Chiang Mai J. Sci. 2021; 48(4) : 1009-1020http://epg.science.cmu.ac.th/ejournal/Short Communication

Species Composition and Distribution Pattern of Stingrays in the Coastal Waters of Terengganu, Malaysia, the South China SeaNur Arina Hayati Binti Mohidin [a], Sukree Hajisamae [b], Maizah M. Abdullah [c], Mazlan Hashim [d], Ahasan Habib [a], Rashedul Islam [e] and Hisam Fazrul*[a,f][a] Faculty of Fisheries and Food Sciences, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu Malaysia.[b] Faculty of Science and Technology, Prince of Songkla University,Pattani, 94000 Thailand.[c] Faculty of Science & Marine Environmental, Universiti Malaysia Terengganu, 21030 Kuala Terengganu,

Terengganu, Malaysia.[d] Faculty of Built Environment and Surveying, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor Darul

Takzim Malaysia.[e] Department of Marine Fisheries and Oceanography, Patuakhali Science and Technology University, Dumki,

Patuakhali-8602, Bangladesh.[f] Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries (AKUATROP),

Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.

*Author for correspondence; e-mail: md.fazrul@umt.edu.myReceived: 21 May 2020

Revised: 6 February 2021 Accepted: 15 February 2021

ABSTRACT Stingraysarepartof commercialfisheriesworldwide;Malaysiaisrankedastheeighth-largest

stingrayfisheryintheworld.SampleswerecollectedmonthlyfromJanuary2018toDecember2018usingstingraygillnetsinCoastalSouthChinaseawatersof Terengganu.Thepresentstudyaimedtodeterminetheabundanceanddistributionof stingraysbasedonspeciesandsizesatdifferenthabitatandseasonsintheTerengganu,Malaysiacoastalwaters.Atotalof 10stingrayspecieswerecollectedfrom122samples.Stingrayspeciesaredistributeddifferentlyaccordingtohabitatandseasonal.Theresultof atwo-wayANOVAshowedthathabitatandseasonsignificantlyaffecttheabundanceof stingrays(P<0.001).Mostcatcheswerein20mdepthduringthedryseason.Theresultof anon-metricmultidimensionalscalingordinationindicatesthatthegroupingoverlappedinhabitatandseasonwithsimilarspeciescollected.

Keyword:ray,stingray,habitat,seasonal,gillnet,Terengganu,coastalSouthChinasea

1. INTRODUCTIONStingrayshavebecomeamajorpartof

commercialfisheriesaroundtheworldduetothehighinterestfromthemarket[1].Mostcatchesof elasmobrancharefrombycatchcases,whichareincidentallycaughtbythefishermanduringthe

fishingactivity.Frompreviousstudies,stingrayswerecaughtasthebycatchspeciesmostlybyusingpelagiclonglineandhook,bottomlongline,surfacelongline,trawlandgillnetsasfishinggear[2-5].

Chiang Mai J. Sci. 2021; 48(4)1010

Mostmarinepopulationdynamicsareinfluencedbybehaviouralresponsestowardstheecologicalprocess, includingbothabioticandbioticfactors[6,7].Understandingthefactorsthataffecthabitatshiftsisimportantforbetterawarenessof populationdynamicsinfisheriesthataretargetorbycatchspecies[6,7].Abioticfactorscantriggermovementandchangesinbehaviourandhabitatof elasmobranchs[8,9].Salinityandwatertemperaturearemostselectivefactorsinmoststudies;however,turbidity,dissolvedoxygenconcentrationandpHalsoprovideanimportantaspectforthespatialdistributionandecologyof rays[8,9].Changesintheenvironmentcantriggerthemovementandchanges inbehaviourandhabitatforelasmobranchspecies[8].Temperatureaffectsthephysiologyof mostsharksandrays;theyaresensitivetotemperaturechanges.Mostraysarestrictlystenohaline; itgivesastronginfluencetowardssalinityonphysiology.Salinityinfluencesthedistributionandabundanceof sharksandrayssuchasCarcharhinus amboinensis (pigeyesharks)andRhinoptera bonasus(cownoserays)[8].Forstudyingtheecologyof rays,itisimportanttounderstandtheroleof thespeciesinthemarineecosystemandtheirtrophicrelations.Understandingthesetrophic interactionsandthepositionof aspecieswithinafoodwebisanimportantstepindefiningthedynamicsof marinecommunitiesandtheimpactstospecies.Failuretoidentifythoseimportantaspectswillleadtogapsinunderstandingtheimportanceof raysinthemarineecosystem.Changesinthefoodwebcanaffectthesystemintensely,resultinginchangesinabundanceandwebconnectivitywithotherspecies.Raysareconsideredakeystonespeciesinmarineecosystemswithanimportantroletomaintainthesustainabilityof theecosystem[10].

