22 eastern tuna and billfish fisherydata.daff.gov.au/brs/data/warehouse/fishrp9abc_011/... ·...

c h a p t e r 2 2 Eastern Tuna and Billfish Fishery 283

c h a p t e r 2 2

22 Eastern Tuna and Billfish FisheryA Sands, R Summerson, S Vieira and D Wilson

F i g u r e 2 2 .1 RelativefishingintensityintheEasternTunaandBillfishFishery(ETBF),2008

284 Fishery status reports 2 0 0 8

ta b l e 2 2 . 2 MainfeaturesandstatisticsoftheETBF

Feature Description

Targetspecies Albacoretuna(Thunnus alalunga)Bigeyetuna(Thunnus obesus)Yellowfintuna(Thunnus albacares)Broadbillswordfish(Xiphias gladius)Stripedmarlin(Tetrapturus audax)

Byproductspecies Blackoilfish(escolar)(Lepidocybium flavobrunnneum)Mahimahi(Coryphaena hippurus)Moonfish(Lampris guttatus)Rudderfish(Centrolophus niger)Wahoo(Acanthocybium solandri)

Fishingmethods PelagiclonglineMinorline(trolling,rodandline,handline)

Primarylandingports Cairns,Mooloolaba,Southport,CoffsHarbour,PortStephens,Sydney,Ulladulla,Narooma,Bermagui,Eden

Managementmethods Inputcontrols:gearrestrictions(numberofhooksthatcanbedeployed)andspatialmanagement.Therearethreezones:AustralianFishingZoneoutsideCoralSea,CoralSeaandhigh-seasOutputcontrols:catchlimits(swordfishonly),bycatchlimits;blackandbluemarlinarenottobetaken

Managementplan Eastern Tuna and Billfish Fishery Management Plan 2005(DAFF2005)(amended18September2007)

ta b l e 2 2 .1 Statusofthefishery

Fishery status 2007 2008 Commentsa

Biological status Overfishing Overfished Overfishing Overfished

Albacoretuna(Thunnus alalunga)

Assessmentindicatesbiomassiswellabovethatrequiredformaximumsustainableyield.Fisherytargetsanarrowbandofoldageclasses.

Bigeyetuna(Thunnus obesus)

Currentlevelsoffishingandhistoricalaveragelevelsofrecruitmentmaymovestocktoanoverfishedstate.

Yellowfintuna(Thunnus albacares)

Currentlevelsoffishingandhistoricalaveragelevelsofrecruitmentmaymovestocktoanoverfishedstate.

Broadbillswordfish(Xiphias gladius)

Rangeofplausibleconclusionsonstockstatus,withmostindicatingnotoverfishedandnooverfishing;however,someuncertaintiesremain.

Stripedmarlin(Tetrapturus audax)

Preliminaryassessment;rangeofplausibleconclusionsonstockstatus.

Economic statusFisherylevel

Neteconomicreturns(NER)negative

NERestimatesnotavailable

Economicstatusislikelytohaveimprovedin2007–08giventhereductioninvesselnumbers.

Not oV eRfiSheD / Not Sub jec t to oV eRfiShiNg oV eRfiSheD / oV eRfiShiNg uNc eRtAiN Not ASSeSSeD

a Ocean-wideassessmentsofspeciesthroughtheWesternandCentralPacificFisheryCommissionwereusedasthebasisforstockstatusdetermination.TherelevanceoftheseregionalassessmentstotheAustralianFishingZoneisunclearbecausemixingandinteractionsbetweenstockcomponentsintheWesternandCentralPacificOceanandAustralianFishingZonearenotwellunderstood.

Table 22.2 continues over the page


Feature Description

Harveststrategy Eastern Tuna and Billfish Fishery Harvest Strategy Framework 2007(AFMA2007);scheduledforimplementationin2009–10

Consultativeforums EasternTunaandBillfishFisheryManagementAdvisoryCommittee(ETBFMAC)(asof1July2009,knownasTropicalTunaMAC),EasternTunaandBillfishFisheryResourceAssessmentGroup(ETBFRAG),WesternandCentralPacificOceanFisheriesCommission

Mainmarkets Domestic:freshInternational:Japan,UnitedStates—mainlyfresh;AmericanSamoa,ThailandandIndonesia—albacore,mainlyforcanning

EPBCActassessments:listedspecies(Part13)internationalmovementofwildlifespecimens(Part13A)

Currentaccreditationdated17December2005Currentaccreditation(WildlifeTradeOperation)dated8July2008;expires20January2011

