ML17227A398

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Vol I to St Lucie 2 Annual Environ Operating Rept,1991.
ML17227A398
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Site: Saint Lucie NextEra Energy icon.png
Issue date: 12/31/1991
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APPLIEDBIOLOGY,INC.IAB-617FLORIDAPOWER&LIGHTCOMPANYST.I.UCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORTItItVOLUMEI19912968ANORTHDECATURROAO~ATLANTA,GEORGIA30033~404-296-3900 92042'70199 920423PDRADOCK05000389' PDR ILIIII)I AB-617FLORIDAPOWER&LIGHTCOMPANYST.LUCIEUNIT2ANNUALENVIRONMENTAL OPERATING REPORT1991VOLUME1APRIL1992FLORIDAPOWER8,LIGHTCOMPANYJUNOBEACH,FLORIDAAPPLIEDBIOLOGY,INC.ATLANTA,GEORGIA

'IIIi1)I iISIIENVIRONMENTAL OPERATING REPORTTABLEOFCONTENTSTABLEOFCONVERSION FACTORSFORMETRICUNITSEXECUTIVE SUMMARYIntroduction TurtleNestingSurveyIntakeCanalMonitoring OtherRelatedActivities INTRODUCTION

Background

AreaDescription PlantDescription TURTLESIntroduction Materials andMethodsNestingSurveyIntakeCanalMonitoring StudiestoEvaluateand/orMitigateIntakeEntrapment ResultsandDiscussion NestingSurveyDistribution ofLoggerhead NestsAlongHutchlnson IslandEstimates ofTotalLoggerhead NestingonHutchinson IslandTemporalLoggerhead NestingPatternsPredation onLoggerhead TurtleNestsGreenandLeatherback TurtleNestingIntakeCanalMonitoring RelativeAbundance andTemporalDistribution Size-Class Distributions SexRatiosCaptureEfficiencies RelativeCondition Mortalities Recapture Incidents SummaryLITERATURE CITEDFIGURESTABLESIVIV1010151515151920212224242729.31323437414971 l~.lgI 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+273.183.937x103.281x103.281x101.0x102.205x103.527x102.4711.0x102.20463.5274x106.214x101.0x101.0x102.642x103.2813.937x101.0941.0x101.01.0x103.937x-103.281x101.550x101.076x101.55x10Toobtainfahrenheit (degrees) kelvin(degrees) inchesfeetfeetpersecondliterspoundsounces(avoirdupois) acresgramspoundsounces(avoirdupois) miles(statute) millimeters cubiccentimeters (cm)gallons(USliquid)feetinchesyardsgramspartspermillion.liters(USliquid)inchesfeetsquareinchessquarefeetsquareinches

EXECUTlVE SUMMARYINTRODUCTION TheSt.LuciePlantisanelectricgenerating stationonHutchinson IslandinSt.LucieCounty,Florida.Theplantconsistsoftwonuclear-fueled 850-MWunits;Unit1wasplacedon-lineinMarch1976andUnit2inMay1983.Thisdocumenthasbeenpreparedtosatisfytherequirements 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".TURTLENESTINGSURVEYSincemonitoring beganin1971,therehavebeenconsiderable year-to-year fluc-tuationsinseaturtlenestingactivityonHutchinson Island.However,datacollected through1991haveshownnolong-term reductions intotalnesting,totalemergences ornestingsuccessontheisland.Relatively highnestingduringrecentyearsmayac-tuallyreflectanincreaseinthenumberofnestingfemalesinthestudyarea.Onasmallerscale,powerplantoperation hashadnosignificant effectonnestingneartheplant.Lownestingactivityin1975andagainin1981-1983inthevicinityoftheplantwasat-tributedtonighttime construction activities associated withinstallation ofplantintakeanddischarge structures.

Nestingreturnedtonormalorabovenormallevelsfollowing III bothperiodsofconstruction.

During1991,daytimecons:truction activities associated withvelocitycaprepairshadnoapparenteffectonnesting.Formalrequirements toconductnestingsurveysexpiredin1986butthisprogramwasvoluntarily continued through1991withagreement fromfederalandstateagencies.

INTAKECANALMONITORING Sinceplantoperation beganin1976,2,314seaturtles(including 108recaptures) representing fivedifferent specieshavebeenremovedfromtheintakecanal.Eighty-fivepercentofthesewereloggerheads.

Differences inthenumbersofturtlesfoundduringdifferent monthsandyearshavebeenattributed primarily tonaturalvariation intheoccurrences ofturtlesinthevicinityoftheplant,ratherthantooperational influen-cesoftheplantitself.Themajorityofturtlesremovedfromtheintakecanal(about93percent)werecapturedaliveandreleasedbackintotheocean.Ongoingevaluations andimprovements tothecanalcaptureprogramhavesubstantially reducedmortalities ofentrapped seaturtlesduringrecentyears.TurtlesconfinedbetweentheA1Abarriernetandintakeheadwalls typically resideinthecanalforarelatively shortperiodpriortocapture,andmostareingoodtoexcellent condition whencaught.OTHERRELATEDACTIVITIES Studiestoevaluatevariousintakedeterrent systems,asrequiredbytheNRC'sUnit2Environmental Protection Plan,wereconducted during1982and1983.Resultsandevaluations ofthosestudieswerepresented toregulatory agenciesduring1984,andtherequirement isnowconsidered completed.

'EIIIIII INTRODUCTION BACKGROUND Thisdocumenthasbeenpreparedtosatisfytherequirements contained intheUnitedStatesNuclearRegulatory Commission's (NRC)AppendixBEnvironmental Protection PlantoSt.LucieUnit2FacilityOperating LicenseNo.NPF-16.In1970,FloridaPower8LightCompany(FPL)wasissuedPermitNo.CPPR-74bytheUnitedStatesAtomicEnergyCommission, nowtheNuclearRegulatory Com-mission,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, IIII 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 ineightan-nualenvironmental operating reportscoveringtheperiodfrom1983through1990(ABI1984b,1985b,1986,1987,1988,1989,1990,1991).Thisreportdescribes the1991environmental protection activities relatedtoseaturtles,asrequiredbySubsection 4.2oftheSt.LuciePlantUnit2Environmental Protection Plan.AREADESCRIPTION TheSt.LuciePlantislocatedona457-hasiteonHutchinson IslandonFlorida's eastcoast(Figures1and2).Theplantisapproximately midwaybetweentheFt.PierceandSt.LucieInlets.ItisboundedonitseastsidebytheAtlanticOceanandonitswestsidebytheIndianRiverLagoon.

g Hutchinson Islandisabarrierislandthatextends36kmbetweeninletsandob-tainsitsmaximumwidthof2kmattheplantsite.Elevations approach5matopdunesbordering thebeachanddecreasetosealevelinthemangroveswampsthatarecom-mononmuchofthewesternside.Islandvegetation istypicalofsoutheastern Floridacoastalareas;densestandsofAustralian pine,palmetto, seagrapeandSpanishbayonetarepresentatthehigherelevations, andmangroves aboundatthelowereleva-tions.Largestandsofblackmangroves, including someontheplantsite,havebeenkilledbyfloodingformosquitocontroloverpastdecades.TheAtlanticshoreline ofHutchinson Islandiscomposedofsandandshellhashwithintermittent rockypromontories protruding throughthebeachfacealongthesouthernendoftheisland.Submerged coquinoid rockformations parallelmuchoftheislandofftheoceanbeaches.Theoceanbottomimmediately offshorefromtheplantsiteconsistsprimarily ofsandandshellsediments.

Theunstablesubstrate limitstheestablishment ofrootedmacrophytes.

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 cooling

'IIIt)IIii)I watersystem.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 to'heatmosphel'B.

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.Allnewnestsandfalsecrawlswillbecountedandrecordedineacharea.Aftercounting, allcrawltrackswillbeobliterated toavoidrecounting.

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

Thestudywilldetermine withlaboratory andfieldexperiments ifsoundand/orlightwillresultinareduction oftotalturtleentrapment rate.

IIIIIII 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, ofthecapturedevice(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 1IIIIII seaturtleswillbepursued.Deadseaturtleswillbesubjected toagrossnecropsy, iffoundinfreshcondition.

INTRODUCTION Hutchinson Island,Florida,isanimportant rookeryfortheloggerhead turtle,Caret-ta~carettandalsosupportssomenestingofthegreenturtle,~Chionia~mdasand59tt~I.~DhI9imatdIdII1.,1959;9 t,1999;91-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 thevitalityofthe5Hutchinson 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 IIIII installed duringthatyear.Installation ofthesestructures includednighttime construc-tionactivities conducted offshorefromandperpendicular tothebeach.Construction hadbeencompleted andtheplantwasinfulloperation duringthe1977and1979sur-veys.Amodifieddaytimenestingsurveywasconducted in1980duringthepreliminary construction oftheoceandischarge structure forSt.LuciePlantUnit2.'During thisstudy,fourofthepreviously established 1.25-km-long surveyareasweremonitored.

