbeenthemajorcauseofturtlenestdestructiononHutchinsonIsland.Researchersatotherlocationshavereportedraccoonpredationlevelsashighas70tonearly100percent(DavisandWhiting,1977;Ehrhart,1979;Hopkinsetal.,1979;Talbertetal.,1980).Raccoonpreda-tionofloggerheadturtlenestsonHutchinsonIslandhasnotapproachedthislevelduringanystudyyear,thoughlevelsforindividual1.25-km-longareashavebeenashighas80percent.Overallpredationratesforsurveyyears1971through1977werebetween21and44percent,withahighof44percentrecordedin1973.Apronounceddecreaseinraccoonpredationoccurredafter1977,andoverallpredationratesforthenineareashavenotexceeded10percentsince1979.AdeclineinpredationratesonHutchinsonIslandhasbeenvariouslyattributedtotrappingprograms,constructionactivities,habitatlossanddisease(Williams-Wallsetal.,1983;ABI,1987).During1990,sixpercent(406)oftheloggerheadnests(n=6,700)ontheislandweredepredatedbyraccoons.Asinpreviousyears(ABI,1989),predationofturtlenestswasprimarilyrestrictedtothemostundevelopedportionoftheisland(i.e.,AreasEthroughS;Figure11).20 IIIIIII Ghostcrabshavebeenreportedbynumerousresearchersasimportantpredatorsofseaturtlenests(BaldwinandLofton,1959;Schulz,1975;Diamond,1976;Fowler,1979;Hopkinsetal~,1979;Stancyk,1982).ThoughturtlenestsonHutchinsonIslandprobablyhavebeendepredatedbyghostcrabssincenestingsurveysbeganin1971,thissourceofnestdestructiondidnotbecomeapparentuntil1983.Quantificationofghostcrabpredationwasinitiatedthesameyear.Overallpredationratesbyghostcrabshavevariedfrom0.1to2.1percentfrom1983-1989(ABI,1990).During1990,0.4percent(27)oftheloggerheadnests(n=6,700)ontheislandweredestroyedbyghostcrabs(Figure11).Nestsdestroyedbyacombinationofraccoonandghostcrabpredationhavebeenincludedasraccoonpredationsinpreviousdiscussions.Whenthesecombinationpredationsareincludedascrabpredations,theoverallpredationratesbyghostcrabsrangefrom0.4to3.2percent.During1990,1.4percent(96nests)weredestroyedbyeitherghostcrabsoracombinationofghostcrabsandraccoons.GreenandLeatherbackTurtleNestinGl'eenandleatherbackturtlesalsonestonHutchinsonIsland,butinfewernumbersthanloggerheadturtles.Priorto1981,bothsurvey(nine1.25-km-longsections)andinter-surveyareasweremonitoredforthepresenceofgreenandleatherbacknests.Thirty-onekilometersofbeachfromArea1southtotheSt.LucieInletwereincludedinthateffort.Duringwhole-islandsurveysfrom1981through1990,onlytwoof182Ieatherbacknestsandonlysevenof601greennestswererecordedonthefivekilometersofbeachnorthofArea1.Therefore,previouscountsofgreenandleather-21 III backnestswithinthe31kilometerssurveyedwereprobablynotappreciablydifferentfromtotaldensitiesfortheentireisland.Basedonthisassumption,greenandleather-backnestdensitiesmaybecomparedamongallsurveyyears,except1980,whenlessthan15kilometersofbeachweresurveyed.Priorto1990,thenumberofnestsobservedontheislandrangedfrom5to74forgreenturtlesandfrom1to36forleatherbacks(Figure12).Duringthe1990survey,132greenturtleand12leatherbackturtlenestswererecordedonHutchinsonIsland.Temporalnestingpatternsforthesespeciesdifferfromthepatternforloggerheadturtles.GreenturtlestypicallynestonHutchinsonIslandfrommid-JunethroughthefirstorsecondweekofSeptember.During1990,greenturtlesnestedfrom28Maythrough11September.Leatherback'turtlesusuallynestontheislandfrommid-Aprilthroughearlytomid-July.During1990thisspeciesnestedfrom10Aprilthrough3July.Considerablefluctuationsingreenturtlenestingontheislandhaveoccurredamongsurveyyears(Figure12).Thisisnotunusualsincetherearedrasticyear-to-yearfluc-tuationsinthenumbersofgreenturtlesnestingatotherbreedinggrounds(Carretal.,1982).Despitethesefluctuations,datacollectedthrough1990suggestanoverallin-creaseinnestingsince1971andmayreflectanincreaseinthenumberofnestingfemalesintheHutchinsonIslandarea.During1990,greenturtlesnestedmostfrequent-lyalongthesouthernhalfoftheisland.Thisisconsistentwithresultsofprevioussur-veys.LeatherbackturtlenestdensitieshaveremainedlowonHutchinsonIsland;however,increasednestingduringrecentyears(Figure12)mayreflectanoverallincreaseinthe22 numberofnestingfemalesintheHutchinsonIslandarea.During1990,leatherbackturtlesprimarilynestedonthesouthernhalfoftheisland.IntakeCanalMonitorinEntrainmentofseaturtlesattheSt.LuciePlanthasbeenattributedtothepresumedphysicalattractivenessoftheoffshorestructureshousingtheintakepipesratherthantoplantoperatingcharacteristics(ABI,1980band1986).Evenwhenbothunitsareoperatingatfullcapacity,turtlesmustactivelyswimintothemouthofoneoftheintakepipesbeforetheyencountercurrentvelocitiessufficientlystrongtoeffectentrainment.Consequently,aturtle'sentrapmentrelatesprimarilytotheprobabilitythatitwilldetectandsubsequentlyenteroneoftheintakestructures.Assumingthatdetectiondistan-cesdonotvaryappreciablyovertimeandthatallturtles(oraconstantproportion)areequallyattractedtothestructures,capturerateswillvaryproportionallytothenumberofturtlesoccurringinthevicinityofthestructures.Ifthisassumptionistrue,datafromthecanalcaptureprogramshouldreflectnaturalvariabilityinthestructureofthepopula-tionbeingsampled.RelativeAbundanceandTemoralDistributionDuring1990,132seaturtlecapturestookplaceintheintakecanaloftheSt.LuciePlant(Table2).OfthefivespeciesofseaturtlesinhabitingcoastalwatersofthesoutheasternUnitedStates,onlytwowererepresentedinthisyear'scatches:112log-gerheadsand20greenturtles.SinceintakecanalmonitoringbeganinMay1976,1,853loggerhead(including99recaptures),306green(including1recapture),9leatherback,8hawksbilland17Kemp'sridleycaptureshavetakenplaceattheSt.LuciePlant.23 Annualcatchesofloggerheadsincreasedsteadilyfromalowof33in1976(partialyearofplantoperationandmonitoring)to172in1979(Figure13).Afterdecliningbe-tween1979and1981,yearlycatchesofloggerheadsagainrosesteadily,reachingahighof195during1986.Captureshavebeenindeclinesince1986,decreasingmorethan40percentoverthelastfouryears.TwooffshoreintakestructureswereinplacepriortoUnit1start-upin1976;thethirdandlargeststructurewasinstalledduring1982-1983.Eventhoughallthreestructuresareinrelativelycloseproximity,theadditionofanotherpipemayhaveincreasedtheprobabilityofaturtlebeingentrained.Becausethischangecannotbequantified,datacollectedpriorto1982maynotbecomparablewiththatcollectedafter1983.Addition-ally,theinfluenceoftheconstructionitselfonseaturtleentrainmentduring1982and1983isunknown.Withtheseconsiderationsinmind,neitheralong-termincreasenordecreaseinthenumberofloggerheadscapturedattheSt.LuciePlantcanbeinferredfromthedata.During1990,themonthlycatchofloggerheadsrangedfrom1(November)to25(June),withamonthlymeanof9.3(+7.0;Table3).ThenumberofcapturesduringMay,JuneandJulywereconsiderablyaboveaverage,whilecapturesthroughouttheIremainderoftheyearweremoderatelytoconsiderablylowerthanaverage(Figure14).Overtheentiremonitoringperiod,monthlycatcheshaverangedfrom0to39;thegreatestnumberofcapturesoccurredduringJanuary1983.Whendatafromallfullyearsofmonitoring(1977-1990)werecombined,thehighestnumberofloggerheadcapturesoccurredinJanuary(11.8percent);fewestcaptures24 IlIlII wererecordedinNovemberandDecember(Table3).However,monthlycatcheshaveshownconsiderableannualvariability.Monthshavingrelativelylowcatchesoneyearoftenhavehadrelativelyhighcatchesinanother.Catchesofgreenturtlesalsohavevariedwidelyamongyears,rangingfrom0in1976(partialyearofsampling)to69in1984(Table4).During1990,20individualswerecaptured.Theaverageannualcatchofgreenturtles,excluding1976,was21.9(+18.0).Althoughhighlyvariable,annualcapturedataforgreenturtlessuggestalong-termin-creaseinthenumberofindividualsinhabitingthenearshorecoastalareaadjacenttotheplant(Figure13).Again,however,theinfluenceoftheadditionofathirdintakepipeduring1982-1983onthesedataisnotknown.Greenturtleshavebeencaughtduringeverymonthoftheyear,withaveragemonth-lycatchesforallyearscombinedrangingfrom0.3inSeptemberto7.1inJanuary(Table4).Seasonalabundancepatternsofgreensaremuchmorepronouncedthanforlog-gerheads,nearly60percentofallcapturesoccurringduringthethreemonthperiodbetweenJanuaryandMarch.During1990,thelargestnumberofgreens(6)werecap-turedinJanuary.Themostgreensevercaughtinonemonthwas37inJanuary1984.Catchesofleatherbacks,hawksbillsandKemp'sridleyshavebeeninfrequentandscatteredthroughoutthe15yearstudyperiod(Table2).Eachspecieshasshownratherpronouncedseasonaloccurrences;allbuttwoofthenineleatherbackswerecollectedbetweenFebruaryandMay,sevenoftheBighthawksbillswerecollectedbetweenJuneandSeptember,andallbuttwoofthe17Kemp'sridleyswerecaughtbetweenNovemberandApril.25 Size-lassDistribtionAlthoughseveralstraight-lineandcurvedmeasurementswererecordedforturtlesremovedfromtheintakecanal,onlyonestraight-linemeasurementhasbeenusedinanalysespresentedhere.Straight-linecarapacelength(SLCL)wasmeasuredfromtheprecentralscutetothenotchbetweenthepostcentralscutes(minimumcarapacelengthofPritchardetal.,1983).Todate,loggerheadsremovedfromtheintakecanalhaverangedinlength(SLCL)from40.2to112.0cm(x=66.8+13.7cm)andinweightfrom10.7kgto169.6kg(x=49.2+31.0kg;Figures15and16).Acarapacelengthof70cmapproximatesthesmallestsizeofnestingloggerheadfemalesobservedalongtheAtlanticeastcoast(Hirth,1980).However,adultscanonlybereliablysexedonexternalmorphologicalcharacteristics(e.g.,relativetaillength)afterobtainingalengthofabout85cm.Previously,80.0cmwasusedasthelowerlimitforadultturtles.However,recentdatasuggestthatsomemalesmaynotmature,andthusmightnotbedistinguishablefromfemales,untiltheyattainaslightlylargersize.Basedonthesedivisions,dataweresegregatedintothreegroups:juveniles(<70cm),adults(>85cm)andtransitional(71-85cm).Thelattergroupprobablyincludessomematureandsomeimmatureindividuals.Ofthe1,744capturesbetween1977and1990forwhichlengthdatawerecollected,69percentwerejuveniles,themajorityofthesemeasuringbetween50and70cmSLCL(Table5).Adultsaccountedforabout15percentofallcaptures,withtheremaining16percentcomprisedofanimalsinthetransitionalsizeclass.Similarsize-frequencydistributions,indicatingapreponderanceofjuveniles,havebeenreportedforthe26 IIII Mosquito/IndianRiverLagoon(MendoncaandEhrhart,1982),theCanaveralshipchannel(Henwood,1987),andGeorgiaandSouthCarolina(Hillestadetal.,1982).ThesedatasuggestthatcoastalwatersofthesoutheasternUnitedStatesconstituteanimportantdevelopmentalhabitatforCarettacaretta.Seasonalpatternsofabundanceforvarioussizeclassesindicatedthatjuvenilelog-gerheadswereslightlymoreabundantduringthewinterthanatothertimesoftheyear(Table5).About45percentofthejuvenileswerecapturedbetweenJanuaryandApril.AbundancesdecreasedinspringandremainedrelativelyconstantduringthesummerandearlyfallbeforedecreasingagaintolowestlevelsinNovemberandDecember.Theseasonaldistributionofadultloggerheadswasmuchmorepronounced,76per-centofallcapturesoccurringbetweenMayandAugust,Thisrepresentsthemajorpro-tionofthenestingseasononHutchinsonIsland.Greenturtlesremovedfromtheintakecanalovertheentirestudyperiodrangedinsizefrom20.0to108.0cmSLCL(x=35.8+14.3cm)and0.9kgto177.8kg(x=9.4+20.2kg;Figures17and18)~Nearlyall(96percent)werejuveniles.About80per-centwere40cmorlessinlength,and66percentweighed5kilogramsorless.Theseimmatureturtlesexhibiteddistinctwinterpulsessuggestingmigratorybehavior(Table4).However,someimmaturegreenturtleswerepresentthroughouttheyear.Todate,onlyeightadultgreenturtles(SLCL>83cm;WitheringtonandEhrhart,1989)havebeenremovedfromthecanal;ailwerecapturedduringorshortlyafterthenestingseason.27 IIl Theeighthawksbillsremovedfromthecanalrangedinsizefrom34.0to70.0cmSLCL(x=46.2+12.9cm)andinweightfrom6.4to52.2kg(x=17.3+16.6kg).Allbutonewerejuveniles(SLCL<63cm;Witzell,1983).Similarly,allbutoneofthe17Kemp'sridleyscapturedattheSt.LuciePlantwerejuveniles(SLCL<60.0cm;Hirth,1980).Carapacelengthsfortheridleysrangedfrom27.0to62.0cmSLCL(x=36.1+9.7cm)andweightsfrom3.1to31.8kg(x=8.0+8.1kg).Thenineleatherbacksremovedfromthecanalrangedinlengthfrom112.5to150.0cm,andatleastsevenwereadults(SLCL>121cm;Hirth,1980).Thelargestleatherbackforwhichanac-curateweightwasobtained,afemalewithacurvedcarapacelengthof158.5cm,weighed334.8kg.~SxRatiosSinceintakecanalmonitoringbeganin1976,255adultloggerheads(SLCL>85.0cm)havebeensexed.Femalespredominatedmalesbyaratioof5.4:1.0,whichsig-nificantlydepartsfroma1:1ratio(X,P<0.05).Consequently,temporalpatternsinthenumberofadultloggerheadcaptureswereheavilyinfluencedbythenumbersoffemalespresent.Whensexeswereseparated,itisevidentthatmaleswererelativelyevenlydistributedamongmonths,whereas90percentofthefemalesweretakenduringthenestingseason(MaythroughSeptember;Figure19).ThenumberofadultfemaleloggerheadscapturedattheSt.LuciePlanthasin-creasedsteadilyoverthelastsevenyears.From1977through1983,anaverageof4.4adultfemales(+3.2;range=1-10)wereentrappedeachyear,whereassincethen,anaverageof26.3femalesperyear(+6.7;range=16-35)werecaptured.Thisin-28 creasecorrespondstoageneralriseinloggerheadnestingactivityneartheplant(Figure20).Increasednearshoremovementassociatedwithnestingincreasestheprobabilityofaturtledetectingoneoftheintakestructuresandhencetheprobabilityofentrainment.Althoughtheadditionofthethirdoffshoreintakestructuremayhaveaccountedforsomeoftheincreaseinthenumberofadultsentrainedsince1983,thecontinuedriseoverthelastsevenyearssuggestsagenuineincreaseinthenumberoffemalesoccurringinthevicinityoftheplant.BetweenSeptember1982andDecember1986,267individualjuvenileandsub-adultloggerheadturtlescapturedinthecanalweresexedbyTexasA8MUniversityre-searchersusingabioimmunoassaytechniqueforbloodserumtestosterone.Aspre-viouslyreported,femalesoutnumberedmalesbyaratioof2.3:1.0(ABI,1989).ThesefindingsareconsistentwiththosereportedforsamplestakenfromtheCapeCanaveralshipchannel(1.7:1.0)andtheIndianRiverLagoon(1.4:1.0),wheresexratiosarealsosignificantlyskewedinfavoroffemales(Wibbelsetal.,1984).Bloodsamplescollectedsince1986arecurrentlybeinganalyzedandtheseresultswillprovideavaluabletoolforassessingtemporalvariabilityinthesexratiosofthelocalloggerheadpopulation.Oftheeightadultgreenturtlescapturedsincemonitoringbegan,sixweremalesandtwowerefemales.Siximmaturegreenturtleshavebeensexedthroughbloodwork;allhavebeenfemales.Ofthesixadultleatherbackturtlesforwhichsexwasrecorded,threewerefemalesandthreeweremales.TheadulthawksbillandKemp'sridleywerebothfemales.Nosexinformationexistsforjuvenilesofthesespecies.29 CatureEfficienciesCapturemethodologieshavebeenundercontinualreviewandrefinementasnetmaterials,configurationsandplacementwerevariedinanefforttominimizeseaturtleentrapmenttimes.Concurrently,alternativecapturetechniqueswereevaluatedandpotentialdeterrentsystemstestedinthelaboratory.Duringthisperiod,captureefficien-ciesvariedinrelationtonettingeffortandtheeffectivenessofthesystemsdeployed.Acapture/recapturestudyconductedintheintakecanalbetweenOctober1980andJanuary1981indicatedthatmostturtlesconfinedbetweentheA1Abridgeandtheintakeheadwallswerecapturedwithintwoweeksoftheirentrainment(ABI,1983)~Basedonmorerecentformaldailyinspections,itappearsthatcaptureefficiencieshavefurtherimproved.Nearly50percentoftheturtlesenteringthecanalarenowcaughtwithin24hoursoffirstsighting,andalmost90percentarecapturedduringtheirfirstweekofentrapment(Figure21).Averagecaptureefficiency,expressedaselapseddaysbetweenfirstsightingandcapture,duringtheperiodfromAprilthroughDecem-ber1990was3.9days(+6.8days;range=1-50days).Betterutilizationofcurrentsandeddies,adjustmentstotetheringlines,multi-netdeploymentsandincreasedef-fortstohandcaptureturtleshavecontributedtoreducedentrapmenttimes.EntrapmenttimesmaybeextendedforturtlesswimmingpasttheA1Abarriernet(ABI,1987).Occasionally,thetopofthenethasbeensubmergedortheanchorcablepulledfreefromthebottom,allowinglargerturtlestopass;turtleswithcarapacewidthslessthanabout30.5cmcanswimthroughthelargemesh.BecausecaptureeffortswestoftheA1Abridgehavegenerallybeenlesseffectivethanthoseneartheintake30 headwalls,mostturtlesbreachingthebarriernetwerenotcaughtuntiltheyenteredtheintakewellsofUnits1and2.PriortoinstallationoftheUIDSbarrierin1986,about15percentofallturtlesentrappedinthecanalwereremovedfromtheintakewells.Be-causeoftheirrelativelysmallsizes,amuchlargerproportionofgreens(51.6percent)reachedtheplantthanloggerheads(10.1pel'cent).Since1986,thepercentageofgreenscaughtattheintakewellshasdecreasedslightly(35.1percent),whilealllog-gerheadshavebeenpreventedfromreachingtheplant.MajorrenovationsweremadetotheA1Abarriernetduring1990tofurtherreducethepotentialforturtleslargerthan30.5cmbecomingtrappedbetweenA1AandtheUIDS.Twologgerheads(lessthan2percentofallloggerheadcaptures)breachedtheA1Abarriernetpriortocompletionofthesemodifications.BothwereremovedfromthecanalattheUIDSbarrier.Additionally,twosmallgreenturtlespassedthroughtheA1Abarriernetandwereremovedattheplant'sintakewells.Thus,nearly97percentofallturtlesentrappedinthecanalduring1990werecapturedbynettingorbyhandeastoftheA1Abridge.TheeffectiveconfinementofturtleseastofA1Awasanothermajorcontributortothehighcaptureefficiencyachievedduring1990.RelativeConditionTurtlescapturedaliveintheintakecanaloftheSt.LuciePlantwereassignedarela-tiveconditionbasedonweight,activity,parasiteinfestation,barnaclecoverage,wounds,injuriesandanyotherabnormalitieswhichmighthaveaffectedoverallwell-being.During1990,92.9percent(104)ofallloggerheadsfoundinthecanalwerealiveandingoodtoexcellentcondition.Only6.3percent(7)ofloggerheadcapturesin-31 IIIII volvedindividualsinfairorpoorcondition;oneloggerheadwasdeadwhenremovedfromthecanal.Ofthe20greenturtlesremovedfromtheintakecanalduring1990,16wereingoodtoexcellentcondition,twowereinfairconditionandtwoweredead.Overtheentiremonitoringperiod,about76and78percent,respectively,ofalllog-gerheadandgreencaptureshaveinvolvedturtlesingoodtoexcellentcondition(Table6).Capturesofindividualsinfairtopoorconditionhaveoccurredabout16percentofthetimeforloggerheadsand14percentofthetimeforgreens.Allofthehawksbillsandleatherbackshavebeenremovedfromthecanalingoodtoexcellentcondition,whileabouthalfoftheKemp'sridleyshavefallenintothesecategories.Relativeconditionratingscanbeinfluencedbyanumberoffactors,somerelatedandothersunrelatedtoentrainmentand/orentrapmentintheintakecanal.Ratingsofgoodtoexcellentindicatethatturtleshavenotbeennegativelyimpactedbytheirentrap-mentinthecanal,atleastasevidencedbyphysicalappearance.Althoughratingsoffairorpoorimplyreducedvitality,theextenttowhichentrainment/entrapmentisresponsibleisoftenindeterminable.Insomeinstances,conditionsresponsibleforlowerratings,suchasinjuries,obviouslyweresustainedpriortoentrainment.During1990,aboutninepercent(10)ofallloggerheadcapturesinvolvedindividualswithnoticeableinjuries,suchasmissingappendages,brokenormissingpiecesofcarapaceanddeeplacerations.Mostofthesewereold,well-healedwounds,andnonewereseriousenoughtorequiremedicalattention.Noneofthegreenturtlescapturedduring1990hadmajorinjuries.32 IIIIIIII
~MrtalitieMortalitieshavebeencloselymonitoredthroughoutthelifeofthecanalcaptureprograminanattempttoassignprobablecausesandtakeappropriateremedialac-tiontominimizefutureoccurrences.Previousanalysesofcapturedataidentifieddrown-inginnets(A1Abarriernet,UIDSbarrier,andtanglenets),drowningintheintakepipesduringperiodsofreducedintakeflow,injuriessustainedfromdredgingoperationsandinjuriessustainedfromthemechanicalrakesusedintheintakewellsasprobablemor-talityfactors(ABI,1987).Althoughdifficulttoquantify,theentrapmentandsubsequentdemiseofinjuredorsickturtleshasprobablyaccountedforaportionofobservedmor-talities.Overtheentire15yearmonitoringperiod,127(6.9percent)ofthe1,853logger-headsand21(6.9percent)ofthe306greenturtlesentrappedinthecanalwerefounddead(Table6).Mortalitiesspannedtherangeofsizeclassesforloggerheads(SLCL=47.5-103cm),whileallgreenturtlemortalitiesinvolvedjuvenileslessthan42cminlength.ThefourKemp'sridleymortalitiesdocumentedattheplantduring1987and1988wel'etheonlydeathsforthisspeciestodate;noleatherbackorhawksbillmor-talitieshaveoccurredattheSt.LuciePlant.Modificationstocaptureprocedures,improvementstotheA1Abarriernetandvir-tualeliminationoflowflowconditionswithinthecanalhaveresultedinasubstantialreductioninseaturtlemortalitiesoverthelifeofthecanalcaptureprogram.Mortalityrates,expressedasthepercentageoftotalcapturesinvolvingdeadanimals,declined42percentbetweenthefirst(1976-1983)andsecond(1984-1990)halvesofthe33 IIIIIIIIII program.During1990,onlythreemortalities(2.3percentoftotalcaptures)wererecorded,oneloggerheadandtwogreenturtles.Thisrepresentsthefewestannualmortalitiessincethecanalcaptureprogrambeganin1976.PreviousobservationssuggestthatsickorinjuredturtlesmaybesusceptibletodrowningattheUIDSbarrier.Theloggerheadmortalityrecordedduring1990occurredatthislocation.Eventhoughthecarcasswastoodecomposedtoassessitsphysicalconditionordeterminecauseofdeath,drowningissuspected.Additionalimprove-mentstotheA1Abarriernetduringthelaterpartof1990shouldpreventfuturelogger-headmovementswestofA1AandtherebyeliminatetheUIDSbarrierasapotentialmortalitysource.Thetwogreenturtlemortalitiesduring1990resultedfromdrowninginABI'stanglenets.Oneofthesewasresuscitated,butitlatersuccumbedwhileunderobservation.Anecropsywasperformedtodetermineifitwasinpoorhealthatthetimeofcapture;resultsoftissueanalyseshavenotyetbeencompleted.Toeliminatethepotentialforfuturenetdrownings,ABIhasbeguncontinualmonitoringofitstanglenetsduringperiodsofdeployment.RecatureIncidentSincetheSt.LuciePlantcaptureprogrambegan,mostturtlesremovedalivefromtheintakecanalhavebeentaggedandreleasedintotheoceanatvariouslocationsalongHutchinsonIsland.Consequently,individualturtlescanbeidentifiedaslongastheyretaintheirtags.Overthe15yearhistoryofturtleentrapmentattheSt.LuciePlant,61individuals(60loggerheadsand1green)havebeenremovedfromthecanalmore34 thanonce.Severalotherturtleswithtagscarshavealsobeenrecovered,indicatingthattheactualnumberofrecapturesmaybehigher.Ofthe60individualloggerheadsknowntohavebeencaughtmorethanonce,42werecaughttwice,9werecaughtthreetimes,5werecaughtfourtimes,2werecap-turedsixtimes,1wascaughtseventimesand1wascaughtonnineseparateoc-casions,yieldingatotalof99recaptureincidents.Releasesitedidnotappeartohaveanyeffectonaturtle'sprobabilityofbeingrecaptured.Turtlesreleasedbothnorthandsouthoftheplantreturned.Recapturesalsodidnotappeartoberelatedtosize,asbothjuvenilesandadultswerecapturedmorethanonce(rangeofSLCL=47-89cm).However,themajorityofrecaptureincidentsinvolvedjuveniles(SLCL<70cm).Recaptureintervalsforloggerheadsrangedfromfourto858days,withameanof157days(+174.0days).Theonlygreenturtlecaughtmorethanoncewascapturedontwooccasions,returningtothecanal59daysafterfirstbeingreleasedintotheocean.About56percentofallloggerheadrecaptureincidentsoccurredwithin90daysofpreviouscaptureand89percentwithinoneyear(Figure22).Theaverageintervalbetweenfirstandlastcapturewas262days(+329.7days).Thelongestperiodbe-tweenfirstandlastcapturewas5.3years.ThesedatasuggestthatresidencytimesofloggerheadswithinthenearshorehabitatadjacenttotheSt.LuciePlantarerelativelyshort.SimilarfindingshavebeenreportedforloggerheadsinhabitingtheMosquito/In-dianRiverLagoonsofeast-centralFlorida(MendoncaandEhrhart,1982).35 SUMMARYAgradientofincreasingloggerheadturtlenestdensitiesfromnorthtosouthalongthenorthernhalfofHutchinsonIslandhasbeenshownduringmostsurveyyears.Thisgradientmayresultfromvariationsinbeachtopography,offshoredepthcontours,dis-tributionofnearshorereefs,onshoreartificiallightingandhumanactivityonthebeachatnight.Lownestingactivityinthevicinityofthepowerplantduring1975andfrom1981through1983wasattributedtoconstructionofpowerplantintakeanddischargesystems.Nestingreturnedtonormalorabovenormallevelsfollowingbothperiodsofconstruction.Powerplantoperation,exclusiveofintake/dischargeconstruction,hashadnosignificanteffectonnestdensities.Therehavebeenconsiderableyear-to-yearfluctuationsinloggerheadnestingac-tivityonHutchinsonIslandfrom1971through1990.Fluctuationsarecommonatotherrookeriesandmayresultfromoverlappingofnon-annualbreedingpopulations.Despitethesefluctuations,loggerheadnestingactivityhasremainedhighduringrecentyearsandmayreflectanoverallincreaseinthenumberofnestingfemalesintheHutchinsonIslandarea.Norelationshipbetweentotalnestingontheislandandpowerplantoperationorintake/dischargeconstructionwasindicated.TemporarydeclinesinloggerheadnestingactivityhavebeenattributedtocoolwaterintrusionsthatfrequentlyoccuroverthecontinentalshelfofsoutheastFlorida.ThoughtemporalnestingpatternsoftheHutchinsonIslandpopulationmaybeinfluencedbynaturalfluctuationsinwatertemperature,nosignificanteffectsduetopowerplantoperationhavebeenindicated.36 Sincenestingsurveysbeganin1971,raccoonpredationwasconsideredthemajorcauseofturtlenestdestructiononHutchinsonIsland.From1971through1977,over-allpredationratesintheninesurveyareaswerebetween21and44percent.However,apronounceddecreaseinraccoonpredationoccurredafter1977,andoverallpreda-tionratesintheninesurveyareashavenotexceededtenpercentsince1979.Decreasedpredationbyraccoonsprobablyreflectsadeclineintheraccoonpopula-tion.During1990,132greenturtleand12leatherbackturtlenestswererecordedonHutchinsonIsland.Nestingactivitybythesetwospeciesexhibitedconsiderableannualfluctuations,ashasbeenrecordedatotherrookeries,buthasremainedrelativelyhighduringrecentyears.ThismayreflectanoverallincreaseinthenumberofnestinggreenandleatherbackturtlesintheHutchinsonIslandarea.During1990,112loggerheadsand20greenturtleswereremovedfromtheSt.LuciePlantintakecanal.SincemonitoringbeganinMay1976,1,843loggerhead,306green,9leatherback,8hawksbilland17Kemp'sridleyturtleshavebeencaptured.Overthelifeofthemonitoringprogram,annualcatchesforloggerheadturtleshaverangedfrom33in1976(partialyearofplantoperationandmonitoring)toahighof195in1986.Yearlycatchesofgreenturtleshaverangedfrom0in1976to69in1984.Differencesinthenumberofturtlesentrappedduringdifferentyearsandmonthsareattributedtonaturalvariationintheoccurrenceofturtlesinthevicinityoftheoffshoreintakestruc-tures,ratherthantoanyinfluenceoftheplantitself.37 IIII Size-classdistributionsofloggerheadturtlesremovedeachyearfromthecanalhaveconsistentlybeenpredominatedbyjuvenilesbetween50and70cminstraightlinecarapacelength.Mostgreenturtlesentrappedinthecanal(about80percent)werejuveniles40cmorlessinlength.Forbothspecies,thelargestnumberofcapturesforallyearscombinedoccurredduringthewinter,buttheseseasonalpeaksweremuchmorepronouncedforgreenturtles.Sexratiosofbothadultandimmatureloggerheadscaughtinthecanalcontinuedtobebiasedtowardsfemales.During1990,about93and80percent,respectively,ofallloggerheadsandgreenturtlesremovedfromthecanalwerecategorizedbyphysicalappearanceasbeingingoodtoexcellentcondition.Overtheentire15yearmonitoringperiod,76and78per-cent,respectively,ofallloggerheadandgreenturtlecaptureshaveinvolvedindividualsinthesecategories;16percentoftheloggerheadsand14percentofthegreenturtlesremovedfromthecanalhavebeeninfairorpoorcondition.Aboutninepercentoftheturtlesremovedfromtheintakecanalduring1990hadsubstantialinjuries.However,mostoftheseinjuriesweresustainedpriortoentrap-ment.Onceinthecanal,turtlesconfinedeastofA1Ausuallyhadverybriefresidencytimesandthustherelativeconditionofmostturtleswasnotaffectedbytheirentrap-ment.During1990,oneloggerheadandtwogreenturtlemortalitiesoccurredintheintakecanal.Thesedeathsprobablyresultedfromdrowning:twoinABItanglenets,oneattheUIDSbarrier.Programmodificationstopermitcontinualsurveillanceoftanglenets38 IIII duringperiodsofdeploymentandimprovementstotheA1Abarriernetwereinitiatedtofurtherreducethepotentialforsimilarmortalitiesinthefuture.Sinceintakecanalmonitoringbeganin1976,6.9percentoftheloggerheadsandasimilarpercentageofgreenturtlesremovedfromthecanalweredead.ThefourKemp'sridleymortalitiesin1987and1988weretheonlydeathsrecordedforthisspeciessincemonitoringbegan.AlloftheleatherbacksandhawksbillsentrappedintheintakecanalattheSt.LuciePlanthavebeencapturedaliveandreleasedintotheocean.Modifica-tionstocaptureprocedures,improvementstotheA1Abarriernetandvirtualelimina-tionoflowflowconditionsinthecanalhasresultedina42percentreductioninseaturtlemortalityratesoverthelifeofthecanalcaptureprogram.39 IIIIIII 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Hopkins,S.R.,T.M.Murphy,Jr.,K.B.StansellandP.M.Wilkinson.1979.BioticandabioticfactorsaffectingnestmortalityintheAtlanticloggerheadturtle.ProceedingsAnnualConferenceofSoutheasternFishandWildlifeAgencies32:213-223.Hughes,G.R.1974.TheseaturtlesofsoutheastAfrica,1.Status,morphologyanddistribu-tions.SouthAfricanAssociationforMarineBiologicalResearch,OceanographicResearchInstitute,InvestigationalReportNo.35:1-144..1976.IrregularreproductivecyclesintheTongalandloggerheadseaturtle,Carettacaretta(L.)(Cryptodira:Chelonidae).ZoologicaAfricana11(2):285-291.Lyons,W.G.1989.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.PartXI.Mollusks.FloridaMarineResearchPublication47:1-131.Martin,R.E.,R.G.Ernest,N.W.WallsandJ.R.Wilcox.1989a.SizedistributionandseasonalabundanceofloggerheadandgreenturtlesinnearshorewatersoffHutchinsonIsland,Florida.Pages334-335inOgren,L.,F.Berry,K.Bjorndal,H.Kumpf,R.Mast,G.Medina,H.ReichartandR.Witham,editors.ProceedingsoftheSecondWesternAt-lanticTurtleSymposium.Mayaguez,PuertoRico,12-16October1987.NOAATechni-calMemorandumNMFS-SEFC-226..1989b.Long-termtrendsinseaturtlenestingonHutchin-sonIsland,Florida.Pages111-113inEckert,S.A.,K.L.EckertandT.H.Richardson,compilers.ProceedingsoftheNinthAnnualWorkshoponSeaTurtleConservationandBiology.NOAATechnicalMemorandumNMFS-SEFC-232.Mendonca,M.T.andL.M.Ehrhart.1982.Activity,populationsizeandstructureoftheimma-tureChelonia~mdasandCarettacarettainMosquitoLagoon,Florida.Copeia1982:(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(CGartta~crettaandthePacificRidleytttid3ptt~lidI3d9dgpI9t11913.3ttalMarineFisheriesService,Dept.ofCommerce,Washington,D.C.
IIII NRC(USNuclearRegulatoryCommission).1982.FinalenvironmentalstatementrelatedtotheoperationofSt.LuciePlantUnit2.DocketNo.50-389.O'ara,J.1980.Thermalinfluencesontheswimmingspeedofloggerheadturtlehatchlings.Copeia1980(4):773-780.Owens,D.W.,J.R.Hendrickson,V.LanceandI.P.Callard.1978.Atechniquefordetermin-ingsexofimmatureChelonia~md~ausingaradioimmunoassay.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.Manualofseaturtleresearchandconservationtechniques.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:t97t-t984.Copeia1986(3):813-816.Raymond,P.W.1984.TheeffectsofbeachrestorationonmarineturtlesnestinginsouthBrevardCounty,Florida.M.S.thesis,UniversityofCentralFlorida.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.
IIIIIII Talbert,O.R.,S.E.Stancyk,J.M.DeanandJ.M.Will.1980.Nestingactivityoftheloggerheadturtle(Caretta~carettainSouthCarolina.I:Arookeryintransition.Copeia1950:(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.Vl.Planktondynamics,1971-1973.FloridaMarineResearchPublications34:1-15.Wibbels,T.,D.Owens,Y.MorrisandM.Amoss.1984.SexratiosofimmatureloggerheadseaturtlescapturedalongtheAtlanticcoastoftheUnitedStates.FinalReporttotheNa-tionalMarineFisheriesService.ContractNo.NA81-GA-C-0039.47pp.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(Chelonia~mdasnestinginFlorida.Pages351-352inOgren,L.,F.Berry,K.Bjorndal,H.Kumpf,R.Mast,G.Medina,H.ReichartandR.Witham,editors.Proceed-ingsoftheSecondWesternAtlanticTurtleSymposium.Mayaguez,PuertoRico,12-16October1987.NOAATechnicalMemorandumNMFS-SEFC-226.Wi*II,WN.'l983.983IIdiIpiIdI83till~I~~EhI(Linnaeus,1766).FAOFisheriesSynopsis,137:1-78.Worth,D.F.andM.L.Hollinger.1977.NearshoremarineecologyatHutchinsonIsland,Florida:1971-1974.III.Physicalandchemicalenvironment.FloridaMarineResearchPublica-tions23:25-85.46 Worth,D.F.,andJ.B.Smith.1976.MarineturtlenestingonHutchinsonIsland,Florida,in1973.FloridaMarineResearchPublications18:1-17.47 GULFOFMEXICO00YAROSKILOMETERSSCALEr~~StLuciaPlantFigure1.LocationoftheSt.LuciePlant.
IIIIIIIII V~g~t'~gW.:,::HUTCHINSONISLAND~o0'F~~IJi7.~iS'~Oc2G'5~.L-....i~00250500METERS~~tr~5pp,>r~DISCHARGE~gG+'..PIPES0G"oi~gAv'~'l"r2VQ9INTAKE'<:.:.c,".'NTAKEHEADWALL';4~':-,.'.'ELLS~'.",STRUCTURESUIDSA1A'-'.:.BARRIERBARRIER:.,,NET;.~;~b~',,'1'a'84'NTAKECANALFigure2.St.LuciePlantcoolingwaterintakeanddischargesystem.
II FLPierceInlet10A\~~'aFaStateGHwyA0a7~'t~aeaaAIg0Q0bb,oOaloH2V+F+3N40FPLST.LUCIEPU.S.HwyId0SkmRtV6.RVw6AA4BBCCDDEFFGGda+HHOdQuSLLudoInletFigure3.Designationandlocationofnine1.25-kmsegmentsandthirty-six1-kmsegmentssurveyedforseaturtlenesting.HutchinsonIsland,1971-1990.
350300250z0200Dz1501005012NORTH3456789POWERPLANTSOUTHFigure4.Meanannualnumberofloggerheadturtlenestsineachofthenine1.25-km-longsurveyareas,HutchinsonIsland,1971-1989,comparedwithnumberofnestsduring1990.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1990values(1980datawereexcludedbecausenotallareasweresurveyed).
IIIIIIIIIIII 350300~~250200(0I-V)z150Dz~~~10050ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH1'OWERPLANTSOUTHFigure5.Meanannualnumberofloggerheadturtlenestsineachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1989,comparedwithnumberofnestsduring1990.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1990values.
IIIIIIIII 700600500400Oz300D200~~100ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTHPOWERPLANTSOUTHFigure6.Meanannualnumberofloggerheadturtleemergencesineachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1989,comparedwiththenumberofemergencesduring1990.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1990values.
IIIIIII 10080gM(0LIJOOP)60(9ZI-0)ILJZ4020ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure7.Meanannualloggerheadturtlenestingsuccess(percentageofemergencesthatresultedinnests)foreachofthethirty-six1-km-longsurveyareas,HutchinsonIsland,1981-1989,comparedwithnestingsuccessduring1990.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1990values.
300250o-oArea4(PowerPlantSite)e--~Area5(ControlSite)200V)I-Z0150Dz100~Or%rr/////////50TTT19711972197319741975197619771978197919801981198219831984198519861987198819891990Figure8.NumberofioggerheadturtlenestsinAreas4and5,HutchinsonIsiand,1971-1990.Arrowsdenoteyearsduringwhichintake/dischargeconstructionoccurredinArea4.
I 6000CD(DI-zDz50004000300020001000CDOz0CCDz12000100008000600040002000gCDCOLIJOO(0(9zCDUJ806040201981198219831984198519861987198819891990Figure9.Annualnumberofnests,numberofemergencesandnestingsuccessalongtheentire36.0-km-longAtlanticcoastlineofHutchinsonIsland,198t-1990.
3130O29285272625Q.242322212012090(0z060z30305153051530515APRMAYJUNJULFigure10.Dailyloggerheadturtlenestingactivityandwatertemperature,HutchinsonIsland,1990.30515AUG30515SEP 27%7060DestroyedbyghostcrabsgDestroyedbyraccoonsandghostcrabsQDestroyedbyraccoons50O0-0KI-Uj40O(0I-(0zrt-30Dz201015%.?~Vxm:('?iAMh((.:9X'~egZps:K(:N<:e.'.gg.r,'(?Fp?'m~$+11%Y??r','my~?(m,:(g~18%r'(I(pjmr~'r'..v&#xc3;r'.rg~b;s(:r.ggCi(5'$.::$p~.?s?:.'$p$j~g>?~PI5%?.'A'(iM:'A?g(;@A;('(?g(??.:N~??jPAQsE(g?gr.m(mi14%Wg'kg$.$yg?gmmeE(.:VP8:.:~a??::,g:)>%!4~?>?:'(pY,~4'.($NScYA(&#xc3;~(??APg.(g'.?'.spi'g~Q4?ih(1%rr:.(1%1%2'/oABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure11.Numberofloggerheadturtlenestsdestroyedbyraccoonsandghostcrabsandpercentageofnestsdestroyedineach1-km-longsurveyarea,HutchinsonIsland,1990.
140120100COIzO80z604020Q--QGreen(Cheloniamydas)O-~Leatherback(Dermochelyscoriacea)pQpHgoIIIIIIlIIIpqII/xIIiIy/XgIIIIII197119731975197719791981198219831984198519861987198819891990Figure12.Annualnumbersofgreenturtleandleatherbackturtlenests,HutchinsonIsland,1971-1990.
200~-eLOGGERHEAD(Carettacaretta)0---wGREEN(Chelcciam~das)80175150O125K1007550z25////r0IIIIIIpi\'I70860O50z40(930mmD2010197619771978197919801981198219831984198519861987198819891990Figure13.Numberofloggerheadandgreenturtlesremovedeachyearfromtheintakecanal,St.LuciePlant,19764990.