Ecologicalriskassessment Level1:ScaleIntensityConsequenceAnalysis(SICA)completedon390species—AFMAwebsiteLevel2:ProductivitySusceptibilityAnalysis(PSA)completedon390species—AFMAwebsite(Webbetal.2007)Level3:SustainabilityAssessmentforFishingEffects(SAFE)completedon207species—AFMAwebsite(AFMA2009)

Bycatchworkplans Australian Tuna and Billfish Longline Fisheries Bycatch and Discarding Workplan 1 November 2008 – 31 October 2010(AFMA2008)

Fishery statistics 2007 2008

Fishingseason Yearround Yearround

TACandcatchbyspecies: TAC Catch TAC Catch

albacoretuna 3200ta 1925t None 1275t

bigeyetuna None 1007t None 1026t

yellowfintuna None 1390t None 1648t

broadbillswordfish 1400t(2007–08) 1353t 1400t(2008–09) 1483t

stripedmarlin None 359t None 425t

Effort Pelagiclongline:8.44millionhooksMinorlines:975lines

Pelagiclongline:8.04millionhooksMinorlines:306lines

Fishingpermits 109longline+11CoralSea44minorline

109longline+11CoralSea32minorline

Activevessels Pelagiclongline:61Minorlines:21

Pelagiclongline:54Minorlines:15

Observercoverage Pelagiclongline:444489hooks(5.26%)Minorline:zero

Pelagiclongline:834698hooks(10.38%)Minorline:zero

Realgrossvalueofproduction(2007–08dollars)

2006–07:$33.7million 2007–08:$32million

Allocatedmanagementcosts 2006–07:$3.0million 2007–08:$3.0million

EPBCAct=Environment Protection and Biodiversity Conservation Act 1999;TAC=totalallowablecatcha Withinthe‘albacorearea’.

ta b l e 2 2 . 2 MainfeaturesandstatisticsoftheETBFc o n T i n u E d


ta b l e 2 2 . 3 HistoryoftheETBF

Year Description

1938 FormationofGameFishingAssociationofAustralia.

1950s Fisheryexpandedrapidlywiththeintroductionoflive-bait-and-poletechniquesforSBT.

Late1950s JapaneselonglinersbeganfishingoffAustralia’seastcoast.

Early1960s Sporadicdomesticlongliningforyellowfintunacommenced.

1970s Catchesincreasedwiththeintroductionofpurse-seiningandthedevelopmentoftheSkipjackFishery(purseseineandpole-and-line).DevelopmentofgamefishindustryforblackmarlinoffCairns(animportantblackmarlinspawningground).

1979 DeclarationoftheAFZ.Japaneselonglinerslicensedunderbilateralagreements.Australiaprogressivelyrestrictedaccessasdomesticcommercialandrecreationalfisheriesfortunaandbillfishgrew.

Early1980s Longliningincreasedmarkedlyaftersuccessfulairfreightingoffresh-chilledtunatoJapan.

1986 Alogbookfordomesticlonglinersintroduced.

1987 NominalCPUEfordomesticlonglinedyellowfinpeakedataround27fishper1000hooks(2millionhooksset).

1990s SecondwaveofexpansioninnorthernQueenslandwaters;highcatchratesofyellowfinandbigeyetuna.

1990s Recreationalcatchesofstripedmarlinincreased.

Mid-1990s AccesstoswordfishmarketsintheUnitedStatesresultedinmanyfishersmovingtosouthernQueenslandports(e.g.Mooloolaba)totargetswordfish.

1992to1996 Catchratesvariedbetween12and18yellowfinper1000hooks.

1995 AFMAbegancompulsorylogbookreturnprogramasaconditionoffishingpermits,maintainedamonthlyauditandsupportedtheprogramwithregularfieldliaison.

southernbluefintuna(SBT)offNewSouthWalesduringwinter,afterfishingfortropicaltunaandbillfishearlierintheyear,whileotherstakethemincidentallywhentargetingothertunas.AllSBTtakenmustbecoveredbyquota.

GamefishingispopularinAustralia.Manygamefisherstagandreleasetheircatch,especiallymarlins.Aswellasorganisedrecreationalfishing,manyotherrecreationalanglerstargettunasandbillfishintheareaoftheETBF.Thereisalsoawell-developedfisheryusingchartervessels.Fewdataareavailableonrecreationalparticipationlevels,catchesandfishingeffortdirectedattunaandbillfish,apartfromdatagatheredthroughfishingtournaments,chartervessellogbooksandtheNationalRecreationalandIndigenousFishingSurvey(Henry&Lyle2003).

