TurkJZool 27(2003)339-343 ©TÜB‹TAK PopulationParametersofthePearlOyster Pinctadaradiata (Leach) inQatariWaters,ArabianGulf. SaadZakariaMOHAMMED MarineScienceDepartment,FacultyofScience,SuezCanalUniversity,Suez,Egypt MohamedHamedYASSIEN NationalInstituteofOceanographyandFisheries,SuezBranch,P.O.Box182,Suez,Egypt Received:27.07.2002 Abstract: Thepearloyster,Pinctadaradiata,representsthemostabundantmarinebivalvespeciesinQatariwaters.Thepopulation parametersofthisspecieswereinvestigatedandcomparedtothoseobtainedpreviouslyfromboththeMediterraneanandRedseas. Fouragegroupswithmeanlengthsof56.75,65.84,77.54and84.66mmwereobtainedforP.radiatafromQatariwaters.The valuesofasymptoticlength,Brody’sgrowthcoefficientandgrowthperformanceindexwere132.18mm,0.34y -1 and1.77 respectively,whilethetotalmortalitycoefficientequals2.47y -1.Themorphometricrelationshipbetweenthetotalweightand dorso-ventralmeasurementwasdeterminedtobeW=0.0002606(DVM) 2.90707. KeyWords: Qatariwaters,Pearloyster,Pinctadaradiata,age,growth,mortalityandrecruitmentpattern ArapKörfezi’ninKatarSular›nda‹nci‹stiridyesinin Pinctadaradiata (Leach) PopulasyonParametreleri Özet: ‹nciistiridyesi( Pinctadaradiata ),Katarsular›ndaenbolbulunanmidyetürüdür.Bunedenle,butüreaitpopulasyon parametreleriincelenmiflveAkdenizileK›z›ldeniz’dedahaöncedenyap›lm›flaraflt›rmalar›nsonuçlar›ylakarfl›laflt›r›lm›flt›r.Ka tar sular›ndakiinciistiridyelerininortalamaboylar›s›ras›yla56.75,65.84,77.54ve84.66mmolandörtyaflgrubu(kohort) saptanm›flt›r.Toplamölümkatsay›s›(Z)2.47y›l-1 efliken;sonuflmaz(asimptotik)boy(Ls),Brody’ninbüyümekatsay›s›(K)vebüyüme performans›indeksi(s)de¤erlerinins›ras›yla132.18mm,0.34y›l -1 ve1.77oldu¤ubelirlenmifltir.Dorsoventraluzunlukvetoplam a¤›rl›karas›ndakimorfometrikiliflkiW=0.0002606(DVM) 2.90707 ileifadeedilebilmifltir. AnahtarSözcükler: Katarsular›,‹nciistiridyesi,Pinctadaradiata,yafl,büyüme,ölüm,sto¤akat›l›mmodeli Introduction BeaumontandKhamdan(1991)andAl-Sayedetal. Pearloysterresourcesinmanycountrieshavebeen (1993)studiedthemorphometriccharactersin exploitedforpearlproduction.Inthepast,pearlfishing populationdifferentiationofpearloyster Pinctada intheArabianGulfwaslargeandrepresentedabout radiata fromaroundBahrain.Yassien(1998)and 80%oftheworld ’sproductionofnaturalpearls(Al- Yassienetal. (2000)studiedthepopulationstructureof Mataretal.,1993a).Somescientificattentionhasbeen thewildstockofPinctadaradiata fromboththeRedand givenwithregardtopearloysterfishinginKuwait(Al- Mediterraneanseas,respectively. Mataretal.,1983;Al-Mataretal.,1993a;Al-Mataret Qatariwatersarerichinpearloysterbeds(morethan al.,1993b)andonitsbiologyinBahrain(Khamdan, 80)famousfortheirexcellentpearls.Itisdistinguished 1988;Al-Sayed etal.,1993;Qureshietal.,1993).Al- bythepresenceofdifferentspeciesofpearloyster. Matar etal (1983)estimatedtheseasonalgrowth Pinctadaradiata representsabout95%ofthetotaloyster parametersinasymptoticlength(L ∞),Brody’sgrowth catch,whilePinctadamargaritifera andPteriamarmorata coefficient(K)and(t o)for Pinctada margaritifera in representsabout5%(Mohammed,1994).Thelackof KuwaitwatersbyusingtheELEFANtechniqueofPauly biological,populationstructureandfisherymanagement andDavid(1981).Sims(1990)determinedL ∞ andKin compelledustostudythisimportantediblemarine wildstocksof Pinctadamargaritifera offCookIsland. bivalveinQatariwaters. 