InMalaysia,thedemandforstingrayshasincreased[11,12].Stingrays(Dasyatidae)areoneof themost importantbatoidfishes incommercialfisheries,consistingof smalltoverylargesizes;adult’sspecimenscanreachbetween22cmand260cmDWwithdiversedistribution

inAsia[13].InAsia,thereislessknownaboutrayecologycomparedtotheAmericas[9];withinAsia,MalaysiahaslessresearchcomparedtoothercountriessuchasIndonesia[14].InMalaysia,previousstudieshavefocusedonfishinggearsuchasbarriernets,gillnetsandbeamtrawlstocatchstingraysincoastalmudflatsinKualaSelangortostudythelength-weightrelationship[15].FewerstudieshavefocusedonstingraydistributioninMalaysia.FromthepreviousresearchinMalaysia,atotalof sixspeciesof stingraysweresampled:Himantura walga,Dasyatis bennetti,Dasyatis zugei,Neotrygon kuhlii,Taeniura lymmaandHimantura pastinacoides[15].

Theresearchconductedonstingrays inMalaysiaisstillinitsearlystageswithmostof theresearchfocusedonothermarineorganismssuchassharksandturtle.Thisstudyisthefirstinvestigationof thehabitatandseasonalpatternsof abundanceanddistributionof stingrayspeciesinTerengganucoastalwaters.Theobjectivesof thisstudyaretodeterminetheabundanceanddistributionof stingraysbasedonspeciesandsizesatdifferenthabitatsandseasonsintheTerengganu,Malaysiacoastalwaters.Thereislessknowledgeof habitat,characteristicsanddistributionof stingrayspecies inMalaysiacomparedtootherAsiancountries.Thisstudyexaminedtheinfluenceof habitatandseasonaldivisionsontheabundanceanddistributionof stingrayspeciesinMalaysia.Moreover,itcontributesdataonthepopulationsizeof stingrayscaughtinTerengganuwaters.ThisstudymayhelptoachieveasustainablestingraystockinMalaysiaandprovideinformationonstingraysforartisanalfisheries.

2. MATERIAL AND METHODS2.1 Study Area

Threedifferentdepthcontoursalongthecoastalareaof Terengganuwereselected:10m,15mand20mdepths.Threesub-stationswereonthelinetransectbasedonlocality:BidongIsland,KapakIslandandGelokIslandwerechosenforeachdepthcontour(Figure1).Allthedepthsat

Chiang Mai J. Sci. 2021; 48(4) 1011

eachsamplingstationweremeasuredbysonarSIMRADEK15.Thestingrayisthemaintargetorganismcaughtbylocalfishermenusinggillnets.

2.2 Collection of SamplesSampleswerecollectedmonthlyfromJanuary

2018toDecember2018byuwsingstingraygillnetsinTerengganuwaters.Thesamplingforthisstudy(Prk.ML.S.04/32/2Jld.9(22)hasbeengivenpermissionbyDepartmentof FisheriesMalaysia.Ateachsub-stationof eachdepthcontour,anetwassetupwith2.00mdeep,2,100mlongand26cmstretchmeshsize.Thegearsweresetat0600hoursinmorning,leftovernightfor24hoursandhauledonboardthenextmorning(Figure2).Altogether,6,300mof nettingweresampledateachdepthcontourtotalling18,900mfromallthreedepthcontourseachsamplingmonths.For

seasonaldivisionbasedonHisametal.(2015),threedifferentseasonswerebasedonthequantityof rainfall:(1)therainyseasonwasfromSeptembertoDecember,(2)themoderatelyrainyseasonwasfromMaytoAugustand(3)thedryseasonwasfromJanuarytoApril.Thestingraysampleswereremovedfromthenetsandtransportedtothelaboratoryforfurtheranalysis.