DomesticmanagementarrangementsreflectAustralia’sobligationstotheWesternandCentralPacificFisheriesCommission(WCPFC)(seeChapter21).

2 2 . 1 b a c k g r o u n d

TheEasternTunaandBillfishFishery(ETBF)extendsfromCapeYorktotheVictoria–SouthAustraliaborder,includingwatersaroundTasmania(Fig.22.1).Domesticlonglinevesselsaremostly15–25mlongandusemonofilamentgear.Fisherscommonlyoperateonabout107daysperyear.Mosttripsarebetween2and15days,butoccasionallytripsmayextendupto30days.Almostnobigeyeorswordfish,andprobablylessthan5%oftheyellowfincatch,aretakenbymethodsotherthanlonglining.

Inresponsetodecliningcatchratessincethelate1990s,theAustralianFisheriesManagementAuthority(AFMA)hassetaTACof1400tforswordfishonafinancialyearbasis.InmanagingtheTAC,triggercatchlimitshavebeensetforthecatchofswordfishineachquarteroftheyear.Vesselsarecurrentlymonitoredthroughlogbooks,verifiedlandingrecords,vesselmonitoringsystemsandobservers.SomeETBFlonglinerstarget

Table 22.3 continues over the page


Year Description

Late1990s Longlinecatchesandcatchratesofstripedmarlinincreasedmarkedly.LocallybasedlonglinefleetsincreasinglytargetedalbacoreinthesubtropicalsouthPacificOceanforcanningmarkets.

1997 Japan’slonglinersexcludedfromtheAFZ—starting1998.NominalCPUEforswordfishandbigeyepeaked(6millionhooksset).

1998 Commercialretentionofblackandbluemarlinbydomesticlonglinersbanned,withoperatorsrequiredtoreleasethem.

1998to2001 Commerciallonglinersreportedhighcatchratesoflarge(~80kgwholeweight)stripedmarlin,followedbydeclines.

1999 Recreationalanglersreportedbeststripedmarlinseasononrecord.

Post-2000 Catchratesofswordfishandbigeyeremainedwellbelowtheirpeak.AFMAplacedspecificoperationalareaandquota-holdingrequirementsonlonglinerstoreducethelikelihoodofSBTbeingcapturedwithoutquota.

2001 Stripedmarlincatchpeakedat782t(treblingsince1997).

2003 AFMAimplementedanat-seaobserverprograminthelonglinesectoroftheETBF.Longlinefishingeffortpeakedat12.4millionhooks.

2004 AFMAestablishedseparatemanagementarrangementsforskipjacktuna(seeChapter23).TheconventionestablishingtheWCPFCenteredintoforceon19June.AustraliabecameamemberofthecommissioninNovember.Spanishlonglinerscommencedfishingforswordfishintheinternationalwatersofthesouth-westernPacificOcean.

2005 WCPFCagreesoncatchlimitsforbigeyetunabylongliners.

2006 Longlinersbegantousedeep-settingtechniquestotargetalbacoreinresponsetoreducedswordfishavailability,highoperatingcostsandmarketdemand.Thestructuraladjustmentpackageresultedinsurrenderof99ofthe218longliningpermitsoriginallyavailabletothefishery.AFMAintroducedcatchdisposalrecordsforthedomesticfishery,whichcollectverifiednumbersandtotalweightsoftargetspecieslandedaftereachtrip.

2007 DeclineinalbacorecatchratesandthestrengtheningoftheAustraliandollarsawtargetingredirectedtootherspecies.AFMAclosedthemainfishingground(the‘albacorearea’)tonewentrants.AFMAintroducedaTACof3200tforalbacorewithinthealbacoreareafor2007.

2008 Harveststrategyframeworkfinalised;scheduledforimplementationin2009.WCPFCagreedoncatchreductionsforbigeyetunaandyellowfintunabylongliners.

AFMA=AustralianFisheriesManagementAuthority;AFZ=AustralianFishingZone;CPUE=catchperuniteffort; ETBF=EasternTunaandBillfishFishery;SBT=southernbluefintuna;TAC=totalallowablecatch;WCPFC=WesternandCentralPacificFisheriesCommission

ta b l e 2 2 . 3 HistoryoftheETBFc o n T i n u E d

2 2 . 2 h a rv e s t s t r at e g y

Aharveststrategy(HS)framework,scheduledforimplementationin2009–10,hasbeendevelopedfortheETBF.Managementstrategyevaluation(MSE)isbeingusedtotestthelikelyperformanceoftheHSforeachofthefivetargetspecies(yellowfin,bigeye,stripedmarlin,broadbillswordfishandalbacore).Theframeworkconsistsofatarget-drivencatchperuniteffort(CPUE)ruleanda‘decisiontree’thatdefinesreferencelevelsforindicatorsandsubsequentadjustmentstotherecommendedbiologicalcatch(RBC)(orleveloffishingeffort)foreachtargetspecies.

