TurkJVetAnimSci 29(2005)417-428 ©TÜB‹TAK ResearchArticle FeedingHabitsandDietCompositionofBrownTrout (Salmotrutta)intheUpperStreamsofRiverCeyhanand RiverEuphratesinTurkey CemilKARA DepartmentofBiology,FacultyofScienceandArts,KahramanmaraflSütçü‹mamUniversity,46100Kahramanmarafl-TURKEY E-mail:[email protected] AhmetALP DepartmentofFisheries,FacultyofAgriculture,KahramanmaraflSütçü‹mamUniversity,46100,Kahramanmarafl-TURKEY E-mail:[email protected] Received:25.09.2003 Abstract: Thefeedinghabitsanddietcompositionofthestreamdwellingresidentbrowntrout Salmotrutta intheupperstreams ofRiverCeyhanandRiverEuphrateswereinvestigatedbyexaminingthestomachcontentsof611specimenscollectedfromMay 2000toApril2001.AnalysisofmonthlyvariationsofstomachfullnessindicatedthatfeedingintensitywashigherbetweenFebruary andJunethanthatforthespawningseasonthatcoveredtheperiodfromNovembertoJanuary.Atotalof42preytaxarepresenting Coleoptera,Trichoptera,Ephemeroptera,Plecoptera,Malacostraca,Diptera,Araneidae,Odonata,Gastropoda,Acridae,Acarii, Heteroptera,fishandfisheggwasidentifiedinthediet.Theindexofrelativeimportance(IRI%)revealedthatfivefooditem s togetherconstitutedmorethan90%ofthediet,withthemostimportantbeingGammarussp.(49.72%),Hydropsychidae (14.61%),anunidentifieddipteranspecies(9.21%),Nemourasp.(8.98%)andIsoperlasp.(6.90%).TheOverlapIndex(OI)values indicatedthattheresidentbrowntroutintheStreamAksu,Sö¤ütlüandHurmandifferedintermsoftheirdietcompositions, comparedtothetroutinotherstreams.Themostimportantfooditemvariedamongthesizeclassesofthebrowntrout,being Rhithrogenasp.,Nemourasp.,Gammarussp.andfishfortheclassesoftroutwith40-80mm,81-120mm,121-280mm,and >320mmforklength,respectively.Dietcompositionofbrowntrout<80mminlengthand>240mminlengthwasdifferentfrom theotherlengthgroups(OI<0.7).Highvalueoverlapindexwasobservedbetweenfemaleandmale(OI=0.989),whileno significantdietaryoverlapwasevidentbetweenimmatureandmatureindividuals(OI=0.465andOI=0.472). KeyWords: Dietcomposition,browntrout,Salmotrutta,riverCeyhan,riverEuphrates CeyhanveF›ratNehirlerininÜstKollar›ndakiAlabal›klar›n( Salmotrutta) BeslenmeveBesinKompozisyonlar› Özet: May›s2000veNisan2001tarihleriaras›ndaCeyhanveF›ratnehirlerininüstkollar›ndanyakalanan611adetalabal›¤›nmide içerikleriincelenerekbesinkompozisyonlar›vebeslenmeleriaraflt›r›lm›flt›r.MideDoluluk‹ndekslerinegörefiubat-Haziranayla r› aras›ndabeslenmenin,üremesezonuolanKas›m-Ocakaylar›nagöredahayo¤unoldu¤ugörülmüfltür.‹ncelenenmideiçeriklerinde 42taksontan›mlanm›flvebunlar›nColeoptera,Trichoptera,Ephemeroptera,Plecoptera,Malacostraca,Diptera,Araneidae,Odonata, Gastropoda,Acridae,Acarii,Heteroptera,bal›kvebal›kyumurtas›gruplar›nadahiloldu¤utesbitedilmifltir.K›smiÖnemlilik‹ndeksine (%IRI)göre5besinselorganizmagrubutoplambesinkompozisyonunun%90danfazlas›n›oluflturmuflvebunlarGammarussp. (%49,72),Hydropsychidae(%14,61),teflhisedilemeyenbirdipterantürü(%9,21),Nemourasp.(%8,98)veIsoperlasp.