FieldsamplingsweredonemonthlyfromJanuary2018toDecember2018,withsupplementarysamplingsonFebruary2019andOctober2019tocomplementexistingdatabasedonseasonal,sizes,sex,habitatchangeandseasonsforthesame months in 2018.

2.3 Laboratory WorkInthelaboratory,stingraysizesweremeasured

bydiscwidth(DW),disclength(DL)andtotal

Figure 1.Threesub-stationsaslinetransectbasedonlocality;BidongIsland(A),KapakIsland(B)andGelokIsland(C)withdifferentdepthcontour(A1,B1,C1:10m;A2,B2,C2:15m;A3,B3,C3:20m).

Chiang Mai J. Sci. 2021; 48(4)1012

length(TL)usingameasuringtape.Thetotallength(TL)wastakenfromthetipof snouttotheendof thetail,discwidth(DW)wastakenfromthemaximumdistancebetweenwingtipsanddisclength(DL)wastakenfromthetipof thesnouttotheposterioredgeof thedisc[16].Stingrayweightsweremeasurewithanelectronicweightbalance;thecalibrationwasdonebeforeweighing.Stingraysweresexedbasedontheoccurrenceof clasper.Thepresenceof aclasperindicatesthatastingrayismale[17].

2.4 Statistical AnalysisAtwo-wayanalysisof variancewasusedto

testwhethertheabundanceof stingrayscollecteddifferedsignificantlyamongstseasonandhabitat.Abundancedatawerelog(x+1)transformedtoreducenon-normalitybeforeanalysis.Oncethedifferencewasdetected,aposthocanalysiswasconductedusingtheTukeyTest.Atwo-wayanalysisof variancewasusedtotestwhethernumbersof stingraysdiffersignificantlyamongsthabitatandseason.Therawdatawaslog(x+1)transformedtoreducenon-normalitybeforeanalysis.ATukeytestwasusedoncethedifferencedetected.Therelationshipbetweenmeandiscwidth(cm),weight(g)of thestingrayandwaterdepth(m)weremeasuredtoquantifyahabitatshift.

Anon-metricmultidimensionalscaling(nMDS)ordinationwasconductedtoassesstheextenttowhichindividualgroupingswerebasedonhabitatsandseasonsforparticularareas.ThenMDSwasperformedusingPRIMERstatisticalpackageversion7.0.ABray-Curtissimilaritybasedonlog(x+1)transformationswasusedtoexaminethedifferencesbetweenstingraycommunityassemblagesinallhabitatsandseasons.Analysisof similarity(ANOSIM)wasusedtodeterminedifferencesinstingrayassemblagesseparatedbynMDSordination.Oncethesignificantdifferenceswerefound,asimilaritypercentage(SIMPER)wasusedtoexaminewhichstingrayspeciescontributedmosttothedifference

3. RESULTSAtotalof 122stingrayswerecollectedwithgill

nets;16(10m),29(15m)and77(20m)stingrayswerecaughtinthisstudy(Table1).Tenstingrayspecieswerepresent inthisstudy(Figure4).Theresultsfrom20mdepthcaughtlarger-sizedstingrayscomparedto10mand15mdepth.Forexample,thesizeof stingrayscaughtwere59.70±28.94cm,81.80±31.42cm,76.20±36.85cmin20mduringthedry,moderateandrainyseasons,respectively.Thereweremorecatchesof femalestingraysthanmalestingrays(Table1).Thedetails

Figure 2.Characteristicof stingraygillnetsusedduringsampling.

Chiang Mai J. Sci. 2021; 48(4) 1013

Table 1.Totalabundance,sex,size,andweightof stingrayspeciescaughtfromgillnetseachhabitatfromJanuary2018toDecember2018.