40403030I-20z201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure14.Meannumberofloggerheadscapturedeachmonth,St.LuciePlantintakecanal,1977-1989,comparedwithnumberofmonthlycapturesduring1990.Horizontallinesaremeans,boxesencloseplusorminusonestandarddeviation,verticallinesareranges,andclosedcirclesare1990values.
===Background===
IIIIIII 400400300300(0DO)0zu-2000KUJlZlDz200100100~4041-4546-5051-5556-6061-6566-7071-7576-8081-8586-9091-9596-101-106->110STRAIGHTLINECARAPACELENGTH(cm)100105110Figure15.Lengthdistribution(SLCL)ofloggerheadturtles(N=1,673)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.Nodatacollectedfor81individuals.
AreaDescription PlantDescription TURTLESIntroduction Materials andMethodsNestingSurveyIntakeCanalMonitoring StudiestoEvaluateand/orMitigateIntakeEntrapment ResultsandDiscussion NestingSurveyDistribution ofLoggerhead NestsAlongHutchinson IslandEstimates ofTotalLoggerhead NestingonHutchinson IslandTemporalLoggerhead NestingPatternsPredation onLoggerhead TurtleNestsGreenandLeatherback TurtleNestingIntakeCanalMonitoring RelativeAbundance andTemporalDistribution Size-Class Distributions SexRatiosCaptureEfficiencies RelativeCondition Mortalities Recapture Incidents SummaryLITERATURE CITEDFIGURESTABLESIVIV10101415151518192021232326.28.3031333436404870 TABLEOFCONVERSION FACTORSFORMETRICUNITSToconvertcentigrade (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+273.183.937x103.281x103.281x101.0x102.205x103.527x102.4711.0x102.20463.5274x106.214x101.0x101.0x102.642x103.2813.937x101.0941.0x101.01.0x103.937x103.281x101.550x101.076x101.55x10Toobtainfahrenheit (degrees) kelvin(degrees) inchesfeetfeetpersecondliterspoundsounces(avoirdupois) acresgramspoundsounces(avoirdupois) miles(statute) millimetcrscubiccentimeters (cm)gallons(USliquid)feetinchesJJardsgramspartspermillionliters(USliquid)inchesfeetsquareinchessquarefeetsquareinches IIIrIe,t EXECUTlVE SUMMARYINTRODUCTION TheSt.LuciePlantisanelectricgenerating stationonHutchinson IslandinSt.LucieCounty,Florida.Theplantconsistsoftwonuclear-fueled 850-MWunits;Unit1wasplacedon-lineinMarch1976andUnit2inMay1983.Thisdocumenthasbeenpreparedtosatisfy.therequirements contained intheUnitedStatesNuclearRegulatory Commission's AppendixBEnvironmental Protection Plan(EPP)toSt.LucieUnit2FacilityOperating LicenseNo.NPF-16.Thisreportdiscusses environmental protection activities relatedtoseaturtlesasrequiredbySubsection 4.2oftheEPP.Otherroutineannualreporting requirements areaddressed inVolume2,alsoentitled"St.LucieUnit2AnnualEnvironmental Operating Report".TURTLENESTINGSURVEYTherehavebeenconsiderable year-to-year fluctuations inseaturtlenestingactivityonHutchinson Islandsincemonitoring beganin1971.Lownestingactivityin1975and1981-1983inthevicinityofthepowerplantwasattributed toconstruction ofplantin-takeanddischarge structures.
400400300300(0DO)DZ2000KIllCODZ200100100+1011-2021-3031-4041-5051-6061-7071-8081-9091-100101-111-121-131-141-i150'I/EiGHT(kg)110120130140150Figure1LWeightdistributionofliveloggerheadturtles(&#xb9;1,487)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.Nodatacollectedfor267individuals.
Nestingreturnedtonormalorabovenormallevelsfol-lowingbothperiodsofconstruction.
12012010010080COD0)0600K(9408060402020-1516-21-26-31-36-41-46-51-56-61-66-71-76-81-86-91-96-101-106->11020253035404550556065707580859095100105110STRAIGHTLINECARAPACELENGTH(cm)Figure17.Lengthdistribution(SLCL)ofgreenturtles(N=295)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.Nodatacollectedfor10individuals.
Powerplantoperation exclusive ofconstruction hashadnosignificant effectonnestingneartheplant.Datacollected through1990haveshownnolong-term reductions intotalnesting,totalemergences ornestingsuc-cessontheisland.Formalrequirements toconductthisprogramexpiredin1986butwerevoluntarily continued in1990withagreement fromfederalandstateagencies.
200200180180160160(D140D9120Dz010080z601401201008060404020201-56-1011-1516-2021-2526-3031-3536-4041-4546-5051-101-151-)200WEIGHT(kg)100150200Figure18.Weightdistributionofgreenturtles(N=291)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.Nodatacollectedfor14individuals.
INTAKECANALMONITORING Sinceplantoperation beganin1976,2,193seaturtles(including 100recaptures) representing fivedifferent specieshavebeenremovedfromtheintakecanal.Eighty-fourpercentofthesewereloggerheads.
IIIIIIII MALESFEMALES60505040V)DCI0300KILJKDz204030201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure19.Numbersofadultloggerheads(SLCL)85.0cm),includingrecaptures,removedeachmonthfromtheintakecanal,St.LuciePlant,1977-1990(N=255;sexnotrecordedforsixindividuals)85.0cm).
Differences inthenumbersofturtlesfoundduringdifferent monthsandyearswereattributed tonaturalvariation intheoccurren-cesofturtlesinthevicinityoftheplant,ratherthantoanyinfluence oftheplantitself.Themajorityofturtlesremovedfromtheintakecanal(about93percent)werecapturedaliveandreleasedbackintotheocean.TurtlesconfinedbetweentheA1Abarriernetandintakeheadwalls usuallyresidedinthecanalforarelatively shortperiodoftime,andmostwereingoodtoexcellent condition whencaught.OTHERRELATEDACTIVITIES Studiestoevaluatevariousintakedeterrent systems,asrequiredbytheNRC'sUnit2Environmental Protection Plan,wereconducted during1982and1983.Resultsandevaluations ofthosestudieswerepresented toregulatory agenciesduring1984,andtherequirement isnowconsidered completed.
50~-eCANALCAPTURES50040302010o---oEMERGENCES00//////]y////r/400300200100ZV)OzGK0zzz19771978197919801981198219831984198519861987198819891990Figure20.Comparisonofcapturesofadultfemaleloggerheads(SLCL>85.0cm)intheintakecanal,St.LuciePlant,1977-1990,andnumbersofloggerheademergencesinarea4adjacenttotheplant.Nestingactivitywasnotmonitoredin1978.  
INTRODUCTION BACKGROUND Thisdocumenthasbeenpreparedtosatisfytherequirements contained intheUnitedStatesNuclearRegulatory Commission's (NRC)AppendixBEnvironmental Protection PlantoSt.LucieUnit2FacilityOperating LicenseNo.NPF-16.In1970,FloridaPower8LightCompany(FPL)wasissuedPermitNo.CPPR-74bytheUnitedStatesAtomicEnergyCommission, nowtheNuclearRegulatory Commis-sion,thatallowedconstruction ofUnit1oftheSt.LuciePlant,an850-MWnuclear-poweredelectricgenerating stationonHutchinson IslandinSt.LucieCounty,Florida.StLuciePlantUnit1wasplacedon-lineinMarch1976.InMay1977,FPLwasissuedPermitNo.CPPR-144bytheNRCfortheconstruction ofasecond850-MWnuclear-poweredunit.Unit2wasplacedon-lineinMay1983andbegancommercial operation inAugustofthatyear.St.LuciePlantUnits1and2usetheAtlanticOceanasasourceofwaterforonce-throughcondenser cooling.Since1971,thepotential environmental effectsresulting fromtheintakeanddischarge ofthiswaterhavebeenthesubjectofFPL-sponsored bioticstudiesatthesite.Baselineenvironmental studiesofthemarineenvironment adjacenttotheSt.LuciePlantweredescribed inaseriesofreportspublished bytheFloridaDepartment ofNaturalResources (Campetal.,1977;FutchandDwinell,1977;Gallagher, 1977;Gal-lagherandHollinger, 1977;WorthandHollinger, 1977;MofflerandVanBreedveld, 1979;TesterandSteidinger, 1979;Walker,1979;Walkeretal.,1979;WalkerandSteidinger, 1979;Lyons,1989).TheresultsofUnit1operational andUnit2preopera-tionalbioticmonitoring attheSt.LuciePlantwerepresented insixannualreports(ABI,1977,1978,1979,1980a,1981b,1982).InJanuary1982,aNationalPollutant Discharge Elimination System(NPDES)permitwasissuedtoFPLbytheUSEnvironmental Protec-tionAgency(EPA).TheEPAguidelines fortheSt.Luciesitebiological studieswerebasedonthedocumententitled"Proposed St.LuciePlantPreoperational andOpera-tionalBiological Monitoring Program-August1981"(ABI,1981c).Findingsfromthesestudieswerereportedinthreeannualreports(ABI,1983,1984a,1985a).TheEPAbioticmonitoring requirements weredeletedfromtheNPDESpermitin1985.Jurisdiction forseaturtlestudiesiswiththeNRC,whichisconsidered tobetheleadfederalagencyrelativetoconsultation undertheEndangered SpeciesAct.Previousresultsdealingexclusively withseaturtlestudiesarecontained insevenenvironmen-taloperating reports(ABI,1984b,1985b,1986,1987,1988,1989,1990).Thisreportdescribes the1990environmental protection activities relatedtoseaturtles,asrequiredbySubsection 4.2oftheSt.LuciePlantUnit2Environmental Protection Plan.AREADESCRIPTION TheSt.LuciePlantislocatedona457-hasiteonHutchinson IslandonFlorida's eastcoast(Figures1and2).Theplantisapproximately midwaybetweentheFt.PierceandSt.LucieInlets.ItisboundedonitseastsidebytheAtlanticOceanandonitswestsidebytheIndianRiverLagoon.
IIIII Hutchinson Islandisabarrierislandthatextends36kmbetweeninletsandobtainsitsmaximumwidthof2kmattheplantsite.Elevations approach5matopdunesbor-deringthebeachanddecreasetosealevelinthemarigrove swampsthatarecommononmuchofthewesternside.Islandvegetation istypicalofsoutheastern Floridacoas-talareas;densestandsofAustralian pine,palmetto, seagrapeandSpanishbayonetarepresentatthehigherelevations, andmangroves aboundatthelowerelevations.
Largestandsofblackmangroves, including someontheplantsite,havebeenkilledbyfloodingformosquitocontroloverpastdecades.TheAtlanticshoreline ofHutchinson Islandiscomposedofsandandshellhashwithintermittent rockypromontories protruding throughthebeachfacealongthesouthernendoftheisland.Submerged coquinoid rockformations parallelmuchoftheislandofftheoceanbeaches.Theoceanbottomimmediately offshorefromtheplantsitecon-sistsprimarily ofsandandshellsediments.
Theunstablesubstrate limitstheestab-lishmentofrootedmacrophytes.
TheFloridaCurrent,whichflowsparalleltothecontinental shelfmargin,beginstodivergefromthecoastline atWestPalmBeach.AtHutchinson Island,thecurrentisapproximately 33kmoffshore.
Oceanicwaterassociated withthewesternboundaryofthecurrentperiodically meandersovertheinnershelf,especially duringsummermonths.PLANTDESCRIPTION TheSt.LuciePlantconsistsoftwo850-MWnuclear-fueled electricgenerating unitsthatusenearshore oceanwatersfortheplant'sonce-through condenser coolingwater system.Waterfortheplantentersthroughthreesubmerged intakestructures locatedabout365moffshore(Figure2).Eachoftheintakestructures isequippedwithavelocitycaptominimizefishentrainment.
Horizontal intakevelocities arelessthan30cm/sec.Fromtheintakestructures, thewaterpassesthroughsubmerged pipes(two3.7mandone4.9mindiameter) underthebeachanddunesthatleadtoa1,500-mlongintakecanal.Thiscanaltransports thewatertotheplant.Afterpassingthroughtheplant,theheatedwaterisdischarged intoa670-mlongcanalthatleadstotwoburieddischarge pipelines.
Thesepassunderneath thedunesandbeachandalongtheoceanfloortothesubmerged discharges, thefirstofwhichisapproximately 365moffshoreand730mnorthoftheintake.Heatedwaterleavesthefirstdischarge linefromaY-shapednozzle(diffuser) atadesignvelocityof396cm/sec.Thishigh-momentum jetentrainsambientwater,result-inginrapidheatdissipation.
Theoceandepthintheareaofthefirstdischarge isabout6m.Heatedwaterleavestheseconddischarge linethroughaseriesof48equallyspacedhighvelocityjetsalonga323-mmanifold(multiport diffuser).
Thisdiffuserstarts168mbeyondthefirstdischarge andterminates 856mfromshore.Theoceandepthatdischarge alongthisdiffuserisfromabout10to12m.Aswiththefirstdiffuser, thepurposeoftheseconddiffuseristoentrainambientwaterandrapidlydissipate heat.Fromthepointsofdischarge atbothdiffusers, thewarmerwaterrisestothesurfaceandformsasurfaceplumeofheatedwater.Theplumethenspreadsoutonthesur-faceoftheoceanundertheinfluence ofwindandcurrentsandtheheatdissipates totheatmosphere.
>tIIIIII TURTLESTheNRC'sSt.LucieUnit2AppendixBEnvironmental Protection PlanissuedApril1983containsthefollowing technical specifications:
4.2Terrestrial AuaticIssuesIssuesonendangered orthreatened seaturtlesraisedintheUnit2FES-OL[NRC,1982)andintheEndangered SpeciesBiological As-sessment(March1982)[Bellmund etal.,1982]willbeaddressed byprogramsasfollows:Beachnestingsurveysforallspeciesofseaturtleswillbeconducted onayearlybasisfortheperiodof1982through1986.Thesesur-veyswillbeconducted duringthenestingseasonfromap-proximately mid-April throughAugust.TheHutchinson Islandbeachwillbedividedinto36one-km-long surveyareas.Inaddition, thenine1.25-km-long surveyareasusedinpreviousstudies(1971-1979) willbemaintained forcomparison purposes.
Surveyareaswillbemarkedwithnumberedwoodenpla-quesand/orexistinglandmarks.
Theentirebeachwillbesurveyedsevendaysaweek.AIInewnestsandfalsecrawlswillbecountedandrecordedineacharea.Aftercounting, allcrawltrackswillbeobliterated toavoidrecounting.
Predation onnestsbyraccoonsorotherpredators willberecordedasitoccurs.Recordswillbekeptofanyseasonalchangesinbeachtopography thatmayaffectthesuitability ofthebeachfornesting.4.2.2Aprogramthatemployslightand/orsoundtodeterturtlesfromtheintakestructure willbeconducted.
Thestudywilldetermine withlaboratory andfieldexperiments ifsoundand/orlightwillresultinareduction oftotalturtleentrapment rate.
Thestudyshallbeimplemented nolaterthanafterthefinalremovalfromtheoceanofequipment andstructures associated withcon-struction ofthethirdintakestructure andtheexperiments shallter-minate18monthslater.Fourmonthsaftertheconclusion oftheexperimental period,areportontheresultsofthestudywillbesub-mittedtoNRC,EPA,NationalMarineFisheries Service(NMFS),andtheUSFishandWildlifeService(USFWS)fortheirevaluation.
Ifastatistically significant reduction inannualtotalturtleentrapment rateof80percentorgreatercanbedemonstrated, usingthedeveloped technology anduponFPLreceiving writtenconcurrence byNRC,EPA,NMFS,andUSFWSthenpermanent installation ofthedeterrent systemshallbecompleted andfunctioning nolaterthan18monthsaftertheagencies'oncurrence.
Thedesignofthisstudyneedstotakeintoaccountthesignificant annualvariation inturtleentrapment observedinthepast.Ifan80percentreduction ofturtleentrapment cannotbeprojected toallthreeintakestructures, thenaninteragency taskforcecom-posedofNRC,EPA,NMFS,'USFWS, andFPLshallconvene18monthsaftercompletion ofthethirdintakeanddetermine ifothercoursesofactiontomitigateand/orreduceturtleentrapment arewarranted (suchasphysicalbarrier,emergence ofnewtechnology ormethodstodeterturtles).
4.2.3Alternative methodsorprocedures forthecaptureofseaturtlesentrapped intheintakecanalwillbeevaluated.
Ifamethodorpro-cedureisconsidered feasibleandcosteffective andmayreducecapturemortality rates,itwillbefieldtestedintheintakecanal.4.2.5CatureandReleaseProramSeaturtleremovalfromtheintakecanalwillbeconducted onacon-tinuingbasis.Theturtleswillbecapturedwithlargemeshnets,orothersuitablenondestructive device(s),
ifdeemedappropriate.
Aformalized dailyinspection, fromtheshoreline, ofthecaptul'Bdevice(s) willbemadebyaqualified individual whenthedevice(s) aredeployed.
Theturtleswillbeidentified tospecies,measured, weighed(ifappropriate),
taggedandreleasedbackintotheocean.Recordsofwounds,freshorold,andasubjective judgement onthecondition oftheturtle(e.g.,barnaclecoverage, underweight) willbemaintained.
Methodsofobtaining additional biological/physiologi-caldata,suchasbloodanalysesandparasiteloads,fromcaptured IIIIII seaturtleswillbepursued.Deadseaturtleswillbesubjected toagrossnecropsy, iffoundinfreshcondition.
INTRODUCTION Hutchinson Island,Florida,isanimportant rookeryfortheloggerhead turtle,Caret-tacarettaandalsosupportssomenestingofthegreenturtle,Chelonia~mdasandthIth5kttl.~OIII1915IIt1.,1959;5 t,1995;9I-lagheretal.,1972;WorthandSmith,1976;Williams-Walls etal.,1983).Allthreespeciesareprotected bystateandfederalstatutes.
Thefederalgovernment classified thelog-gerheadturtleasathreatened species.Theleatherback turtleandtheFloridanestingpopulation ofthegreenturtlearelistedbythefederalgovernment asendangered species.Becauseofreductions inworldpopulations ofmarineturtlesresulting fromcoastaldevelopment andfishingpressure(NMFS,1978),maintaining thevitalityoftheHutchinson Islandrookeryisimportant.
IthasbeenaprimeconcernofFPLthattheconstruction andsubsequent opera-tionoftheSt.LuciePlantwouldnotadversely affecttheHutchinson Islandrookery.Becauseofthisconcern,FPLhassponsored monitoring ofmarineturtlenestingac-tivityontheislandsince1971.Daytimesurveystoquantifynesting,aswellasnighttime turtletaggingprograms, wereconducted inoddnumberedyearsfrom1971through1979.Duringdaytimenest-ingsurveys,nine1.25-km-long surveyareasweremonitored fivedaysperweek(Figure3).TheSt.LuciePlantbeganoperation in1976;therefore, thefirstthreesurveyyears(1971,1973and1975)werepreoperational.
Thoughthepowerplantwasnotoperat-ingduring1975,St.LuciePlantUnitNo.1oceanintakeanddischarge structures were IIIIII installed duringthatyear.Installation ofthesestructures includedconstruction activities conducted offshorefromandperpendicular tothebeach.Construction hadbeencom-pletedandtheplantwasinfulloperation duringthe1977and1979surveys.Amodifieddaytimenestingsurveywasconducted in1980duringthepreliminary construction oftheoceandischarge structure forSt.LuciePlantUnit2.Duringthisstudy,fourofthepreviously established 1.25-km-long surveyareasweremonitored.
Additionally, eggsfromturtlenestspotentially endangered byconstruction activities wererelocated.
Everyyearfrom1981through1990,361-km-long surveyareascomprising theen-tireislandweremonitored sevendaysaweekduringthenestingseason(Figure3).TheSt.LuciePlantUnit2discharge structure wasinstalled duringthe1981nestingseason.Offshoreandbeachconstruction oftheUnit2intakestructure proceeded throughout the1982nestingseasonandwascompleted neartheendofthe1983lseason.Construction activities associated withinstallation ofbothstructures weresimilartothoseconducted whenUnit1intakeanddischarge structures wereinstalled.
Eggsfromturtlenestspotentially endangered byconstruction activities wererelocated duringallthreeyears.Requirement 4.2.1oftheNRC'sSt.LucieUnit2AppendixBEnvironmental Protec-tionPlanwascompleted withsubmission ofthe1986nestingsurveydata(ABI,1987).Thenestingsurveywascontinued voluntarily through1990withagreement fromfederalandstateagencies.
Resultsarepresented inthisreportanddiscussed inrelationtopreviousfindings.
I~pIIIIIII,)ClII Inadditiontomonitoring seaturtlenestingactivities andrelocating nestsawayfromplantconstruction areas,removalofturtlesfromtheintakecanalhasbeenanintegralpartoftheSt.LuciePlantenvironmental monitoring program.Turtlesenteringtheoceanintakestructures areentrained withcoolingwaterandrapidlytransported throughtheintakepipesintoanenclosedcanalsystemwheretheymustbemanuallycapturedandreturnedtotheocean.Sincetheplantbecameoperational in1976,turtlesentrapped intheintakecanalhavebeensystematically
: captured, measured, weighed,taggedandreleased.
Previouspublications andtechnical reportshavepresented findingsofthenestingsurveys,nestrelocation activities andcanalcaptureprogram(Gallagher etal.,1972;WorthandSmith,1976;ABI,1978,1980a,1981a,1982,1983,1984b,1985b,1986,1987,1988,1989,1990;Williams-Walls etal.,1983;Proffittetal.,1986;Ernestetal.,1988,1989;Martinetal.,1989a,1989b).Resultsofstudiestoassesstheeffectsofther-maldischarges onhatchling swimmingspeedhavealsobeenreported(ABI,1978;O'ara,1980).Thepurposeofthisreportisto1)present1990seaturtlenestingsur-veydataandsummarize observedspatialandtemporalnestingpatternssince1971,2)documentandsummarize predation onturtlenestssince1971,and3)present1990canalcapturedataandsummarize comparable datacollected since1976.
IIIIIII MATERIALS ANDMETHODSNestinSurveMethodologies usedduringpreviousturtlenestingsurveysonHutchinson Islandweredescribed byGallagher etal.(1972),WorthandSmith(1976)andABI(1978,1981a,1982,1987,1988,1989).Methodsusedduringthe1990surveyweredesignedtoallowcomparisons withthesepreviousstudies.On11and13April1990,preliminary nestsurveyswereconducted alongHutchin-sonIslandfromtheFt.PierceInletsouthtotheSt.LucieInlet.From16Aprilthrough7September, nestsurveyswereconducted onadailybasis.After7September, severaladditional surveyswereconducted toconfirmthatnestinghadceased,thelastsurveybeingconducted on14September.
Biologists usedsmalloff-roadmotorcycles tosur-veytheislandeachmorning.Newnests,non-nesting emergences (falsecrawls),andnestsdestroyed bypredators wererecordedforeachofthe361-km-long surveyareascomprising theentireisland(Figure3).Thenine1.25-km-long surveyareasestablished byGallagher etal.(1972)alsoweremonitored socomparisons couldbemadewithpreviousstudies.Duringthedailynestmonitoring, anymajorchangesintopography thatmayhaveaffectedthebeach'ssuitability fornestingwererecorded.
Inaddition, eachofthe361-km-long surveyareashasbeensystematically analyzedandcategorized basedonbeachslope(steep,moderate, etc.),widthfromhightidelinetothedune,presenceofbenches(areasofabruptverticalrelief)andmiscellaneous characteristics (packed10
'lI sand,scattered rock,vegetation onthebeach,exposedrootsontheprimarydune,etc.).Inacooperative effort,datafromstrandedturtlesfoundduringbeachsurveyswereroutinely providedtotheNationalMaiineFisheries Service(NMFS)throughtheSeaTurtleStranding andSalvageNetwork.IntakeCanalMonitorin Mostturtlesentrapped intheSt.LuciePlantintakecanalwereremovedbymeansoflarge-mesh tanglenetsfishedbetweentheintakeheadwalls andabarriernetlocatedattheHighwayA1Abridge(Figure2).Netsusedduring1990werefrom30to40minlength,3to4mdeepandcomposedof40cmstretchmeshnylontwine.Largefloatswereattachedtothesurface,andunweighted linesusedalongthebottom.Turtlesen-tangledinthenetsgenerally remainedatthewater'ssurfaceuntilremoved.Sinceitsinception in1976,ABI'scanalcaptureprogramhasbeenundercontinual reviewandrefinement inanattempttominimizebothentrapment timesandin-juries/mortalities toentrapped seaturtles.PriortoApril1990,turtlenetswereusuallydeployedonMondaymorningsandretrieved onFridayafternoons.
Duringperiodsofdeployment, thenetswereinspected forcapturesbyABIpersonnel atleasttwiceeachday(mornings andafternoons).
Additionally, St.LuciePlantpersonnel checkedthenetsperiodically, andABIwasnotifiedimmediately ifacapturewasobserved.
ABI'sseaturtlespecialists wereoncall24hoursadaytoretrievecapturedturtlesfromtheplant.11 I
Beginning April1990,afterconsultation withNMFS,netdeployment wasscaledbacktodaylighthoursonly.Concurrently, surveillance oftheintakecanalwasin-creasedandABIpersonnel remainedonsiteforthedurationofeachday'snettingac-tivities.
Thismeasuredecreased responsetimeforremovalofentangled turtlesfromnetsandprovidedanopportunity toimprovedailyassessments ofturtlelevelswithinthecanal.Recordsofdailycanalobservations werecomparedwithcapturedatatoas-sesscaptureefficiencies.
TheA1Abarriernetisusedtoconfineturtlestotheeasternmost sectionofthein-takecanal,wherecapturetechniques havebeenmosteffective.
Thisnetisconstructed oflargediameterpolypropylene ropeandhasameshsizeof30.5cmx30.5cm.Acableandseriesoflargefloatsareusedtokeepthetopofthenetabovethewater'surface,andthebottomisanchoredbyaseriesofheavyblocks.Thenetisinclinedataslopeof3:1,withthebottompositioned upstreamofthesurfacecable.Thisreducesbowinginthecenterandminimizes theriskofaweakorinjuredturtlebeingpinnedun-derwaterbystrongcurrents.
Inthepast,theintegrity ofthebarriernetwasoccassionally compromised, andturtleswereabletomovewestofA1A.Theseturtleswerefurtherconstrained downstream byanunderwater intrusion detection system(UIDS)consisting, inpart,ofalargebarrierpositioned perpendicular tothenorth-south armofthecanal(Figure2).TheUIDSsecuritybarrieralsoconsistsof30.5cmx30.5cmmesh,butthenetisconstructed ofheavychainlinksratherthanrope.12 III Priortocompletion oftheUIDSinDecember1986,turtlesuncontained bytheA1AbarriernetwereusuallyremovedfromthecanalattheintakewellsofUnits1and2(Figure2).Theretheywereretrieved bymeansoflargemechanical rakesorspecially designednets.Following construction oftheUIDSbarrier,individuals withcarapacewidthslargerthan30.5cmwereunabletoreachtheintakewells.Thus,asrequired, tanglenetswerealsodeployedwestofA1A.Improvements madetotheA1Abarriernetduring1990shouldproveeffective inconfining allturtleslargerthan30.5cmtotheeasternendofthecanal.Formaldailyinspections oftheintakecanalweremadetodetermine thenumbers,locations andspeciesofturtlespresent.Surfaceobservations wereaugmented withperiodicunderwater inspections usingSCUBA,particularly inandaroundtheA1Abar-riernetandUIDSbarrier.Becauseofthereduction intotalnettinghoursduring1990,increased effortwasdirectedtowardhandcaptureofturtles.Thiswasaccomplished bydivinganduseofdipnets,anditprovedveryeffective whengoodwaterclaritycon-ditionsprevailed.
Regardless ofcapturemethod,allturtlesremovedfromthecanalwereidentified tospecies,measured, weighed,tagged,andexaminedforoverallcondition (wounds,abnormalities, parasites, etc.).Healthyturtleswerereleasedintotheoceanthesamedayofcapture.Sickorinjuredturtlesweretreatedandoccasionally heldforobserva-tionpriortorelease.Whentreatment waswarranted, injections ofantibiotics andvitaminswereadministered byalocalveterinarian.
Resuscitation techniques wereusedifaturtlewasfoundthatappearedtohavediedrecently.
Beginning in1982,necrop-13 Ili~l sieswereconducted ondeadturtlesfoundinfreshcondition; onenecropsywasper-formedduring1990.Since1982,bloodsampleshavebeencollected andanalyzedtodetermine thesexofimmatureturtles.Bloodwasremovedfromthepaireddorsalcervicalsinusesofsub-jectturtlesusingthetechnique described byOwensandRuiz(1980).Thesamplesweremaintained oniceandlatercentrifuged for15minutestoseparatecellsandserum.Sexdeterminations weresubsequently madebyresearchers atTexasA8MUniver-sityusingradioimmunoassay forserumtestosterone (Owensetal.,1978).FloridaPower8LightCompanyandAppliedBiology,Inc.continued toassistotherseaturtleresearchers in1990.Data,specimens and/orassistance havebeengiventotheFloridaDepartment ofNaturalResources, NationalMarineFisheries Service,USFishandWildlifeService,USArmyCorpsofEngineers, Smithsonian Institution; SouthCarolinaWildlifeandMarineResources
: Division, CenterforSeaTurtleResearch(University ofFlorida),
TexasA&MUniversity, University ofRhodeIsland,University ofSouthCarolina, University ofIllinois, University ofCentralFlorida,University ofGeor-gia,VirginiaInstitute ofMarineScienceandtheWesternAtlanticTurtleSymposium.
StudiestoEvaluateandorMitiateIntakeEntramentAprogramthatassessedthefeasibility ofusinglightand/orsoundtodeterturtlesfromenteringtheSt.LuciePlantintakestructures wasconducted in1982and1983andcompleted inJanuary1984.Asrequired, testresultsandevaluations werewrittenupandapresentation wasmadetotheNRC,NationalMarineFisheries ServiceandtheFloridaDepartment ofNaturalResources on11April1984.Requirement 4.2.2of Il1lI theNRC'sSt.LucieUnit2AppendixBEnvironmental Protection Planisconsidered completed withsubmission ofdeterrent studyfindings.
RESULTSANDDISCUSSION NestinSurveDistribution ofLoerheadNestsAlonHutchinson IslandWhenseaturtlenestingsurveysbeganonHutchinson Island,nine1.25-km-long surveyareaswereusedtoestimateloggerhead nestingactivityfortheentireisland.Since1981,all361-km-long segmentscomprising theisland'scoastline havebeensurveyed.
Regardless oftechnique, loggerhead nestdensities haveshowncon-siderable annualvariation withinindividual surveyareas(Figures4and5).Yet,theannualspatialdistribution ofthosenestsamongsurveyareashasproducedaratheruniformgradient, nestdensities consistently increasing fromnorthtosouth(ABI,1987).Thegradientappearstobelinearwhenonlythenine1.25-km-long surveyareasareused(Figure4),butbecomesnon-linear whenall361-km-long surveyareasarein-cludedintheanalysis(Figure5).During1990thedistribution ofloggerhead nestsalongtheislandwascharacterized byrecordhighnestingalongthenorthernandcentralpor-tionsoftheisland(Figure5).Inthepast,thepronounced gradientobservedonthenorthernendoftheislandwasoccasionally influenced byphysicalprocesses occurring there;periodsofheavyaccretion reducedthegradient, whileperiodsoferosionaccentuated it(WorthandSmith,1976;Williams-Walls etal.,1983).However,duringrecentyearsnoconsistent IIlI relationship wasapparentwhenfieldobservations ofbeachwidthswerecomparedtothespatialdistribution ofnestsalongtheisland(ABI,1987).Thus,eventhoughbeachdynamicsmaysometimes affecttheselection ofnestingsitesbyloggerhead turtles,otherfactorsmustalsocontribute totheselection process.Offshorebottomcontours, spatialdistribution ofnearshore reefs,typeandextentofdunevegetation, anddegreeofhumanactivityonthebeachatnighthavebeenidentified assomeofthefactorsaf-fectingnesting(Caldwell, 1962;Hendrickson andBalasingam, 1966;Bustard,1968;BustardandGreenham, 1968;Hughes,1974;DavisandWhiting,1977;Mortimer, 1982).Relationships betweenspatialnestingpatternsandspecificenvironmental con-ditionsareoftendifficult toestablish becauseoftheinterrelationship ofthefactorsin-volved.Notallventuresontothebeachbyafemaleturtleculminate insuccessful nests.These"falsecrawls"(non-nesting emergences) mayoccurformanyreasonsandarecommonlyencountered atotherrookeries (BaldwinandLofton,1959;Schulz,1975;DavisandWhiting,1977;Talbertetal.,1980;Raymond,1984).DavisandWhiting(1977)suggested thatrelatively highpercentages offalsecrawlsmayreflectdisturban-cesorunsatisfactory nestingbeachcharacteristics.
Therefore, certainfactorsmayaf-fectaturtle'spreference toemergeonabeach,whileotherfactorsmayaffectaturtle'tendencytonestafterithasemerged.Anindexwhichrelatesthenumberofneststothenumberoffalsecrawlsinanareais.usefulinestimating thepost-emergence suitability ofabeachfornesting.Inthepresentstudythisindexistermed"nestingsuc-cess"andisdefinedasthepercentage oftotalemergences thatresultinnests.
loHistorically, thepatternofloggerhead emergences ontheislandhasgenerally paral-leledthedistribution ofnests(ABI,1987,1988),andthissametrendwasapparentin1990(Figure6).Incontrast, nestingsuccessbyloggerheads alongtheislandhastypi-Pcallylackedgradients (Figure7).Thus,therelatively highnumbersofloggerhead nestsobservedincertainareasareusuallyaresultofmoreturtlescomingashoreinthoseareasratherthanofmorepreferable nestingconditions beingencountered bytheturtlesaftertheyemerged.Loggerhead nestingdensities during1990weregenerally highwhencomparedwithpreviously recordedvalues(Figures4and5).Recordhighnestingwasrecordedin21ofthe36one-kilometer-long surveyareasandwasmostnotableonthenorthernhalfoftheisland.Therewerenoapparentchangesinthephysicalcharacteristics ofthebeachthatwouldaccountforthisincreaseinnesting.Ingeneral,recordhighnestingwasduetorecordhighemergence rates,andthismayreflectanincreaseinthenum-berofnestingfemalesintheHutchinson Islandarea.NestingsurveysonHutchinson Islandwereinitiated inresponsetoconcernsthattheoperation oftheSt.LuciePlantmightnegatively impactthelocalseaturtlerookery.Previousanalysis, usinglog-likelihood testsofindependence (G-test;SokalandRohlf,1981)demonstrated thattheconstruction oftheplant'soffshoreintakeanddischarge structures significantly reducednestingattheplantsiteduringconstruction years-1975,1981,1982and1983(Proffitt etal.,1986;ABI,1987).However,nestingattheplantconsistently returnedtolevelssimilartoorgreaterthanthoseatacontrolsiteinyearsfollowing construction.
Thistrendcontinued during1990(Figure8).Thus,power plantoperation exclusive ofintake/discharge construction hashadnoapparenteffectonnesting.Datacollected through1990haveshownnolong-term reduction inloggerhead nestdensities, totalemergences ornestingsuccessineitherthenine1.25-km-long surveyareasorthe361-km-long surveyareas(Table1;Figure9).EstimatesofTotaILo erheadNestin onHutchinsonlsland Variousmethodswereusedduringsurveyspriorto1981toestimatethetotalnum-berofloggerhead nestsonHutchinson Islandbasedonthenumberofnestsfoundinthenine1.25-km-long surveyareas(Gallagher etal.,1972;WorthandSmith,1976;ABI,1980a).Eachofthesemethodsweresubsequently foundtoconsistently overes-timateislandtotals(ABI,1987).Sincewhole-island surveysbeganin1981,ithasbeenpossibletodetermine theactualproportion oftotalnestsdeposited inthenineareas.Thishasthenallowedextrapolation fromtheninesurveyareastotheentireislandforyearspriorto1981.From1981through1990thetotalnumberofnestsinthenineareasvariedfrom32.5to35.6percentofthetotalnumberofnestsontheisland(Table1).Thisisslight-lyhigherthanthe31.3percentwhichwouldbeexpectedbasedstrictlyonthepropor-tionoflinearcoastline comprised bythenineareas.Usingtheten-yearmeanof33.8percent,estimates ofthetotalnumberofnestsonHutchinson Islandcanbecalculated bymultiplying thenumberofnestsinthenineareasby2.96.Thistechnique, whenap-pliedtotheninesurveyareasduringthetenyearsinwhichtheentireislandwassur-veyed,producedwhole-island estimates within5.3percentoftheactualnumberof18 IIl nestscounted.Becausetheproportion ofnestsrecordedintheninesurveyareasremainedrelatively constantoverthelasttenyears,thisextrapolation procedure shouldprovideafairlyaccurateestimateoftotalloggerhead nestingforyearspriorto1981.Itisclearthatloggerhead nestingactivityonHutchinson Islandfluctuates con-siderably fromyeartoyear(Table1).Annualvariations innestdensities alsoarecom-monatotherrookeries (Hughes,1976;DavisandWhiting,1977;Ehrhart,1980)andmayresultfromtheoverlapping ofnon-annual breedingpopulations.
Nonetheless, datacollected through1990suggestanoverallincreaseinnestingonHutchinson Is-landsincesurveysbeganin1971.Totalnestingactivitywasgreatestduring1990when6,700loggerhead nestswererecorded.
Norelationships betweentotalnestingactivityandpowerplantoperation orintake/discharge construction wereindicated byyear-to-yearvariations intotalnestingonHutchinson Island.TemoralLoerheadNestinPatternsTheloggerhead turtlenestingseasonusuallybeginsbetweenmid-April andearlyMay,attainsamaximumduringJuneorJuly,andendsbylateAugustorearlySep-tember(ABI,1987).Nestingactivityduring1990followedthissamepattern(Figure10).Coolwaterintrusions frequently occuroverthecontinental shelfofsoutheast Floridaduringthesummer(TaylorandStewart,1958;Smith,1982).WorthandSmith(1976),Williams-Walls etal.(1983)andABI(1982,1983,1984b,1985b,1986,1987,1988,1989,1990)suggested thattheseintrusions mayhavebeenresponsible forthetemporary declinesinloggerhead turtlenestingactivitypreviously observedonHutchinson Is-19 IIIIII land.Similarly, asubstantial decreaseinnestingduringmid-July1990wasapparently duetoanintrusion ofcoolwater(Figure10).Thoughnaturalfluctuations intemperature havebeenshowntoaffecttemporalnest-ingpatternsonHutchinson Island,therehasbeennoindication thatpowerplantopera-tionhasaffectedthesetemporalpatterns(ABI,1988)~Predation onLoerheadTurtleNestsSincenestsurveysbeganin1971,raccoonpredation probablyhasbeenthemajorcauseofturtlenestdestruction onHutchinson Island.Researchers atotherlocations havereportedraccoonpredation levelsashighas70tonearly100percent(DavisandWhiting,1977;Ehrhart,1979;Hopkinsetal.,1979;Talbertetal.,1980).Raccoonpreda-tionofloggerhead turtlenestsonHutchinson Islandhasnotapproached thislevelduringanystudyyear,thoughlevelsforindividual 1.25-km-long areashavebeenashighas80percent.Overallpredation ratesforsurveyyears1971through1977werebetween21and44percent,withahighof44percentrecordedin1973.Apronounced decreaseinraccoonpredation occurredafter1977,andoverallpredation ratesforthenineareashavenotexceeded10percentsince1979.Adeclineinpredation ratesonHutchinson Islandhasbeenvariously attributed totrappingprograms, construction activities, habitatlossanddisease(Williams-Walls etal.,1983;ABI,1987).During1990,sixpercent(406)oftheloggerhead nests(n=6,700)ontheislandweredepredated byraccoons.
Asinpreviousyears(ABI,1989),predation ofturtlenestswasprimarily restricted tothemostundeveloped portionoftheisland(i.e.,AreasEthroughS;Figure11).20 IIIIIII Ghostcrabshavebeenreportedbynumerousresearchers asimportant predators ofseaturtlenests(BaldwinandLofton,1959;Schulz,1975;Diamond,1976;Fowler,1979;Hopkinsetal~,1979;Stancyk,1982).ThoughturtlenestsonHutchinson Islandprobablyhavebeendepredated byghostcrabssincenestingsurveysbeganin1971,thissourceofnestdestruction didnotbecomeapparentuntil1983.Quantification ofghostcrabpredation wasinitiated thesameyear.Overallpredation ratesbyghostcrabshavevariedfrom0.1to2.1percentfrom1983-1989(ABI,1990).During1990,0.4percent(27)oftheloggerhead nests(n=6,700)ontheislandweredestroyed byghostcrabs(Figure11).Nestsdestroyed byacombination ofraccoonandghostcrabpredation havebeenincludedasraccoonpredations inpreviousdiscussions.
Whenthesecombination predations areincludedascrabpredations, theoverallpredation ratesbyghostcrabsrangefrom0.4to3.2percent.During1990,1.4percent(96nests)weredestroyed byeitherghostcrabsoracombination ofghostcrabsandraccoons.
GreenandLeatherback TurtleNestinGl'eenandleatherback turtlesalsonestonHutchinson Island,butinfewernumbersthanloggerhead turtles.Priorto1981,bothsurvey(nine1.25-km-long sections) andinter-survey areasweremonitored forthepresenceofgreenandleatherback nests.Thirty-one kilometers ofbeachfromArea1southtotheSt.LucieInletwereincludedinthateffort.Duringwhole-island surveysfrom1981through1990,onlytwoof182Ieatherback nestsandonlysevenof601greennestswererecordedonthefivekilometers ofbeachnorthofArea1.Therefore, previouscountsofgreenandleather-21 III backnestswithinthe31kilometers surveyedwereprobablynotappreciably different fromtotaldensities fortheentireisland.Basedonthisassumption, greenandleather-backnestdensities maybecomparedamongallsurveyyears,except1980,whenlessthan15kilometers ofbeachweresurveyed.
Priorto1990,thenumberofnestsobservedontheislandrangedfrom5to74forgreenturtlesandfrom1to36forleatherbacks (Figure12).Duringthe1990survey,132greenturtleand12leatherback turtlenestswererecordedonHutchinson Island.Temporalnestingpatternsforthesespeciesdifferfromthepatternforloggerhead turtles.Greenturtlestypically nestonHutchinson Islandfrommid-JunethroughthefirstorsecondweekofSeptember.
During1990,greenturtlesnestedfrom28Maythrough11September.
Leatherback'turtles usuallynestontheislandfrommid-April throughearlytomid-July.
During1990thisspeciesnestedfrom10Aprilthrough3July.Considerable fluctuations ingreenturtlenestingontheislandhaveoccurredamongsurveyyears(Figure12).Thisisnotunusualsincetherearedrasticyear-to-year fluc-tuationsinthenumbersofgreenturtlesnestingatotherbreedinggrounds(Carretal.,1982).Despitethesefluctuations, datacollected through1990suggestanoverallin-creaseinnestingsince1971andmayreflectanincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.During1990,greenturtlesnestedmost frequent-lyalongthesouthernhalfoftheisland.Thisisconsistent withresultsofprevioussur-veys.Leatherback turtlenestdensities haveremainedlowonHutchinson Island;however,increased nestingduringrecentyears(Figure12)mayreflectanoverallincreaseinthe22 numberofnestingfemalesintheHutchinson Islandarea.During1990,leatherback turtlesprimarily nestedonthesouthernhalfoftheisland.IntakeCanalMonitorin Entrainment ofseaturtlesattheSt.LuciePlanthasbeenattributed tothepresumedphysicalattractiveness oftheoffshorestructures housingtheintakepipesratherthantoplantoperating characteristics (ABI,1980band1986).Evenwhenbothunitsareoperating atfullcapacity, turtlesmustactivelyswimintothemouthofoneoftheintakepipesbeforetheyencounter currentvelocities sufficiently strongtoeffectentrainment.
Consequently, aturtle'sentrapment relatesprimarily totheprobability thatitwilldetectandsubsequently enteroneoftheintakestructures.
Assumingthatdetection distan-cesdonotvaryappreciably overtimeandthatallturtles(oraconstantproportion) areequallyattracted tothestructures, capturerateswillvaryproportionally tothenumberofturtlesoccurring inthevicinityofthestructures.
Ifthisassumption istrue,datafromthecanalcaptureprogramshouldreflectnaturalvariability inthestructure ofthepopula-tionbeingsampled.RelativeAbundance andTemoralDistribution During1990,132seaturtlecapturestookplaceintheintakecanaloftheSt.LuciePlant(Table2).Ofthefivespeciesofseaturtlesinhabiting coastalwatersofthesoutheastern UnitedStates,onlytwowererepresented inthisyear'scatches:112log-gerheadsand20greenturtles.Sinceintakecanalmonitoring beganinMay1976,1,853loggerhead (including 99recaptures),
306green(including 1recapture),
9leatherback, 8hawksbill and17Kemp'sridleycaptureshavetakenplaceattheSt.LuciePlant.23 Annualcatchesofloggerheads increased steadilyfromalowof33in1976(partialyearofplantoperation andmonitoring) to172in1979(Figure13).Afterdeclining be-tween1979and1981,yearlycatchesofloggerheads againrosesteadily, reachingahighof195during1986.Captureshavebeenindeclinesince1986,decreasing morethan40percentoverthelastfouryears.Twooffshoreintakestructures wereinplacepriortoUnit1start-upin1976;thethirdandlargeststructure wasinstalled during1982-1983.
Eventhoughallthreestructures areinrelatively closeproximity, theadditionofanotherpipemayhaveincreased theprobability ofaturtlebeingentrained.
Becausethischangecannotbequantified, datacollected priorto1982maynotbecomparable withthatcollected after1983.Addition-ally,theinfluence oftheconstruction itselfonseaturtleentrainment during1982and1983isunknown.Withtheseconsiderations inmind,neitheralong-term increasenordecreaseinthenumberofloggerheads capturedattheSt.LuciePlantcanbeinferredfromthedata.During1990,themonthlycatchofloggerheads rangedfrom1(November) to25(June),withamonthlymeanof9.3(+7.0;Table3).ThenumberofcapturesduringMay,JuneandJulywereconsiderably aboveaverage,whilecapturesthroughout theIremainder oftheyearweremoderately toconsiderably lowerthanaverage(Figure14).Overtheentiremonitoring period,monthlycatcheshaverangedfrom0to39;thegreatestnumberofcapturesoccurredduringJanuary1983.Whendatafromallfullyearsofmonitoring (1977-1990) werecombined, thehighestnumberofloggerhead capturesoccurredinJanuary(11.8percent);
fewestcaptures24 IlIlII wererecordedinNovemberandDecember(Table3).However,monthlycatcheshaveshownconsiderable annualvariability.
Monthshavingrelatively lowcatchesoneyearoftenhavehadrelatively highcatchesinanother.Catchesofgreenturtlesalsohavevariedwidelyamongyears,rangingfrom0in1976(partialyearofsampling) to69in1984(Table4).During1990,20individuals werecaptured.
Theaverageannualcatchofgreenturtles,excluding 1976,was21.9(+18.0).Althoughhighlyvariable, annualcapturedataforgreenturtlessuggestalong-term in-creaseinthenumberofindividuals inhabiting thenearshore coastalareaadjacenttotheplant(Figure13).Again,however,theinfluence oftheadditionofathirdintakepipeduring1982-1983 onthesedataisnotknown.Greenturtleshavebeencaughtduringeverymonthoftheyear,withaveragemonth-lycatchesforallyearscombinedrangingfrom0.3inSeptember to7.1inJanuary(Table4).Seasonalabundance patternsofgreensaremuchmorepronounced thanforlog-gerheads, nearly60percentofallcapturesoccurring duringthethreemonthperiodbetweenJanuaryandMarch.During1990,thelargestnumberofgreens(6)werecap-turedinJanuary.Themostgreensevercaughtinonemonthwas37inJanuary1984.Catchesofleatherbacks, hawksbills andKemp'sridleyshavebeeninfrequent andscattered throughout the15yearstudyperiod(Table2).Eachspecieshasshownratherpronounced seasonaloccurrences; allbuttwoofthenineleatherbacks werecollected betweenFebruaryandMay,sevenoftheBighthawksbills werecollected betweenJuneandSeptember, andallbuttwoofthe17Kemp'sridleyswerecaughtbetweenNovemberandApril.25 Size-lassDistribtionAlthoughseveralstraight-line andcurvedmeasurements wererecordedforturtlesremovedfromtheintakecanal,onlyonestraight-line measurement hasbeenusedinanalysespresented here.Straight-line carapacelength(SLCL)wasmeasuredfromtheprecentral scutetothenotchbetweenthepostcentral scutes(minimumcarapacelengthofPritchard etal.,1983).Todate,loggerheads removedfromtheintakecanalhaverangedinlength(SLCL)from40.2to112.0cm(x=66.8+13.7cm)andinweightfrom10.7kgto169.6kg(x=49.2+31.0kg;Figures15and16).Acarapacelengthof70cmapproximates thesmallestsizeofnestingloggerhead femalesobservedalongtheAtlanticeastcoast(Hirth,1980).However,adultscanonlybereliablysexedonexternalmorphological characteristics (e.g.,relativetaillength)afterobtaining alengthofabout85cm.Previously, 80.0cmwasusedasthelowerlimitforadultturtles.However,recentdatasuggestthatsomemalesmaynotmature,andthusmightnotbedistinguishable fromfemales,untiltheyattainaslightlylargersize.Basedonthesedivisions, dataweresegregated intothreegroups:juveniles
(<70cm),adults(>85cm)andtransitional (71-85cm).Thelattergroupprobablyincludessomematureandsomeimmatureindividuals.
Ofthe1,744capturesbetween1977and1990forwhichlengthdatawerecollected, 69percentwerejuveniles, themajorityofthesemeasuring between50and70cmSLCL(Table5).Adultsaccounted forabout15percentofallcaptures, withtheremaining 16percentcomprised ofanimalsinthetransitional sizeclass.Similarsize-frequency distributions, indicating apreponderance ofjuveniles, havebeenreportedforthe26 IIII Mosquito/Indian RiverLagoon(Mendonca andEhrhart,1982),theCanaveral shipchannel(Henwood, 1987),andGeorgiaandSouthCarolina(Hillestad etal.,1982).Thesedatasuggestthatcoastalwatersofthesoutheastern UnitedStatesconstitute animportant developmental habitatforCarettacaretta.Seasonalpatternsofabundance forvarioussizeclassesindicated thatjuvenilelog-gerheadswereslightlymoreabundantduringthewinterthanatothertimesoftheyear(Table5).About45percentofthejuveniles werecapturedbetweenJanuaryandApril.Abundances decreased inspringandremainedrelatively constantduringthesummerandearlyfallbeforedecreasing againtolowestlevelsinNovemberandDecember.
Theseasonaldistribution ofadultloggerheads wasmuchmorepronounced, 76per-centofallcapturesoccurring betweenMayandAugust,Thisrepresents themajorpro-tionofthenestingseasononHutchinson Island.Greenturtlesremovedfromtheintakecanalovertheentirestudyperiodrangedinsizefrom20.0to108.0cmSLCL(x=35.8+14.3cm)and0.9kgto177.8kg(x=9.4+20.2kg;Figures17and18)~Nearlyall(96percent)werejuveniles.
About80per-centwere40cmorlessinlength,and66percentweighed5kilograms orless.Theseimmatureturtlesexhibited distinctwinterpulsessuggesting migratory behavior(Table4).However,someimmaturegreenturtleswerepresentthroughout theyear.Todate,onlyeightadultgreenturtles(SLCL>83cm;Witherington andEhrhart,1989)havebeenremovedfromthecanal;ailwerecapturedduringorshortlyafterthenestingseason.27 IIl Theeighthawksbills removedfromthecanalrangedinsizefrom34.0to70.0cmSLCL(x=46.2+12.9cm)andinweightfrom6.4to52.2kg(x=17.3+16.6kg).Allbutonewerejuveniles (SLCL<63cm;Witzell,1983).Similarly, allbutoneofthe17Kemp'sridleyscapturedattheSt.LuciePlantwerejuveniles (SLCL<60.0cm;Hirth,1980).Carapacelengthsfortheridleysrangedfrom27.0to62.0cmSLCL(x=36.1+9.7cm)andweightsfrom3.1to31.8kg(x=8.0+8.1kg).Thenineleatherbacks removedfromthecanalrangedinlengthfrom112.5to150.0cm,andatleastsevenwereadults(SLCL>121cm;Hirth,1980).Thelargestleatherback forwhichanac-curateweightwasobtained, afemalewithacurvedcarapacelengthof158.5cm,weighed334.8kg.~SxRatiosSinceintakecanalmonitoring beganin1976,255adultloggerheads (SLCL>85.0cm)havebeensexed.Femalespredominated malesbyaratioof5.4:1.0,whichsig-nificantly departsfroma1:1ratio(X,P<0.05).Consequently, temporalpatternsinthenumberofadultloggerhead captureswereheavilyinfluenced bythenumbersoffemalespresent.Whensexeswereseparated, itisevidentthatmaleswererelatively evenlydistributed amongmonths,whereas90percentofthefemalesweretakenduringthenestingseason(MaythroughSeptember; Figure19).Thenumberofadultfemaleloggerheads capturedattheSt.LuciePlanthasin-creasedsteadilyoverthelastsevenyears.From1977through1983,anaverageof4.4adultfemales(+3.2;range=1-10)wereentrapped eachyear,whereassincethen,anaverageof26.3femalesperyear(+6.7;range=16-35)werecaptured.
Thisin-28 creasecorresponds toageneralriseinloggerhead nestingactivityneartheplant(Figure20).Increased nearshore movementassociated withnestingincreases theprobability ofaturtledetecting oneoftheintakestructures andhencetheprobability ofentrainment.
Althoughtheadditionofthethirdoffshoreintakestructure mayhaveaccounted forsomeoftheincreaseinthenumberofadultsentrained since1983,thecontinued riseoverthelastsevenyearssuggestsagenuineincreaseinthenumberoffemalesoccurring inthevicinityoftheplant.BetweenSeptember 1982andDecember1986,267individual juvenileandsub-adult loggerhead turtlescapturedinthecanalweresexedbyTexasA8MUniversity re-searchers usingabioimmunoassay technique forbloodserumtestosterone.
Aspre-viouslyreported, femalesoutnumbered malesbyaratioof2.3:1.0(ABI,1989).Thesefindingsareconsistent withthosereportedforsamplestakenfromtheCapeCanaveral shipchannel(1.7:1.0) andtheIndianRiverLagoon(1.4:1.0),
wheresexratiosarealsosignificantly skewedinfavoroffemales(Wibbelsetal.,1984).Bloodsamplescollected since1986arecurrently beinganalyzedandtheseresultswillprovideavaluabletoolforassessing temporalvariability inthesexratiosofthelocalloggerhead population.
Oftheeightadultgreenturtlescapturedsincemonitoring began,sixweremalesandtwowerefemales.Siximmaturegreenturtleshavebeensexedthroughbloodwork;allhavebeenfemales.Ofthesixadultleatherback turtlesforwhichsexwasrecorded, threewerefemalesandthreeweremales.Theadulthawksbill andKemp'sridleywerebothfemales.Nosexinformation existsforjuveniles ofthesespecies.29 CatureEfficiencies Capturemethodologies havebeenundercontinual reviewandrefinement asnetmaterials, configurations andplacement werevariedinanefforttominimizeseaturtleentrapment times.Concurrently, alternative capturetechniques wereevaluated andpotential deterrent systemstestedinthelaboratory.
Duringthisperiod,captureefficien-ciesvariedinrelationtonettingeffortandtheeffectiveness ofthesystemsdeployed.
Acapture/recapture studyconducted intheintakecanalbetweenOctober1980andJanuary1981indicated thatmostturtlesconfinedbetweentheA1Abridgeandtheintakeheadwalls werecapturedwithintwoweeksoftheirentrainment (ABI,1983)~Basedonmorerecentformaldailyinspections, itappearsthatcaptureefficiencies havefurtherimproved.
Nearly50percentoftheturtlesenteringthecanalarenowcaughtwithin24hoursoffirstsighting, andalmost90percentarecapturedduringtheirfirstweekofentrapment (Figure21).Averagecaptureefficiency, expressed aselapseddaysbetweenfirstsightingandcapture,duringtheperiodfromAprilthroughDecem-ber1990was3.9days(+6.8days;range=1-50days).Betterutilization ofcurrentsandeddies,adjustments totethering lines,multi-net deployments andincreased ef-fortstohandcaptureturtleshavecontributed toreducedentrapment times.Entrapment timesmaybeextendedforturtlesswimmingpasttheA1Abarriernet(ABI,1987).Occasionally, thetopofthenethasbeensubmerged ortheanchorcablepulledfreefromthebottom,allowinglargerturtlestopass;turtleswithcarapacewidthslessthanabout30.5cmcanswimthroughthelargemesh.BecausecaptureeffortswestoftheA1Abridgehavegenerally beenlesseffective thanthoseneartheintake30 headwalls, mostturtlesbreaching thebarriernetwerenotcaughtuntiltheyenteredtheintakewellsofUnits1and2.Priortoinstallation oftheUIDSbarrierin1986,about15percentofallturtlesentrapped inthecanalwereremovedfromtheintakewells.Be-causeoftheirrelatively smallsizes,amuchlargerproportion ofgreens(51.6percent)reachedtheplantthanloggerheads (10.1pel'cent).
Since1986,thepercentage ofgreenscaughtattheintakewellshasdecreased slightly(35.1percent),
whilealllog-gerheadshavebeenprevented fromreachingtheplant.Majorrenovations weremadetotheA1Abarriernetduring1990tofurtherreducethepotential forturtleslargerthan30.5cmbecomingtrappedbetweenA1AandtheUIDS.Twologgerheads (lessthan2percentofallloggerhead captures) breachedtheA1Abarriernetpriortocompletion ofthesemodifications.
BothwereremovedfromthecanalattheUIDSbarrier.Additionally, twosmallgreenturtlespassedthroughtheA1Abarriernetandwereremovedattheplant'sintakewells.Thus,nearly97percentofallturtlesentrapped inthecanalduring1990werecapturedbynettingorbyhandeastoftheA1Abridge.Theeffective confinement ofturtleseastofA1Awasanothermajorcontributor tothehighcaptureefficiency achievedduring1990.RelativeCondition TurtlescapturedaliveintheintakecanaloftheSt.LuciePlantwereassignedarela-tivecondition basedonweight,activity, parasiteinfestation, barnaclecoverage, wounds,injuriesandanyotherabnormalities whichmighthaveaffectedoverallwell-being.During1990,92.9percent(104)ofallloggerheads foundinthecanalwerealiveandingoodtoexcellent condition.
Only6.3percent(7)ofloggerhead capturesin-31 IIIII volvedindividuals infairorpoorcondition; oneloggerhead wasdeadwhenremovedfromthecanal.Ofthe20greenturtlesremovedfromtheintakecanalduring1990,16wereingoodtoexcellent condition, twowereinfaircondition andtwoweredead.Overtheentiremonitoring period,about76and78percent,respectively, ofalllog-gerheadandgreencaptureshaveinvolvedturtlesingoodtoexcellent condition (Table6).Capturesofindividuals infairtopoorcondition haveoccurredabout16percentofthetimeforloggerheads and14percentofthetimeforgreens.Allofthehawksbills andleatherbacks havebeenremovedfromthecanalingoodtoexcellent condition, whileabouthalfoftheKemp'sridleyshavefallenintothesecategories.
Relativecondition ratingscanbeinfluenced byanumberoffactors,somerelatedandothersunrelated toentrainment and/orentrapment intheintakecanal.Ratingsofgoodtoexcellent indicatethatturtleshavenotbeennegatively impactedbytheirentrap-mentinthecanal,atleastasevidenced byphysicalappearance.
Althoughratingsoffairorpoorimplyreducedvitality, theextenttowhichentrainment/entrapment isresponsible isoftenindeterminable.
Insomeinstances, conditions responsible forlowerratings,suchasinjuries, obviously weresustained priortoentrainment.
During1990,aboutninepercent(10)ofallloggerhead capturesinvolvedindividuals withnoticeable
: injuries, suchasmissingappendages, brokenormissingpiecesofcarapaceanddeeplacerations.
Mostofthesewereold,well-healed wounds,andnonewereseriousenoughtorequiremedicalattention.
Noneofthegreenturtlescapturedduring1990hadmajorinjuries.
32 IIIIIIII
~Mrtalitie Mortalities havebeencloselymonitored throughout thelifeofthecanalcaptureprograminanattempttoassignprobablecausesandtakeappropriate remedialac-tiontominimizefutureoccurrences.
Previousanalysesofcapturedataidentified drown-inginnets(A1Abarriernet,UIDSbarrier,andtanglenets),drowningintheintakepipesduringperiodsofreducedintakeflow,injuriessustained fromdredgingoperations andinjuriessustained fromthemechanical rakesusedintheintakewellsasprobablemor-talityfactors(ABI,1987).Althoughdifficult toquantify, theentrapment andsubsequent demiseofinjuredorsickturtleshasprobablyaccounted foraportionofobservedmor-talities.
Overtheentire15yearmonitoring period,127(6.9percent)ofthe1,853logger-headsand21(6.9percent)ofthe306greenturtlesentrapped inthecanalwerefounddead(Table6).Mortalities spannedtherangeofsizeclassesforloggerheads (SLCL=47.5-103cm),whileallgreenturtlemortalities involvedjuveniles lessthan42cminlength.ThefourKemp'sridleymortalities documented attheplantduring1987and1988wel'etheonlydeathsforthisspeciestodate;noleatherback orhawksbill mor-talitieshaveoccurredattheSt.LuciePlant.Modifications tocaptureprocedures, improvements totheA1Abarriernetandvir-tualelimination oflowflowconditions withinthecanalhaveresultedinasubstantial reduction inseaturtlemortalities overthelifeofthecanalcaptureprogram.Mortality rates,expressed asthepercentage oftotalcapturesinvolving deadanimals,declined42percentbetweenthefirst(1976-1983) andsecond(1984-1990) halvesofthe33 IIIIIIIIII program.During1990,onlythreemortalities (2.3percentoftotalcaptures) wererecorded, oneloggerhead andtwogreenturtles.Thisrepresents thefewestannualmortalities sincethecanalcaptureprogrambeganin1976.Previousobservations suggestthatsickorinjuredturtlesmaybesusceptible todrowningattheUIDSbarrier.Theloggerhead mortality recordedduring1990occurredatthislocation.
Eventhoughthecarcasswastoodecomposed toassessitsphysicalcondition ordetermine causeofdeath,drowningissuspected.
Additional improve-mentstotheA1Abarriernetduringthelaterpartof1990shouldpreventfuturelogger-headmovements westofA1Aandtherebyeliminate theUIDSbarrierasapotential mortality source.Thetwogreenturtlemortalities during1990resultedfromdrowninginABI'stanglenets.Oneofthesewasresuscitated, butitlatersuccumbed whileunderobservation.
Anecropsywasperformed todetermine ifitwasinpoorhealthatthetimeofcapture;resultsoftissueanalyseshavenotyetbeencompleted.
Toeliminate thepotential forfuturenetdrownings, ABIhasbeguncontinual monitoring ofitstanglenetsduringperiodsofdeployment.
RecatureIncidentSincetheSt.LuciePlantcaptureprogrambegan,mostturtlesremovedalivefromtheintakecanalhavebeentaggedandreleasedintotheoceanatvariouslocations alongHutchinson Island.Consequently, individual turtlescanbeidentified aslongastheyretaintheirtags.Overthe15yearhistoryofturtleentrapment attheSt.LuciePlant,61individuals (60loggerheads and1green)havebeenremovedfromthecanalmore34 thanonce.Severalotherturtleswithtagscarshavealsobeenrecovered, indicating thattheactualnumberofrecaptures maybehigher.Ofthe60individual loggerheads knowntohavebeencaughtmorethanonce,42werecaughttwice,9werecaughtthreetimes,5werecaughtfourtimes,2werecap-turedsixtimes,1wascaughtseventimesand1wascaughtonnineseparateoc-casions,yieldingatotalof99recapture incidents.
Releasesitedidnotappeartohaveanyeffectonaturtle'sprobability ofbeingrecaptured.
Turtlesreleasedbothnorthandsouthoftheplantreturned.
Recaptures alsodidnotappeartoberelatedtosize,asbothjuveniles andadultswerecapturedmorethanonce(rangeofSLCL=47-89cm).However,themajorityofrecapture incidents involvedjuveniles (SLCL<70cm).Recapture intervals forloggerheads rangedfromfourto858days,withameanof157days(+174.0days).Theonlygreenturtlecaughtmorethanoncewascapturedontwooccasions, returning tothecanal59daysafterfirstbeingreleasedintotheocean.About56percentofallloggerhead recapture incidents occurredwithin90daysofpreviouscaptureand89percentwithinoneyear(Figure22).Theaverageintervalbetweenfirstandlastcapturewas262days(+329.7days).Thelongestperiodbe-tweenfirstandlastcapturewas5.3years.Thesedatasuggestthatresidency timesofloggerheads withinthenearshore habitatadjacenttotheSt.LuciePlantarerelatively short.Similarfindingshavebeenreportedforloggerheads inhabiting theMosquito/In-dianRiverLagoonsofeast-central Florida(Mendonca andEhrhart,1982).35 SUMMARYAgradientofincreasing loggerhead turtlenestdensities fromnorthtosouthalongthenorthernhalfofHutchinson Islandhasbeenshownduringmostsurveyyears.Thisgradientmayresultfromvariations inbeachtopography, offshoredepthcontours, dis-tribution ofnearshore reefs,onshoreartificial lightingandhumanactivityonthebeachatnight.Lownestingactivityinthevicinityofthepowerplantduring1975andfrom1981through1983wasattributed toconstruction ofpowerplantintakeanddischarge systems.Nestingreturnedtonormalorabovenormallevelsfollowing bothperiodsofconstruction.
Powerplantoperation, exclusive ofintake/discharge construction, hashadnosignificant effectonnestdensities.
Therehavebeenconsiderable year-to-year fluctuations inloggerhead nestingac-tivityonHutchinson Islandfrom1971through1990.Fluctuations arecommonatotherrookeries andmayresultfromoverlapping ofnon-annual breedingpopulations.
Despitethesefluctuations, loggerhead nestingactivityhasremainedhighduringrecentyearsandmayreflectanoverallincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.Norelationship betweentotalnestingontheislandandpowerplantoperation orintake/discharge construction wasindicated.
Temporary declinesinloggerhead nestingactivityhavebeenattributed tocoolwaterintrusions thatfrequently occuroverthecontinental shelfofsoutheast Florida.ThoughtemporalnestingpatternsoftheHutchinson Islandpopulation maybeinfluenced bynaturalfluctuations inwatertemperature, nosignificant effectsduetopowerplantoperation havebeenindicated.
36 Sincenestingsurveysbeganin1971,raccoonpredation wasconsidered themajorcauseofturtlenestdestruction onHutchinson Island.From1971through1977,over-allpredation ratesintheninesurveyareaswerebetween21and44percent.However,apronounced decreaseinraccoonpredation occurredafter1977,andoverallpreda-tionratesintheninesurveyareashavenotexceededtenpercentsince1979.Decreased predation byraccoonsprobablyreflectsadeclineintheraccoonpopula-tion.During1990,132greenturtleand12leatherback turtlenestswererecordedonHutchinson Island.Nestingactivitybythesetwospeciesexhibited considerable annualfluctuations, ashasbeenrecordedatotherrookeries, buthasremainedrelatively highduringrecentyears.Thismayreflectanoverallincreaseinthenumberofnestinggreenandleatherback turtlesintheHutchinson Islandarea.During1990,112loggerheads and20greenturtleswereremovedfromtheSt.LuciePlantintakecanal.Sincemonitoring beganinMay1976,1,843loggerhead, 306green,9leatherback, 8hawksbill and17Kemp'sridleyturtleshavebeencaptured.
Overthelifeofthemonitoring program,annualcatchesforloggerhead turtleshaverangedfrom33in1976(partialyearofplantoperation andmonitoring) toahighof195in1986.Yearlycatchesofgreenturtleshaverangedfrom0in1976to69in1984.Differences inthenumberofturtlesentrapped duringdifferent yearsandmonthsareattributed tonaturalvariation intheoccurrence ofturtlesinthevicinityoftheoffshoreintakestruc-tures,ratherthantoanyinfluence oftheplantitself.37 IIII Size-class distributions ofloggerhead turtlesremovedeachyearfromthecanalhaveconsistently beenpredominated byjuveniles between50and70cminstraightlinecarapacelength.Mostgreenturtlesentrapped inthecanal(about80percent)werejuveniles 40cmorlessinlength.Forbothspecies,thelargestnumberofcapturesforallyearscombinedoccurredduringthewinter,buttheseseasonalpeaksweremuchmorepronounced forgreenturtles.Sexratiosofbothadultandimmatureloggerheads caughtinthecanalcontinued tobebiasedtowardsfemales.During1990,about93and80percent,respectively, ofallloggerheads andgreenturtlesremovedfromthecanalwerecategorized byphysicalappearance asbeingingoodtoexcellent condition.
Overtheentire15yearmonitoring period,76and78per-cent,respectively, ofallloggerhead andgreenturtlecaptureshaveinvolvedindividuals inthesecategories; 16percentoftheloggerheads and14percentofthegreenturtlesremovedfromthecanalhavebeeninfairorpoorcondition.
Aboutninepercentoftheturtlesremovedfromtheintakecanalduring1990hadsubstantial injuries.
However,mostoftheseinjuriesweresustained priortoentrap-ment.Onceinthecanal,turtlesconfinedeastofA1Ausuallyhadverybriefresidency timesandthustherelativecondition ofmostturtleswasnotaffectedbytheirentrap-ment.During1990,oneloggerhead andtwogreenturtlemortalities occurredintheintakecanal.Thesedeathsprobablyresultedfromdrowning:
twoinABItanglenets,oneattheUIDSbarrier.Programmodifications topermitcontinual surveillance oftanglenets38 IIII duringperiodsofdeployment andimprovements totheA1Abarriernetwereinitiated tofurtherreducethepotential forsimilarmortalities inthefuture.Sinceintakecanalmonitoring beganin1976,6.9percentoftheloggerheads andasimilarpercentage ofgreenturtlesremovedfromthecanalweredead.ThefourKemp'sridleymortalities in1987and1988weretheonlydeathsrecordedforthisspeciessincemonitoring began.Alloftheleatherbacks andhawksbills entrapped intheintakecanalattheSt.LuciePlanthavebeencapturedaliveandreleasedintotheocean.Modifica-tionstocaptureprocedures, improvements totheA1Abarriernetandvirtualelimina-tionoflowflowconditions inthecanalhasresultedina42percentreduction inseaturtlemortality ratesoverthelifeofthecanalcaptureprogram.39 IIIIIII LITERATURE CITEDABI(AppliedBiology,Inc).1977.Ecological monitoring attheFloridaPower&LightCo.St.LuciePlant,annualreport1976.VolumesIandII.AB-44.PreparedbyAppliedBiology,Inc.forFloridaPower8LightCo.,Miami..1978.Ecological monitoring attheFloridaPower8LightCo.St.LuciePlant,annualreport1977.VolumesIandII.AB-101.PreparedbyAppliedBiology,Inc.forFloridaPower&LightCo.,Miami..1979.FloridaPower8LightCompany,St.LuciePlantannualnon-radiologi-calenvironmental monitoring report1978.VolumesIIandIII,Bioticmonitoring.
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IX.Dielplankton, 1973-1974.
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47pp.Williams-Walls, N.,J.O'ara,R.M.Gallagher, D.F.Worth,B.D.PeeryandJ.R.Wilcox.1983.SpatialandtemporaltrendsofseaturtlenestingonHutchinson Island,Florida,1971-1979.BulletinofMarineScience33(1):55-66.
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~mdasnestinginFlorida.Pages351-352inOgren,L.,F.Berry,K.Bjorndal, H.Kumpf,R.Mast,G.Medina,H.ReichartandR.Witham,editors.Proceed-ingsoftheSecondWesternAtlanticTurtleSymposium.
: Mayaguez, PuertoRico,12-16October1987.NOAATechnical Memorandum NMFS-SEFC-226.
Wi*II,WN.'l983.98 3IIdiIpiIdI83till~I~~EhI(Linnaeus, 1766).FAOFisheries
: Synopsis, 137:1-78.
Worth,D.F.andM.L.Hollinger.
1977.Nearshore marineecologyatHutchinson Island,Florida:1971-1974.
III.Physicalandchemicalenvironment.
FloridaMarineResearchPublica-tions23:25-85.46 Worth,D.F.,andJ.B.Smith.1976.MarineturtlenestingonHutchinson Island,Florida,in1973.FloridaMarineResearchPublications 18:1-17.47 GULFOFMEXICO00YAROSKILOMETERS SCALEr~~StLuciaPlantFigure1.LocationoftheSt.LuciePlant.
IIIIIIIII V~g~t'~gW.:,::HUTCHINSON ISLAND~o0'F~~IJi7.~iS'~Oc2G'5~.L-....i~00250500METERS~~tr~5pp,>r~DISCHARGE
~gG+'..PIPES0G"oi~gAv'~'l"r2VQ9INTAKE'<:.:.c,".'NTAKE HEADWALL';
4~':-,.'.'ELLS~'.",STRUCTURES UIDSA1A'-'.:.
BARRIERBARRIER:.
,,NET;.~;~b~',,'1'a'84'NTAKECANALFigure2.St.LuciePlantcoolingwaterintakeanddischarge system.
II FLPierceInlet10A\~~'aFaStateGHwyA0a7~'t~aeaaAIg0Q0bb,oOaloH2V+F+3N40FPLST.LUCIEPU.S.HwyId0SkmRtV6.RVw6AA4BBCCDDEFFGGda+HHOdQuSLLudoInletFigure3.Designation andlocationofnine1.25-kmsegmentsandthirty-six 1-kmsegmentssurveyedforseaturtlenesting.Hutchinson Island,1971-1990.
350300250z0200Dz1501005012NORTH3456789POWERPLANTSOUTHFigure4.Meanannualnumberofloggerhead turtlenestsineachofthenine1.25-km-long surveyareas,Hutchinson Island,1971-1989, comparedwithnumberofnestsduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values(1980datawereexcludedbecausenotallareasweresurveyed).
IIIIIIIIIIII 350300~~250200(0I-V)z150Dz~~~10050ABCDEFGHIJKLMNOPQRSTUVWXYZABCDE FGHIJABCDEFGHIJNORTH1'OWERPLANTSOUTHFigure5.Meanannualnumberofloggerhead turtlenestsineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1989, comparedwithnumberofnestsduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.
IIIIIIIII 700600500400Oz300D200~~100ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHI JABCDEFGHIJNORTHPOWERPLANTSOUTHFigure6.Meanannualnumberofloggerhead turtleemergences ineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1989, comparedwiththenumberofemergences during1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.
IIIIIII 10080gM(0LIJOOP)60(9ZI-0)ILJZ4020ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGH IJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure7.Meanannualloggerhead turtlenestingsuccess(percentage ofemergences thatresultedinnests)foreachofthethirty-six 1-km-longsurveyareas,Hutchinson Island,1981-1989, comparedwithnestingsuccessduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.
300250o-oArea4(PowerPlantSite)e--~Area5(ControlSite)200V)I-Z0150Dz100~Or%rr/////////50TTT19711972197319741975197619771978197919801981198219831984198519861987198819891990Figure8.Numberofioggerhead turtlenestsinAreas4and5,Hutchinson Isiand,1971-1990.
Arrowsdenoteyearsduringwhichintake/discharge construction occurredinArea4.
I 6000CD(DI-zDz50004000300020001000CDOz0CCDz12000100008000600040002000gCDCOLIJOO(0(9zCDUJ806040201981198219831984198519861987198819891990Figure9.Annualnumberofnests,numberofemergences andnestingsuccessalongtheentire36.0-km-long Atlanticcoastline ofHutchinson Island,198t-1990.
3130O29285272625Q.242322212012090(0z060z30305153051530515APRMAYJUNJULFigure10.Dailyloggerhead turtlenestingactivityandwatertemperature, Hutchinson Island,1990.30515AUG30515SEP 27%7060Destroyed byghostcrabsgDestroyed byraccoonsandghostcrabsQDestroyed byraccoons50O0-0KI-Uj40O(0I-(0zrt-30Dz201015%.?~Vxm:('?iAMh((.:9X'~egZps:K(:N<:e.'.gg.r,'(?Fp?'m~$+11%Y??r','my~?(m,:(g~18%r'(I(pjmr~'r'..v&#xc3;r'.rg~b;s(:r.ggCi(5'$.::$p~.?s?:.'$p$j~g>?~PI5%?.'A'(iM:'A?g(;@A;('(?g(??.:N~??jPAQsE(g?gr.m(mi14%Wg'kg$.$yg?gmmeE(.:VP8:.:~a??::,g:)>%!4~?>?:'(pY,~4'.($NScYA(&#xc3;~(??APg.(g'.?'.spi'g~Q4?ih(1%rr:.(1%1%2'/oABCDEFGHIJKLMNOPQRS TUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure11.Numberofloggerhead turtlenestsdestroyed byraccoonsandghostcrabsandpercentage ofnestsdestroyed ineach1-km-long surveyarea,Hutchinson Island,1990.
140120100COIzO80z604020Q--QGreen(Chelonia mydas)O-~Leatherback (Dermochelys coriacea) pQpHgoIIIIIIlIIIpqII/xIIiIy/XgIIIIII197119731975197719791981198219831984198519861987198819891990Figure12.Annualnumbersofgreenturtleandleatherback turtlenests,Hutchinson Island,1971-1990.
200~-eLOGGERHEAD (Carettacaretta)0---wGREEN(Chelccia m~das)80175150O125K1007550z25////r0IIIIIIpi\'I70860O50z40(930mmD2010197619771978197919801981198219831984198519861987198819891990Figure13.Numberofloggerhead andgreenturtlesremovedeachyearfromtheintakecanal,St.LuciePlant,19764990.  