Additionally, eggsfromturtlenestspotentially endangered byconstruction activities wererelocated.

Everyyearfrom1981through1991,361-km-long surveyareascomprising theentireislandweremonitored sevendaysaweekduringthenestingseason(Figure3).TheSt.LuciePlantUnit2discharge structure wasinstalled duringthe1981nestingseason.Offshoreandbeachconstruction oftheUnit2intakestructure proceeded throughout the1982nestingseasonandwascompleted neartheendofthe1983season.Construction activities associated withinstallation ofbothstructures weresimilartothoseconducted whenUnit1intakeanddischarge structures wereinstalled.

Eggsfromturtlenestspotentially endangered byconstruction activities wererelocated duringallthreeyears.During1991,anothermajoroffshoreconstruction projectwasundertaken toreplacedamagedvelocitycapsonthethreeintakestructures.

Alargeelevatedplat-form,fromwhichrepairactivities wereconducted, waserectedaroundthethreestruc-tures.Construction occurredthroughout thenestingseason.However,incontrastto IiOl) previousoffshoreprojects, workwasrestricted almostentirelytodaylighthours,nighttime lightingoftheworkareawasminimal,andnoequipment ormaterials wereusedonthebeach.Aseaturtleprotection planimplemented insupportoftheprojectincludedcagingofnestsalonga1,500msectionofbeachwestoftheplatformandreleaseofhatchlings tounaffected areastothenorthandsouth.Thisplanwasintendedtomitigateanynegativeeffectspotentially resulting fromrequiredsafetyandnaviga-tionallightingonandneartheplatform.

Requirement 4.2.1oftheNRC'sSt.LucieUnit2AppendixBEnvironmental Protec-tionPlanwascompleted withsubmission ofthe1986nestingsurveydata(ABI,1987).Thenestingsurveywascontinued voluntarily through1991withagreement fromfederalandstateagencies.

Resultsarepresented inthisreportanddiscussed inrelationtopreviousfindings.

Inadditiontomonitoring seaturtlenestingactivities andrelocating nestsawayfromplantconstruction areas,removalofturtlesfromtheintakecanalhasbeenanin-tegralpartoftheSt.LuciePlantenvironmental monitoring program.Turtlesenteringtheoceanintakestructures areentrained withcoolingwaterandrapidlytransported throughtheintakepipesintoanenclosedcanalsystemwheretheymustbemanuallycapturedandreturnedtotheocean.Sincetheplantbecameoperational in1976,turtlesentrapped intheintakecanalhavebeensystematically

captured, measured, weighed,taggedandreleased.

Previouspublications andtechnical reportshavepresented findingsofthenest-ingsurveys,nestrelocation activities andcanalcaptureprogram(Gallagher etal.,1972; IIIILIOtt WorthandSmith,1976;ABI,1978,1980a,1981a,1982,1983,1984b,1985b,1986,1987,1988,1989,1990,1991;Williams-Walls etal.,1983;Proffittetal.,1986;Ernestetal.,1988,1989;Martinetal.,1989a,1989b).Resultsofstudiestoassesstheeffectsofthermaldischarges onhatchling swimmingspeedhavealsobeenreported(ABI,1978;O'ara,1980).Thepurposeofthisreportisto1)present1991seaturtlenestingsur-veydataandsummarize observedspatialandtemporalnestingpatternssince1971,2)documentandsummarize predation onturtlenestssince1971,and3)present1991canalcapturedataandsummarize comparable datacollected since1976.MATERIALS ANDMETHODSNestinSurveMethodologies usedduringpreviousturtlenestingsurveysonHutchinson Islandweredescribed byGallagher etal.(1972),WorthandSmith(1976)andABI(1978,1981a,1982,1987,1988,1989).Methodsusedduringthe1991surveyweredesignedtoallowcomparisons withthesepreviousstudies.On10and12April1991,preliminary nestsurveyswereconducted alongHutchin-sonIslandfromtheFt.PierceInletsouthtotheSt.LucieInlet.From15Aprilthrough6September, nestsurveyswereconducted onadailybasis.Toconfirmthatnestinghadceased,afinalsurveywasconducted on9September.

Biologists usedsmalloff-roadmotorcycles tosurveytheislandeachmorning.Newnests,non-nesting emer-gences(falsecrawls),andnestsdestroyed bypredators wererecordedforeachofthe361-km-long surveyareascomprising theentireisland(Figure3).Thenine1.25-km-10 IIIII longsurveyareasestablished byGallagher etal.(1972)alsoweremonitored socom-parisonscouldbemadewithpreviousstudies.Duringthedailynestmonitoring, anymajorchangesintopography thatmayhaveaffectedthebeach'ssuitability fornestingwererecorded.

In,addition, eachofthe361-km-long surveyareashasbeensystematically analyzedandcategorized basedonbeachslope(steep,moderate, etc.),widthfromhightidelinetothedune,presenceofbenches(areasofabruptverticalrelief)andmiscellaneous characteristics (packedsand,scattered rock,vegetation onthebeach,exposedrootsontheprimarydune,etc.).Inacooperative effort,datafromstrandedturtlesfoundduringbeachsurveyswereroutinely providedtotheNationalMarineFisheries Service(NMFS)throughtheSeaTurtleStranding andSalvageNetwork.IntakeCanalMonitorin Mostturtlesentrapped intheSt.LuciePlantintakecanalwereremovedbymeansoflarge-mesh tanglenetsfishedbetweentheintakeheadwalls andabarriernetlocatedattheHighwayA1Abridge(Figure2).Netsusedduring1991werefrom30to40minlength,3to4mdeepandcomposedof40cmstretchmeshnylontwine.Largefloatswereattachedtothesurface,andunweighted linesusedalongthebottom.Turtlesen-tangledinthenetsgenerally remainedatthewater'ssurfaceuntilremoved.Sinceitsinception in1976,ABI'scanalcaptureprogramhasbeenundercontinual reviewandrefinement inanattempttominimizebothentrapment timesandin-11

'7IIlIIIIllliI juries/mortalities toentrapped seaturtles.PriortoApril1990,turtlenetswereusuallydeployedonMondaymorningsandretrieved onFridayafternoons.

Duringperiodsofdeployment, thenetswereinspected forcapturesbyABIpersonnel atleasttwiceeachday(mornings andafternoons).

Additionally, St.LuciePlantpersonnel checkedthenetsperiodically, andABIwasnotifiedimmediately ifacapturewasobserved.

ABI'sseaturtlespecialists wereoncall24hoursadaytoretrievecapturedturtlesfromtheplant.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.

12 IIIIIII Inthepast,theintegrity ofthebarriernetwasoccasionally compromised, andturtleswereabletomovewestofA1A.Theseturtleswerefurtherconstrained downstream byanunderwater intrusion detection system(UIDS)consisting, inpart,ofalargebarrierpositioned perpendicular tothenorth-south armofthecanal(Figure2).TheUIDSsecuritybarrieralsoconsistsof30.5cmx30.5cmmesh.Priortocompletion oftheUIDSinDecember1986,turtlesuncontained bytheA1AbarriernetwereusuallyremovedfromthecanalattheintakewellsofUnits1and2(Figure2)~Theretheywereretrieved bymeansoflargemechanical rakesorspecially designednets.Following construction oftheUIDSbarrier,individuals withcarapacewidthslargerthan30.5cmwereunabletoreachtheintakewells.Thus,asrequired, tanglenetswerealsodeployedwestofA1A.Improvements madetotheA1Abarriernetduring1990haveeffectively confinedallturtleslargerthan30.5cmtotheeasternendofthecanal.Formaldailyinspections oftheintakecanalweremadetodetermine thenumbers,locations andspeciesofturtlespresent.Surfaceobservations wereaugmented withperiodicunderwater inspections usingSCUBA,particularly inandaroundtheA1Abar-riernet.Becauseofthereduction intotalnettinghourssinceApril1990,increased ef-forthasbeendirectedtowardhandcaptureofturtles.Thiseffort,accomplished bydivinganduseofdipnets,hasprovedveryeffective duringperiodsofgoodwaterclarity.Regardless ofcapturemethod,allturtlesremovedfromthecanalwereidentified tospecies,measured, weighed,tagged,andexaminedforoverallcondition (wounds,13 IIII abnormalities, parasites, etc.).Healthyturtleswerereleasedintotheoceanthesamedayofcapture.Sickorinjuredturtlesweretreatedandoccasionally heldforobserva-tionpriortorelease.Whentreatment waswarranted, injections ofantibiotics andvitaminswereadministered bypermitted veterinarians.

Resuscitation techniques wereusedifaturtlewasfoundthatappearedtohavediedrecently.