Source Total Male Female BW±SD DW±SD

10 m

Dry 10 5 5 1239.00±6500.13 36.65±12.53

Moderate 1 1 0 4900.00 58.60

Rainy 5 2 3 4200.00±1823.46 54.00±15.46

Total 16 8 8

15m

Dry 14 7 7 7720.00±14835.17 36.65±39.84

Moderate 13 4 9 16000.00±13474.58 85.20±32.22

Rainy 2 1 1 8050.00±2474.87 61.35±4.88

Total 29 12 17

20 m

Dry 43 16 27 7130.00±16702.97 76.20±36.85

Moderate 31 22 9 14000.00±14708.54 81.80±31.42

Rainy 3 1 2 7750.00±12325.37 59.70±28.94

Total 77 39 38

Figure 3. Measurementof discwidth(DW),disclength(DL)andtotallength(TL).

Chiang Mai J. Sci. 2021; 48(4)1014

forthetotalcatch,sex,bodyweightanddiscwidthof stingrayscaughtatdifferenthabitatsandseasonarepresentedinTable1.

TheresultsfromtheANOVAfoundthatthecatchesof stingrayspeciesweresignificantlyinfluencedbothbyhabitatandseason(P<0.001,respectively;Table2).Detailof resultsforTukeyHSDtestforhabitatcanbefoundinTables3

and4.Bothmeanabundanceof stingrayswasnosignificantdifferentatdepthof 10mand15m,andalsoatdryandmoderateseason.Monthlycatchesof stingrayspeciesfromdifferenthabitatsandseasonsaredetailedinTable5.

ResultfromnMDSplotsrevealedthatthegroupingof stingrayspeciesoverlappedbasedondifferenthabitatdepths(Figure5).However,

Figure 4. Stingray’sspeciescollected,A,Himantura uarnak;B,Pastinachus ater;C,Maculabatis gerrardi; D,Aetobatus acellatus;E,Hemitrygon parvonigra;F,Urogymnus asperrimus;G,Gymnura poecilura;H,Pateobatis jenkinsii;I,Rhinoptera javanica;J,Brevitrygon walgai.

Table 2.Two-wayanalysisof varianceof theeffectsof habitatandseasononabundanceof stingrayscollectedbygillnets.

SourceAbundance

df MS P-value

Habitat(h) 2 114.70 1.12 × 10-4

Season (s) 2 91.81 3.81×10-4

h × s 4 35.09 8.14×10-3

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Table 3.TukeyHSDtestonmeanabundanceof stingrayscollectedbygillnetsindifferenthabitat.

Habitat (mean abundance)

10 m 15 m 20 m

10m - - -

15m >0.05 - -

20 m <0.05 <0.05 -

Table 4.TukeyHSDtestonmeanabundanceof stingrayscollectedbygillnetsduringdifferentseason.

Season (mean abundance)

Dry Moderate Rainy

Dry - - -

Moderate >0.05 - -

Rainy <0.05 <0.05 -

Table 5.Numberof stingray’sspeciescaughtateachhabitatandseasonineachmonthatthesamplingsiteof TerengganuwatersfromJanuary2018toDecember2018.

MonthsHabitat

TotalDry Moderate Rainy 10 m 15 m 20 m

January 11 0 0 1 3 7 22

February 26 0 0 8 8 10 52

March 19 0 0 0 2 17 38

April 11 0 0 1 1 9 22

May 0 5 0 0 1 4 10

June 0 11 0 1 3 7 22

July 0 13 0 0 3 10 26

August 0 16 0 0 6 10 32

September 0 0 4 1 0 3 8

October 0 0 1 0 1 0 2

November 0 0 4 4 0 0 8

December 0 0 1 0 1 0 2

Total 67 45 10 16 29 77 244

Chiang Mai J. Sci. 2021; 48(4)1016

Non-metric MDSTransform: Square rootResemblance: S17 Bray-Curtis similarity

Depth10M15M20M

2D Stress: 0.01

Figure 5.ThenMDSplotforassemblagesatvarioushabitatof stingrayspeciescollectedbygillnetinBidong,GelokandKapakislands.

allhabitatassemblagesweresimilar toeachother.ThenMDSplotsrevealedthatthestingrayspeciesdistributionoverlappedbasedondifferentseasons(Figure6).Speciesof stingraysineachof habitatandseasonwereidentifiedbysimilarityof percentage(Table6).