JLJCCI-CLOCIJCJCIZ0I-ZILJOIZILJQ.ILJI-O10080604020'100806040201020304050DAYSBETWEENFIRSTSIGHTINGANDCAPTUREFigure21.Captureefficiency,expressedasdaysbetweenfirstsightingandcapture,forloggerheadturtlesentrappedintheintakecanal,St.LuciePlant,April-December,1990(N=90).
40403030I-20z201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure14.Meannumberofloggerheads capturedeachmonth,St.LuciePlantintakecanal,1977-1989, comparedwithnumberofmonthlycapturesduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.
100100~80(9za-60I-DD<40fIt///80604020IIIIIt~-----~IntervalbetweensuccessivecapturesIntervalbetweenfirstandlastcapture20500250175075010001250RECAPTUREINTERVAL(days)Figure22.Cumulativepercentageofallloggerheadrecapturesoccurringwithinvarioustimeintervalsbetweensuccessivecaptures(&#xb9;97jandfirstandlastcapture(&#xb9;58),St.LuciePlantintakecanal1976-1990.  
IIIIIII 400400300300(0DO)0zu-2000KUJlZlDz200100100~4041-4546-5051-5556-6061-6566-7071-7576-8081-8586-9091-9596-101-106->110STRAIGHTLINECARAPACELENGTH(cm)100105110Figure15.Lengthdistribution (SLCL)ofloggerhead turtles(N=1,673) removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.
Nodatacollected for81individuals.
400400300300(0DO)DZ2000KIllCODZ200100100+1011-2021-3031-4041-5051-6061-7071-8081-9091-100101-111-121-131-141-i150'I/EiGHT(kg)110120130140150Figure1LWeightdistribution ofliveloggerhead turtles(&#xb9;1,487)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.
Nodatacollected for267individuals.
12012010010080COD0)0600K(9408060402020-1516-21-26-31-36-41-46-51-56-61-66-71-76-81-86-91-96-101-106->11020253035404550556065707580859095100105110STRAIGHTLINECARAPACELENGTH(cm)Figure17.Lengthdistribution (SLCL)ofgreenturtles(N=295)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.
Nodatacollected for10individuals.
200200180180160160(D140D9120Dz010080z601401201008060404020201-56-1011-1516-2021-2526-3031-3536-4041-4546-5051-101-151-)200WEIGHT(kg)100150200Figure18.Weightdistribution ofgreenturtles(N=291)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.
Nodatacollected for14individuals.
IIIIIIII MALESFEMALES60505040V)DCI0300KILJKDz204030201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure19.Numbersofadultloggerheads (SLCL)85.0 cm),including recaptures, removedeachmonthfromtheintakecanal,St.LuciePlant,1977-1990 (N=255;sexnotrecordedforsixindividuals)85.0 cm).
50~-eCANALCAPTURES 50040302010o---oEMERGENCES 00//////]y////r/400300200100ZV)OzGK0zzz19771978197919801981198219831984198519861987198819891990Figure20.Comparison ofcapturesofadultfemaleloggerheads (SLCL>85.0cm)intheintakecanal,St.LuciePlant,1977-1990, andnumbersofloggerhead emergences inarea4adjacenttotheplant.Nestingactivitywasnotmonitored in1978.  