(% 6,90)dir.Benzerlik‹ndekslerine(OI)göre,Aksu,Sö¤ütlüveHurmançaylar›ndakipopulasyonlar›nbesinkompozisyonlar›di¤er derelerdenfarkl›l›kgöstermifltir(OI<0,7).Besinselorganizmalarbal›kbüyüklü¤ünegörefarkl›olup40-80mmboyasahip alabal›klardaRhithrogenasp.,81-120mmboygruplar›ndaNemourasp.,121-280mmboygruplar›ndaGammarussp.ve320 mm’denbüyükalabal›klardaiseenönemlibesingrububal›kt›r.Benzerlik‹ndekslerinde80mm’denküçükve240mm’denbüyük alabal›klar›nbesinkompozisyonlar›di¤erboydakibal›klardanfarkl›d›r(OI<0,7).Difliveerkekbireylerinbesiniçerikleribüyükölçüde birbirinebenzerken(OI=0,989),erginolmayanbireylerinbesiniçeriklerierginlerdenfarkl›bulunmufltur(OI=0,465,OI=0,472). AnahtarSözcükler: Besinkompozisyonu,alabal›k,Salmotrutta,Ceyhannehri,F›ratnehri 417 FeedingHabitsandDietCompositionofBrownTrout( Salmotrutta)intheUpperStreamsofRiverCeyhanandRiverEuphratesinTurkey Introduction containing4%formalinsolutionforlateranalysis.For Threepotentialfoodgroupsforbrowntroutare eachfish,totalweight(g),forklength(mm)andsex available:substrate-associatedpreys,surfacedriftand wererecorded.Foreachfishfollowingtheremovalof suspendeddrift(1).Itisgenerallybelievedthatbrown digestivetract,stomachwasopened,itscontentwas troutfeedchieflyondriftinginvertebrates(2-5); flushedintoaPetridishandcontentswereweighed(g). however,severalreportshavenotedthatdwelling Stomachcontentfloodedwithdistilledwaterwere salmonidscanusebenthicprey(6-10).Troutdietis examinedunderastereoscopicmicroscope.Contents mainlydeterminedbythehabitat(11,12),season(1,12- weresortedandpreyitemswereidentifiedtothelowest 14),preyavailability(10),ontogeny(12)andsexofthe feasibletaxonomicunitsusingtheidentificationkeysof fish(15). Edmondson(19),Demirsoy(20)andGeldiayandBal›k (17).Fooditemsweredampdriedonpapertowelsand Salmotrutta formsresidentpopulationsintheupper thenumberofindividualsandtotalweightofeachprey streamsofriversandoccursinNorthAfrica,Europe, categorywererecorded.Tractcontentshavingnofood WestAsiaandAnatolia(16,17)anditisanimportant itemswerealsorecordedasemptystomachs. potentialspeciesforrecreationalfishery.However,in mostpartsoftheseareas,riversystemshaveundergone TheFullnessIndex(FI)wascalculatedtoinvestigate greatchangesintheirecologyandmorphologyinrecent thevariationsinfeedingintensity,usingtheequation:FI yearsandriverdamminganddegradationofspawning =(Weightofstomachcontents/Totalweightof habitatshavecausedadeclineinthestocksof S.trutta. fish)*10000(21).Onewayanalysisofvarianceand Tukey’stestwereusedtotestfordeviationsinfeeding ScarceinformationisavailableonfeedingactivityofS. intensityamongthedifferenthabitats,monthsandfish trutta populationsinTurkey.Inaddition,naturalfood sizes. organismsusedasfeedbythebrowntrouthavereceived littleattention,exceptarecentstudyinwhichstomach Dietaryimportanceoffoodcategorieswas contentsof24 S.trutta fromtheStreamÇatakofthe determinedusingthemodifiedindexofrelative RiverTigriswereexaminedfortwomonths(18). importance;IRI=(N%+W%)*FO%(22),whereFO%: percentagefrequencyoccurrenceofstomachsinwhicha Inthispaper,wedescribedietcompositionofthe fooditemoccurredrelativetothetotalnumberof nativeresidentbrowntroutineightstreamsofRiver stomachscontainingfooditems;N%isthenumeric CeyhanandRiverEuphratesinTurkeybyanalysisof percentageofindividualsofafooditemrelativetothe stomachcontents,withcomparisonbylocality,season, totalnumberoffooditemsinthestomachandW%isthe sizeclassesoffish,sexoffishandfooddiversity. percentageweightofafooditemrelativetotheweight