Beginning in1982,necropsies wereconducted ondeadturtlesfoundinfreshcondition; nonecropsies wereperformed during1991.Since1982,bloodsampleshavebeencollected andanalyzedtodetermine thesexofimmatureturtles.Bloodwasremovedfromthepaireddorsalcervicalsinusesofsubjectturtlesusingthetechnique described byOwensandRuiz(1980).Thesamplesweremaintained oniceandlatercentrifuged for15minutestoseparatecellsandserum.Sexdeterminations weresubsequently madebyresearchers atTexasA8MUniver-sityusingradioimmunoassay forserumtestosterone (Owensetal.,1978).FloridaPower8LightCompanyandAppliedBiology,Inc.continued toassistotherseaturtleresearchers in1991.Sincetheprogrambegan, data,specimens and/orassistance havebeengiventotheFloridaDepartment ofNaturalResources, NationalMarineFisheries Service,USFishandWildlifeService,USArmyCorpsofEngineers, Smithsonian Institution, SouthCarolinaWildlifeandMarineResources

Division, CenterforSeaTurtleResearch(University ofFlorida),

FloridaAtlanticUniversity, University ofCentralFlorida,TexasA8MUniversity, University ofRhodeIsland,University ofSouthCarolina, University ofIllinois, University ofGeorgia,VirginiaInstitute ofMarineScienceandtheWesternAtlanticTurtleSymposium.

14 IIIIIII StudiestoEvaluateandorMitiateIntakeEntramentAprogramthatasses'sed thefeasibility ofusinglightand/orsoundtodeterturtlesfromenteringtheSt.LuciePlantintakestructures wasconducted in1982and1983andcompleted inJanuary1984.Asrequired, testresultsandevaluations werewrittenupandapresentation wasmadetotheNRC,NationalMarineFisheries ServiceandtheFloridaDepartment ofNaturalResources on11April1984.Requirement 4.2.2oftheNRC'sSt.LucieUnit2AppendixBEnvironmental Protection Planisconsidered completed withsubmission ofdeterrent studyfindings.

RESULTSANDDISCUSSION NestinSurveDistribution ofLoerheadNestsAlonHutchinson IslandWhenseaturtlenestingsurveysbeganonHutchinson Island,nine1.25-km-long surveyareaswereusedtoestimateloggerhead nestingactivityfortheentireisland.From1971through1988,thedistribution ofnestsamongthesenineareasindicated agradientofincreased nestingfromnorthtosouth(ABI,1989).Thegradienthasbe-comelesspronounced duringthelastthreeyearsandduring1991nogradientwasapparent(Figure4).Thischangeinthespatialdistribution ofnestswasapparently duetoadisproportionate increaseinnestinginnorthernversussouthernsurveyareas.Since1981,all361-km-long segmentscomprising theisland'scoastline havebeensurveyed.

Thedistribution ofnestsamongthese36surveyareashasshownanincreaseinnestingfromnorthtosouthonlyalongthenorthernhalfoftheisland(Figure15 Ii~i) 5).Alongthesouthernhalfoftheislandtherehasbeenagradientofdecreasing nest-ingfromnorthtosouth.Aswiththenineareas,therehasbeenadisproportionate in-creaseinnestinginnorthernversussouthernsurveyareasduringthelastthreeyears.Inthepast,thepronounced gradientobservedonthenorthernendoftheislandwasoccasionally influenced byphysicalprocesses occurring there;periodsofheavyaccretion reducedthegradient, whileperiodsoferosionaccentuated it(WorthandSmith,1976;Williams-Walls etal.,1983).However,duringrecentyearsnoconsistent 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-16 IIIII cesorunsatisfactory nestingbeachcharacteristics.

Therefore, certainfactorsmayaf-fectaturtle'spreference toemergeonabeach,whileotherfactorsmayaffectaturtle'tendencytonestafterithasemerged.Anindexwhichrelatesthenumberofneststothenumberoffalsecrawlsinanareaisusefulinestimating thepost-emergence suitability ofabeachfornesting.Inthepresentstudythisindexistermed"nestingsuc-cess"andisdefinedasthepercentage oftotalemergences thatresultinnests.Historically, thepatternofloggerhead emergences ontheislandhasgenerally paralleled thedistribution ofnests(ABI,1987,1988),andthissametrendwasapparentin1991(Figure6).Incontrast, nestingsuccessbyloggerheads alongtheislandhastypically lackedgradients (Figure7).Thus,therelatively highnumbersofloggerhead nestsobservedincertainareasareusuallyaresultofmoreturtlescomingashoreinthoseareasratherthanofmorepreferable nestingconditions beingencountered bytheturtlesaftertheyemerged.Loggerhead nestingdensities during1991weregenerally highwhencomparedwithpreviously recordedvalues(Figures4and5).Recordhighnestingwasrecordedin12ofthe36one-kilometer-long surveyareasandwasmostnotableonthenorthernhalfoftheisland.Therewerenoapparentchangesinthephysicalcharacteristics ofthebeachthatwouldaccountforthisincreaseinnesting.Ingeneral,recordhighnest-ingwasduetorecordhighemergence rates,andthismayreflectanincreaseinthenumberofnestingfemalesintheHutchinson Islandarea'.NestingsurveysonHutchinson Islandwereinitiated inresponsetoconcernsthattheoperation oftheSt.LuciePlantmightnegatively impactthelocalseaturtlerookery.17 IIIIIIIIItI)i 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 (Figure8).Powerplantoperation exclusive ofintake/dis-chargeconstruction hashadnoapparenteffectonnesting.During1991,nestingatthepowerplantsiteremainedhigherthanatthecontrolsitedespiteconstruction activities (velocity caprepairs)ontheintakestructures.

Thoughtheseconstruction activities proceeded throughout thesummer,includedtheconstruction ofalargeoffshoreplatform, andinvolvedtheuseofheavyequipment, therewasnoapparenteffectonseaturtlenestinginthevicinityoftheconstruction.

Severalaspectsoftheconstruction projectminimized potential effectsonnestingseaturtles.Construction activities tookplacealmostexclusively duringtheday,thusmini-mizinginterference withthenocturnal nestingbehaviorofturtles.Also,safetyandnavigational lightingontheplatformandsupportvesselswasdesignedtominimizeef-fectstoseaturtles.Furthermore, nostructures ormaterials wereplacedonthebeach,therebyavoidinginterference withthenestingbehaviorofemergentturtles.Datacollected through1991haveshownnolong-term reduction inloggerhead nestdensities, totalemergences ornestingsuccessineitherthenine1.25-km-long surveyareasorthe361-km-long surveyareas(Table1;Figure9).Tothecontrary, datacollected frombothsetsofsurveyareasindicatealong-term increaseinlogger-18 1IIIII EstimatsofTotalLrheNestinnHuthinsonIslandVariousmethodsw'ereusedduringsurveyspriorto1981toestimatethetotalnumberofloggerhead nestsonHutchinson Islandbasedonthenumberofnestsfoundinthenine1.25-km-long surveyareas(Gallagher etal.,1972;WorthandSmith,1976;ABI,1980a).Eachofthesemethodsweresubsequently foundtoconsistently overes-Itimateislandtotals(ABI,1987).Sincewhole-island surveysbeganin1981,ithasbeenpossibletodetermine theactualproportion oftotalnestsdeposited inthenineareas.Thishasthenallowedextrapolation fromtheninesurveyareastotheentireislandforyearspriorto1981.From1981through1991thetotalnumberofnestsinthenineareasvariedfrom32.5to35.6percentofthetotalnumberofnestsontheisland(Table1).Thisisslight-lyhigherthanthe31.3percentwhichwouldbeexpectedbasedstrictlyonthepropor-tionoflinearcoastline comprised bythenineareas.Usingtheeleven-year meanof33.97percent,estimates ofthetotalnumberofnestsonHutchinson Islandcanbecal-culatedbymultiplying thenumberofnestsinthenineareasby2.944.Thistechnique, whenappliedtotheninesurveyareasduringtheelevenyearsinwhichtheentireis-landwassurveyed, producedwhole-island estimates within5.0percentoftheactualnumberofnestscounted.Becausetheproportion ofnestsrecordedintheninesur-veyareasremainedrelatively constantoverthelastelevenyears,thisextrapolation procedure shouldprovideafairlyaccurateestimateoftotalloggerhead nestingforyearspriorto1981~19 IIII Itisclearthatloggerhead nestingactivityonHutchinson Islandfluctuates con-siderably fromyeartoyear(Table1).Annualvariations innestdensities alsoarecom-monatotherrookeries (Hughes,1976;DavisandWhiting,1977;Ehrhart,1980)andmayresultfromnon-annual reproductive behavior(Frazer,1989).Nonetheless, datacollected through1991suggestanoverallincreaseinnestingonHutchinson Islandsincesurveysbeganin1971.Totalnestingactivitywasgreatestduring1991when6,812loggerhead nestswererecorded.