WTABLE1ESTIMATESOFTHENUMBERSOFLOGGERHEADTURTLENESTSONHUTCHINSONISLANDBASEDONSURVEYSOFNINE1.25-KM-LONGSURVEYAREAS,1971-1990,COMPAREDTOTHEACTUALNUMBEROFNESTSONTHEISLAND,1981-1990197119731975197719791981198219831984198519861987198819891990Numberofnestsinthenine1420126014939321449103115921439162318391645170117742177ExtrapolationfromtheninesurveyareastotheiI4203373044192759428930524837471242594804486950355251Actualnumberofnestsonthe311546904743427748775483462351936700 IIIII TABLE2TOTALNUMBEROFSEATURTLECAPTURESAND(NUMBEROFDEAD)TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-199019761977197819791980198119821983198419851986198719881989TotalAnnualMean's(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)1853(127)130.05(2)6(1)3(1)10(3)32(2)823(4)69(2)1422(1)3542(2)17(1)20(2)306(21)21.99(0)0.6will8(0)0.6Km'l16(2)5(2)217(4)1.2ss(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)1s2(s)2193(152)154.3Excludes1976(partialyearofplantoperation).
JLJCCI-CLOCIJCJCIZ0I-ZILJOIZILJQ.ILJI-O10080604020'100806040201020304050DAYSBETWEENFIRSTSIGHTINGANDCAPTUREFigure21.Captureefficiency, expressed asdaysbetweenfirstsightingandcapture,forloggerhead turtlesentrapped intheintakecanal,St.LuciePlant,April-December, 1990(N=90).
TABLE3TOTALNUMBEROF(ANDNUMBEROFDEAD)LOGGERHEADTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-19901976197713s(1)2075(2)157(1)75(3)15(1)9(1)5933(4)580(5)19781911(2)27(2)19(5)3(1)101217(2)15(7)4138(19)19791980198119824&1983198419851986198719881989199024(3)29(1)111703(1)1621(2)14078(3)11(1)11(3)6106627(2)16(2)8(1)12192(1)15(3)1274006(2)141417(4)72(1)9(1)9(5)4(2)391313(1)047(1)62(1)728(1)12(1)26s(2)16152013161720(3)19(1)1426(3)8(1)24(3)23(1)26(1)19(1)17(1)1751097311(2)83510(3)1113(2)283011(1)-254(2)11131699232521(1)15167(1)35(1)4115(2)16(4)14(4)20(2)1220(1)26(2)34(6)9(4)10172(13)8116(5)362(5)1(1)101(16)12119(4)8148(3)2157(4)10195(27)9175(11)9134(6)2111(4)3112(1)Total219(11)178(17)152(9)157(15)162(6)208(8)172(11)177(11)126(12)121(13)86(13)95(1)1853(127)MonthlyMean15.6%TotalCatch11.812.79.611.58.28.58.711.29.310.911.210.813.911.89.68.46.86.54.68.15.76.35.1eludes1976(partialyearofplantoperation).
100100~80(9za-60I-DD<40fIt///80604020IIIIIt~-----~Intervalbetweensuccessive capturesIntervalbetweenfirstandlastcapture20500250175075010001250RECAPTURE INTERVAL(days)Figure22.Cumulative percentage ofallloggerhead recaptures occurring withinvarioustimeintervals betweensuccessive captures(&#xb9;97jandfirstandlastcapture(&#xb9;58),St.LuciePlantintakecanal1976-1990.
IIII TABLE4TOTALNUMBEROF(ANDNUMBEROFDEAD)GREENTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPIANT,1976-19901976197719781979198019811982198310018(1)43(2)22(1)01(1)012201(1)0101(1)00,5(1)4(1)0020(1)7110000000101(1)000000000002(1)02.04(1)5(2)6(1)3(1)10(3)32(2)23(4)1984198537(1)1041121986116(1)31198741332198819891990Total12114233(1)06316(1)3(1)31199(5)48(3)33(4)19(2)9(1)MonthlyMean7.13.42.41.40.62.9%TotalCatch32.415.710.86.25.92.60211316(2)1101018(3)81.20.59(1)0.62.90.31.6140.94.64(1)51102022120(2)241.31.66.57.869(2)1422(1)3542(2)17(1)20(2)306(21)
 