Bodyweightanddiscwidthof stingrayspeciesincreasedtowardsthedeeperwaterdepth(Figure7).Bodyweightof stingrayspeciesfromeachhabitatwassignificantlydifferentasthesmallersizestingraytendedtoinhabitshallowwatersandmigratetodeeperwaterwhengrowinglarger.

4. DISCUSSION Totalof 10stingrayspecieswerecollected

basedonhabitatandseason.Thisstudyshowsthathabitatandseasonhaveanimpactontheabundanceof stingrayspecies inTerengganuwaters.Therearesignificantdifferencesbetweentheinteractionof habitatandseasonwiththeabundanceof stingrayscaught(Table2).Thisis

duetodifferentphysicalandbiologicalconditionsbetweenthedifferenthabitatsandseasons.However,forthehabitatsat10mand15mdepth,therewasnosignificanteffectonspeciesabundancecomparedto10mwith20mand15mwith20mdepth(Table3).Stingraystendedtolocateatadeeperdepthcomparedtoshallowwater.Theseasonalfactorshowedasignificantdifferenceof thespeciesabundancebetweendryandrainyandbetweenmoderateandrainyseasons;therewasnodifferencebetweenthedryandmoderateseasons(Table4).

Thisstudyshowsthatmostof thestingraycatchesoccurredindeeperwater(20m)andduringthedryseason(Table5).Previousresearchstatedthatsomeof thestingrayspeciesreactdifferentlyduringdayandnight;theysearchforpreyinshallowwaterduringthenightandrestindeeperplacesduringtheday.Thedistributionof youngstingrayswascloselyrelatedtotheshallowwaterandsandybeaches[18,19].Somelarge

Chiang Mai J. Sci. 2021; 48(4) 1017

Non-metric MDSTransform: Square rootResemblance: S17 Bray-Curtis similarity

SeasonDryModerateRainy

2D Stress: 0.01

Figure 6.ThenMDSplotforassemblagesatdifferentseasonof stingrayspeciescollectedbygillnetinBidong,GelokandKapakislands.

Table 6.StingrayspeciesassemblagesinhabitatandseasonbasedonnMDSplots.

Habitat Season Species %Contribution

10 m Dry Hemitrygon parvonigra 50

Brevitrygon walga 50

Moderate Nosimilarities 0

Rainy Nosimilarities 0

15m Dry Maculabatis gerrardi 53.68

Hemitrygon parvonigra 25.48

Moderate Maculabatis gerrardi 60.85

Pastinachus ater 21.64

Rainy Nosimilarities 0

20 m Dry Pateobatis jenkinsii 27.72

Pastinachus ater 25.81

Aetobatus acellatus 16.48

Moderate Maculabatis gerrardi 26.26

Rhinoptera javanica 24.57

Himantura uarnak 24.14

Rainy Nosimilarities 0

Chiang Mai J. Sci. 2021; 48(4)1018

Rainy No similarities 0

20 m Dry Pateobatis jenkinsii 27.72

Pastinachus ater 25.81

Aetobatus acellatus 16.48

Moderate Maculabatis gerrardi 26.26

Rhinoptera javanica 24.57

Himantura uarnak 24.14

Rainy No similarities 0

224

225

Body weight and disc width of stingray species increased towards the deeper water depth 226

(Figure 7). Body weight of stingray species from each habitat was significantly different as the 227

smaller size stingray tended to inhabit shallow waters and migrate to deeper water when 228

growing larger. 229

a) 230

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Figure 7. Relationship between water depth (m) and a) body weight; and b) disc width of 250

stingray species caught by gill net. 251

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4. DISCUSSION 253

Total of 10 stingray species were collected based on habitat and season. This study shows that 254

habitat and season have an impact on the abundance of stingray species in Terengganu waters. 255

There are significant differences between the interaction of habitat and season with the 256

abundance of stingrays caught (Table 2). This is due to different physical and biological 257

conditions between the different habitats and seasons. However, for the habitats at 10 m and 258

15 m depth, there was no significant effect on species abundance compared to 10 m with 20 m 259

and 15 m with 20 m depth (Table 3). Stingrays tended to locate at a deeper depth compared to 260

shallow water. The seasonal factor showed a significant difference of the species abundance 261

between dry and rainy and between moderate and rainy seasons; there was no difference 262

between the dry and moderate seasons (Table 4). 263

This study shows that most of the stingray catches occurred in deeper water (20 m) and 264

during the dry season (Table 5). Previous research stated that some of the stingray species react 265

713.5

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Figure 7.Relationshipbetweenwaterdepth(m)andbodyweight(a);anddiscwidthof stingrayspeciescaughtbygillnet(b).