339 PopulationParametersofthePearlOyster Pinctadaradiata (Leach)inQatariWaters,ArabianGulf. MaterialsandMethods Z wasdeterminedbyapplyingthelinearizedlength ThespecimenswerecollectedfromQatarioysterbeds convertedcatchcurvemethod(LLCCCM)ofPauly (lat25°19’60”N,long52°03’52”E)byscubadiversand (1983). theassociatedfoulingcleanedoff.Foreachindividual, Therecruitmentpatternwasobtainedbyprojecting shellheight(dorso-ventralmeasurement),shelllength thelengthfrequencydatawithconstantclasssize (anterior-posterioraxis),shellwidthandhingelength backwardontothetimeaxisusingthegrowth weremeasuredtothenearestmillimeterbyvernier parametersL∞ andKtoshowthenumberofrecruitment calipers.Thetotalweightforeachindividualwasweighed pulsesperyear(Pauly,1986b)bynormalseparation. towithin0.001g.Lengthfrequencyanalysiswasapplied usingmodalprogressionanalysis(MPA),andthe Bhattacharyamethod(Bhattacharya,1967)toassessthe ResultsandDiscussion agegroups.TheestimationofvonBertalanffygrowth Growthparameters parametersforlengthwasperformedusingFiSAT Alengthfrequencysampleof566specimenscollected software(Gayaniloetal.,1995).TheWetherallmethod fromQatariwaters,intheArabianGulfwasincorporated (Wetherall,1986)wasusedtoestimateL ∞ andthevalue intheFiSATsoftware(Gayaniloetal.,1995)toapply ofthetotalmortalitycaefficient(Z)\Kfrompooled MPAandtheBhattacharyamethod(Bhattacharya,1967). samplesinatimeseriesoflengthfrequencydata;where Thismethodsplitthecompositedistributionintofour KwasdeterminedusingELEFANI. separateagegroupswithmeanlengthsof56.75,65.84, Thegrowthperformanceindex(Φ`)wasestimatedby 77.54and84.66mmrespectively(Fig.1). applyingtheequationderivedbyMunroandPauly(1983) NarayananandMichael(1968)studiedthegrowthin Φ intheformof `=log 10 (K)+2log 10 (L∞),whereL ∞ shellheightDVMofthepearloyster Pinctadafucata andKarethegrowthparameters. (=Pinctadaradiata )rearedintheGulfofKutch,India, Amorphometricrelationshipbetweenthedorso- basedongrowthringsandfoundthatoystersgrewto ventralmeasurement(DVM)andthetotalweightwas 44.1,61.7,76.2,81.6,85.2and86.6mmattheendof calculatedaccordingtotheequationderivedbyLeCren yearsonethroughsixrespectively;thesecond,thirdand (1951),W=aL b whereWisthetotalweightingrams, fourthagegroupsarecomparablewiththoseofthe (L)istheDVMinmillimeters,and(a)and(b)are presentstudy.Chellam(1987),whiletracingthegrowth constants. formsof Pinctadafucata inTuticorinharbor,foundthe .1 — N) ∆ 0 — In( -.1 — 8 — 4 — Freq(Nx10) 0 — shelllength(mm) Figure1. ObservedagegroupsusingBhattacharya’smethodforPinctadaradiata collected fromtheQatariwaters. 340 S.Z.MOHAMMED,M.H.YASSIEN spatattainedasizeof47.0,64.5and75.0mmshell 34 — heightattheendofthefirst,secondandthirdyears respectively.Thesecondandthirdagegroupsarealsoin agreementwiththoseofthepresentstudy.InJapan, Wada(1990)foundthattheaverageshellheightfor5- st year-oldPinctadafucata was46.4mm(1 year),58.2 17 — mm(2 nd year)and72.7mm(3 rd year).Themaximum L-L’ sizerecordedwasabout100.0mmovera10-year lifespan.Mohammed(1994)calculatedthemeansizein shellheight(=DVMinthepresentstudy)offivedifferent agegroupsofPinctadaradiatainQatariwatersusingage 