IIIIII TABLE5NUMBEROFMONTHLYCAPTURESBYSIZECLASSFORLOGGERHEADTURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1977-1990SizeclassesSLCLincm)JanuaryFebruaryMarch16AprilMayJune13Total101%ofTotalJulyAugustSeptember4October8November4December473475150'24248352034592765648523835483832242651717812011210010581977548121014.711.69.99.38.38.76.78.07.46.24.05.369.42621182717262835162?19132739.57.76.6996.29.510.312.85.9997.04.815.772022006150132613826321294191815825114414011613114406738152613.41.52.72.315.325.720.714.65.72.73.41.915.0Excludes1976(partialyearofdata).Nodatawerecollectedfor76individuals.
WTABLE1ESTIMATES OFTHENUMBERSOFLOGGERHEAD TURTLENESTSONHUTCHINSON ISLANDBASEDONSURVEYSOFNINE1.25-KM-LONG SURVEYAREAS,1971-1990,COMPAREDTOTHEACTUALNUMBEROFNESTSONTHEISLAND,1981-1990197119731975197719791981198219831984198519861987198819891990Numberofnestsinthenine1420126014939321449103115921439162318391645170117742177Extrapolation fromtheninesurveyareastotheiI4203373044192759428930524837471242594804486950355251Actualnumberofnestsonthe311546904743427748775483462351936700 IIIII TABLE2TOTALNUMBEROFSEATURTLECAPTURESAND(NUMBEROFDEAD)TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990 19761977197819791980198119821983198419851986198719881989TotalAnnualMean's(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)1853(127)130.05(2)6(1)3(1)10(3)32(2)823(4)69(2)1422(1)3542(2)17(1)20(2)306(21)21.99(0)0.6will8(0)0.6Km'l16(2)5(2)217(4)1.2ss(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)1s2(s)2193(152)154.3Excludes1976(partialyearofplantoperation).
TABLE6RELATIVECONDITIONOFSEATURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990RelativeTotal39321.251127.650327.122111.9713.81276.9271.5185312841.85919.35116.73511.472.3216.951.6306111.1111.1777.8211.8317631763176211.8423.51775.025.053024.257626.356425.725911.8803.61526.9321.521931Excellent:normalorabovenormalweight,active,veryfewornobarnaclesorleeches,nowounds.2Verygood:intermediategoodtoexcellent.3Good:normalweight,active,lighttomediumcoverageofbarnaclesand/orleeches,woundsabsent,healedordonotappeartodebilitatetheanimal.4Fair:intermediatepoortogood.5Poor:emaciated,sloworinactive,heavybarnaclecoverageand/orleechinfestation,debilitatingwoundsormissingappendages.6Dead7Alivebutotherwiseconditionnotrecorded.
TABLE3TOTALNUMBEROF(ANDNUMBEROFDEAD)LOGGERHEAD TURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990 1976197713s(1)2075(2)157(1)75(3)15(1)9(1)5933(4)580(5)19781911(2)27(2)19(5)3(1)101217(2)15(7)4138(19)19791980198119824&1983198419851986198719881989199024(3)29(1)111703(1)1621(2)14078(3)11(1)11(3)6106627(2)16(2)8(1)12192(1)15(3)1274006(2)141417(4)72(1)9(1)9(5)4(2)391313(1)047(1)62(1)728(1)12(1)26s(2)16152013161720(3)19(1)1426(3)8(1)24(3)23(1)26(1)19(1)17(1)1751097311(2)83510(3)1113(2)283011(1)-254(2)11131699232521(1)15167(1)35(1)4115(2)16(4)14(4)20(2)1220(1)26(2)34(6)9(4)10172(13)8116(5)362(5)1(1)101(16)12119(4)8148(3)2157(4)10195(27)9175(11)9134(6)2111(4)3112(1)Total219(11)178(17)152(9)157(15)162(6)208(8)172(11)177(11)126(12)121(13)86(13)95(1)1853(127)
MonthlyMean15.6%TotalCatch11.812.79.611.58.28.58.711.29.310.911.210.813.911.89.68.46.86.54.68.15.76.35.1eludes1976(partialyearofplantoperation).
IIII TABLE4TOTALNUMBEROF(ANDNUMBEROFDEAD)GREENTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPIANT,1976-1990 1976197719781979198019811982198310018(1)43(2)22(1)01(1)012201(1)0101(1)00,5(1)4(1)0020(1)7110000000101(1)000000000002(1)02.04(1)5(2)6(1)3(1)10(3)32(2)23(4)1984198537(1)1041121986116(1)31198741332198819891990Total12114233(1)06316(1)3(1)31199(5)48(3)33(4)19(2)9(1)MonthlyMean7.13.42.41.40.62.9%TotalCatch32.415.710.86.25.92.60211316(2)1101018(3)81.20.59(1)0.62.90.31.6140.94.64(1)51102022120(2)241.31.66.57.869(2)1422(1)3542(2)17(1)20(2)306(21)
IIIIII TABLE5NUMBEROFMONTHLYCAPTURESBYSIZECLASSFORLOGGERHEAD TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1977-1990 SizeclassesSLCLincm)JanuaryFebruaryMarch16AprilMayJune13Total101%ofTotalJulyAugustSeptember 4October8November4December473475150'24248352034592765648523835483832242651717812011210010581977548121014.711.69.99.38.38.76.78.07.46.24.05.369.42621182717262835162?19132739.57.76.6996.29.510.312.85.9997.04.815.772022006150132613826321294191815825114414011613114406738152613.41.52.72.315.325.720.714.65.72.73.41.915.0Excludes1976(partialyearofdata).Nodatawerecollected for76individuals.
TABLE6RELATIVECONDITION OFSEATURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990RelativeTotal39321.251127.650327.122111.9713.81276.9271.5185312841.85919.35116.73511.472.3216.951.6306111.1111.1777.8211.8317631763176211.8423.51775.025.053024.257626.356425.725911.8803.61526.9321.521931Excellent:
normalorabovenormalweight,active,veryfewornobarnacles orleeches,nowounds.2Verygood:intermediate goodtoexcellent.
3Good:normalweight,active,lighttomediumcoverageofbarnacles and/orleeches,woundsabsent,healedordonotappeartodebilitate theanimal.4Fair:intermediate poortogood.5Poor:emaciated, sloworinactive, heavybarnaclecoverageand/orleechinfestation, debilitating woundsormissingappendages.
6Dead7Alivebutotherwise condition notrecorded.
IIII}}
IIII}}

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St.Lucie Unit 2 Annual Environ Operating Rept,Vo1 1 for 1990.
ML17223B174
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APPLIEDBI0L'06Y,INC.AB-610I'LORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORTVOLUMEI1990I2968ANORTHDECATURROAD9105070294 910025PDRADOCK05000389RPDR~ATLANTA,GEORGIA30033~404-296-3900 AB-610FLORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORT1990VOLUME1APRIL1991FLORIDAPOWER&LIGHTCOMPANYJUNOBEACH,FLORIDAAPPLIEDBIOLOGY,INC.ATLANTA,GEORGIA IIIIII ENVIRONMENTAL OPERATING REPORTTABLEOFCONTENTSTABLEOFCONVERSION FACTORSFORMETRICUNITSEXECUTIVE SUMMARYIntroduction TurtleNestingSurveyIntakeCanalMonitoring OtherRelatedActivities INTRODUCTION

Background

AreaDescription PlantDescription TURTLESIntroduction Materials andMethodsNestingSurveyIntakeCanalMonitoring StudiestoEvaluateand/orMitigateIntakeEntrapment ResultsandDiscussion NestingSurveyDistribution ofLoggerhead NestsAlongHutchinson IslandEstimates ofTotalLoggerhead NestingonHutchinson IslandTemporalLoggerhead NestingPatternsPredation onLoggerhead TurtleNestsGreenandLeatherback TurtleNestingIntakeCanalMonitoring RelativeAbundance andTemporalDistribution Size-Class Distributions SexRatiosCaptureEfficiencies RelativeCondition Mortalities Recapture Incidents SummaryLITERATURE CITEDFIGURESTABLESIVIV10101415151518192021232326.28.3031333436404870 TABLEOFCONVERSION FACTORSFORMETRICUNITSToconvertcentigrade (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+273.183.937x103.281x103.281x101.0x102.205x103.527x102.4711.0x102.20463.5274x106.214x101.0x101.0x102.642x103.2813.937x101.0941.0x101.01.0x103.937x103.281x101.550x101.076x101.55x10Toobtainfahrenheit (degrees) kelvin(degrees) inchesfeetfeetpersecondliterspoundsounces(avoirdupois) acresgramspoundsounces(avoirdupois) miles(statute) millimetcrscubiccentimeters (cm)gallons(USliquid)feetinchesJJardsgramspartspermillionliters(USliquid)inchesfeetsquareinchessquarefeetsquareinches IIIrIe,t EXECUTlVE SUMMARYINTRODUCTION TheSt.LuciePlantisanelectricgenerating stationonHutchinson IslandinSt.LucieCounty,Florida.Theplantconsistsoftwonuclear-fueled 850-MWunits;Unit1wasplacedon-lineinMarch1976andUnit2inMay1983.Thisdocumenthasbeenpreparedtosatisfy.therequirements contained intheUnitedStatesNuclearRegulatory Commission's AppendixBEnvironmental Protection Plan(EPP)toSt.LucieUnit2FacilityOperating LicenseNo.NPF-16.Thisreportdiscusses environmental protection activities relatedtoseaturtlesasrequiredbySubsection 4.2oftheEPP.Otherroutineannualreporting requirements areaddressed inVolume2,alsoentitled"St.LucieUnit2AnnualEnvironmental Operating Report".TURTLENESTINGSURVEYTherehavebeenconsiderable year-to-year fluctuations inseaturtlenestingactivityonHutchinson Islandsincemonitoring beganin1971.Lownestingactivityin1975and1981-1983inthevicinityofthepowerplantwasattributed toconstruction ofplantin-takeanddischarge structures.