Empiricalindicatorsofstockstatusareusedbecauserobust,region-specificassessmentsarenotavailableforstockswithintheETBF.Foreachtargetspecies,thedecisionruleusesinformationontherelativevaluesandtrendsinthestandardisedcatchratesofthreesizeclassesoffish(small,prime,large)andtheproportionof‘large’fishinthecatch.Thevaluesoftheseindicatorsarecomparedwithtargetreferencelevels.Thetargetreferencelevelsarebasedontheexpectedcatchratesandsizeproportionwhenthelevelofmeanspawnersperrecruitisat48%ofthepre-fishedlevelofspawnersperrecruit(SPR48).SPR48wasusedasaproxyforthedefault


runofsmallblackmarlinappearedoffTownsvilleinJuly–August,asexpected,inreasonablenumbers.However,thisrundidnotcontinueoffNewSouthWalesthefollowingJanuary–March.AnecdotalevidencesuggeststhattheabundanceofmostprimaryspecieshasbeenlowinwaterscoveredbygamefishtournamentanglersoffNewSouthWales.The2008–09seasonislikelytobeoneoftheworstseasonstodate.PooravailabilityofjuvenileyellowfintunatoNewSouthWalesisapparent.However,chartervesseloperatorshavereportedreasonablenumbersofstripedmarlinoffNewSouthWales.Reasonablenumbersofyellowfintuna,inthe30–70kgrange,andmahimahihavebeentaken.Therehavealsoapparentlybeenreasonablenumbersofalbacorecaught,withcatchesreportedduringtournamentshigherthaninpreviousyears.

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F i g u r e 2 2 . 2 FishingintensityintheETBF,1985to2008

Totalgrossvalueofproduction(GVP)fortheETBFdecreasedby5.2%in2007–08,from$33.7millionin2006–07to$32millionin2007–08,andremainssignificantlybelowthepeakrecordedin2001–02of$93.7million(2007–08dollars)(Fig.22.3).

In2007–08,therewasasubstantialshiftinthecontributiontoGVPbyspecies.Areducedcontributionfromyellowfintuna,albacoretunaandbroadbillswordfishwasreplacedbyanincreasedcontributionfromhigh-valuebigeyetunaand,toalesserextent,increasedvalueofproductionofstripedmarlin.Thisshifthasmadebigeyetunathedominantspeciesinthe

targetreferencepointsrequiredbytheCommonwealth Fisheries Harvest Strategy Policy(HSP).Theframeworkdoesnotcontainanexplicitlimitreferencepoint;ratherithasbeendesignedtobetargetdriven.MSEsarebeingusedtotunetheHSforeachspeciessothattheycomplywiththespecificationsofthepolicy.Theseevaluationswillalsotakeintoaccountthemultispeciesnatureofthefishery,sothattheHSmaintainsthebreedingpotentialofeachspeciesaboveanimplicitlimitreferencepointofSPR20.

Theintentofincludingthesize-basedindicatorswastomaketheHSmorerobusttopotentialbiasesinlonglinecatchratesasindicesofstockabundance.TheimpactofuncertaintyabouttheextentoflinkagesbetweentheETBFandwiderPacificOceanstockswillbeinvestigatedaspartoftheevaluationsconductedduring2009.TheHSiscosteffectiveinusingdatafromexistingprogramsthatmonitorcommercialfishingactivities.Thiswillnecessitaterigorousdataverificationandthecollectionofauxiliarydata—forexample,independentestimatesoftrendsinfishingmortalityandthelevelofdiscarding.

2 2 . 3 t h e 2 0 0 8 F i s h e ry

Totalcatcheshavedecreasedfrom6867tin2007to6686tin2008.Annuallonglineeffortinthedomesticfisherydecreasedfrom8.44millionhooksin2007to8.04millionhooksin2008(Fig.22.2).Efforthasfallenfromapeakof12.40millionhooksin2003asaresultofthestrengthoftheAustraliandollar,increasedoperatingcosts,implementationofatotalallowablecatch(TAC)forswordfishand,possibly,thesurrenderofpermitsunderthe2006restructurepackage.Atotalof54vesselsreportedlongliningduring2008.