ofthetotalstomachcontents.Percentageofweight MaterialsandMethods (W%)wasusedinsteadofvolumetricpercentage(23) ThestudywasconductedinthestreamsofF›rn›z, UsingtheIRI%tocomparedietcompositionbetween Terbüzek,Kömür,Hurman,Sö¤ütlü,NergeleandAksuof thepairsoflocations,months,lengthgroupsorsex,an theRiverCeyhan,whichrunsintotheeastern overlapindex(OI)wasestimated(24); MediterraneanSea,andintheStreamGöksuoftheRiver Σ P P Euphrates,whichrunsintothePersianGulf(Figure1). OI= ij ik 2 2 Someinformationaboutsamplingstationsisgivenin Σ PijPik Table1. Atotalof611individualsofthebrowntroutwas wherePij andPik aretheproportionaluseofpreytypei caughtmonthlyatthreeselectedsamplingsites,50m atlocations,months,lengthgroupsorsexjandk, apartfromeachotherineachstream,betweenMay2000 respectively.Thisindexrangesfrom0(nooverlap)to1 andApril2001byelectrofishing.Allthecapturedfish (completeoverlap).Overlapindexvalues>0.7areusually specimenswereimmediatelypreservedinaplasticbarrel consideredtoindicatesignificantoverlap(25). 418 C.KARA,A.ALP Figure1.Themapoftheworkingareaandstreamslocations. 419 FeedingHabitsandDietCompositionofBrownTrout( Salmotrutta)intheUpperStreamsofRiverCeyhanandRiverEuphratesinTurkey Table1. Geographiclocationsofthestreamsandnumberofthefishcaughtduringthestudy,theirforklengthandtotalweight. (FL±CI:The meanforklength±Confidenceinterval(95%),W±CI:Totalweight±Confidenceinterval(95%)). Stream River Latitude Longitude Altitude Number FL±CI W±CI system (N) (E) (m) offish (Min-Max) (Min-Max) (mm) (g) F›rn›z Ceyhan 37°45´ 36°39´ 720 186 162±8.60 95.5±9.66 (80.1-395.0) (11.4-842.0) Aksu Ceyhan 37°46´ 37°21´ 1125 79 120±7.70 33.8±9.64 (81.7-264.4) (8.4-256.8) Nergele Ceyhan 38°00´ 37°13´ 1213 32 115±11.00 30.3±8.86 (76.8-179.8) (6.7-97.5) Hurman Ceyhan 38°26´ 36°54´ 1258 110 165±8.80 80.2±12.39 (73.3-296.0) (5.7-344.7) Göksu Euphrates 37°52´ 37°18´ 1280 31 129±16.40 46.1±15.33 (63.2-217.1) (3.6-152.0) Terbüzek Ceyhan 38°04´ 36°27´ 1390 92 120±9.30 38.7±8.87 (57.5-260.1) (2.8-247.9) Kömür Ceyhan 38°08´ 36°33´ 1417 64 122±12.10 41.8±12.63 (64.4-365.0) (3.9-549.0) Sö¤ütlü Ceyhan 38°09´ 37°36´ 1474 17 193±37.10 131.3±70.60 (67.0-369.0) (3.7-548.0) Results Significantmonthlyvariationwasfound[F (8,602) = a d bc cd Feedingintensity 7.976;P<0.01;January ,February ,April ,May , Junebcd,July ab,September a,November abc,December abcd]in Residentbrowntroutrangedfrom57.5mmto FIanditfluctuatedthroughouttheyear[Figure2(a)]. 395.0mminforklength(FL)withameanvalueof143.4 MaximumfullnessindexwereobservedinFebruary, mm,andtheirtotalweightrangedfrom2.8gto842.0 April,MayandJune,whiletheindexshowedadecline g,withameanvalueof65.64g.Thenumberof fromSeptembertoJanuary.Theresidentbrowntrout specimens,meanforklengthandmeanweightsfrom fedmostintensivelyduringspringandearlysummer differentstreampopulationsinthestudyarepresentedin (February–June).TheresultsindicatedthatFIwasalso Table1.Ofthe611residentbrowntrout,259(42.39%) b influencedbyhabitat[F (7,603)=7.415;P<0.01;F›rn›z , werefemales,230(37.64%)malesand122(19.97%) Tebüzekab,Kömür ab,Hurman ab,Nergele ab,Göksu ab, immatures. a a Sö¤ütlü andAksu ]andlengthgroups[F(8,602) =1.961;P Ofthetotalstomachanalysed,8.70%wereempty.In <0.05;40-80 ab,80-120 ab,120-160 b,160-200