Nestingreturnedtonormalorabovenormallevelsfol-lowingbothperiodsofconstruction.

Powerplantoperation exclusive ofconstruction hashadnosignificant effectonnestingneartheplant.Datacollected through1990haveshownnolong-term reductions intotalnesting,totalemergences ornestingsuc-cessontheisland.Formalrequirements toconductthisprogramexpiredin1986butwerevoluntarily continued in1990withagreement fromfederalandstateagencies.

INTAKECANALMONITORING Sinceplantoperation beganin1976,2,193seaturtles(including 100recaptures) representing fivedifferent specieshavebeenremovedfromtheintakecanal.Eighty-fourpercentofthesewereloggerheads.

Differences inthenumbersofturtlesfoundduringdifferent monthsandyearswereattributed tonaturalvariation intheoccurren-cesofturtlesinthevicinityoftheplant,ratherthantoanyinfluence oftheplantitself.Themajorityofturtlesremovedfromtheintakecanal(about93percent)werecapturedaliveandreleasedbackintotheocean.TurtlesconfinedbetweentheA1Abarriernetandintakeheadwalls usuallyresidedinthecanalforarelatively shortperiodoftime,andmostwereingoodtoexcellent condition whencaught.OTHERRELATEDACTIVITIES Studiestoevaluatevariousintakedeterrent systems,asrequiredbytheNRC'sUnit2Environmental Protection Plan,wereconducted during1982and1983.Resultsandevaluations ofthosestudieswerepresented toregulatory agenciesduring1984,andtherequirement isnowconsidered completed.

INTRODUCTION BACKGROUND Thisdocumenthasbeenpreparedtosatisfytherequirements contained intheUnitedStatesNuclearRegulatory Commission's (NRC)AppendixBEnvironmental Protection PlantoSt.LucieUnit2FacilityOperating LicenseNo.NPF-16.In1970,FloridaPower8LightCompany(FPL)wasissuedPermitNo.CPPR-74bytheUnitedStatesAtomicEnergyCommission, nowtheNuclearRegulatory Commis-sion,thatallowedconstruction ofUnit1oftheSt.LuciePlant,an850-MWnuclear-poweredelectricgenerating stationonHutchinson IslandinSt.LucieCounty,Florida.StLuciePlantUnit1wasplacedon-lineinMarch1976.InMay1977,FPLwasissuedPermitNo.CPPR-144bytheNRCfortheconstruction ofasecond850-MWnuclear-poweredunit.Unit2wasplacedon-lineinMay1983andbegancommercial operation inAugustofthatyear.St.LuciePlantUnits1and2usetheAtlanticOceanasasourceofwaterforonce-throughcondenser cooling.Since1971,thepotential environmental effectsresulting fromtheintakeanddischarge ofthiswaterhavebeenthesubjectofFPL-sponsored bioticstudiesatthesite.Baselineenvironmental studiesofthemarineenvironment adjacenttotheSt.LuciePlantweredescribed inaseriesofreportspublished bytheFloridaDepartment ofNaturalResources (Campetal.,1977;FutchandDwinell,1977;Gallagher, 1977;Gal-lagherandHollinger, 1977;WorthandHollinger, 1977;MofflerandVanBreedveld, 1979;TesterandSteidinger, 1979;Walker,1979;Walkeretal.,1979;WalkerandSteidinger, 1979;Lyons,1989).TheresultsofUnit1operational andUnit2preopera-tionalbioticmonitoring attheSt.LuciePlantwerepresented insixannualreports(ABI,1977,1978,1979,1980a,1981b,1982).InJanuary1982,aNationalPollutant Discharge Elimination System(NPDES)permitwasissuedtoFPLbytheUSEnvironmental Protec-tionAgency(EPA).TheEPAguidelines fortheSt.Luciesitebiological studieswerebasedonthedocumententitled"Proposed St.LuciePlantPreoperational andOpera-tionalBiological Monitoring Program-August1981"(ABI,1981c).Findingsfromthesestudieswerereportedinthreeannualreports(ABI,1983,1984a,1985a).TheEPAbioticmonitoring requirements weredeletedfromtheNPDESpermitin1985.Jurisdiction forseaturtlestudiesiswiththeNRC,whichisconsidered tobetheleadfederalagencyrelativetoconsultation undertheEndangered SpeciesAct.Previousresultsdealingexclusively withseaturtlestudiesarecontained insevenenvironmen-taloperating reports(ABI,1984b,1985b,1986,1987,1988,1989,1990).Thisreportdescribes the1990environmental protection activities relatedtoseaturtles,asrequiredbySubsection 4.2oftheSt.LuciePlantUnit2Environmental Protection Plan.AREADESCRIPTION TheSt.LuciePlantislocatedona457-hasiteonHutchinson IslandonFlorida's eastcoast(Figures1and2).Theplantisapproximately midwaybetweentheFt.PierceandSt.LucieInlets.ItisboundedonitseastsidebytheAtlanticOceanandonitswestsidebytheIndianRiverLagoon.

IIIII Hutchinson Islandisabarrierislandthatextends36kmbetweeninletsandobtainsitsmaximumwidthof2kmattheplantsite.Elevations approach5matopdunesbor-deringthebeachanddecreasetosealevelinthemarigrove swampsthatarecommononmuchofthewesternside.Islandvegetation istypicalofsoutheastern Floridacoas-talareas;densestandsofAustralian pine,palmetto, seagrapeandSpanishbayonetarepresentatthehigherelevations, andmangroves aboundatthelowerelevations.

Largestandsofblackmangroves, including someontheplantsite,havebeenkilledbyfloodingformosquitocontroloverpastdecades.TheAtlanticshoreline ofHutchinson Islandiscomposedofsandandshellhashwithintermittent rockypromontories protruding throughthebeachfacealongthesouthernendoftheisland.Submerged coquinoid rockformations parallelmuchoftheislandofftheoceanbeaches.Theoceanbottomimmediately offshorefromtheplantsitecon-sistsprimarily ofsandandshellsediments.

Theunstablesubstrate limitstheestab-lishmentofrootedmacrophytes.

TheFloridaCurrent,whichflowsparalleltothecontinental shelfmargin,beginstodivergefromthecoastline atWestPalmBeach.AtHutchinson Island,thecurrentisapproximately 33kmoffshore.

Oceanicwaterassociated withthewesternboundaryofthecurrentperiodically meandersovertheinnershelf,especially duringsummermonths.PLANTDESCRIPTION TheSt.LuciePlantconsistsoftwo850-MWnuclear-fueled electricgenerating unitsthatusenearshore oceanwatersfortheplant'sonce-through condenser coolingwater system.Waterfortheplantentersthroughthreesubmerged intakestructures locatedabout365moffshore(Figure2).Eachoftheintakestructures isequippedwithavelocitycaptominimizefishentrainment.

Horizontal intakevelocities arelessthan30cm/sec.Fromtheintakestructures, thewaterpassesthroughsubmerged pipes(two3.7mandone4.9mindiameter) underthebeachanddunesthatleadtoa1,500-mlongintakecanal.Thiscanaltransports thewatertotheplant.Afterpassingthroughtheplant,theheatedwaterisdischarged intoa670-mlongcanalthatleadstotwoburieddischarge pipelines.

Thesepassunderneath thedunesandbeachandalongtheoceanfloortothesubmerged discharges, thefirstofwhichisapproximately 365moffshoreand730mnorthoftheintake.Heatedwaterleavesthefirstdischarge linefromaY-shapednozzle(diffuser) atadesignvelocityof396cm/sec.Thishigh-momentum jetentrainsambientwater,result-inginrapidheatdissipation.

Theoceandepthintheareaofthefirstdischarge isabout6m.Heatedwaterleavestheseconddischarge linethroughaseriesof48equallyspacedhighvelocityjetsalonga323-mmanifold(multiport diffuser).

Thisdiffuserstarts168mbeyondthefirstdischarge andterminates 856mfromshore.Theoceandepthatdischarge alongthisdiffuserisfromabout10to12m.Aswiththefirstdiffuser, thepurposeoftheseconddiffuseristoentrainambientwaterandrapidlydissipate heat.Fromthepointsofdischarge atbothdiffusers, thewarmerwaterrisestothesurfaceandformsasurfaceplumeofheatedwater.Theplumethenspreadsoutonthesur-faceoftheoceanundertheinfluence ofwindandcurrentsandtheheatdissipates totheatmosphere.

>tIIIIII TURTLESTheNRC'sSt.LucieUnit2AppendixBEnvironmental Protection PlanissuedApril1983containsthefollowing technical specifications:

4.2Terrestrial AuaticIssuesIssuesonendangered orthreatened seaturtlesraisedintheUnit2FES-OL[NRC,1982)andintheEndangered SpeciesBiological As-sessment(March1982)[Bellmund etal.,1982]willbeaddressed byprogramsasfollows:Beachnestingsurveysforallspeciesofseaturtleswillbeconducted onayearlybasisfortheperiodof1982through1986.Thesesur-veyswillbeconducted duringthenestingseasonfromap-proximately mid-April throughAugust.TheHutchinson Islandbeachwillbedividedinto36one-km-long surveyareas.Inaddition, thenine1.25-km-long surveyareasusedinpreviousstudies(1971-1979) willbemaintained forcomparison purposes.

Surveyareaswillbemarkedwithnumberedwoodenpla-quesand/orexistinglandmarks.

Theentirebeachwillbesurveyedsevendaysaweek.AIInewnestsandfalsecrawlswillbecountedandrecordedineacharea.Aftercounting, allcrawltrackswillbeobliterated toavoidrecounting.

Predation onnestsbyraccoonsorotherpredators willberecordedasitoccurs.Recordswillbekeptofanyseasonalchangesinbeachtopography thatmayaffectthesuitability ofthebeachfornesting.4.2.2Aprogramthatemployslightand/orsoundtodeterturtlesfromtheintakestructure willbeconducted.

Thestudywilldetermine withlaboratory andfieldexperiments ifsoundand/orlightwillresultinareduction oftotalturtleentrapment rate.

Thestudyshallbeimplemented nolaterthanafterthefinalremovalfromtheoceanofequipment andstructures associated withcon-struction ofthethirdintakestructure andtheexperiments shallter-minate18monthslater.Fourmonthsaftertheconclusion oftheexperimental period,areportontheresultsofthestudywillbesub-mittedtoNRC,EPA,NationalMarineFisheries Service(NMFS),andtheUSFishandWildlifeService(USFWS)fortheirevaluation.

Ifastatistically significant reduction inannualtotalturtleentrapment rateof80percentorgreatercanbedemonstrated, usingthedeveloped technology anduponFPLreceiving writtenconcurrence byNRC,EPA,NMFS,andUSFWSthenpermanent installation ofthedeterrent systemshallbecompleted andfunctioning nolaterthan18monthsaftertheagencies'oncurrence.

Thedesignofthisstudyneedstotakeintoaccountthesignificant annualvariation inturtleentrapment observedinthepast.Ifan80percentreduction ofturtleentrapment cannotbeprojected toallthreeintakestructures, thenaninteragency taskforcecom-posedofNRC,EPA,NMFS,'USFWS, andFPLshallconvene18monthsaftercompletion ofthethirdintakeanddetermine ifothercoursesofactiontomitigateand/orreduceturtleentrapment arewarranted (suchasphysicalbarrier,emergence ofnewtechnology ormethodstodeterturtles).

4.2.3Alternative methodsorprocedures forthecaptureofseaturtlesentrapped intheintakecanalwillbeevaluated.

Ifamethodorpro-cedureisconsidered feasibleandcosteffective andmayreducecapturemortality rates,itwillbefieldtestedintheintakecanal.4.2.5CatureandReleaseProramSeaturtleremovalfromtheintakecanalwillbeconducted onacon-tinuingbasis.Theturtleswillbecapturedwithlargemeshnets,orothersuitablenondestructive device(s),

ifdeemedappropriate.

Aformalized dailyinspection, fromtheshoreline, ofthecaptul'Bdevice(s) willbemadebyaqualified individual whenthedevice(s) aredeployed.

Theturtleswillbeidentified tospecies,measured, weighed(ifappropriate),

taggedandreleasedbackintotheocean.Recordsofwounds,freshorold,andasubjective judgement onthecondition oftheturtle(e.g.,barnaclecoverage, underweight) willbemaintained.

Methodsofobtaining additional biological/physiologi-caldata,suchasbloodanalysesandparasiteloads,fromcaptured IIIIII seaturtleswillbepursued.Deadseaturtleswillbesubjected toagrossnecropsy, iffoundinfreshcondition.

INTRODUCTION Hutchinson Island,Florida,isanimportant rookeryfortheloggerhead turtle,Caret-tacarettaandalsosupportssomenestingofthegreenturtle,Chelonia~mdasandthIth5kttl.~OIII1915IIt1.,1959;5 t,1995;9I-lagheretal.,1972;WorthandSmith,1976;Williams-Walls etal.,1983).Allthreespeciesareprotected bystateandfederalstatutes.

Thefederalgovernment classified thelog-gerheadturtleasathreatened species.Theleatherback turtleandtheFloridanestingpopulation ofthegreenturtlearelistedbythefederalgovernment asendangered species.Becauseofreductions inworldpopulations ofmarineturtlesresulting fromcoastaldevelopment andfishingpressure(NMFS,1978),maintaining thevitalityoftheHutchinson Islandrookeryisimportant.

IthasbeenaprimeconcernofFPLthattheconstruction andsubsequent opera-tionoftheSt.LuciePlantwouldnotadversely affecttheHutchinson Islandrookery.Becauseofthisconcern,FPLhassponsored monitoring ofmarineturtlenestingac-tivityontheislandsince1971.Daytimesurveystoquantifynesting,aswellasnighttime turtletaggingprograms, wereconducted inoddnumberedyearsfrom1971through1979.Duringdaytimenest-ingsurveys,nine1.25-km-long surveyareasweremonitored fivedaysperweek(Figure3).TheSt.LuciePlantbeganoperation in1976;therefore, thefirstthreesurveyyears(1971,1973and1975)werepreoperational.

Thoughthepowerplantwasnotoperat-ingduring1975,St.LuciePlantUnitNo.1oceanintakeanddischarge structures were IIIIII installed duringthatyear.Installation ofthesestructures includedconstruction activities conducted offshorefromandperpendicular tothebeach.Construction hadbeencom-pletedandtheplantwasinfulloperation duringthe1977and1979surveys.Amodifieddaytimenestingsurveywasconducted in1980duringthepreliminary construction oftheoceandischarge structure forSt.LuciePlantUnit2.Duringthisstudy,fourofthepreviously established 1.25-km-long surveyareasweremonitored.

Additionally, eggsfromturtlenestspotentially endangered byconstruction activities wererelocated.

Everyyearfrom1981through1990,361-km-long surveyareascomprising theen-tireislandweremonitored sevendaysaweekduringthenestingseason(Figure3).TheSt.LuciePlantUnit2discharge structure wasinstalled duringthe1981nestingseason.Offshoreandbeachconstruction oftheUnit2intakestructure proceeded throughout the1982nestingseasonandwascompleted neartheendofthe1983lseason.Construction activities associated withinstallation ofbothstructures weresimilartothoseconducted whenUnit1intakeanddischarge structures wereinstalled.

Eggsfromturtlenestspotentially endangered byconstruction activities wererelocated duringallthreeyears.Requirement 4.2.1oftheNRC'sSt.LucieUnit2AppendixBEnvironmental Protec-tionPlanwascompleted withsubmission ofthe1986nestingsurveydata(ABI,1987).Thenestingsurveywascontinued voluntarily through1990withagreement fromfederalandstateagencies.

Resultsarepresented inthisreportanddiscussed inrelationtopreviousfindings.

I~pIIIIIII,)ClII Inadditiontomonitoring seaturtlenestingactivities andrelocating nestsawayfromplantconstruction areas,removalofturtlesfromtheintakecanalhasbeenanintegralpartoftheSt.LuciePlantenvironmental monitoring program.Turtlesenteringtheoceanintakestructures areentrained withcoolingwaterandrapidlytransported throughtheintakepipesintoanenclosedcanalsystemwheretheymustbemanuallycapturedandreturnedtotheocean.Sincetheplantbecameoperational in1976,turtlesentrapped intheintakecanalhavebeensystematically

captured, measured, weighed,taggedandreleased.

Previouspublications andtechnical reportshavepresented findingsofthenestingsurveys,nestrelocation activities andcanalcaptureprogram(Gallagher etal.,1972;WorthandSmith,1976;ABI,1978,1980a,1981a,1982,1983,1984b,1985b,1986,1987,1988,1989,1990;Williams-Walls etal.,1983;Proffittetal.,1986;Ernestetal.,1988,1989;Martinetal.,1989a,1989b).Resultsofstudiestoassesstheeffectsofther-maldischarges onhatchling swimmingspeedhavealsobeenreported(ABI,1978;O'ara,1980).Thepurposeofthisreportisto1)present1990seaturtlenestingsur-veydataandsummarize observedspatialandtemporalnestingpatternssince1971,2)documentandsummarize predation onturtlenestssince1971,and3)present1990canalcapturedataandsummarize comparable datacollected since1976.

IIIIIII MATERIALS ANDMETHODSNestinSurveMethodologies usedduringpreviousturtlenestingsurveysonHutchinson Islandweredescribed byGallagher etal.(1972),WorthandSmith(1976)andABI(1978,1981a,1982,1987,1988,1989).Methodsusedduringthe1990surveyweredesignedtoallowcomparisons withthesepreviousstudies.On11and13April1990,preliminary nestsurveyswereconducted alongHutchin-sonIslandfromtheFt.PierceInletsouthtotheSt.LucieInlet.From16Aprilthrough7September, nestsurveyswereconducted onadailybasis.After7September, severaladditional surveyswereconducted toconfirmthatnestinghadceased,thelastsurveybeingconducted on14September.

Biologists usedsmalloff-roadmotorcycles tosur-veytheislandeachmorning.Newnests,non-nesting emergences (falsecrawls),andnestsdestroyed bypredators wererecordedforeachofthe361-km-long surveyareascomprising theentireisland(Figure3).Thenine1.25-km-long surveyareasestablished byGallagher etal.(1972)alsoweremonitored socomparisons couldbemadewithpreviousstudies.Duringthedailynestmonitoring, anymajorchangesintopography thatmayhaveaffectedthebeach'ssuitability fornestingwererecorded.

Inaddition, eachofthe361-km-long surveyareashasbeensystematically analyzedandcategorized basedonbeachslope(steep,moderate, etc.),widthfromhightidelinetothedune,presenceofbenches(areasofabruptverticalrelief)andmiscellaneous characteristics (packed10

'lI sand,scattered rock,vegetation onthebeach,exposedrootsontheprimarydune,etc.).Inacooperative effort,datafromstrandedturtlesfoundduringbeachsurveyswereroutinely providedtotheNationalMaiineFisheries Service(NMFS)throughtheSeaTurtleStranding andSalvageNetwork.IntakeCanalMonitorin Mostturtlesentrapped intheSt.LuciePlantintakecanalwereremovedbymeansoflarge-mesh tanglenetsfishedbetweentheintakeheadwalls andabarriernetlocatedattheHighwayA1Abridge(Figure2).Netsusedduring1990werefrom30to40minlength,3to4mdeepandcomposedof40cmstretchmeshnylontwine.Largefloatswereattachedtothesurface,andunweighted linesusedalongthebottom.Turtlesen-tangledinthenetsgenerally remainedatthewater'ssurfaceuntilremoved.Sinceitsinception in1976,ABI'scanalcaptureprogramhasbeenundercontinual reviewandrefinement inanattempttominimizebothentrapment timesandin-juries/mortalities toentrapped seaturtles.PriortoApril1990,turtlenetswereusuallydeployedonMondaymorningsandretrieved onFridayafternoons.

Duringperiodsofdeployment, thenetswereinspected forcapturesbyABIpersonnel atleasttwiceeachday(mornings andafternoons).

Additionally, St.LuciePlantpersonnel checkedthenetsperiodically, andABIwasnotifiedimmediately ifacapturewasobserved.

ABI'sseaturtlespecialists wereoncall24hoursadaytoretrievecapturedturtlesfromtheplant.11 I

Beginning April1990,afterconsultation withNMFS,netdeployment wasscaledbacktodaylighthoursonly.Concurrently, surveillance oftheintakecanalwasin-creasedandABIpersonnel remainedonsiteforthedurationofeachday'snettingac-tivities.

Thismeasuredecreased responsetimeforremovalofentangled turtlesfromnetsandprovidedanopportunity toimprovedailyassessments ofturtlelevelswithinthecanal.Recordsofdailycanalobservations werecomparedwithcapturedatatoas-sesscaptureefficiencies.

TheA1Abarriernetisusedtoconfineturtlestotheeasternmost sectionofthein-takecanal,wherecapturetechniques havebeenmosteffective.

Thisnetisconstructed oflargediameterpolypropylene ropeandhasameshsizeof30.5cmx30.5cm.Acableandseriesoflargefloatsareusedtokeepthetopofthenetabovethewater'surface,andthebottomisanchoredbyaseriesofheavyblocks.Thenetisinclinedataslopeof3:1,withthebottompositioned upstreamofthesurfacecable.Thisreducesbowinginthecenterandminimizes theriskofaweakorinjuredturtlebeingpinnedun-derwaterbystrongcurrents.

Inthepast,theintegrity ofthebarriernetwasoccassionally compromised, andturtleswereabletomovewestofA1A.Theseturtleswerefurtherconstrained downstream byanunderwater intrusion detection system(UIDS)consisting, inpart,ofalargebarrierpositioned perpendicular tothenorth-south armofthecanal(Figure2).TheUIDSsecuritybarrieralsoconsistsof30.5cmx30.5cmmesh,butthenetisconstructed ofheavychainlinksratherthanrope.12 III Priortocompletion oftheUIDSinDecember1986,turtlesuncontained bytheA1AbarriernetwereusuallyremovedfromthecanalattheintakewellsofUnits1and2(Figure2).Theretheywereretrieved bymeansoflargemechanical rakesorspecially designednets.Following construction oftheUIDSbarrier,individuals withcarapacewidthslargerthan30.5cmwereunabletoreachtheintakewells.Thus,asrequired, tanglenetswerealsodeployedwestofA1A.Improvements madetotheA1Abarriernetduring1990shouldproveeffective inconfining allturtleslargerthan30.5cmtotheeasternendofthecanal.Formaldailyinspections oftheintakecanalweremadetodetermine thenumbers,locations andspeciesofturtlespresent.Surfaceobservations wereaugmented withperiodicunderwater inspections usingSCUBA,particularly inandaroundtheA1Abar-riernetandUIDSbarrier.Becauseofthereduction intotalnettinghoursduring1990,increased effortwasdirectedtowardhandcaptureofturtles.Thiswasaccomplished bydivinganduseofdipnets,anditprovedveryeffective whengoodwaterclaritycon-ditionsprevailed.

Regardless ofcapturemethod,allturtlesremovedfromthecanalwereidentified tospecies,measured, weighed,tagged,andexaminedforoverallcondition (wounds,abnormalities, parasites, etc.).Healthyturtleswerereleasedintotheoceanthesamedayofcapture.Sickorinjuredturtlesweretreatedandoccasionally heldforobserva-tionpriortorelease.Whentreatment waswarranted, injections ofantibiotics andvitaminswereadministered byalocalveterinarian.

Resuscitation techniques wereusedifaturtlewasfoundthatappearedtohavediedrecently.

Beginning in1982,necrop-13 Ili~l sieswereconducted ondeadturtlesfoundinfreshcondition; onenecropsywasper-formedduring1990.Since1982,bloodsampleshavebeencollected andanalyzedtodetermine thesexofimmatureturtles.Bloodwasremovedfromthepaireddorsalcervicalsinusesofsub-jectturtlesusingthetechnique described byOwensandRuiz(1980).Thesamplesweremaintained oniceandlatercentrifuged for15minutestoseparatecellsandserum.Sexdeterminations weresubsequently madebyresearchers atTexasA8MUniver-sityusingradioimmunoassay forserumtestosterone (Owensetal.,1978).FloridaPower8LightCompanyandAppliedBiology,Inc.continued toassistotherseaturtleresearchers in1990.Data,specimens and/orassistance havebeengiventotheFloridaDepartment ofNaturalResources, NationalMarineFisheries Service,USFishandWildlifeService,USArmyCorpsofEngineers, Smithsonian Institution; SouthCarolinaWildlifeandMarineResources

Division, CenterforSeaTurtleResearch(University ofFlorida),

TexasA&MUniversity, University ofRhodeIsland,University ofSouthCarolina, University ofIllinois, University ofCentralFlorida,University ofGeor-gia,VirginiaInstitute ofMarineScienceandtheWesternAtlanticTurtleSymposium.

StudiestoEvaluateandorMitiateIntakeEntramentAprogramthatassessedthefeasibility ofusinglightand/orsoundtodeterturtlesfromenteringtheSt.LuciePlantintakestructures wasconducted in1982and1983andcompleted inJanuary1984.Asrequired, testresultsandevaluations werewrittenupandapresentation wasmadetotheNRC,NationalMarineFisheries ServiceandtheFloridaDepartment ofNaturalResources on11April1984.Requirement 4.2.2of Il1lI theNRC'sSt.LucieUnit2AppendixBEnvironmental Protection Planisconsidered completed withsubmission ofdeterrent studyfindings.

RESULTSANDDISCUSSION NestinSurveDistribution ofLoerheadNestsAlonHutchinson IslandWhenseaturtlenestingsurveysbeganonHutchinson Island,nine1.25-km-long surveyareaswereusedtoestimateloggerhead nestingactivityfortheentireisland.Since1981,all361-km-long segmentscomprising theisland'scoastline havebeensurveyed.