Chiang Mai J. Sci. 2021; 48(4) 1019

stingraysoccupiedlocationswithdifferentdepthsduringdayandnight,alsoknownasbathymetricmigrations[18,19].Inpresentstudy,itislikelythatmoreindividualswerecaughtinthe40mhabitatbecausewehauledduringthedaytimewhenstingrayswerelocatedindeeperhabitats.Theseasonalfactorshowedasignificantimpactonthespeciesabundancebetweendryandrainyandbetweenmoderateandrainyseasons,butnotbetweenthedryandmoderateseasons.Themovementof stingrayspeciesduringtheseasonaldivisionmaybeduetobiologicalfactorssuchasreproduction,feedingorpredatoravoidance,orbecauseof seasonalphysicalchangessuchastemperature,currentsandphotoperiod[20].

Thespeciesabundanceof stingrays inTerengganuwaterswas influencedbothbyhabitatandseason.BasedonnMDSordination,theresponseof stingrayassemblageswassimilarineachhabitatandseason.Thismayleadtoaconclusionthatthespeciesassemblagescollectedbystingraygillnetfisheriesaregenerallysimilarfromdifferenthabitatandseason.Thestingrayspeciesweresimilarfromdifferenthabitatsandseasons.Thisreflectsthatmarineorganismsinthat community structure are geographically connected.

Thedeepertheseabed,thebiggerthesizeof stingraycaughtinstingraygillnets(Figure6).Thepresentfindingisconsideredthefirststudyreportingandtestingdirectlybetweenthedepthandsizeof stingrays,apartfromindirectobser-vationbysomepreviousstudies[9,14,15,21].Normallythesizesof femalestingraysaremuchbiggerthatmalestingrays.Previousresearchfocusedonthemaximumandminimumdiscwidthsizesof malesandfemalesforcertainstingrayspecies. Dasyatis violacea caughtasbycatchonlonglinesforswordfishandtunawasarelativelysmallraywithanof 800mm[21].

InIndonesia,Rhinobatos jimbaranensis females rangedfrom491to994mm,whereasmalesrangedfrom506to953mm.Thesizeof Dasyatis cf. kuhlii (Javaform)forfemalesisfrom118to379

mmandformalesisfrom128to324mmWD,whilethesizeof Dasyatis cf. kuhlii (Baliform)forfemale’srangesfrom240to471mmandmalesisfrom172to450mmWD,respectively.Moreover,Dasyatis cf. ushiei hasbeenreportedforthefemalestorangefrom729to2,020mmWDandmalesrangefrom629to1,624mmWD.Mostof thefemalestingrayscaughtwerelargerthanmalestingraysinthisstudy(Table1).

5. CONCLUSIONS Stingrayspeciesaredistributedwidely in

differenthabitatsandseasons.Theabundanceof stingrayspeciescaughtwassignificantlyaffectedbybothhabitatandseason.Thespeciesabundancewassimilaramonghabitatandseason.Thisstudyalsoconfirmsthatyoungstingraysprefershallowwatercomparedtodeeperwater,demonstratingthathabitatshifted.

ACKNOWLEDGEMENTSSpecialthankstotheMinistryof Education

forprovidinggrant researchfor thisstudyFRGS/1/2017/WAB09/UMT/03/5(No.Vot:59490).ThankstoDepartmentof FisheriesMalaysiaforgivingpermissiontoconductthesamplingforthisstudy(Prk.ML.S.04/32/2Jld.9(22).Besides, thankstoUniversityMalaysiaTerengganuespecially,theFacultyof FisheriesandFoodScienceswhoprovidedthelabfortheconvenienceof thestudy.Thanksalsotoallthefishermeninvolvedduringthesamplingactivities.Next,thankstotheDepartmentof Fisherieswhohavepermittedtousethestingraygillnetsforthisstudy.

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