0 — — — frequencydistribution,basedongrowthrings.Theywere 33.75 80.5 127.25 63.4,67.4,76.3,81.7,and92.1mmrespectively.Inhis Cutofflength(L;mm) study,themeanlengthobtainedforthefirstagegroupis Figure2. WetherallplottoestimateL∞ andZ/KforPinctadaradiata highbutthoseobtainedforthesecond,thirdandfourth fromQatariwaters. agegroupsarecomparablewiththoseofthepresent study. isnodefinitepatternfortheparametersestimatedby Yassien(1998)identifiedsixcohortswithmean differentauthorsandtheresultsdivergebetween lengthsof20.3,47.9,66.4,78.8,87.0and91.7mm differentauthorsindifferentareas.Thesedifferences respectivelyforthewildpopulationofPinctadaradiata in canbeexplainedbythedifferentmethodsappliedfor theRedSeaandthelargestspecimenhadalengthof agedetermination;theyalsocanbeexplainedbythe 93.2mm.Hesuggestedthatthefirstcohortrepresents differentsurvivalstrategiesandecologicalfactors the0agegroup.Yassienetal.(2000)estimatedfourage presentatdifferentlatitudes. groupsforPinctadaradiatafromthe Mediterraneanwith meanlengthsof23.9,43.3,54.5and60.8mm Growthperformanceindex respectively,andthemaximumobservedlengthwas64.0 The Φ`maybeequalwithinspeciesorbetweenclosely mm. relatedtaxaandbetweendifferentstocksofthesame Φ EstimationofL∞ andZ/K species(Moreauetal.,1986).The `of Pinctadaradiata inQatariwatersaccordingtotheformulaofMunroand InthemethodofWetherall(1986), thecutofflength Pauly(1983)equals Φ`=1.77.Table1showsthe usedwas93.75mmanddatacorrespondingtoclassmid- Φ lengthof93.75mmonwardswereonlyusedinthe differenceinthevalueof `forthe Pinctadaradiata in Φ regressionastheyrepresentthefullyrecruitedspecimens differentareas.The `ishigherthanthatreportedby (Fig.2).Thealignmentofpointsonthestraightlinewas Mohammed(1994),Yassien(1998)andYassienetal., quitesatisfactorywithagoodcoefficientofcorrelation(r (2000).Comparativegrowthstudiescanbeusedto investigatetheeffectsofvariousfactorssuchaspollution, =0.852).Thefollowingestimatesareobtained:L ∞ = 132.218mmandZ/K=0.419,andtheresultantK= environmentalstresshazardsanddifferenthabitats. -1 0.34y . Length-weightrelationship Mohammed(1994)estimatedL ∞ for Pinctada Morphometricrelationshipsareusedtodifferentiate radiata inQatariwatersas107.0mmbyusingaFord- betweengeneticgroups,wherethelength-weight Walfordplotforback-calculatedgrowthrings,andKas relationshipisrequiredinpopulationdynamicsand -1 0.2497y .Yassien(1998)calculatedL ∞ =9.574cm fisheriesstockassessment,sincetherateofincreasein andZ/K=4.723forPinctadaradiata intheRedSea He weightreflectshowtheecologicalfactorsofahabitat -1 . foundthatKequals0.414y .Yassienetal.(2000) affecttheanimalwhichlivesinit.Figure3showsthe estimatedL ∞ as6.918cm,andZ/Kas5.415for relationshipbetweentheDVMandWof Pinctadaradiata Pinctadaradiatainthe MediterraneanSeaandKvalueas fromQatariwatersandtheresultantformulais:W= -1 0.56y .Comparingtheabovementionedparameters 0.0002606(DVM)2.90707 witharegressioncoefficientof withthoseinthepresentwork,itcanbeseenthatthere 0.8586. 341 PopulationParametersofthePearlOyster Pinctadaradiata (Leach)inQatariWaters,ArabianGulf. Table1. Growthparametersinlengthof Pinctadaradiata from Table2. Constantsofthelength-weightrelationshipof Pinctada differentareas. radiata