Regardless oftechnique, loggerhead nestdensities haveshowncon-siderable annualvariation withinindividual surveyareas(Figures4and5).Yet,theannualspatialdistribution ofthosenestsamongsurveyareashasproducedaratheruniformgradient, nestdensities consistently increasing fromnorthtosouth(ABI,1987).Thegradientappearstobelinearwhenonlythenine1.25-km-long surveyareasareused(Figure4),butbecomesnon-linear whenall361-km-long surveyareasarein-cludedintheanalysis(Figure5).During1990thedistribution ofloggerhead nestsalongtheislandwascharacterized byrecordhighnestingalongthenorthernandcentralpor-tionsoftheisland(Figure5).Inthepast,thepronounced gradientobservedonthenorthernendoftheislandwasoccasionally influenced byphysicalprocesses occurring there;periodsofheavyaccretion reducedthegradient, whileperiodsoferosionaccentuated it(WorthandSmith,1976;Williams-Walls etal.,1983).However,duringrecentyearsnoconsistent IIlI relationship wasapparentwhenfieldobservations ofbeachwidthswerecomparedtothespatialdistribution ofnestsalongtheisland(ABI,1987).Thus,eventhoughbeachdynamicsmaysometimes affecttheselection ofnestingsitesbyloggerhead turtles,otherfactorsmustalsocontribute totheselection process.Offshorebottomcontours, spatialdistribution ofnearshore reefs,typeandextentofdunevegetation, anddegreeofhumanactivityonthebeachatnighthavebeenidentified assomeofthefactorsaf-fectingnesting(Caldwell, 1962;Hendrickson andBalasingam, 1966;Bustard,1968;BustardandGreenham, 1968;Hughes,1974;DavisandWhiting,1977;Mortimer, 1982).Relationships betweenspatialnestingpatternsandspecificenvironmental con-ditionsareoftendifficult toestablish becauseoftheinterrelationship ofthefactorsin-volved.Notallventuresontothebeachbyafemaleturtleculminate insuccessful nests.These"falsecrawls"(non-nesting emergences) mayoccurformanyreasonsandarecommonlyencountered atotherrookeries (BaldwinandLofton,1959;Schulz,1975;DavisandWhiting,1977;Talbertetal.,1980;Raymond,1984).DavisandWhiting(1977)suggested thatrelatively highpercentages offalsecrawlsmayreflectdisturban-cesorunsatisfactory nestingbeachcharacteristics.

Therefore, certainfactorsmayaf-fectaturtle'spreference toemergeonabeach,whileotherfactorsmayaffectaturtle'tendencytonestafterithasemerged.Anindexwhichrelatesthenumberofneststothenumberoffalsecrawlsinanareais.usefulinestimating thepost-emergence suitability ofabeachfornesting.Inthepresentstudythisindexistermed"nestingsuc-cess"andisdefinedasthepercentage oftotalemergences thatresultinnests.

loHistorically, thepatternofloggerhead emergences ontheislandhasgenerally paral-leledthedistribution ofnests(ABI,1987,1988),andthissametrendwasapparentin1990(Figure6).Incontrast, nestingsuccessbyloggerheads alongtheislandhastypi-Pcallylackedgradients (Figure7).Thus,therelatively highnumbersofloggerhead nestsobservedincertainareasareusuallyaresultofmoreturtlescomingashoreinthoseareasratherthanofmorepreferable nestingconditions beingencountered bytheturtlesaftertheyemerged.Loggerhead nestingdensities during1990weregenerally highwhencomparedwithpreviously recordedvalues(Figures4and5).Recordhighnestingwasrecordedin21ofthe36one-kilometer-long surveyareasandwasmostnotableonthenorthernhalfoftheisland.Therewerenoapparentchangesinthephysicalcharacteristics ofthebeachthatwouldaccountforthisincreaseinnesting.Ingeneral,recordhighnestingwasduetorecordhighemergence rates,andthismayreflectanincreaseinthenum-berofnestingfemalesintheHutchinson Islandarea.NestingsurveysonHutchinson Islandwereinitiated inresponsetoconcernsthattheoperation oftheSt.LuciePlantmightnegatively impactthelocalseaturtlerookery.Previousanalysis, usinglog-likelihood testsofindependence (G-test;SokalandRohlf,1981)demonstrated thattheconstruction oftheplant'soffshoreintakeanddischarge structures significantly reducednestingattheplantsiteduringconstruction years-1975,1981,1982and1983(Proffitt etal.,1986;ABI,1987).However,nestingattheplantconsistently returnedtolevelssimilartoorgreaterthanthoseatacontrolsiteinyearsfollowing construction.

Thistrendcontinued during1990(Figure8).Thus,power plantoperation exclusive ofintake/discharge construction hashadnoapparenteffectonnesting.Datacollected through1990haveshownnolong-term reduction inloggerhead nestdensities, totalemergences ornestingsuccessineitherthenine1.25-km-long surveyareasorthe361-km-long surveyareas(Table1;Figure9).EstimatesofTotaILo erheadNestin onHutchinsonlsland Variousmethodswereusedduringsurveyspriorto1981toestimatethetotalnum-berofloggerhead nestsonHutchinson Islandbasedonthenumberofnestsfoundinthenine1.25-km-long surveyareas(Gallagher etal.,1972;WorthandSmith,1976;ABI,1980a).Eachofthesemethodsweresubsequently foundtoconsistently overes-timateislandtotals(ABI,1987).Sincewhole-island surveysbeganin1981,ithasbeenpossibletodetermine theactualproportion oftotalnestsdeposited inthenineareas.Thishasthenallowedextrapolation fromtheninesurveyareastotheentireislandforyearspriorto1981.From1981through1990thetotalnumberofnestsinthenineareasvariedfrom32.5to35.6percentofthetotalnumberofnestsontheisland(Table1).Thisisslight-lyhigherthanthe31.3percentwhichwouldbeexpectedbasedstrictlyonthepropor-tionoflinearcoastline comprised bythenineareas.Usingtheten-yearmeanof33.8percent,estimates ofthetotalnumberofnestsonHutchinson Islandcanbecalculated bymultiplying thenumberofnestsinthenineareasby2.96.Thistechnique, whenap-pliedtotheninesurveyareasduringthetenyearsinwhichtheentireislandwassur-veyed,producedwhole-island estimates within5.3percentoftheactualnumberof18 IIl nestscounted.Becausetheproportion ofnestsrecordedintheninesurveyareasremainedrelatively constantoverthelasttenyears,thisextrapolation procedure shouldprovideafairlyaccurateestimateoftotalloggerhead nestingforyearspriorto1981.Itisclearthatloggerhead nestingactivityonHutchinson Islandfluctuates con-siderably fromyeartoyear(Table1).Annualvariations innestdensities alsoarecom-monatotherrookeries (Hughes,1976;DavisandWhiting,1977;Ehrhart,1980)andmayresultfromtheoverlapping ofnon-annual breedingpopulations.

Nonetheless, datacollected through1990suggestanoverallincreaseinnestingonHutchinson Is-landsincesurveysbeganin1971.Totalnestingactivitywasgreatestduring1990when6,700loggerhead nestswererecorded.

Norelationships betweentotalnestingactivityandpowerplantoperation orintake/discharge construction wereindicated byyear-to-yearvariations intotalnestingonHutchinson Island.TemoralLoerheadNestinPatternsTheloggerhead turtlenestingseasonusuallybeginsbetweenmid-April andearlyMay,attainsamaximumduringJuneorJuly,andendsbylateAugustorearlySep-tember(ABI,1987).Nestingactivityduring1990followedthissamepattern(Figure10).Coolwaterintrusions frequently occuroverthecontinental shelfofsoutheast Floridaduringthesummer(TaylorandStewart,1958;Smith,1982).WorthandSmith(1976),Williams-Walls etal.(1983)andABI(1982,1983,1984b,1985b,1986,1987,1988,1989,1990)suggested thattheseintrusions mayhavebeenresponsible forthetemporary declinesinloggerhead turtlenestingactivitypreviously observedonHutchinson Is-19 IIIIII land.Similarly, asubstantial decreaseinnestingduringmid-July1990wasapparently duetoanintrusion ofcoolwater(Figure10).Thoughnaturalfluctuations intemperature havebeenshowntoaffecttemporalnest-ingpatternsonHutchinson Island,therehasbeennoindication thatpowerplantopera-tionhasaffectedthesetemporalpatterns(ABI,1988)~Predation onLoerheadTurtleNestsSincenestsurveysbeganin1971,raccoonpredation probablyhasbeenthemajorcauseofturtlenestdestruction onHutchinson Island.Researchers atotherlocations havereportedraccoonpredation levelsashighas70tonearly100percent(DavisandWhiting,1977;Ehrhart,1979;Hopkinsetal.,1979;Talbertetal.,1980).Raccoonpreda-tionofloggerhead turtlenestsonHutchinson Islandhasnotapproached thislevelduringanystudyyear,thoughlevelsforindividual 1.25-km-long areashavebeenashighas80percent.Overallpredation ratesforsurveyyears1971through1977werebetween21and44percent,withahighof44percentrecordedin1973.Apronounced decreaseinraccoonpredation occurredafter1977,andoverallpredation ratesforthenineareashavenotexceeded10percentsince1979.Adeclineinpredation ratesonHutchinson Islandhasbeenvariously attributed totrappingprograms, construction activities, habitatlossanddisease(Williams-Walls etal.,1983;ABI,1987).During1990,sixpercent(406)oftheloggerhead nests(n=6,700)ontheislandweredepredated byraccoons.

Asinpreviousyears(ABI,1989),predation ofturtlenestswasprimarily restricted tothemostundeveloped portionoftheisland(i.e.,AreasEthroughS;Figure11).20 IIIIIII Ghostcrabshavebeenreportedbynumerousresearchers asimportant predators ofseaturtlenests(BaldwinandLofton,1959;Schulz,1975;Diamond,1976;Fowler,1979;Hopkinsetal~,1979;Stancyk,1982).ThoughturtlenestsonHutchinson Islandprobablyhavebeendepredated byghostcrabssincenestingsurveysbeganin1971,thissourceofnestdestruction didnotbecomeapparentuntil1983.Quantification ofghostcrabpredation wasinitiated thesameyear.Overallpredation ratesbyghostcrabshavevariedfrom0.1to2.1percentfrom1983-1989(ABI,1990).During1990,0.4percent(27)oftheloggerhead nests(n=6,700)ontheislandweredestroyed byghostcrabs(Figure11).Nestsdestroyed byacombination ofraccoonandghostcrabpredation havebeenincludedasraccoonpredations inpreviousdiscussions.

Whenthesecombination predations areincludedascrabpredations, theoverallpredation ratesbyghostcrabsrangefrom0.4to3.2percent.During1990,1.4percent(96nests)weredestroyed byeitherghostcrabsoracombination ofghostcrabsandraccoons.

GreenandLeatherback TurtleNestinGl'eenandleatherback turtlesalsonestonHutchinson Island,butinfewernumbersthanloggerhead turtles.Priorto1981,bothsurvey(nine1.25-km-long sections) andinter-survey areasweremonitored forthepresenceofgreenandleatherback nests.Thirty-one kilometers ofbeachfromArea1southtotheSt.LucieInletwereincludedinthateffort.Duringwhole-island surveysfrom1981through1990,onlytwoof182Ieatherback nestsandonlysevenof601greennestswererecordedonthefivekilometers ofbeachnorthofArea1.Therefore, previouscountsofgreenandleather-21 III backnestswithinthe31kilometers surveyedwereprobablynotappreciably different fromtotaldensities fortheentireisland.Basedonthisassumption, greenandleather-backnestdensities maybecomparedamongallsurveyyears,except1980,whenlessthan15kilometers ofbeachweresurveyed.

Priorto1990,thenumberofnestsobservedontheislandrangedfrom5to74forgreenturtlesandfrom1to36forleatherbacks (Figure12).Duringthe1990survey,132greenturtleand12leatherback turtlenestswererecordedonHutchinson Island.Temporalnestingpatternsforthesespeciesdifferfromthepatternforloggerhead turtles.Greenturtlestypically nestonHutchinson Islandfrommid-JunethroughthefirstorsecondweekofSeptember.

During1990,greenturtlesnestedfrom28Maythrough11September.

Leatherback'turtles usuallynestontheislandfrommid-April throughearlytomid-July.

During1990thisspeciesnestedfrom10Aprilthrough3July.Considerable fluctuations ingreenturtlenestingontheislandhaveoccurredamongsurveyyears(Figure12).Thisisnotunusualsincetherearedrasticyear-to-year fluc-tuationsinthenumbersofgreenturtlesnestingatotherbreedinggrounds(Carretal.,1982).Despitethesefluctuations, datacollected through1990suggestanoverallin-creaseinnestingsince1971andmayreflectanincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.During1990,greenturtlesnestedmost frequent-lyalongthesouthernhalfoftheisland.Thisisconsistent withresultsofprevioussur-veys.Leatherback turtlenestdensities haveremainedlowonHutchinson Island;however,increased nestingduringrecentyears(Figure12)mayreflectanoverallincreaseinthe22 numberofnestingfemalesintheHutchinson Islandarea.During1990,leatherback turtlesprimarily nestedonthesouthernhalfoftheisland.IntakeCanalMonitorin Entrainment ofseaturtlesattheSt.LuciePlanthasbeenattributed tothepresumedphysicalattractiveness oftheoffshorestructures housingtheintakepipesratherthantoplantoperating characteristics (ABI,1980band1986).Evenwhenbothunitsareoperating atfullcapacity, turtlesmustactivelyswimintothemouthofoneoftheintakepipesbeforetheyencounter currentvelocities sufficiently strongtoeffectentrainment.

Consequently, aturtle'sentrapment relatesprimarily totheprobability thatitwilldetectandsubsequently enteroneoftheintakestructures.

Assumingthatdetection distan-cesdonotvaryappreciably overtimeandthatallturtles(oraconstantproportion) areequallyattracted tothestructures, capturerateswillvaryproportionally tothenumberofturtlesoccurring inthevicinityofthestructures.

Ifthisassumption istrue,datafromthecanalcaptureprogramshouldreflectnaturalvariability inthestructure ofthepopula-tionbeingsampled.RelativeAbundance andTemoralDistribution During1990,132seaturtlecapturestookplaceintheintakecanaloftheSt.LuciePlant(Table2).Ofthefivespeciesofseaturtlesinhabiting coastalwatersofthesoutheastern UnitedStates,onlytwowererepresented inthisyear'scatches:112log-gerheadsand20greenturtles.Sinceintakecanalmonitoring beganinMay1976,1,853loggerhead (including 99recaptures),

306green(including 1recapture),

9leatherback, 8hawksbill and17Kemp'sridleycaptureshavetakenplaceattheSt.LuciePlant.23 Annualcatchesofloggerheads increased steadilyfromalowof33in1976(partialyearofplantoperation andmonitoring) to172in1979(Figure13).Afterdeclining be-tween1979and1981,yearlycatchesofloggerheads againrosesteadily, reachingahighof195during1986.Captureshavebeenindeclinesince1986,decreasing morethan40percentoverthelastfouryears.Twooffshoreintakestructures wereinplacepriortoUnit1start-upin1976;thethirdandlargeststructure wasinstalled during1982-1983.

Eventhoughallthreestructures areinrelatively closeproximity, theadditionofanotherpipemayhaveincreased theprobability ofaturtlebeingentrained.

Becausethischangecannotbequantified, datacollected priorto1982maynotbecomparable withthatcollected after1983.Addition-ally,theinfluence oftheconstruction itselfonseaturtleentrainment during1982and1983isunknown.Withtheseconsiderations inmind,neitheralong-term increasenordecreaseinthenumberofloggerheads capturedattheSt.LuciePlantcanbeinferredfromthedata.During1990,themonthlycatchofloggerheads rangedfrom1(November) to25(June),withamonthlymeanof9.3(+7.0;Table3).ThenumberofcapturesduringMay,JuneandJulywereconsiderably aboveaverage,whilecapturesthroughout theIremainder oftheyearweremoderately toconsiderably lowerthanaverage(Figure14).Overtheentiremonitoring period,monthlycatcheshaverangedfrom0to39;thegreatestnumberofcapturesoccurredduringJanuary1983.Whendatafromallfullyearsofmonitoring (1977-1990) werecombined, thehighestnumberofloggerhead capturesoccurredinJanuary(11.8percent);

fewestcaptures24 IlIlII wererecordedinNovemberandDecember(Table3).However,monthlycatcheshaveshownconsiderable annualvariability.

Monthshavingrelatively lowcatchesoneyearoftenhavehadrelatively highcatchesinanother.Catchesofgreenturtlesalsohavevariedwidelyamongyears,rangingfrom0in1976(partialyearofsampling) to69in1984(Table4).During1990,20individuals werecaptured.

Theaverageannualcatchofgreenturtles,excluding 1976,was21.9(+18.0).Althoughhighlyvariable, annualcapturedataforgreenturtlessuggestalong-term in-creaseinthenumberofindividuals inhabiting thenearshore coastalareaadjacenttotheplant(Figure13).Again,however,theinfluence oftheadditionofathirdintakepipeduring1982-1983 onthesedataisnotknown.Greenturtleshavebeencaughtduringeverymonthoftheyear,withaveragemonth-lycatchesforallyearscombinedrangingfrom0.3inSeptember to7.1inJanuary(Table4).Seasonalabundance patternsofgreensaremuchmorepronounced thanforlog-gerheads, nearly60percentofallcapturesoccurring duringthethreemonthperiodbetweenJanuaryandMarch.During1990,thelargestnumberofgreens(6)werecap-turedinJanuary.Themostgreensevercaughtinonemonthwas37inJanuary1984.Catchesofleatherbacks, hawksbills andKemp'sridleyshavebeeninfrequent andscattered throughout the15yearstudyperiod(Table2).Eachspecieshasshownratherpronounced seasonaloccurrences; allbuttwoofthenineleatherbacks werecollected betweenFebruaryandMay,sevenoftheBighthawksbills werecollected betweenJuneandSeptember, andallbuttwoofthe17Kemp'sridleyswerecaughtbetweenNovemberandApril.25 Size-lassDistribtionAlthoughseveralstraight-line andcurvedmeasurements wererecordedforturtlesremovedfromtheintakecanal,onlyonestraight-line measurement hasbeenusedinanalysespresented here.Straight-line carapacelength(SLCL)wasmeasuredfromtheprecentral scutetothenotchbetweenthepostcentral scutes(minimumcarapacelengthofPritchard etal.,1983).Todate,loggerheads removedfromtheintakecanalhaverangedinlength(SLCL)from40.2to112.0cm(x=66.8+13.7cm)andinweightfrom10.7kgto169.6kg(x=49.2+31.0kg;Figures15and16).Acarapacelengthof70cmapproximates thesmallestsizeofnestingloggerhead femalesobservedalongtheAtlanticeastcoast(Hirth,1980).However,adultscanonlybereliablysexedonexternalmorphological characteristics (e.g.,relativetaillength)afterobtaining alengthofabout85cm.Previously, 80.0cmwasusedasthelowerlimitforadultturtles.However,recentdatasuggestthatsomemalesmaynotmature,andthusmightnotbedistinguishable fromfemales,untiltheyattainaslightlylargersize.Basedonthesedivisions, dataweresegregated intothreegroups:juveniles

(<70cm),adults(>85cm)andtransitional (71-85cm).Thelattergroupprobablyincludessomematureandsomeimmatureindividuals.

Ofthe1,744capturesbetween1977and1990forwhichlengthdatawerecollected, 69percentwerejuveniles, themajorityofthesemeasuring between50and70cmSLCL(Table5).Adultsaccounted forabout15percentofallcaptures, withtheremaining 16percentcomprised ofanimalsinthetransitional sizeclass.Similarsize-frequency distributions, indicating apreponderance ofjuveniles, havebeenreportedforthe26 IIII Mosquito/Indian RiverLagoon(Mendonca andEhrhart,1982),theCanaveral shipchannel(Henwood, 1987),andGeorgiaandSouthCarolina(Hillestad etal.,1982).Thesedatasuggestthatcoastalwatersofthesoutheastern UnitedStatesconstitute animportant developmental habitatforCarettacaretta.Seasonalpatternsofabundance forvarioussizeclassesindicated thatjuvenilelog-gerheadswereslightlymoreabundantduringthewinterthanatothertimesoftheyear(Table5).About45percentofthejuveniles werecapturedbetweenJanuaryandApril.Abundances decreased inspringandremainedrelatively constantduringthesummerandearlyfallbeforedecreasing againtolowestlevelsinNovemberandDecember.

Theseasonaldistribution ofadultloggerheads wasmuchmorepronounced, 76per-centofallcapturesoccurring betweenMayandAugust,Thisrepresents themajorpro-tionofthenestingseasononHutchinson Island.Greenturtlesremovedfromtheintakecanalovertheentirestudyperiodrangedinsizefrom20.0to108.0cmSLCL(x=35.8+14.3cm)and0.9kgto177.8kg(x=9.4+20.2kg;Figures17and18)~Nearlyall(96percent)werejuveniles.

About80per-centwere40cmorlessinlength,and66percentweighed5kilograms orless.Theseimmatureturtlesexhibited distinctwinterpulsessuggesting migratory behavior(Table4).However,someimmaturegreenturtleswerepresentthroughout theyear.Todate,onlyeightadultgreenturtles(SLCL>83cm;Witherington andEhrhart,1989)havebeenremovedfromthecanal;ailwerecapturedduringorshortlyafterthenestingseason.27 IIl Theeighthawksbills removedfromthecanalrangedinsizefrom34.0to70.0cmSLCL(x=46.2+12.9cm)andinweightfrom6.4to52.2kg(x=17.3+16.6kg).Allbutonewerejuveniles (SLCL<63cm;Witzell,1983).Similarly, allbutoneofthe17Kemp'sridleyscapturedattheSt.LuciePlantwerejuveniles (SLCL<60.0cm;Hirth,1980).Carapacelengthsfortheridleysrangedfrom27.0to62.0cmSLCL(x=36.1+9.7cm)andweightsfrom3.1to31.8kg(x=8.0+8.1kg).Thenineleatherbacks removedfromthecanalrangedinlengthfrom112.5to150.0cm,andatleastsevenwereadults(SLCL>121cm;Hirth,1980).Thelargestleatherback forwhichanac-curateweightwasobtained, afemalewithacurvedcarapacelengthof158.5cm,weighed334.8kg.~SxRatiosSinceintakecanalmonitoring beganin1976,255adultloggerheads (SLCL>85.0cm)havebeensexed.Femalespredominated malesbyaratioof5.4:1.0,whichsig-nificantly departsfroma1:1ratio(X,P<0.05).Consequently, temporalpatternsinthenumberofadultloggerhead captureswereheavilyinfluenced bythenumbersoffemalespresent.Whensexeswereseparated, itisevidentthatmaleswererelatively evenlydistributed amongmonths,whereas90percentofthefemalesweretakenduringthenestingseason(MaythroughSeptember; Figure19).Thenumberofadultfemaleloggerheads capturedattheSt.LuciePlanthasin-creasedsteadilyoverthelastsevenyears.From1977through1983,anaverageof4.4adultfemales(+3.2;range=1-10)wereentrapped eachyear,whereassincethen,anaverageof26.3femalesperyear(+6.7;range=16-35)werecaptured.

Thisin-28 creasecorresponds toageneralriseinloggerhead nestingactivityneartheplant(Figure20).Increased nearshore movementassociated withnestingincreases theprobability ofaturtledetecting oneoftheintakestructures andhencetheprobability ofentrainment.

Althoughtheadditionofthethirdoffshoreintakestructure mayhaveaccounted forsomeoftheincreaseinthenumberofadultsentrained since1983,thecontinued riseoverthelastsevenyearssuggestsagenuineincreaseinthenumberoffemalesoccurring inthevicinityoftheplant.BetweenSeptember 1982andDecember1986,267individual juvenileandsub-adult loggerhead turtlescapturedinthecanalweresexedbyTexasA8MUniversity re-searchers usingabioimmunoassay technique forbloodserumtestosterone.

Aspre-viouslyreported, femalesoutnumbered malesbyaratioof2.3:1.0(ABI,1989).Thesefindingsareconsistent withthosereportedforsamplestakenfromtheCapeCanaveral shipchannel(1.7:1.0) andtheIndianRiverLagoon(1.4:1.0),

wheresexratiosarealsosignificantly skewedinfavoroffemales(Wibbelsetal.,1984).Bloodsamplescollected since1986arecurrently beinganalyzedandtheseresultswillprovideavaluabletoolforassessing temporalvariability inthesexratiosofthelocalloggerhead population.

Oftheeightadultgreenturtlescapturedsincemonitoring began,sixweremalesandtwowerefemales.Siximmaturegreenturtleshavebeensexedthroughbloodwork;allhavebeenfemales.Ofthesixadultleatherback turtlesforwhichsexwasrecorded, threewerefemalesandthreeweremales.Theadulthawksbill andKemp'sridleywerebothfemales.Nosexinformation existsforjuveniles ofthesespecies.29 CatureEfficiencies Capturemethodologies havebeenundercontinual reviewandrefinement asnetmaterials, configurations andplacement werevariedinanefforttominimizeseaturtleentrapment times.Concurrently, alternative capturetechniques wereevaluated andpotential deterrent systemstestedinthelaboratory.

Duringthisperiod,captureefficien-ciesvariedinrelationtonettingeffortandtheeffectiveness ofthesystemsdeployed.

Acapture/recapture studyconducted intheintakecanalbetweenOctober1980andJanuary1981indicated thatmostturtlesconfinedbetweentheA1Abridgeandtheintakeheadwalls werecapturedwithintwoweeksoftheirentrainment (ABI,1983)~Basedonmorerecentformaldailyinspections, itappearsthatcaptureefficiencies havefurtherimproved.

Nearly50percentoftheturtlesenteringthecanalarenowcaughtwithin24hoursoffirstsighting, andalmost90percentarecapturedduringtheirfirstweekofentrapment (Figure21).Averagecaptureefficiency, expressed aselapseddaysbetweenfirstsightingandcapture,duringtheperiodfromAprilthroughDecem-ber1990was3.9days(+6.8days;range=1-50days).Betterutilization ofcurrentsandeddies,adjustments totethering lines,multi-net deployments andincreased ef-fortstohandcaptureturtleshavecontributed toreducedentrapment times.Entrapment timesmaybeextendedforturtlesswimmingpasttheA1Abarriernet(ABI,1987).Occasionally, thetopofthenethasbeensubmerged ortheanchorcablepulledfreefromthebottom,allowinglargerturtlestopass;turtleswithcarapacewidthslessthanabout30.5cmcanswimthroughthelargemesh.BecausecaptureeffortswestoftheA1Abridgehavegenerally beenlesseffective thanthoseneartheintake30 headwalls, mostturtlesbreaching thebarriernetwerenotcaughtuntiltheyenteredtheintakewellsofUnits1and2.Priortoinstallation oftheUIDSbarrierin1986,about15percentofallturtlesentrapped inthecanalwereremovedfromtheintakewells.Be-causeoftheirrelatively smallsizes,amuchlargerproportion ofgreens(51.6percent)reachedtheplantthanloggerheads (10.1pel'cent).

Since1986,thepercentage ofgreenscaughtattheintakewellshasdecreased slightly(35.1percent),

whilealllog-gerheadshavebeenprevented fromreachingtheplant.Majorrenovations weremadetotheA1Abarriernetduring1990tofurtherreducethepotential forturtleslargerthan30.5cmbecomingtrappedbetweenA1AandtheUIDS.Twologgerheads (lessthan2percentofallloggerhead captures) breachedtheA1Abarriernetpriortocompletion ofthesemodifications.

BothwereremovedfromthecanalattheUIDSbarrier.Additionally, twosmallgreenturtlespassedthroughtheA1Abarriernetandwereremovedattheplant'sintakewells.Thus,nearly97percentofallturtlesentrapped inthecanalduring1990werecapturedbynettingorbyhandeastoftheA1Abridge.Theeffective confinement ofturtleseastofA1Awasanothermajorcontributor tothehighcaptureefficiency achievedduring1990.RelativeCondition TurtlescapturedaliveintheintakecanaloftheSt.LuciePlantwereassignedarela-tivecondition basedonweight,activity, parasiteinfestation, barnaclecoverage, wounds,injuriesandanyotherabnormalities whichmighthaveaffectedoverallwell-being.During1990,92.9percent(104)ofallloggerheads foundinthecanalwerealiveandingoodtoexcellent condition.