The2008–09heavytacklerecreationalgamefishfisheryforlargeblackmarlin(Makaira indica)offCairnswasverypoor,probablytheworstonrecord.Itwassuggestedthatthiswasaresultofseasonalvariabilityandstrongcurrentsfromthesouth.Thetraditional


Thevalueandvolumeofthefishery’sexportsaredifficulttodeterminebecausetunaproductscomefromavarietyofAustralianfisheries,andtradedatadonotdistinguishaccordingtofishery.EstimatescanbedrawnfromtunaexportdataafterSBTexportshavebeenremoved,butthesedataincludeexportsfromthemuchsmallerWesternTunaandBillfishFishery(WTBF).TheprincipaldestinationforAustraliantunaisJapan,whichreceived$11.4millionor58%oftotaltunaexports(excludingSBT)in2007–08.NewZealand,AmericanSamoa,ThailandandtheUnitedStateswerealsoimportantmarketsin2007–08,receiving10%,9%,9%and7%ofAustralianexports,respectively.

Australiaexportsarangeoftuna-basedproducts,manyofwhichhavebeenderivedfromtheETBF.Ofspeciescaughtinthefishery,bigeyetunawasthefishery’smostimportantexportcommodity,withAustralianexportsofthisspeciesvaluedat$7.9millionin2007–08.Exportsofotherkeyspeciesincludedalbacoretuna($3.5million),yellowfintuna($2.5million)andbroadbillswordfish($2.3million).

fisheryingrossvalueterms.Itsvaluemorethandoubledfrom$5millionin2006–07to$10.9millionin2007–08.Reducedcatchesofalbacoretunaresultedina55%declineinthegrossvalueofthisspecies,from$6.1millioninthe2006–07financialyearto$2.8millionin2007–08.ThegrossvalueofyellowfintunaproductionintheETBFfellby35%asaresultofreducedcatches,from$11.7millionin2006–07to$7.6millionin2007–08.Thegrossvalueofbroadbillswordfishproductionfellby11%to$6.6million.Thegrossvalueofstripedmarlinproductionincreasedby30%to$2.4million.

1999−00 2001−02 2003−04 2005−06 2007−080

20

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GVP: all species, ETBF

OtherStriped marlinAlbacore tuna

Bigeye tunaSwordfishYellowfin tuna

2007

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illion

F i g u r e 2 2 . 3 GVPintheETBFbyfinancialyear,1999–2000to2007–08

Gaffing tuna PHOTO:BRADLEYMILIC,AFMA Tuna catch PHOTO:MIkEGERNER,AFMA


1984 1988 1992 1996 2000 2004 20080.0

0.5

1.0

1.5

2.0

2.5

Catch: albacore tuna, ETBF

Australia (domestic and charter)Japan (bilateral and joint venture)

Cat

ch (t

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tonn

es)

F i g u r e 2 2 . 4 Albacoretunacatchhistory,1984 to2008

previous assessment

ETBF: ThereisnostockassessmentofETBFalbacore.

WCPFC convention area: ThepreviousformalstockassessmentforsouthPacificalbacorewasconductedin2005;thisassessmentwasupdatedin2006usingnewdatafor2004and2005.Thekeyconclusionswerethatoverfishingisnotoccurring(Fcurrent/FMSY<1)andthestockisnotinanoverfishedstate(Bcurrent/BMSY>1).Themodelestimatedthatrecentrecruitmentwasbelowaverage,andtheportionofthepopulationvulnerabletolonglinewaspredictedtodecline.Theconclusionsoftheassessmentwererelativelyinsensitivetoarangeofdifferentassumptionsregardingkeybiologicalparameters;however,theneedtorefinesomeofthesekeyparameterswashighlighted.Duetoremaininguncertaintiesinthemodel,itwasrecommendedthatcatchesremainatcurrentlevels.

2008 update

Resultsforthe2008southPacificalbacoreassessmentbytheSecretariatofthePacificCommunity(SPC;conductedusingMULTIFAN-CL)differconsiderablyfromthe2006assessment(Hoyleetal.2008).Thisisduetochangesinrelativeabundanceindices

2 2 . 4 b i o l o g i c a l s tat u s

ALbAcoRe tuNA

ta b l e 2 2 . 4 Biologyofalbacoretuna

Parameter Description

General ConsistofasinglestockinthesouthPacificOcean

Range 50°N–50°S,180°W–180°E.Thejuvenilesliveinthecooler,temperatewatersofthesubtropicalconvergencezone,whereastheadultsmostlylivetoitsnorth.Thewatersoffsouth-easternTasmaniaareatthesouthernlimitofalbacoredistribution.Highlymigratorypelagicspecies

Depth 0–600m

Longevity >14years

Ageatmaturity 5–6years,~85cmFLfemales,~60cmmales

Spawningseason November–March;spawninsubtropicalandtropicalwaters,at~10°S–25°S

Size Maximum:~127cmFL,40kgwholeweight;theaverageweightofalbacorecaughtbyAustralianlonglinersis~15kg

SOURCES:Collette&Nauen(1983);Campbell(2008); Pepperell(inpress).

