TurkJVetAnimSci 29(2005)1225-1231 ©TÜB‹TAK ResearchArticle InvestigationsonDrift-NetFisheryforSwordfish (Xiphiasgladius L.)intheAegeanSea OkanAKYOL EgeUniversity,FacultyofFisheries35100,Bornova-Izmir-TURKEY MustafaERDEM Mu¤laUniversity,FacultyofFisheries48000,Mu¤la-TURKEY VahdetÜNAL,TevfikCEYHAN EgeUniversity,FacultyofFisheries35100,Bornova-Izmir-TURKEY Received:19.02.2003 Abstract: Thisstudyreportsaninvestigationcarriedoutonswordfishdrift-netfisheryat2mainswordfishfishingports,Sivrice (northern)andFethiye(southern),intheAegeanSeain2001-2002.Forty-fiveboatsareusedforswordfishfishingintheTurki sh AegeanSea.Inthesemajorareas,thehighestnumberofboats6-10minlengthand11.5-80hpinenginepowerwasintheSivrice area,whilethehighestnumber10-14minlengthand85-135hpinenginepowerwasintheFethiyearea.Almostalloftheboats weremadeofwood.Swordfishdrift-nettingaccursinpracticebetweenSivriceandtheislandofLesvosandinbothnationaland internationalwatersbetweenFethiyeandRhodes.Thedriftnetsaremadeofmultiflamentpolyamide(PA)nettingyarn,210d/54- 60no,areabout3to7kmlong,havea500mmmeshopeningandare20meshesdeepatSivrice.Theyareabout14kmlong, madeupofvariousnetsmixedtogetherwith4kmforleerfish( Lichiaamia)and6kmforbullettuna( Auxisrochei),havea440 mmmeshopening,andare30meshesdeepinthepartforswordfishinFethiye.Illuminatedbuoysareattachedtoeachsideofth e net.Fishingeffortandcatchperuniteffort(CPUE)intheswordfishbiomasswereratherlowatSivrice.ThelowCPUEinthe biomasswasprobablytheresultofworseningmeteorologicalconditionsintheregion.Ineacharea,bluefintuna(Thunnusthynnus), littletunnies( Euthynnusalletteratus ),Mediterraneanspearfish( Tetrapturusbelone ),albacores( Thunnusalalunga ),bullettuna (Auxisrochei),dolphinfish(Coryphaenahippurus),dolphins(Delphinusdelphis),mantarays(Mobulamobular),sunfish(Molamola) andsharks(Mustelusvulgaris)wererecordedasnon-targetcatches. KeyWords: Swordfish,Xiphiasgladius,drift-nets,AegeanSea. EgeDenizi’nde(Türkiye)K›l›çBal›klar›( Xiphiasgladius L.)‹çinKullan›lan SürüklenenSolungaçA¤lar›Bal›kç›l›¤›ÜzerineAraflt›rmalar Özet: Buçal›flma,EgeDenizi’ndeikianabal›kç›l›kliman›olanSivriceveFethiye’dek›l›çavc›l›¤›içinkullan›lansürüklenensolun gaç a¤lar›üzerine2001ve2002y›l›ndayürütülenaraflt›rmasonuçlar›n›içermektedir.Toplam45tekneEgeDenizi’ndek›l›çbal›¤›avc›l›¤› yapmaktad›r.Fethiyealan›nda10-14mboyundave85-135BG’ndekiteknelerenyükseksay›dayken,Sivricealan›nda6-10m boyundave11,5-80BG’ndekiteknelerço¤unluktad›r.Hemenhementeknelerintamam›ahflapmalzemedenyap›lm›flt›r.Sürüklenen solungaça¤lar›ilek›l›çbal›¤›avc›l›¤›pratikteSivriceveMidilliaras›ndaveFethiyek›y›lar›aç›klar›ileRodosadas›ara s›ndaulusalve uluslararas›sulardayap›lmaktad›r.Sivrice’desürüklenena¤lar,multiflamentpolyamid(PA)ip,210d/54-60numaraipkal›nl›¤›n da, yaklafl›k3-7kmuzunlu¤unda,500mmtamgözboyuve20gözderinli¤inde;Fethiye’de4km’siakya(Lichiaamia),6km’sitombik (Auxisrochei)olmaküzeretoplam14kmuzunlu¤undakar›fl›ka¤lardanoluflmufl,k›l›ça¤›bölümü440mmtamgözboyundave30 gözderinli¤indedir.Ifl›kl›flamand›ralara¤›nherikiucunatutturulmufltur.Sivrice’debal›kç›l›kgücüvea¤›rl›kçabirimçabay adüflen avmiktar›oldukçadüflükde¤erlerdekaydedilmifltir.A¤›rl›kçadüflükde¤erdekibirimçabayadüflenav,muhtemelenbölgedekötü