Norelationships betweentotalnestingactivityandpowerplantoperation orintake/discharge construction wereindicated byyear-to-yearvariations intotalnestingonHutchinson Island.TemoralLoerheadNestinPatternsTheloggerhead turtlenestingseasonusuallybeginsbetweenmid-April andearlyMay,attainsamaximumduringJuneorJuly,andendsbylateAugustorearlySep-tember(ABI,1987).Nestingactivityduring1991followedthissamepattern(Figure10).Coolwaterintrusions frequently occuroverthecontinental shelfofsoutheast Floridaduringthesummer(TaylorandStewart,1958;Smith,1982).WorthandSmith(1976),Williams-Walls etal.(1983)andABI(1982,1983,1984b,1985b,1986,1987,1988,1989,1990,1991)suggested thattheseintrusions mayhavebeenresponsible forthetemporary declinesinloggerhead turtlenestingactivitypreviously observedonHutchinson Island.Similarly, anintrusion ofcoolwaterduringlateJuly1991mayhavecontributed tothesubstantial decreaseinnestingbetweenlateJulyandearlyAugust(Figure10).20 IIiIII Thoughnaturalfluctuations intemperature havebeenshowntoaffecttemporalnestingpatternsonHutchinson Island,therehasbeennoindication thatpowerplantoperation hasaffectedthesetemporalpatterns(ABI,1988).Predation nLoerheadTurtleNestsSincenestsurveysbeganin1971,raccoonpredation hasbeenamajorcauseofturtlenestdestruction onHutchinson Island.Researchers atotherlocations havereportedraccoonpredation levelsashighas70tonearly100percent(DavisandWhit-ing,1977;Ehrhart,1979;Hopkinsetal.,1979;Talbertetal.,1980).Raccoonpredation ofloggerhead 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)~During1991,fourpercent(301)oftheloggerhead nests(n=6,812)ontheislandweredepredated byraccoons.

Asinpreviousyears(ABI,1991),predation ofturtlenestswasprimarily restricted tothemostundeveloped portionoftheisland(i.e.,AreasEthroughS;Figure11).However,predation ratesinAreas0andPduring1991wereconsiderably lowerthanduringpreviousyears.Thisreduction isattributed tothefactthatmostofthenestsinthesetwoareaswerecoveredwithwirecages.Thesecages,21 IIIII originally installed toretainhatchlings duringvelocitycaprepairs,werealsoeffective inexcluding raccoons.

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 ratesbyghostcrabshavevariedfrom0.1to2.1percentfrom1983-1990(ABI,1991).During1991,0.5percent(31)oftheloggerhead nests(n=6,812)ontheislandweredepredated byghostcrabs(Figure11).Nestsdestroyed byacombination ofraccoonandghostcrabpredation havebeenincludedasraccoonpredations inpreviousdiscussions.

Whenthesecombination predations areincludedascrabpredations, theoverallpredation ratesbyghostcrabsrangefromOAto3.2percent.During1991,1.3percent(90nests)weredestroyed byeitherghostcrabsoracombination ofghostcrabsandraccoons.

GreenandLeatherback TurtleNestinGreenandleatherback turtlesalsonestonHutchinson Island,butinfewernum-bersthanloggerhead turtles.Priorto1981,bothsurvey(nine1.25-km-long sections) andinter-survey areasweremonitored forthepresenceofgreenandleatherback nests.Thirty-one kilometers ofbeachfromArea1southtotheSt.LucieInletwerein-cludedinthateffort.Duringwhole-island surveysfrom1981through1991,onlysixof22 IIII 226leatherback nestsandonlyeightof648greennestswererecordedonthefivekilometers ofbeachnorthofArea1.Therefore, previouscountsofgreenandleather-backnestswithinthe31kilometers surveyedwereprobablynotappreciably different fromtotaldensities fortheentireisland.Basedonthisassumption, greenandleather-backnestdensities maybecomparedamongallsurveyyears,except1980,whenlessthan15kilometers ofbeachweresurveyed.

Priorto1991,thenumberofnestsobservedontheislandrangedfrom5to132forgreenturtlesandfrom1to36forleatherbacks (Figure12).Duringthe1991survey,47greenturtleand44leatherback turtlenestswererecordedonHutchinson Island.Temporalnestingpatternsforthesespeciesdifferfromthepatternforloggerhead turtles.Greenturtlestypically nestonHutchinson Islandfrommid-JunethroughthefirstorsecondweekofSeptember.

During1991,greenturtlesnestedfrom2Junethrough1September.

Leatherback turtlesusuallynestontheislandfrommid-April throughearlytomid-July.

During1991thisspeciesnestedfrom5Aprilthrough18July.Considerable fluctuations ingreenturtlenestingontheislandhaveoccurredamongsurveyyears(Figure12).Thisisnotunusualsincetherearedrasticyear-to-yearfluctuations inthenumbersofgreenturtlesnestingatotherbreedinggrounds(Carretal.,1982).Despitethesefluctuations, datacollected through1991suggestanoverallincreaseinnestingsince1971andmayreflectanincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.During1991,greenturtlesnestedmostfrequently alongthesouthernhalfoftheisland.Thisisconsistent withresultsofpre-vioussurveys.23 IIIII~II Leatherback turtlenestdensities haveremainedlowonHutchinson Island;however,increased nestingduringrecentyears(Figure12)mayreflectanoverallin-creaseinthenumberofnestingfemalesintheHutchinson Islandarea.During1991,leatherback turtlesprimarily nestedonthesouthernhalfoftheisland.IntakeCanalMonitorin Entrainment ofseaturtlesattheSt.LuciePlanthasbeenattributed tothepresumedphysicalattractiveness oftheoffshorestructures housingtheintakepipesratherthantoplantoperating characteristics (ABI,1980band1986).Thevelocitycapssupported abovetheopeningstoeachintakepipeeliminate verticalwaterentrainment andsubstantially reducecurrentvelocities nearthestructures byspreading horizontal drawoveranarcof360.Thus,evenwhenbothunitsareoperating atfullcapacity, turtlesmustactivelyswimintothemouthofoneoftheintakepipesbeforetheyen-countercurrentvelocities sufficiently strongtoeffectentrainment.

Consequently, aturtle'sentrapment relatesprimarily totheprobability thatitwilldetectandsubsequently enteroneoftheintakestructures.

Assumingthatdetection distances donotvaryap-preciably overtimeandthatallturtles(oraconstantproportion) areequallyattracted tothestructures, capturerateswillvaryproportionally tothenumberofturtlesoccur-ringinthevicinityofthestructures.

RelativeAbundance andTemoralDistribution During1991,121seaturtlecapturestookplaceintheintakecanaloftheSt.LuciePlant:107loggerheads, 12greenturtles,1hawksbill and1Kemp'sridley(Table2).Allbutoneofthefivespeciesofseaturtlesinhabiting coastalwatersofthesoutheastern 24

~3'll1'II~III UnitedStateswerepresent.Sinceintakecanalmonitoring beganinMay1976,1,960loggerhead (including 107recaptures),

318green(including 1recapture),

9leather-back,9hawksbill and18Kemp'sridleycaptureshavetakenplaceattheSt.LuciePlant.Annualcatchesofloggerheads increased steadilyfromalowof33in1976(par-tialyearofplantoperation andmonitoring) to172in1979(Figure13).Afterdeclining between1979and1981,yearlycatchesofloggerheads againrosesteadily, reachingahighof195during1986.Captureshavebeenindeclinesince1986,decreasing about45percentoverthelastfiveyears.Twooffshoreintakestructures wereinplacepriortoUnit1start-upin1976;thethirdandlargeststructure wasinstalled during1982-1983.

Eventhoughallthreestruc-turesareinrelatively closeproximity, theadditionofanotherpipemayhaveincreased theprobability ofaturtlebeingentrained.

Becausethischangecannotbequantified, datacollected priorto1982maynotbecomparable withthatcollected after1983.Ad-ditionally, theinfluence oftheconstruction itselfonseaturtleentrainment during1982and1983isunknown.Similarly, damagetothecenterportionsoftwoofthethreevelocitycapswasobservedin1989.Thisdamageaddedastrongverticalcomponent towaterentrainment.

Following athoroughevaluation oftheextentandcause(s)ofthedamage,amajorrepairoperation wasundertaken during1991.Thedegreetowhichashiftinentrainment characteristics andsubsequent repairoperations affectedseaturtleentrapment isalsounknown.Withtheseconsiderations inmind,neitheralong-term increasenordecreaseinthenumberofloggerheads capturedattheSt.LuciePlantcanbeinferredfromthedata.25 IIIrig During1991,themonthlycatchofloggerheads rangedfrom1(November andDecember) to20(March),withamonthlymeanof8.9(+7.0;Table3).ThenumberofcapturesduringMarch,AprilandMaywereconsiderably aboveaverage,whilecap-turesthroughout theremainder oftheyearwereslightlytoconsiderably lowerthanaverage(Figure14).Overtheentiremonitoring period,monthlycatcheshaverangedfrom0to39;thegreatestnumberofcapturesoccurredduringJanuary1983.Whendatafromallfullyearsofmonitoring (1977-1991) werecombined, thehighestnumberofloggerhead capturesoccurredinJanuary;fewestcaptureswererecordedinNovemberandDecember(Table3).However,monthlycatcheshaveshownconsiderable annualvariability.