ETBF: Catchesofalbacoredecreasedfrom1925tin2007to1275tin2008(Fig.22.4).Thisisaresultoflonglinersswitchingfromalbacoretoothertargetspecies,mainlyduetomarketforces.

WCPFC convention area: The2007southPacificalbacorecatch(59495t)waslowerthantherecordcatchof2006(69273t)(WCPFC2008);however,itwasstillhigherthantheaverageoverthepast10years.Longlinehasaccountedforthemajority(>75%)ofsouthPacificalbacorecatch,otherthanin1989,whendrift-netsaccountedforthemajority.


Future assessment needs

ReducingparameteruncertaintiesforsouthPacificalbacore,includingselectivity,andunderstandingrecentdeclinesinCPUEtrendsfortheChineseTaipeifleetwereidentifiedasbeingofhighpriority,andshouldbeincludedinthefutureworkprogram.Aregionalstudyofthestockstructureandlife-historycharacteristicsofsouthPacificalbacoreiscurrentlybeingundertaken.AcomparativeassessmentwillbepresentedtotheSCoftheWCPFCin2009.

bigeYe tuNA

ta b l e 2 2 . 5 Biologyofbigeyetuna


Range 40°N–40°S,180°W–180°E;highlymigratorypelagicspecies;inhabittropicalandsubtropicalwatersworldwideintemperaturesof13–29°C,exceptfortheMediterraneanSea.Theyhaveawidedistributionbothlatitudinallyandverticallybecauseoftheirtoleranceoflowoxygenlevelsandlowtemperatures;geneticstudiesindicateasinglestockacrossthePacificOcean

Depth 0–600m

Longevity ~16years

Ageatmaturity ~3years

Spawningseason Spawninequatorialwatersthroughouttheyear,15°N–15°S

Size Maximum:197kgwholeweight.TheaverageweightofbigeyecaughtbyAustralianlonglinersis~37kg


(specifically,theinclusionofstandardisedCPUEdataasrelativeabundanceindicesfortheJapanese,koreanandChineseTaipeilonglinefisheries,andtheNewZealandtrollfishery),selectivityandbiologicalparametersfornaturalmortalityandreproductivepotential.Theserepresentchangestothedatainputsoftheassessmentandmodelstructure,aswellasrefinementstothemodelspecification;theresultingestimatesindicatedthatspawningbiomasswaslowerandfishingmortalitywashigherthanindicatedbyearlierassessments.However,thekeyconclusionsfromtheassessmentremainthesame;basedonWCPFCreferencepoints,overfishingisnotoccurring,andthestockisnotoverfished.

reliability of the assessment

TheWCPFCScientificCommittee(SC)notedthat,despiteimprovementstomodelfitandtheremovalofsomebiases,significantfittingproblemsremain,withcontradictorytrendsinsizeandCPUE.Inparticular,recentfishingmortalityestimatesareuncertain,andFcurrent/FMSYisstronglyaffectedbythestructuralmodeluncertainty.Someofthestructuraluncertaintyisrelatedtothefailuretomodeltheincreasinglengthoffishselected(selectivity)bythefisherythroughtime,aswellastheuncertaintyaboutwhethertherecentlargedeclineinstandardisedCPUEoftheChineseTaipeifleetaccuratelyreflectsadeclineinbiomass.

Tuna catch PHOTO:MIkEGERNER,AFMA


previous assessment

ETBF:ThereisnospecificbigeyeassessmentfortheETBF.ItisunlikelythatETBFbigeyeareaseparatestock,buttherecouldbesomeseparationfromthebroaderWCPO.

WCPFC convention area: Forseveralyears,ageandspatiallystructuredassessmentmodelshaveconsistentlyindicatedthatoverfishingofbigeyeisoccurringinboththeWCPOandtheeasternPacificOcean.Thepreviousassessment(2006)estimatedthatfishingmortalityis25%abovethelevelthatwouldproducemaximumsustainableyield(MSY).Thismeansthat,accordingtotheWCPFC’sdefaultdefinitions,thestockwouldwarrantclassificationasoverfished(Bcurrent/BMSY<1)iffishingcontinuedat2001to2004levelsandrecruitmentremainedatthelong-termaveragelevel.Forbigeye,thegreatestimpactfromfishingisinequatorialwaters;bigeyeathigherlatitudes,suchasintheETBF,wereestimatedtobemoderatelyexploited.