gidenmeteorolojikflartlar›nsonucudur.Herikialandayunus( Delphinusdelphis),manta( Mobulamobular),pervanebal›¤›( Mola mola),köpekbal›klar›(Mustelusvulgaris),maviyüzgeçliorkinos(Thunnusthynnus),yaz›l›orkinos(Euthynnusalletteratus),Akdeniz k›l›c›(Tetrapturusbelone),albakor(Thunnusalalunga),tombik(Auxisrochei),velambukalar( Coryphaenahippurus),hedefd›fl›av olarakkaydedilmifltir. AnahtarSözcükler: K›l›çbal›¤›,Xiphiasgladius,Sürüklenensolungaça¤lar›,EgeDenizi. Introduction wasonly230t(1).Theexacttimewhenswordfish AmongthelargepelagicsexploitedinTurkey,the fisherystartsinTurkeyisunknown.Onat(2)reported swordfish(Xiphiasgladius L.)isleastimportantbasedon that,inthelate1960s,swordfishfisherybyharpoon lowannuallandings.Forexample,in1999,theamount startedinApril,MayandJune,andalsoswordfishwere 1225 InvestigationsonDrift-NetFisheryforSwordfish( Xiphiasgladius L.)intheAegeanSea caughtusingdrift-netsintheBosphorusonmoonless throughdirectinvestigationsandinterviewswith nightsbetweenSeptemberandNovember. fishermen. Northridge(3)statedthatdriftgillnets(ordrift-nets), Fishingeffort(f)andcatchperuniteffort(CPUE) incommonwithothertypesofgillnet,areamongthe werecalculatedusingthefollowingformula,modified simplestandoldestmethodsoffishing.Suchnetsoperate fromDeMetrioandMegalafonou(9):f=(a’/100)xg bygillingorentanglingfishinthemeshesofasheetof where(a’/100)representstheaveragelengthofnets netting.Thenettingisheldmoreorlessverticallyinthe placeddailyintheseadividedbythe100netunit(200 watercolumnbymeansofabuoyantfloatlineatthetop mlengthofstretchednetiscalled1unitandthelength ofthenet.Netsriggedinthiswaymaybeusedsinglyor, ofthedrift-netis66mafterbeingmountedontheupper byjoiningthemtogetherserially,asafleetofnets.Drift- andlowerropes).Therefore,100netunitisequalto100 netsareusuallyfishedatnight,asthemeshesofthenet x66=6600mforthedrift-netsusedforswordfish.“g” arelessvisibletothefish,andmultiflamenttwinesare isthenumberoffishingdays.TheCPUEwascomputed alsousedinmanydrift-netfisheries,andhavean inthebiomasswiththeformulaCPUE=kg/f. advantagethattheyarelessrigidthanmonoflament Forklength(fromthetipofthelowerjawtothefork ones,whichmeansthatonceafishisgilled,itislesslikely ofthecaudalfin=LJFL)andtotalweightof115 tobeabletoescape(3). swordfishweremeasuredduring9surveysonboardoff Currently,2methodsarecommonlyusedinswordfish theFethiyecoast. fisheryinTurkishwaters:drift-nettingandlong-lining. TheallometricgrowthformulaW=aL b wasusedto Accordingtorecentactivities,swordfishfisheryislimited determinethelength-weightrelationship,whereWis to2mainfishingports,SivriceandFethiye. totalweight,Lisforklength,andaandbareconstants. Onlyfragmentaryinformationonswordfishfisheryin Turkeyexists,suchasthestudiesbyOnat(2),Artüz(4), Tokaçetal.(5),Göko¤luandOray(6),Al›çl›(7),and Results ErdemandAkyol(8). FishingPorts Theaimofthisinvestigationwastogiveasatisfactory Theinvestigationshowedthat45boatsfromthe2 pictureofthedrift-netfisheryforswordfishandto mainports,in2majorareas,fishedforswordfishin producethefirstsetofbasicdatafordrift-netfisheryin Turkeyduring2001-2002.Thenumberofboats, theAegeanSea. groupedbysizeandenginepower(hp),areshownin Table1. MaterialsandMethods Table1showsthatSivricehasahighernumberof