Monthshavingrelatively lowcatchesoneyearoftenhavehadrelatively highcatchesinanother.Catchesofgreenturtlesalsohavevariedwidelyamongyears,rangingfrom0in1976(partialyearofsampling) to69in1984(Figure13;Table4).During1991,12in-dividuals werecaptured.

Theaverageannualcatchofgreenturtles,excluding 1976,was21.2(+17.5).Asforloggerheads, nolong-term trendscanbeinferredfromthedata.Greenturtleshavebeencaughtduringeverymonthoftheyear,withaveragemonthlycatchesforallyearscombinedrangingfrom0.4inSeptember to6.7inJanuary(Table4).Seasonalabundance patternsofgreenturtlesweremuchmorepronounced thanforloggerheads, nearly60percentofallcapturesoccurring duringthethreemonthperiodbetweenJanuaryandMarch.During1991,thelargestnumberofgreenturtles26 lIIlII (4)werecapturedinFebruary.

Themostevercaughtinonemonthwas37inJanuary1984.Catchesofleatherbacks, hawksbills andKemp'sridleyshavebeeninfrequent andscattered throughout the16yearstudyperiod(Table2).Eachspecieshasshownratherpronounced seasonaloccurrences; allbuttwoofthenineleatherbacks werecollected betweenFebruaryandMay,sevenoftheninehawksbills werecollected be-tweenJuneandSeptember, andallbuttwoofthe18Kemp'sridleyswerecaughtbe-tweenNovemberandApril.Size-Class Distributions Althoughseveralstraight-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=49.3+31.1kg;Figures15and16).Acarapacelengthof70cmapproximates thesmallestsizeofnestingloggerhead femalesobservedalongtheAtlanticeastcoast(Hirth,1980).However,adultscanonlybereliablysexedonexternalmorphological characteristics (i.e.,relativetaillength)afterattaining asomewhatlargersize.Inearlierannualreports,80.0cmwasusedasthelowerlimitforadultturtles.However,recentdatasuggestthatsomemalesmaynotmature,andthusmightnot-bedistinguishable fromfemales,untiltheyareabout85.027 cmlong.Basedonthesedivisions, dataweresegregated intothreegroups:Juveniles

((70cm),adults()85cm)andtransitional (71-85cm)~Thelattergroupprobablyin-cludesbothmatureandimmatureindividuals.

Ofthe1,848loggerhead capturesbetween1977and1991forwhichlengthdatawererecorded, 69.3percentwerejuveniles, themajorityofthesemeasuring between50and70cmSLCL(Table5).Theremaining individuals werenearlyequallydividedbetweenadultsandanimalsinthetransitional sizeclass.Similarsize-frequency dis-tributions, indicating apreponderance ofjuveniles, havebeenreportedforloggerheads inhabiting theMosquito/Indian RiverLagoon(Mendonca andEhrhart,1982),theCanaveral shipchannel(Henwood, 1987),andGeorgiaandSouthCarolina(Hillestad etal.,1982).Thesedatasuggestthatcoastalwatersofthesoutheastern UnitedStatesconstitute animportant developmental habitatforloggerhead seaturtles.Seasonalpatternsofabundance forvarioussizeclassesindicated thatjuvenileloggerheads wereslightlymoreabundantduringthewinterthanatothertimesoftheyear(Table5).About47percentofthejuveniles wer'ecapturedbetweenJanuaryandApril.Abundances decreased inspringandremainedrelatively constantduringthesummerandearlyfallbeforedecreasing againtolowestlevelsinNovemberandDecember.

Theseasonaldistribution ofadultloggerheads wasmuchmorepronounced, 76percentofallcapturesoccurring betweenMayandAugust.Thisrep-resentsthemajorportionofthenestingseasononHutchinson Island.Greenturtlesremovedfromtheintakecanalovertheentirestudyperiodrangedinsizefrom20.0to108.0cmSLCL(x=35.8+14.0cm)and0.9kgto177.8kg(x=28 lIttg 9.3+19.9kg;Figures17and18).Nearlyall(98percent)werejuveniles.

About80per-centwere40cmorlessinlength,and65percentweighed5kilograms orless.Al-thoughtheseimmatureturtlesexhibited distinctwinterpulses,somesmallindividuals werecapturedthroughout theyear(Table4).Todate,onlyeightadultgreenturtles(SLCL)83cm;Witherington andEhrhart,1989)havebeenremovedfromthecanal;allwerecapturedduringorshortlyafterthenestingseason.Theninehawksbills removedfromthecanalrangedinsizefrom34.0to83.4cmSLCL(x=50.3+17.3cm)andinweightfrom6.4to86.6kg(x=25.0+27.8kg).Allbuttwowerejuveniles (SLCL<63cm;Witzell,1983).Similarly, allbutoneofthe18Kemp'sridleyscapturedattheSt.LuciePlantwerejuveniles (SLCL<60.0cm;Hirth,1980).Carapacelengthsfortheridleysrangedfrom27.0to62.0cmSLCL(x=37.0+10.1cm)andweightsfrom3.1to31.8kg(x=8.6+8.2kg).Thenineleather-backsremovedfromthecanalrangedinlengthfrom112.5to150.0cm,andatleastsevenwereadults(SLCL)121cm;Hirth,1980).Thelargestleatherback forwhichanaccurateweightwasobtained, afemalewithacurvedcarapacelengthof158.5cm,'eighed 334.8kg.SexRatiosSinceintakecanalmonitoring beganin1976,282adultloggerheads (SLCL>85.0cm)havebeensexed.Femalespredominated malesbyaratioof5.3:1.0,whichsig-nificantly departsfroma1:1ratio(X,P<0.05).Consequently, temporalpatternsinthenumberofadultloggerhead captureswereheavilyinfluenced bythenumbersoffemalespresent.Whensexeswereseparated, itwasevidentthatmaleswererelative-29 lyevenlydistributed amongmonths,whereasalmost90percentofthefemalesweretakenduringthenestingseason(MaythroughSeptember; Figure19).Thenumberofadultfemaleloggerheads capturedattheSt.LuciePlanthasin-creasednoticeably since1983.From1977(firstfullyearofplantoperation) through1983,anaverageof4.4adultfemales(+3.2;range=1-10)wereentrapped eachyear,whereassincethen,anaverageof25.3femalesperyearwerecaptured(+6.9;range=16-35).Thisincreasecorresponds toageneralriseinloggerhead nestingac-tivityneartheplant(Figure20).Increased nearshore movementassociated withnest-ingincreases theprobability ofaturtledetecting oneoftheintakestructures andhencetheprobability ofentrainment.

Thesharpdeclineincapturesduring1991isprobablyrelatedtothevelocitycaprepairproject.Construction oftheoffshoreplatformandsub-sequentdaytimerepairactivities mayhavereducedtheattractiveness oftheintakestructures asarestingorstagingareaforadultfemalesbetweensuccessive nestingforays.Reducedassociation withthestructures woulddecreasethelikelihood ofentrainment.

Despitetherecentdeclineincaptures, theoveralltrendsince1983sug-gestsagenuineincreaseinthenumberoffemaleloggerheads occurring inthevicinityoftheplant.BetweenSeptember 1982andDecember1986,267individual juvenileandsub-adultloggerhead turtlescapturedinthecanalweresexedbyTexasA8MUniversity researchers usingabioimmunoassay technique forbloodserumtestosterone.

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

wheresexratiosarealso30 I1III significantly skewedinfavoroffemales(WibbeIsetal.,1984).Bloodsamplescollected since1986arecurrently beinganalyzedandtheseresultswillprovideavaluabletoolforassessing temporalvariability inthesexratiosofthelocalloggerhead population.

Oftheeightadultgreenturtlescapturedsincemonitoring began,sixweremalesandtwowerefemales.Siximmaturegreenturtleshavebeensexedthroughbloodwork;allhavebeenfemales.Ofthesixadultleatherback turtlesforwhichsexwasrecorded, threewerefemalesandthreeweremales.Thetwoadulthawksbills andoneKemp'sridleywereallfemales.Nosexinformation existsforjuveniles ofanyofthesespecies.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, and90percentarecapturedduringtheirfirstweekofentrapment (Figure21).Averagecaptureefficiency, expressed aselapseddaysbe-tweenfirstsightingandcapture,duringtheperiodfromApril1990throughDecember IIIII 1991was3.8days(+5.9days;range=1-50days).Betterutilization ofcurrentsandeddies,adjustments totethering lines,multi-net deployments andincreased effortstohandcaptureturtleshavecontributed toreducedentrapment times.Entrapment timesmaybeextendedforturtlesswimmingpasttheA1Abarriernet(ABI,1987).Priortobarriernetrepairsin1990,thetopofthenetwasoccasionally sub-mergedortheanchorcablepulledfreefromthebottom,allowingturtleswiderthan30.5cmtopass.BecausecaptureeffortswestoftheA1Abridgeweregenerally lesseffective thanthoseneartheintakeheadwalls, mostturtlesbreaching thebarriernetwerenotcaughtuntiltheyenteredtheintakewellsofUnits1and2.Priortoinstallation oftheUIDSbarrierin1986,about15percentofallturtlesentrapped inthecanalwereremovedfromtheintakewells.Becauseoftheirrelatively smallsizes,amuchlargerproportion ofgreens(51.6percent)reachedtheplantthanloggerheads (10.1percent).