Only6.3percent(7)ofloggerhead capturesin-31 IIIII volvedindividuals infairorpoorcondition; oneloggerhead wasdeadwhenremovedfromthecanal.Ofthe20greenturtlesremovedfromtheintakecanalduring1990,16wereingoodtoexcellent condition, twowereinfaircondition andtwoweredead.Overtheentiremonitoring period,about76and78percent,respectively, ofalllog-gerheadandgreencaptureshaveinvolvedturtlesingoodtoexcellent condition (Table6).Capturesofindividuals infairtopoorcondition haveoccurredabout16percentofthetimeforloggerheads and14percentofthetimeforgreens.Allofthehawksbills andleatherbacks havebeenremovedfromthecanalingoodtoexcellent condition, whileabouthalfoftheKemp'sridleyshavefallenintothesecategories.

Relativecondition ratingscanbeinfluenced byanumberoffactors,somerelatedandothersunrelated toentrainment and/orentrapment intheintakecanal.Ratingsofgoodtoexcellent indicatethatturtleshavenotbeennegatively impactedbytheirentrap-mentinthecanal,atleastasevidenced byphysicalappearance.

Althoughratingsoffairorpoorimplyreducedvitality, theextenttowhichentrainment/entrapment isresponsible isoftenindeterminable.

Insomeinstances, conditions responsible forlowerratings,suchasinjuries, obviously weresustained priortoentrainment.

During1990,aboutninepercent(10)ofallloggerhead capturesinvolvedindividuals withnoticeable

injuries, suchasmissingappendages, brokenormissingpiecesofcarapaceanddeeplacerations.

Mostofthesewereold,well-healed wounds,andnonewereseriousenoughtorequiremedicalattention.

Noneofthegreenturtlescapturedduring1990hadmajorinjuries.

32 IIIIIIII

~Mrtalitie Mortalities havebeencloselymonitored throughout thelifeofthecanalcaptureprograminanattempttoassignprobablecausesandtakeappropriate remedialac-tiontominimizefutureoccurrences.

Previousanalysesofcapturedataidentified drown-inginnets(A1Abarriernet,UIDSbarrier,andtanglenets),drowningintheintakepipesduringperiodsofreducedintakeflow,injuriessustained fromdredgingoperations andinjuriessustained fromthemechanical rakesusedintheintakewellsasprobablemor-talityfactors(ABI,1987).Althoughdifficult toquantify, theentrapment andsubsequent demiseofinjuredorsickturtleshasprobablyaccounted foraportionofobservedmor-talities.

Overtheentire15yearmonitoring period,127(6.9percent)ofthe1,853logger-headsand21(6.9percent)ofthe306greenturtlesentrapped inthecanalwerefounddead(Table6).Mortalities spannedtherangeofsizeclassesforloggerheads (SLCL=47.5-103cm),whileallgreenturtlemortalities involvedjuveniles lessthan42cminlength.ThefourKemp'sridleymortalities documented attheplantduring1987and1988wel'etheonlydeathsforthisspeciestodate;noleatherback orhawksbill mor-talitieshaveoccurredattheSt.LuciePlant.Modifications tocaptureprocedures, improvements totheA1Abarriernetandvir-tualelimination oflowflowconditions withinthecanalhaveresultedinasubstantial reduction inseaturtlemortalities overthelifeofthecanalcaptureprogram.Mortality rates,expressed asthepercentage oftotalcapturesinvolving deadanimals,declined42percentbetweenthefirst(1976-1983) andsecond(1984-1990) halvesofthe33 IIIIIIIIII program.During1990,onlythreemortalities (2.3percentoftotalcaptures) wererecorded, oneloggerhead andtwogreenturtles.Thisrepresents thefewestannualmortalities sincethecanalcaptureprogrambeganin1976.Previousobservations suggestthatsickorinjuredturtlesmaybesusceptible todrowningattheUIDSbarrier.Theloggerhead mortality recordedduring1990occurredatthislocation.

Eventhoughthecarcasswastoodecomposed toassessitsphysicalcondition ordetermine causeofdeath,drowningissuspected.

Additional improve-mentstotheA1Abarriernetduringthelaterpartof1990shouldpreventfuturelogger-headmovements westofA1Aandtherebyeliminate theUIDSbarrierasapotential mortality source.Thetwogreenturtlemortalities during1990resultedfromdrowninginABI'stanglenets.Oneofthesewasresuscitated, butitlatersuccumbed whileunderobservation.

Anecropsywasperformed todetermine ifitwasinpoorhealthatthetimeofcapture;resultsoftissueanalyseshavenotyetbeencompleted.

Toeliminate thepotential forfuturenetdrownings, ABIhasbeguncontinual monitoring ofitstanglenetsduringperiodsofdeployment.

RecatureIncidentSincetheSt.LuciePlantcaptureprogrambegan,mostturtlesremovedalivefromtheintakecanalhavebeentaggedandreleasedintotheoceanatvariouslocations alongHutchinson Island.Consequently, individual turtlescanbeidentified aslongastheyretaintheirtags.Overthe15yearhistoryofturtleentrapment attheSt.LuciePlant,61individuals (60loggerheads and1green)havebeenremovedfromthecanalmore34 thanonce.Severalotherturtleswithtagscarshavealsobeenrecovered, indicating thattheactualnumberofrecaptures maybehigher.Ofthe60individual loggerheads knowntohavebeencaughtmorethanonce,42werecaughttwice,9werecaughtthreetimes,5werecaughtfourtimes,2werecap-turedsixtimes,1wascaughtseventimesand1wascaughtonnineseparateoc-casions,yieldingatotalof99recapture incidents.

Releasesitedidnotappeartohaveanyeffectonaturtle'sprobability ofbeingrecaptured.

Turtlesreleasedbothnorthandsouthoftheplantreturned.

Recaptures alsodidnotappeartoberelatedtosize,asbothjuveniles andadultswerecapturedmorethanonce(rangeofSLCL=47-89cm).However,themajorityofrecapture incidents involvedjuveniles (SLCL<70cm).Recapture intervals forloggerheads rangedfromfourto858days,withameanof157days(+174.0days).Theonlygreenturtlecaughtmorethanoncewascapturedontwooccasions, returning tothecanal59daysafterfirstbeingreleasedintotheocean.About56percentofallloggerhead recapture incidents occurredwithin90daysofpreviouscaptureand89percentwithinoneyear(Figure22).Theaverageintervalbetweenfirstandlastcapturewas262days(+329.7days).Thelongestperiodbe-tweenfirstandlastcapturewas5.3years.Thesedatasuggestthatresidency timesofloggerheads withinthenearshore habitatadjacenttotheSt.LuciePlantarerelatively short.Similarfindingshavebeenreportedforloggerheads inhabiting theMosquito/In-dianRiverLagoonsofeast-central Florida(Mendonca andEhrhart,1982).35 SUMMARYAgradientofincreasing loggerhead turtlenestdensities fromnorthtosouthalongthenorthernhalfofHutchinson Islandhasbeenshownduringmostsurveyyears.Thisgradientmayresultfromvariations inbeachtopography, offshoredepthcontours, dis-tribution ofnearshore reefs,onshoreartificial lightingandhumanactivityonthebeachatnight.Lownestingactivityinthevicinityofthepowerplantduring1975andfrom1981through1983wasattributed toconstruction ofpowerplantintakeanddischarge systems.Nestingreturnedtonormalorabovenormallevelsfollowing bothperiodsofconstruction.

Powerplantoperation, exclusive ofintake/discharge construction, hashadnosignificant effectonnestdensities.

Therehavebeenconsiderable year-to-year fluctuations inloggerhead nestingac-tivityonHutchinson Islandfrom1971through1990.Fluctuations arecommonatotherrookeries andmayresultfromoverlapping ofnon-annual breedingpopulations.

Despitethesefluctuations, loggerhead nestingactivityhasremainedhighduringrecentyearsandmayreflectanoverallincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.Norelationship betweentotalnestingontheislandandpowerplantoperation orintake/discharge construction wasindicated.

Temporary declinesinloggerhead nestingactivityhavebeenattributed tocoolwaterintrusions thatfrequently occuroverthecontinental shelfofsoutheast Florida.ThoughtemporalnestingpatternsoftheHutchinson Islandpopulation maybeinfluenced bynaturalfluctuations inwatertemperature, nosignificant effectsduetopowerplantoperation havebeenindicated.

36 Sincenestingsurveysbeganin1971,raccoonpredation wasconsidered themajorcauseofturtlenestdestruction onHutchinson Island.From1971through1977,over-allpredation ratesintheninesurveyareaswerebetween21and44percent.However,apronounced decreaseinraccoonpredation occurredafter1977,andoverallpreda-tionratesintheninesurveyareashavenotexceededtenpercentsince1979.Decreased predation byraccoonsprobablyreflectsadeclineintheraccoonpopula-tion.During1990,132greenturtleand12leatherback turtlenestswererecordedonHutchinson Island.Nestingactivitybythesetwospeciesexhibited considerable annualfluctuations, ashasbeenrecordedatotherrookeries, buthasremainedrelatively highduringrecentyears.Thismayreflectanoverallincreaseinthenumberofnestinggreenandleatherback turtlesintheHutchinson Islandarea.During1990,112loggerheads and20greenturtleswereremovedfromtheSt.LuciePlantintakecanal.Sincemonitoring beganinMay1976,1,843loggerhead, 306green,9leatherback, 8hawksbill and17Kemp'sridleyturtleshavebeencaptured.

Overthelifeofthemonitoring program,annualcatchesforloggerhead turtleshaverangedfrom33in1976(partialyearofplantoperation andmonitoring) toahighof195in1986.Yearlycatchesofgreenturtleshaverangedfrom0in1976to69in1984.Differences inthenumberofturtlesentrapped duringdifferent yearsandmonthsareattributed tonaturalvariation intheoccurrence ofturtlesinthevicinityoftheoffshoreintakestruc-tures,ratherthantoanyinfluence oftheplantitself.37 IIII Size-class distributions ofloggerhead turtlesremovedeachyearfromthecanalhaveconsistently beenpredominated byjuveniles between50and70cminstraightlinecarapacelength.Mostgreenturtlesentrapped inthecanal(about80percent)werejuveniles 40cmorlessinlength.Forbothspecies,thelargestnumberofcapturesforallyearscombinedoccurredduringthewinter,buttheseseasonalpeaksweremuchmorepronounced forgreenturtles.Sexratiosofbothadultandimmatureloggerheads caughtinthecanalcontinued tobebiasedtowardsfemales.During1990,about93and80percent,respectively, ofallloggerheads andgreenturtlesremovedfromthecanalwerecategorized byphysicalappearance asbeingingoodtoexcellent condition.

Overtheentire15yearmonitoring period,76and78per-cent,respectively, ofallloggerhead andgreenturtlecaptureshaveinvolvedindividuals inthesecategories; 16percentoftheloggerheads and14percentofthegreenturtlesremovedfromthecanalhavebeeninfairorpoorcondition.

Aboutninepercentoftheturtlesremovedfromtheintakecanalduring1990hadsubstantial injuries.

However,mostoftheseinjuriesweresustained priortoentrap-ment.Onceinthecanal,turtlesconfinedeastofA1Ausuallyhadverybriefresidency timesandthustherelativecondition ofmostturtleswasnotaffectedbytheirentrap-ment.During1990,oneloggerhead andtwogreenturtlemortalities occurredintheintakecanal.Thesedeathsprobablyresultedfromdrowning:

twoinABItanglenets,oneattheUIDSbarrier.Programmodifications topermitcontinual surveillance oftanglenets38 IIII duringperiodsofdeployment andimprovements totheA1Abarriernetwereinitiated tofurtherreducethepotential forsimilarmortalities inthefuture.Sinceintakecanalmonitoring beganin1976,6.9percentoftheloggerheads andasimilarpercentage ofgreenturtlesremovedfromthecanalweredead.ThefourKemp'sridleymortalities in1987and1988weretheonlydeathsrecordedforthisspeciessincemonitoring began.Alloftheleatherbacks andhawksbills entrapped intheintakecanalattheSt.LuciePlanthavebeencapturedaliveandreleasedintotheocean.Modifica-tionstocaptureprocedures, improvements totheA1Abarriernetandvirtualelimina-tionoflowflowconditions inthecanalhasresultedina42percentreduction inseaturtlemortality ratesoverthelifeofthecanalcaptureprogram.39 IIIIIII LITERATURE CITEDABI(AppliedBiology,Inc).1977.Ecological monitoring attheFloridaPower&LightCo.St.LuciePlant,annualreport1976.VolumesIandII.AB-44.PreparedbyAppliedBiology,Inc.forFloridaPower8LightCo.,Miami..1978.Ecological monitoring attheFloridaPower8LightCo.St.LuciePlant,annualreport1977.VolumesIandII.AB-101.PreparedbyAppliedBiology,Inc.forFloridaPower&LightCo.,Miami..1979.FloridaPower8LightCompany,St.LuciePlantannualnon-radiologi-calenvironmental monitoring report1978.VolumesIIandIII,Bioticmonitoring.

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1979.Nearshore marineecologyatHutchinson Island,Florida:1971-1974.

Vll.Phytoplankton, 1971-1973.

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IX.Dielplankton, 1973-1974.

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47pp.Williams-Walls, N.,J.O'ara,R.M.Gallagher, D.F.Worth,B.D.PeeryandJ.R.Wilcox.1983.SpatialandtemporaltrendsofseaturtlenestingonHutchinson Island,Florida,1971-1979.BulletinofMarineScience33(1):55-66.

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~mdasnestinginFlorida.Pages351-352inOgren,L.,F.Berry,K.Bjorndal, H.Kumpf,R.Mast,G.Medina,H.ReichartandR.Witham,editors.Proceed-ingsoftheSecondWesternAtlanticTurtleSymposium.

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Synopsis, 137:1-78.

Worth,D.F.andM.L.Hollinger.

1977.Nearshore marineecologyatHutchinson Island,Florida:1971-1974.

III.Physicalandchemicalenvironment.

FloridaMarineResearchPublica-tions23:25-85.46 Worth,D.F.,andJ.B.Smith.1976.MarineturtlenestingonHutchinson Island,Florida,in1973.FloridaMarineResearchPublications 18:1-17.47 GULFOFMEXICO00YAROSKILOMETERS SCALEr~~StLuciaPlantFigure1.LocationoftheSt.LuciePlant.

IIIIIIIII V~g~t'~gW.:,::HUTCHINSON ISLAND~o0'F~~IJi7.~iS'~Oc2G'5~.L-....i~00250500METERS~~tr~5pp,>r~DISCHARGE

~gG+'..PIPES0G"oi~gAv'~'l"r2VQ9INTAKE'<:.:.c,".'NTAKE HEADWALL';

4~':-,.'.'ELLS~'.",STRUCTURES UIDSA1A'-'.:.

BARRIERBARRIER:.

,,NET;.~;~b~',,'1'a'84'NTAKECANALFigure2.St.LuciePlantcoolingwaterintakeanddischarge system.

II FLPierceInlet10A\~~'aFaStateGHwyA0a7~'t~aeaaAIg0Q0bb,oOaloH2V+F+3N40FPLST.LUCIEPU.S.HwyId0SkmRtV6.RVw6AA4BBCCDDEFFGGda+HHOdQuSLLudoInletFigure3.Designation andlocationofnine1.25-kmsegmentsandthirty-six 1-kmsegmentssurveyedforseaturtlenesting.Hutchinson Island,1971-1990.

350300250z0200Dz1501005012NORTH3456789POWERPLANTSOUTHFigure4.Meanannualnumberofloggerhead turtlenestsineachofthenine1.25-km-long surveyareas,Hutchinson Island,1971-1989, comparedwithnumberofnestsduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values(1980datawereexcludedbecausenotallareasweresurveyed).

IIIIIIIIIIII 350300~~250200(0I-V)z150Dz~~~10050ABCDEFGHIJKLMNOPQRSTUVWXYZABCDE FGHIJABCDEFGHIJNORTH1'OWERPLANTSOUTHFigure5.Meanannualnumberofloggerhead turtlenestsineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1989, comparedwithnumberofnestsduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.

IIIIIIIII 700600500400Oz300D200~~100ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHI JABCDEFGHIJNORTHPOWERPLANTSOUTHFigure6.Meanannualnumberofloggerhead turtleemergences ineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1989, comparedwiththenumberofemergences during1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.

IIIIIII 10080gM(0LIJOOP)60(9ZI-0)ILJZ4020ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGH IJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure7.Meanannualloggerhead turtlenestingsuccess(percentage ofemergences thatresultedinnests)foreachofthethirty-six 1-km-longsurveyareas,Hutchinson Island,1981-1989, comparedwithnestingsuccessduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.

300250o-oArea4(PowerPlantSite)e--~Area5(ControlSite)200V)I-Z0150Dz100~Or%rr/////////50TTT19711972197319741975197619771978197919801981198219831984198519861987198819891990Figure8.Numberofioggerhead turtlenestsinAreas4and5,Hutchinson Isiand,1971-1990.

Arrowsdenoteyearsduringwhichintake/discharge construction occurredinArea4.

I 6000CD(DI-zDz50004000300020001000CDOz0CCDz12000100008000600040002000gCDCOLIJOO(0(9zCDUJ806040201981198219831984198519861987198819891990Figure9.Annualnumberofnests,numberofemergences andnestingsuccessalongtheentire36.0-km-long Atlanticcoastline ofHutchinson Island,198t-1990.

3130O29285272625Q.242322212012090(0z060z30305153051530515APRMAYJUNJULFigure10.Dailyloggerhead turtlenestingactivityandwatertemperature, Hutchinson Island,1990.30515AUG30515SEP 27%7060Destroyed byghostcrabsgDestroyed byraccoonsandghostcrabsQDestroyed byraccoons50O0-0KI-Uj40O(0I-(0zrt-30Dz201015%.?~Vxm:('?iAMh((.:9X'~egZps:K(:N<:e.'.gg.r,'(?Fp?'m~$+11%Y??r','my~?(m,:(g~18%r'(I(pjmr~'r'..vÃr'.rg~b;s(:r.ggCi(5'$.::$p~.?s?:.'$p$j~g>?~PI5%?.'A'(iM:'A?g(;@A;('(?g(??.:N~??jPAQsE(g?gr.m(mi14%Wg'kg$.$yg?gmmeE(.:VP8:.:~a??::,g:)>%!4~?>?:'(pY,~4'.($NScYA(Ã~(??APg.(g'.?'.spi'g~Q4?ih(1%rr:.(1%1%2'/oABCDEFGHIJKLMNOPQRS TUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure11.Numberofloggerhead turtlenestsdestroyed byraccoonsandghostcrabsandpercentage ofnestsdestroyed ineach1-km-long surveyarea,Hutchinson Island,1990.

140120100COIzO80z604020Q--QGreen(Chelonia mydas)O-~Leatherback (Dermochelys coriacea) pQpHgoIIIIIIlIIIpqII/xIIiIy/XgIIIIII197119731975197719791981198219831984198519861987198819891990Figure12.Annualnumbersofgreenturtleandleatherback turtlenests,Hutchinson Island,1971-1990.

200~-eLOGGERHEAD (Carettacaretta)0---wGREEN(Chelccia m~das)80175150O125K1007550z25////r0IIIIIIpi\'I70860O50z40(930mmD2010197619771978197919801981198219831984198519861987198819891990Figure13.Numberofloggerhead andgreenturtlesremovedeachyearfromtheintakecanal,St.LuciePlant,19764990.

40403030I-20z201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure14.Meannumberofloggerheads capturedeachmonth,St.LuciePlantintakecanal,1977-1989, comparedwithnumberofmonthlycapturesduring1990.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1990values.

IIIIIII 400400300300(0DO)0zu-2000KUJlZlDz200100100~4041-4546-5051-5556-6061-6566-7071-7576-8081-8586-9091-9596-101-106->110STRAIGHTLINECARAPACELENGTH(cm)100105110Figure15.Lengthdistribution (SLCL)ofloggerhead turtles(N=1,673) removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.

Nodatacollected for81individuals.

400400300300(0DO)DZ2000KIllCODZ200100100+1011-2021-3031-4041-5051-6061-7071-8081-9091-100101-111-121-131-141-i150'I/EiGHT(kg)110120130140150Figure1LWeightdistribution ofliveloggerhead turtles(¹1,487)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.

Nodatacollected for267individuals.

12012010010080COD0)0600K(9408060402020-1516-21-26-31-36-41-46-51-56-61-66-71-76-81-86-91-96-101-106->11020253035404550556065707580859095100105110STRAIGHTLINECARAPACELENGTH(cm)Figure17.Lengthdistribution (SLCL)ofgreenturtles(N=295)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.

Nodatacollected for10individuals.

200200180180160160(D140D9120Dz010080z601401201008060404020201-56-1011-1516-2021-2526-3031-3536-4041-4546-5051-101-151-)200WEIGHT(kg)100150200Figure18.Weightdistribution ofgreenturtles(N=291)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1990.

Nodatacollected for14individuals.

IIIIIIII MALESFEMALES60505040V)DCI0300KILJKDz204030201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure19.Numbersofadultloggerheads (SLCL)85.0 cm),including recaptures, removedeachmonthfromtheintakecanal,St.LuciePlant,1977-1990 (N=255;sexnotrecordedforsixindividuals)85.0 cm).

50~-eCANALCAPTURES 50040302010o---oEMERGENCES 00//////]y////r/400300200100ZV)OzGK0zzz19771978197919801981198219831984198519861987198819891990Figure20.Comparison ofcapturesofadultfemaleloggerheads (SLCL>85.0cm)intheintakecanal,St.LuciePlant,1977-1990, andnumbersofloggerhead emergences inarea4adjacenttotheplant.Nestingactivitywasnotmonitored in1978.

JLJCCI-CLOCIJCJCIZ0I-ZILJOIZILJQ.ILJI-O10080604020'100806040201020304050DAYSBETWEENFIRSTSIGHTINGANDCAPTUREFigure21.Captureefficiency, expressed asdaysbetweenfirstsightingandcapture,forloggerhead turtlesentrapped intheintakecanal,St.LuciePlant,April-December, 1990(N=90).

100100~80(9za-60I-DD<40fIt///80604020IIIIIt~-----~Intervalbetweensuccessive capturesIntervalbetweenfirstandlastcapture20500250175075010001250RECAPTURE INTERVAL(days)Figure22.Cumulative percentage ofallloggerhead recaptures occurring withinvarioustimeintervals betweensuccessive captures(¹97jandfirstandlastcapture(¹58),St.LuciePlantintakecanal1976-1990.

WTABLE1ESTIMATES OFTHENUMBERSOFLOGGERHEAD TURTLENESTSONHUTCHINSON ISLANDBASEDONSURVEYSOFNINE1.25-KM-LONG SURVEYAREAS,1971-1990,COMPAREDTOTHEACTUALNUMBEROFNESTSONTHEISLAND,1981-1990197119731975197719791981198219831984198519861987198819891990Numberofnestsinthenine1420126014939321449103115921439162318391645170117742177Extrapolation fromtheninesurveyareastotheiI4203373044192759428930524837471242594804486950355251Actualnumberofnestsonthe311546904743427748775483462351936700 IIIII TABLE2TOTALNUMBEROFSEATURTLECAPTURESAND(NUMBEROFDEAD)TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990 19761977197819791980198119821983198419851986198719881989TotalAnnualMean's(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)1853(127)130.05(2)6(1)3(1)10(3)32(2)823(4)69(2)1422(1)3542(2)17(1)20(2)306(21)21.99(0)0.6will8(0)0.6Km'l16(2)5(2)217(4)1.2ss(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)1s2(s)2193(152)154.3Excludes1976(partialyearofplantoperation).

TABLE3TOTALNUMBEROF(ANDNUMBEROFDEAD)LOGGERHEAD TURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990 1976197713s(1)2075(2)157(1)75(3)15(1)9(1)5933(4)580(5)19781911(2)27(2)19(5)3(1)101217(2)15(7)4138(19)19791980198119824&1983198419851986198719881989199024(3)29(1)111703(1)1621(2)14078(3)11(1)11(3)6106627(2)16(2)8(1)12192(1)15(3)1274006(2)141417(4)72(1)9(1)9(5)4(2)391313(1)047(1)62(1)728(1)12(1)26s(2)16152013161720(3)19(1)1426(3)8(1)24(3)23(1)26(1)19(1)17(1)1751097311(2)83510(3)1113(2)283011(1)-254(2)11131699232521(1)15167(1)35(1)4115(2)16(4)14(4)20(2)1220(1)26(2)34(6)9(4)10172(13)8116(5)362(5)1(1)101(16)12119(4)8148(3)2157(4)10195(27)9175(11)9134(6)2111(4)3112(1)Total219(11)178(17)152(9)157(15)162(6)208(8)172(11)177(11)126(12)121(13)86(13)95(1)1853(127)

MonthlyMean15.6%TotalCatch11.812.79.611.58.28.58.711.29.310.911.210.813.911.89.68.46.86.54.68.15.76.35.1eludes1976(partialyearofplantoperation).

IIII TABLE4TOTALNUMBEROF(ANDNUMBEROFDEAD)GREENTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPIANT,1976-1990 1976197719781979198019811982198310018(1)43(2)22(1)01(1)012201(1)0101(1)00,5(1)4(1)0020(1)7110000000101(1)000000000002(1)02.04(1)5(2)6(1)3(1)10(3)32(2)23(4)1984198537(1)1041121986116(1)31198741332198819891990Total12114233(1)06316(1)3(1)31199(5)48(3)33(4)19(2)9(1)MonthlyMean7.13.42.41.40.62.9%TotalCatch32.415.710.86.25.92.60211316(2)1101018(3)81.20.59(1)0.62.90.31.6140.94.64(1)51102022120(2)241.31.66.57.869(2)1422(1)3542(2)17(1)20(2)306(21)

IIIIII TABLE5NUMBEROFMONTHLYCAPTURESBYSIZECLASSFORLOGGERHEAD TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1977-1990 SizeclassesSLCLincm)JanuaryFebruaryMarch16AprilMayJune13Total101%ofTotalJulyAugustSeptember 4October8November4December473475150'24248352034592765648523835483832242651717812011210010581977548121014.711.69.99.38.38.76.78.07.46.24.05.369.42621182717262835162?19132739.57.76.6996.29.510.312.85.9997.04.815.772022006150132613826321294191815825114414011613114406738152613.41.52.72.315.325.720.714.65.72.73.41.915.0Excludes1976(partialyearofdata).Nodatawerecollected for76individuals.

TABLE6RELATIVECONDITION OFSEATURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1990RelativeTotal39321.251127.650327.122111.9713.81276.9271.5185312841.85919.35116.73511.472.3216.951.6306111.1111.1777.8211.8317631763176211.8423.51775.025.053024.257626.356425.725911.8803.61526.9321.521931Excellent:

normalorabovenormalweight,active,veryfewornobarnacles orleeches,nowounds.2Verygood:intermediate goodtoexcellent.

3Good:normalweight,active,lighttomediumcoverageofbarnacles and/orleeches,woundsabsent,healedordonotappeartodebilitate theanimal.4Fair:intermediate poortogood.5Poor:emaciated, sloworinactive, heavybarnaclecoverageand/orleechinfestation, debilitating woundsormissingappendages.

6Dead7Alivebutotherwise condition notrecorded.

IIII