boatsthanFethiye.Inthesemajorareas,thehighest Dataonthenumberoffishingvessels,the numberofboats6-10minlengthand11.5-80hpin correspondingcatch,non-targetcatches,thefishing enginepowerwasintheSivricearea,whilethehighest gear’scharacteristics,andthelocationofthefishing number10-14minlengthand85-135hpinengine groundswereobtainedthroughdirectinvestigationsat powerwasintheFethiyearea.Almostalloftheboats Sivricefishingportduring2001andFethiyefishingport weremadeofwoodwithonlyone(17mlong;280hp) during2002.Estimatesofthetotalcatchwereobtained beingmadeofsteel,intheSivricearea.Twoorthree Table1.Divisionofvesselsaccordingtosizeandenginepower. Length(m) EnginePower(hp) MajorRegion Number orFishingPort ofBoats 6-10 10-14 14-18 Min. Max. Mean Sum Sivrice 25 19 5 1 11.5 280 68±11 1700 Fethiye 20 6 10 4 11 335 101.6±16.2 2032 Total 45 25 15 5 11 335 83±9.7 3732 1226 O.AKYOL,M.ERDEM,V.ÜNAL,T.CEYHAN personsworkoneachboat.Concerningtheenginepower June1toJuly31andfromOctober1toJanuary31 ofthefishingboats,theFethiyefleethashigherengine (totally6months)inallTurkishterritorialwaters(10). powerthantheSivricefleet.Thisisobviouslydueto Duringtherestoftheyear,fishingiscarriedoutonly boatsfromtheFethiyeareaconductingtheiractivities 70-80daysayearduetothemeteorologicalconditions muchfurtherfromport. andphaseofthemoon.Fishingtakesplaceonlyon moonlessnights.However,theFethiyefleetcarriesout FishingGrounds itsfishingactivityusingdrift-netsordriftinglong-linesin internationalwatersoftheMediterraneanuntil15July. Swordfishdrift-nettingoccursinpracticebetween SivriceandtheislandofLesvos,namedtheMüsellim Strait,andinbothnationalandinternationalwaters Drift-netCharacteristics betweenFethiyeandRhodes(Figure1).Fisherytakes Thedrift-netsaremadeof210d/54-60no, placeatadepthrangeof150to350mintheMüsellim multiflamentpolyamide(PA)500mmmeshsizenetting, Strait,and1000to3000mintheFethiyeregion. riggedas3to7kmlong,and20meshesdeepatSivrice (Figure2).WhileintheFethiyeregionthenetsareabout FishingPeriod 14kmlong,madeupof4kmforleerfish( Lichiaamia) (210d/24no,480mmmeshsize),6kmforbullettuna AccordingtoaTurkishfisherycircular,thereare2 (Auxisrochei)(210d/18-24no,340mmmeshsize)and seasonalclosuresforswordfishfishing.Thesearefrom 28° Sivrice N Scale:1/4,000,000 Aegean Sea 36° Figure1.Distributionofdrift-netactivitiesforswordfishintheAegeanSea. 1227 InvestigationsonDrift-NetFisheryforSwordfish( Xiphiasgladius L.)intheAegeanSea Lashedwithnylontwine Head(Upper)Rope PP∅5mm 20 MeshSize:500mm Meshin PA210d/54-60No Height HangingRatio(E)=0.33 LowerRopePP∅5mm Figure2.Drift-netscheme,usedintheSivriceregion. 4kmforswordfish(210d/42no,440mmmeshsize,30 SizeDistribution meshesdeep).Illuminatedbuoysareattachedtoeach Forklengthsof115swordfishcaughtintheseaoff side,foreaseofvisibilityatnight.Thesettingofdrift- Fethiyeweremeasuredin2002.Mostofthecatch netsbeginsataboutsunset,withhaulingatabout rangedfrom130to160cm.Theproportionof midnightforchecking,andthenonceortwicemore individualslongerthan130cm,whichistheminimum beforesunrise. landingsizeinTurkey(10),was90%(Figure3). Non-targetCatches Length-weightRelationship IntheSivriceregion,bluefintuna(Thunnusthynnus), Thelength-weightrelationshipfor115specimensfor littletunnies( Euthynnusalletteratus