Since1986,thepercentage ofgreenscaughtattheintakewellshasdecreased to33.3percent,whileallloggerheads havebeenprevented fromreachingtheplant.During1991,onlytwoofthe12greenturtlecapturesoccurredattheintakewells.During1991,98percentofallturtlesentrapped inthecanalwerecapturedeastoftheA1Abridge,71bynettingand48byhand.Theeffective confinement ofturtleseastofA1Ahasbeenamajorcontributor tothehighcaptureefficiency achievedduringrecentyears.RelativeCondition TurtlescapturedaliveintheintakecanaloftheSt.LuciePlantwereassignedarelativecondition basedonweight,activity, parasiteinfestation, barnaclecoverage, 32 IIy~IIIIIIII wounds,injuriesandanyotherabnormalities whichmighthaveaffectedoverallvitality.

During1991,88.8percent(95)ofallloggerheads foundinthecanalwerealiveandingoodtoexcellent condition.

Only10.3percent(11)ofloggerhead capturesinvolvedindividuals infairorpoorcondition; oneloggerhead wasdeadwhenremovedfromthecanal.Ofthe12greenturtlesremovedfromtheintakecanalduring1991,allbuttwowereingoodtoexcellent condition (oneinfaircondition andoneinpoorcondition).

Overtheentiremonitoring period,about77and78percent,respectively, ofallloggerhead andgreencaptureshaveinvolvedturtlesingoodtoexcellent condition (Table6).Capturesofindividuals infairtopoorcondition haveoccurredabout15per-centofthetimeforloggerheads and14percentofthetimeforgreens.Allofthehawksbills'and leatherbacks havebeenremovedfromthecanalingoodtoexcellent condition, whilehalfoftheKemp'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.

During1991,onlyfourofthe107loggerhead captures(3.7percent)involvedin-dividuals withnoticeable

injuries, suchasmissingappendages, brokenormissingpiecesofcarapaceanddeeplacerations.

Mostofthesewereold,well-healed wounds,33 andnonewereseriousenoughtorequiremedicalattention.

Noneofthegreenturtlescapturedduring1991hadmajorinjuries.

Themajorityofloggerheads ratedasfairorpoorduring1991didnotsufferfromphysicaldisabilities butratherappearedlethargic.

Mostwereunderweight andheavi-lyinfestedwithbarnacles andleeches.Thiscondition, referredtoas"diseased turtlesyndrome" (Ehrhart, 1987)hasbeenreportedfromseveralotherlocalesandisunre-latedtoaturtle'sentrapment inthecanal~Intwocases,theinfirmity wassoextremethattheanimalsweretransferred toSeaWorldofFloridafortreatment andrehabilita-tion.Onewassubsequently

released, theotherdiedincaptivity.

Mortalities Seaturtlemortalities havebeencloselymonitored throughout thelifeofthecanalcaptureprograminanattempttoassignprobablecausesandtakeappropriate remedialactiontominimizefutureoccurrences.

Previousanalysesofcapturedataiden-tifieddrowninginnets(A1Abarriernet,UIDSbarrier,andtanglenets),drowningintheintakepipesduringperiodsofreducedintakeflow,injuriessustained fromdredgingoperations andinjuriessustained fromthemechanical rakesusedintheintakewellsasprobablemortality factors(ABI,1987).Althoughdifficult toquantify, theentrapment andsubsequent demiseofinjuredorsickturtleshasprobablyaccounted foraportionofobservedmortalities.

Overtheentire16yearmonitoring period,128(6.5percent)ofthe1,960logger-headsand21(6.6percent)ofthe318greenturtlesentrapped inthecanalwerefounddead(Table6).Mortalities spannedtherangeofsizeclassesforloggerheads (SLCL34

=47.5-103cm),whileallgreenturtlemortalities involvedjuveniles lessthan42cminlength.ThefourKemp'sridleymortalities documented attheplantduring1987and1988weretheonlydeathsforthisspeciestodate;noleatherback orhawksbill mor-talitieshaveoccurredattheSt.LuciePlant.Modifications tocaptureprocedures, improvements totheA1Abarriernetandvirtualelimination oflowflowconditions withinthecanalhaveresultedinasubstantial reduction inseaturtlemortalities overthelifeofthecanalcaptureprogram.Mortality rate,expressed asthepercentage oftotalcapturesinvolving deadanimals,declinednearly50percentbetweenthefirst(1976-1983) andsecond(1984-1991) halvesoftheprogram(Table2).During1991,onlyonemortality, aloggerhead, wasdocumented.

Thisrepresents thelowestannualmortality rate(<1.0percentoftotalcaptures) sincethecanalcaptureprogrambeganandcontinues thedeclining trendreferenced above.Thedeadloggerhead removedfromthecanalin1991wasfoundfloatingattheA1Abarriernet.Noapparentphysicalinjurieswerenoted.Becauseofitsadvancedstageofdecomposition, nonecropsywasperformed, andcauseofdeathcouldnotbedetermined.

RecatureIncidents SincetheSt.LuciePlantcaptureprogrambegan,mostturtlesremovedfromtheintakecanalhavebeentaggedandreleasedintotheoceanatvariouslocations alongHutchinson Island.Consequently, individual turtlescanbeidentified aslongastheyretaintheirtags.Overthe16yearhistoryofturtleentrapment attheSt.LuciePlant,64individuals (63loggerheads and1green)havebeenremovedfromthecanalmorethan35 III~II once.Severalotherturtleswithtagscarshavealsobeenrecovered, indicating thattheactualnumberofrecaptures maybehigher.Ofthe63individual loggerheads knowntohavebeencaughtmorethanonce,43werecaughttwice,10werecaughtthreetimes,4werecaughtfourtimes,2werecap-turedfivetimes,2werecapturedsixtimes,1wascaughtseventimesand1wascaughtonnineseparateoccasions, yieldingatotalof107recapture incidents.

Releasesitedidnotappeartohaveanyeffectonaturtle'sprobability ofbeingrecaptured.

Turtlesreleasedbothnorthandsouthoftheplantreturned.

Recaptures alsodidnotappeartoberelatedtosize,asbothjuveniles andadultswerecapturedmorethanonce(rangeofSLCL=47-89cm).Asforoverallcaptures, themajorityofrecapture incidents in-volvedjuveniles (SLCL<70cm).Recapture intervals forloggerheads rangedfromfourto858days,withameanof149days(+169.4days).TheonlygreenturtlecaughtmorethanoncewascapturedIontwooccasions, returning tothecanal59daysafterfirstbeingreleasedintotheocean.About57percentofallloggerhead recapture incidents occurredwithin90daysofpreviouscaptureand90percentwithinoneyear(Figure22).Theaverageintervalbetweenfirstandlastcapturewas257days(+325.2days).Thelongestperiodbe-tweenfirstandlastcapturewas5.3years.Thesedatasuggestthatresidency timesofloggerheads withinthenearshore habitatadjacenttotheSt.LuciePlantarerelatively short.Similarfindingshavebeenreportedforloggerheads inhabiting theMosquito/In-dianRiverLagoonsofeast-central Florida(Mendonca andEhrhart,1982).36 lII~>II SUMMARYAgradientofincreasing loggerhead turtlenestdensities fromnorthtosouthalongthenorthernhalfofHutchinson Islandhasbeenshownduringmostsurveyyears.Thisgradientmayresultfromvariations inbeachtopography, offshoredepthcontours, dis-tribution ofnearshore reefs,onshoreartificial lightingandhumanactivityonthebeachatnight.Lownestingactivityinthevicinityofthepowerplantduring1975andfrom1981through1983wasattributed tonighttime construction activities associated withinstallation ofpowerplantintakeanddischarge structures.

Nestingreturnedtonormalorabovenormallevelsfollowing bothperiodsofconstruction.

During1991,daytimeconstruction activities associated withvelocitycaprepairshadnoapparenteffectonnesting.Statistical analysesindicatethatpowerplantoperation, exclusive ofnighttime construction, hashadnosignificant effectonnestdensities neartheplant.Therehavebeenconsiderable year-to-year fluctuations inloggerhead nestingac-tivityonHutchinson Islandfrom1971through1991.Fluctuations arecommonatotherrookeries andmayresultfromnon-annual re'productive behavior.