2008 update

Asimilarmodellingapproach(MULTIFAN-CL)wasusedinthe2008assessment(Langleyetal.2008).Catch,effort,sizeandtaggingdatawereupdatedfromthe2006assessment.The2008assessmentincludesadditionalfisheriesandchangesinfisheryconfigurations;however,theserepresentrefinementstothemodelratherthansubstantivechangestothestructure.Fcurrent/FMSYismorepessimisticthanunderthe2006assessment(1.44comparedwith1.32),whileBcurrent/BMSYismoreoptimistic(1.37comparedwith1.27);however,thesevariationsarenotconsideredtobesignificant,giventheuncertaintiesinthemodel.UsingWCPFCreferencepoints,thekeyconclusionsremainthesame:bigeyeissubjecttooverfishing(Fcurrent/FMSY>1),butthestockisnotoverfished(Bcurrent/BMSY>1).Further,boththeadultandtotalbiomassarepredictedtobecomeoverfishedat2003–06levelsoffishingmortalityandlong-termaveragelevelsofrecruitment.

ETBF: Catchesofbigeyetunaincreasedslightlyin2008to1026t,from1007tin2007(Fig.22.5).In2008,CPUEremainedconstantatapproximatelythreefishper1000hooks.Catcheswerequitegoodinthefirsthalfof2008,whichcoincidedwithhighfuelcosts,astrongAustraliandollarandsignificantreductionsinpricesofalbacore;however,Japanesedemandandpricesforbigeyewerealsohighduringthisperiod.

WCPFC convention area: Thetotalbigeyecatchfor2007(143059t)wasthesecondhighestonrecord(after2004—156768t);itwas6%ofthetotalwesternandcentralPacificOcean(WCPO)catch(WCPFC2008).Thisismainlyduetotheincreaseinestimatedbigeyecatchfromthepurse-seinefishery.Theprovisionalpurse-seinecatchestimateforbigeyetunafor2007(38324t)wasthesecondhighestonrecord.However,thismayberevisedafteralltheobserverdatafor2007havebeenreceivedandprocessed.Provisionalbigeyelonglinecatch(82735t)wasclosetotheaveragefor2000–07.

1984 1988 1992 1996 2000 2004 20080.0

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Catch: bigeye tuna, ETBF


Cat

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F i g u r e 2 2 . 5 Bigeyetunacatchhistory,1984to2008


YeLLoWfiN tuNA

ta b l e 2 2 . 6 Biologyofyellowfintuna


Range 40°N–40°S,180°W–180°E;highlymigratorypelagicspecies;inhabittropicalandsubtropicalwatersworldwideexceptfortheMediterraneanSea.ConsideredtoconsistofasinglestockinthewesternandcentralPacificOcean

Depth 1–250m,usuallyoccurinthemixedlayer(<100m)

Longevity ~9years

Ageatmaturity ~2–3years

Spawningseason Spawnmainlyduringsummerwheresea-surfacetemperaturesareatleast26°C.Inequatorialwaters,maturefemalesarecapableofreleasingmillionsofeggsatatime,andcanspawnevery1or2daysduringthespawningseason

Size Maximumreported:176kgwholeweight;theaverageweightofyellowfincaughtbyAustralianlonglinersis~34kgwholeweight


ETBF: Catchesofyellowfinincreasedin2008to1648t,from1390tin2007(Fig.22.6).Thisisbelowtherecordcatchof3148tin2003.CPUEalsoincreasedfromfivefishper1000hooksin2007tosevenfishper1000hooksin2008.

WCPFC convention area: Thetotalyellowfincatchin2007(431814t)waslowerthanin2006(442288t),buthigherthantheaveragecatchfortheperiodsince2000(~424000t)(WCPFC2008).ApproximatelyhalfoftheWCPOyellowfincatchistakenbypurseseine(228426t).Theprovisional2007longlinecatchforyellowfintuna(69857t)isthelowestsince1999.


Generally,thebigeyetunaassessmentisquitecomprehensive.2007datawerenotcompleteforsomefisheries—mostnotablythedistantwaterlonglinefisheries—atthetimeoftheassessment.Thereareindicationsthatthehighrecruitmentestimatedinthisandotherassessmentsmayactuallybeanartefactofstructuralassumptionsofthemodel.MSY-basedreferencepointsarenotdirectlycomparableamongassessmentsduetotheshiftinage-specificfishingmortalityinrecentyears(becauseofadeclineinlonglinecatch).Thebase-casescenariowasoneofthemoreoptimisticmodelsforbigeye;otherscenarioshadmorepessimisticconclusionsonstockstatus.