Despitethesefluc-tuations, loggerhead nestingactivityhasremainedhighduringrecentyearsandmayreflectanoverallincreaseinthenumberofnestingfemalesintheHutchinson Islandarea.Norelationship betweentotalnestingontheislandandpowerplantoperation orintake/discharge construction wasindicated.

Temporary declinesinloggerhead nestingactivityhavebeenattributed tocoolwaterintrusions thatfrequently occuroverthecontinental shelfofsoutheast Florida.ThoughtemporalnestingpatternsoftheHutchinson Islandpopulation maybein-37 fluencedbynaturalfluctuations inwatertemperature, nosignificant effectsduetopowerplantoperation havebeenindicated.

Sincenestingsurveysbeganin1971,raccoonpredation wasconsidered themajorcauseofturtlenestdestruction onHutchinson Island.From1971through1977,overallpredation ratesintheninesurveyareaswerebetween21and44percent.However,apronounced decreaseinraccoonpredation occurredafter1977,andover-allpredation ratesintheninesurveyareashavenotexceededtenpercentsince1979.Decreased predation byraccoonsprobablyreflectsadeclineintheraccoonpopula-tion.During1991,47greenturtleand44leatherback turtlenestswererecordedonHutchinson Island.Nestingactivitybythesetwospeciesexhibited considerable annualfluctuations, ashasbeenrecordedatotherrookeries, buthasremainedrelatively highduringrecentyears.Thismayreflectanoverallincreaseinthenumberofnestinggreenandleatherback turtlesintheHutchinson Islandarea.During1991,107loggerheads, 12greenturtles,1hawksbill and1Kemp'sridleywereremovedfromtheSt.LuciePlantintakecanal.Sincemonitoring beganinMay1976,1,960loggerhead, 318green,9leatherback, 9hawksbill and18Kemp'sridleyturtleshavebeencaptured.

Overthelifeofthemonitoring program,annualcatchesforloggerhead turtleshaverangedfrom33in1976(partialyearofplantoperation andmonitoring) toahighof195in1986.Yearlycatchesofgreenturtleshaverangedfrom0in1976to69in1984.Differences inthenumberofturtlesentrapped duringdifferent yearsandmonthsareattributed primarily tonaturalvariation intheoccurrence ofturtles38 IIOglII inthevicinityoftheoffshoreintakestructures, ratherthantoplantoperating charac-teristics.

Size-class distributions ofloggerhead turtlesremovedeachyearfromthecanalhaveconsistently beenpredominated byjuveniles between50and70cminstraightlinecarapacelength.Mostgreenturtlesentrapped inthecanal(about80percent)werejuveniles 40cmorlessinlength.Forbothspecies,thelargestnumberofcapturesforallyearscombinedoccurredduringthewinter,buttheseseasonalpeaksweremuchmorepronounced forgreenturtles.Sexratiosofbothadultandimmatureloggerheads caughtinthecanalcontinued tobebiasedtowardsfemales.During1991,about93and80percent,respectively, ofallloggerheads andgreenturtlesremovedfromthecanalwerecategorized byphysicalappearance asbeingingoodtoexcellent condition.

Overtheentire16yearmonitoring period,77and78per-cent,respectively, ofallloggerhead andgreenturtlecaptureshaveinvolvedindividuals inthesecategories; 15percentoftheloggerheads and14percentofthegreenturtlesremovedfromthecanalhavebeeninfairorpoorcondition.

Onlyfourpercentoftheturtlesremovedfromtheintakecanalduring1991hadsubstantial

injuries, andmostofthosewereapparently sustained priortoentrapment.

Onceinthecanal,turtlesconfinedeastofA1Atypically hadverybriefresidency times.Thustherelativecondition ofmostturtleswasnotaffectedbytheirentrapment.

During1991,oneloggerhead mortality occurredintheintakecanal.Causeofdeathcouldnotbedetermined.

Programmodifications, including continual surveillance oftanglenetsduringperiodsofdeployment, improvements totheintegrity oftheA1A39 barriernetandgreaterefforttohandcaptureturtleshavecontributed toasubstantial declineinseaturtlemortalities duringrecentyears.40 CIIII LITERATURE CITEDABI(AppliedBiology,Inc).1977.Ecological monitoring attheFloridaPower&LightCo.St.LuciePlant,annualreport1976.

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~mdasnestinginFlorida.Pages35t-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.

WitIIWN1993939IitiIpiIdtk33tillI~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.Worth,D.F.,andJ.B.Smith.1976.MarineturtlenestingonHutchinson Island,Florida,in1973.rFloridaMarineResearchPublications 18:1-17.I48 GULFOFMEXICO0C)IYAROSKILOMETERS SCALE~~C~CT-N-yiOI't.LuclePlantFigurei.LocationoftheSt.LuciePlant.

IIII

~,'l'r7~~V~0<2G00.r';~~~I/~.:,::HUTCHINSON ISLAND.'SI7J'~g~@X~~ye0'IQ~o,...,-.:::::

'"""INTAKEWELLSUIDSBARRIER0Ph1jI4<t0250500METERS~~rTgI'"8,PrI@Gas'DISCHARGE

~gG+'.:PIPES~i::INTAKE'I:

HEADWALL'.

INTAKE~-.",STRUCTURES A1A'::.:.

BARRIER,.NET;%.,'vINTAKECANALFigure2.St.LuciePlantcoolingwaterintakeanddischarge system.

,I~l~~)

Ft.PierceInletoA((s\~(EPStateHwyA0'pi'('(~(AlgQ(bb,tOF1GH2F+p+3I.MN40FPLFSTLUCIEPLANTQ~"U.S.Hwy1$6v0SkrnR)VER'0e'(BBCCDDEE8FFGGoa((HH0aPin~~St.I.ucleInletFigure3.Designation andlocationofnine1.25-kmsegmentsandthirty-six 1-kmsegmentssurveyedforseaturtlenesting.Hutchinson Island,1971-1991.

350300250zg200DZ1501005012NORTH450POWERPLANT9SOUTHFigure4.Meanannualnumberofloggerhead turtlenestsineachofthenine1.25-km-long surveyareas,Kutchinson Island,1971-1990, comparedwithnumberofnestsduring1991.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1991values(1980datawereexcludedbecausenotallareasweresurveyed).

II) 350300z250200Z150100ABCDEFGHIJKLMN0PQRSTUVWXYZABCDEFGHIJABCDEFGHIJ.NORTH0POWERPLANTSOUTHFigure5.Meanannualnumberofloggerhead turtlenestsineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1990, comparedwithnumberofnestsduring1991.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1991values.

lI 700600(o500Oz400Dz300200100~A8CDEFGHIJKLMN0PQRSTUVWXYZA8CDEFGHIJA8CDEFGHIJNORTHPOWERPLANTSOUTHFigure6.Meanannualnumberofloggerhead turtleemergences ineachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1990, comparedwiththenumberofemergences during1991.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1991values.

,IIIIIII 10080KMMillOOg60C9ZI-MZ4020ABCDEFGHIJKLMN0PQRSTUVWXYZABCDEFGHIJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure7.Meanannualloggerhead turtlenestingsuccess(percentage ofemergences thatresultedinnests)foreachofthethirty-six 1-km-long surveyareas,Hutchinson Island,1981-1990, comparedwithnestingsuccessduring1991.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1991values.

300250Area4(PowerPlantSite)~----0Area5(ControlSite)IIIIIIII200//zO150DZ10050197119721973197419751976197719781979198019811982198319841985198619871988198919901991Figure8.Numberofloggerhead turtlenestsinAreas4and5,1971-1991.

Arrowsdenoteyearsduringwhichintake/discharge construction occurredinArea4.

,I 6000I-COz0CLDz50004000300020001000COOz(9KDz12000100008000600040002000gCOCOIllOODCOC9zI-COLUz8060402019811982198319841985198619871988198919901991Figure9.Annualnumberofnests,annualnumberofemergences andannualnestingsuccessforloggerhead turtles,Hutchinson Island,1981-1991.

.I 3130O29o2827P262524232212090z60Dz3015.30515APRMAY30515JUN30515JUL30515AUG30515SEPFigure10.Dailyloggerhead turtlenestingactivityandwatertemperature, Hutchinson Island,1991.

,III 605018'/oDestroyed byghostcrabsgDestroyed byraccoonsandghostcrabsQg-,'estroyed byraccoonsOO40OzO30z2016'/o.:'/o1g/o10:::6'/o4o/o3'/o2%1%1%(1%1o/o(1%ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGH IJABCDEFGHIJNORTH0POWERPLANTSOUTHFigure11.Numberofloggerhead turtlenestsdestroyed byraccoons.and ghostcrabsandpercentage ofnestsdestroyed ineach1-km-long surveyarea,Hutchinson Island,1991.

lItItt(I 120100I-(0zO80z604020~---wGreen(Chelonia mydas)~Leatherback(Oermochetyacoriacea) r~rII)IIIIp--$lI>IIy/II'lg~IIIIII1971197319751977197919811982198319841985198619871988198919901991Figure12.Annualnumbersofgreenturtleandleatherback turtlenests,Hutchinson Island,1971-1991.

,I 200~-eLOGGERHEAD (Carettacaretta)o---oGREEN(Chelcnia m~das)80(0KDQ.OCIzCCG(900Kz175150125100755025I1III'IIp'iIPLp/h//P-0o19761977197819791980 19811982198319841985198619871988198919901991706050z403020D10Figure13.Numberofloggerhead andgreenturtlesremovedeachyearfromtheintakecanal,St.LuciePlant,1976-1991.

,I mmmmmmmmm4040m3020z30201010JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure14.Meannumberofloggerheads capturedeachmonth,St.LuciePlantintakecanal,1977-1990, comparedwithnumberofmonthlycapturesduring1991.Horizontal linesaremeans,boxesencloseplusorminusonestandarddeviation, verticallinesareranges,andclosedcirclesare1%Ivalues.

I 400400CODo300oz0Kg200DZ300200100100+4041-4546-5051-5556-6061-6566-7071-7576-8081-8586-9091-9596-STRAIGHTLINECARAPACELENGTH(cm)100101-106->110105110Figure15.Lengthdistribution (SLCL)ofloggerhead turtles(N=1,771) removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-199I.

Nodatacollected for82individuals.

400400MDQ300CIz0Kg200Dz300200100100~1011-2021-3031-4041-5051-6061-7071-8081-9091-100101-111-121-131-141-<<150WEIGHT(kg)110120130140150Figure1LWeightdistribution ofloggerhead turtles(¹1,584)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1991.

Nodatacollected for269individuals.

120120-10010080COO0Z600KQ)408060402020-1516-21-26-31-36-41-46-51-56-61-66-71-76-81-86-91-96-101-106->11020253035404550556065707580859095100105110STRAIGHTLINECARAPACELENGTH(cm)Figure17.Lengthdistribution (SLCL)ofgreenturtles(N=307)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-1%I.

Nodatacollected for10individuals.

,I 200200180180160160m140D0)120Zrt-10080140120100806060404020201-56-1011-1516-2021-2526-3031-3536-4041-4546-5051-101-151-)200WEIGHT(kg)100150200Figure18.Weightdistribution ofgreenturtles(N=303)removedforthefirsttimefromtheintakecanal,St.LuciePlant,1976-199I.

Nodatacollected for14individuals.

.II 8080MDO60DZ0KLlj40Z60402020JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMONTHOFCAPTUREFigure19.Numbersofadultloggerheads (SLCL>85.0 cm),including recaptures, removedeachmonthfromtheintakecanal,St.LuciePlant,1976-1991 (N=278;sexnotrecordedfor4individuals

>85.0cm).

,IIIIII

~CANALCAPTURES0lZI-Ol~D00KQlzzz5040302010o---oEMERGENCES p~]///o~P//I0////~op/500400300200100ILJKz(0OzUJGCCUl0zzz197719781979198019811982198319841985198619871988198919901991Figure20.Comparison ofcapturesofadultfemaleloggerheads (SLCL>85.0 cm)intheintakecanal,St.LuciePlant,19774991, andnumbersofloggerhead emergences inarea4adjacenttotheplant.Nestingactivitywasnotmonitored in1978.

II ILJKI-CLO(090Z0I-ZUJOKUJ0UjI-O1OO806040201008060402010203040DAYSBETWEENFIRSTSIGHTINGANDCAPTURE50Figure21.Captureefficiency, expressed asdaysbetweenfirstsightingandcapture,forloggerhead turtlesentrapped intheintakecanal,St.LuciePlant,April,1990-December, 1991.(N=119).

.IIIl 100100tu80(9Z~60DD>40200vr'o~I0//9IPIIII0IIIIIIntervalbetweenfirstandlastcapture0---0Intervalbetweensuccessive captures8060402025050075010001250RECAPTURE INTERVAL(days)15001750Figure22.Cumulative percentage ofallloggerhead recaptures occurring withinvarioustimeintervals betweensuccessive captures(N=105)andfirstandlastcapture(N=61),St.LuciePlantintakecanal1976-1991.

,IIIIIIIII TABLE1ESTIMATES OFTHENUMBERSOFLOGGERHEAD TURTLENESTSONHUTCHINSON ISLANDBASEDONSURVEYSOFNINE1.25-KM-LONG SURVEYAREAS,1971-1991,COMPAREDTOTHEACTUALNUMBEROFNESTSONTHEISLAND,1981-1991NumberofnestsinthenineExtrapolation fromtheninesurveyareastotheActualnumberofnestsonthe19711973197519771979198119821983198419851986198719881989199114201260149393214491031163415921439162318391645170117742177240941803709439527444266303548104687423647785414484350085223640970923115474342774877548346234990519367006812 TABLE2TOTALNUMBEROFSEATURTLECAPTURESAND(NUMBEROFDEAD)TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1976-1991 1976197719781979198019811982198319841985198619871988198919901991TotalAnnualMean~33(4)80(5)138(19)172(13)116(5)62(5)101(16)119(4)148(3)157(4)195(27)175(11)134(6)111(4)112(1)107(1)1960(128) 128.55(2)6(1)3(1)10(3)32(2)823(4)69(2)1422(1)3542(2)17(1)20(2)12318(21)21.29(0)0.619(0)0.616(2)5(2)2118(4)1.233(4)86(7)148(20)175(14)126(8)97(7)110(16)142(8)220(5)172(4)220(28)218(13)181(10)133(5)132(3)121(1)2314(153)152.1Excludes1976(partialyearofplantoperation).

,IIIII TABLE3TOTALNUMBEROF(ANDNUMBEROFDEAD)LOGGERHEAD TURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-1991 19761977197819791980138(1)75(2)11911(2)27(2)19(5)3(1)24(3)29(1)111701621(2)-14103(1)8(3)7(1)2175(3)9315(1)9(1)5512117(2)15(7)41027(2)16(2)8(1)15(3)12121933(4)80(5)138(19)172(13)116(5)198111(1)11(3)6106162(1)0062(5)19826(2)141417(4)772(1)9(1)9(5)4(2)101(16)198319843913(1)104131162(1)77(1)768(2)17528(1)12(1)261610912119(4)148(3)198511152013161720(3)19(1)1473157(4)198615(2)16(4)14(4)20(2)1220(1)26(2)34(6)9(4)11(2)810195(27)198726(3)118(1)24(3)23(1)26(1)19(1)17(1)435175(11)198819891310(3)1113(2)284(2)111330165311(1)2521(1)15235(1)134(6)111(4)199099232516.7(1)112(1)1991131220191511632(1)4107(1)Total232(11)190(17)172(9)176(15)177(6)219(8)178(11)180(11)128(13)125(13)87(13)96(1)1960(128)

MonthlyMean15.5%TotalCatch12.012.79.98.99.19.111.48.99.26.611.511.711.113.711.111.38.07.8~6.15.46.04.34.5Excludes1976(partialyearofplantoperation).

TABLE4TOTALNUMBEROF(ANDNUMBEROFDEAD)GREENTURTLESREMOVEDEACHMONTHFROMTHEINTAKECANALST.LUCIEPLANT,1976-1991 197619771978197919801981198219831984198522(1)120105(1)20(1)7108(1)437(1)104(1)3(2)2(1)4(1)4(1)5(2)6(1)3(1)10(3)32(2)23(4)69(2)19866(1)22(1)198719884112113342319891991Total3(1)06316(1)3(1)31114210100(5)52(3)35(4)20(2)9(1)MonthlyMean6.73.32.31.30.6%TotalCatch31.416.411.06.32.8316(2)10100018(3)81.10.55.72.59(1)0.62.8041.9150.94.75110202211121(2)251.31.66.67.93542(2)17(1)20(2)12318(21)

TABLE5NUMBEROFMONTHLYCAPTURESBYSIZECLASSFORLOGGERHEAD TURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPLANT,1977-1991 Sizeclasses(SLCLincm)January16February12March8April15May12June12JulyAugust7September 4October7453585050355357403548383515213512511010698927814.811.910.59.88.68.36.57.67.26.1262120301729293616289.27.47.010.66.010.210.212.75.69.92216261528442723301919585110745739153.51.43.22.815.626.220.213.85.32.5November4December4Total106%ofTotal213424265404912823.85.069.31967134615.412913815102823.22.115.3Excludes1976(partialyearofdata).Nodatawerecollected for79individuals.

WWWWTABLE6RELATIVECONDITION OFSEATURTLESREMOVEDFROMTHEINTAKECANALST.LUCIEPIANT,1976-1991Relative43122.054928.052226.623111.8723.71286.5271.413442.16119.25316.73611.382.5216.651.6111.1111.1777.8316.7316.7316.7316.7211.1422.2777.8222.257624.961626.658525.327011.7823.51536.6321.4Total3181823141Excellent:

normalorabovenormalweight,active,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.

6Dead7Alivebutothenvise condition notrecorded.