Futureassessmentneedsincludetherefinementofbigeyeparameters(includingage,growthandreproductivebiology),refinedestimatesofhistoricalbigeyecatchbypurse-seiners,andthecontinuationoftheIndonesiaandPhilippinesDataCollectionProject.

Yellowfin tuna catch PHOTO:MIkEGERNER,AFMA


2008 update

NonewstockassessmentwasundertakenforWCPOyellowfintunain2008.Therefore,thestockstatusdescriptionandmanagementrecommendationsfromthe2007assessmentarestillcurrent.


Modeldiagnosticsindicatethattherearenoseriousfailuresintheassumptionsofthemodel;however,somedeparturesinthemodel’sassumptionswereidentified,includingthelackoffittothejuvenilemodesinthesizefrequencyforsomefisheries,andalackoffittothesizedataforsomefisheries.


Anumberofrecommendationsforfutureyellowfinassessmentswereidentified.Theseincludedadditionalmodelrunstoillustrateuncertaintieswithrespecttonaturalmortalityassumptions,alternativecatchhistoriesforIndonesia(andthePhilippines)andchangesinlonglinecatchabilitytrends;modellingofselectivitychangesovertimetodescribesomelonglinesettingpractices(e.g.dayversusnightsets);andincludingtemporaltrendsinthecatchsizecomposition.Also,furtherresearchisrequiredtoexploretherelationshipbetweenlonglineCPUEandyellowfinabundance.AnewstockassessmentwillbepresentedtotheSCoftheWCPFCin2009.

1984 1988 1992 1996 2000 2004 20080

1

2

3

4

5

Catch: yellowfin tuna, ETBF


Cat

ch (t

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F i g u r e 2 2 . 6 Yellowfintunacatchhistory,1984to2008

previous assessment

ETBF: ThereisnospecificyellowfinassessmentfortheETBF.TheamountofmixingbetweenWCPOandETBFstocksisuncertain;however,taggingstudiesarecurrentlyinprogresstoobtaininformationonmovement.

WCPFC convention area: TheSecretariatofthePacificCommunity—OceanicFisheriesProgram(SPC–OFP)developedanintegrated,spatialandage-structuredmodel(MULTIFAN-CL)thatestimatespopulationparametersatregionalandsubregionallevels.TheWCPFC2007assessmentofyellowfinstockstatuswasconsistentwiththe2005and2006assessments;however,theFcurrent/FMSYratiofor2007wasslightlylower(0.95,comparedwith1.11inthe2006assessment)(Langleyetal.2007).Thisdifferencewaslargelyduetothenewconfigurationofthefisheries,theirupdatedsizedataandimprovementstothemodel,andthevariationsarenotconsideredtobesignificant.Currentlevelsofcatchandfishingeffortarenotsustainable;accordingtothe2007assessment,WCPOyellowfintunaisclassifiedasnotoverfished,witharelativelyhighprobability(47%)thatthestockissubjecttooverfishing.

Yellowfin tuna PHOTO:QUENTINVARDY,CUSTOMS


conventionarea(WCPFC2008).Atotalof12983tofthisswordfishcatchwascaughtintheWCPFCconventionareasouthoftheequator.

1984 1988 1992 1996 2000 2004 20080.0

0.5

1.0

1.5

2.0

2.5

Catch: swordfish, ETBF


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and

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es)

F i g u r e 2 2 .7 Broadbillswordfishcatchhistory,1984to2008

previous assessment

ETBF:ThereisnospecificbroadbillswordfishassessmentfortheETBF.Itisassumedthatthestockinthesouth-westernPacificOceanisindependentofthebroaderPacificOceanstocks.

WCPFC convention area:In2006,thefirststockassessmentofswordfishinthesouth-westernPacificwasundertakenbyAustralia’sCommonwealthScientificandIndustrialResearchOrganisation(CSIRO),incollaborationwithNewZealand.Twoassessmentpackageswereusedfortheassessment,MULTIFAN-CLandCASAL.AstheMULTIFAN-CLassessmentincludedanextensiveexplorationofmodeluncertainty,itsresultsformedthebasisforthestocksummary.Theassessmentexploredavarietyofplausiblescenariosandassumptions,butnodefinitiveconclusionsweremadeonstockstatus.Nevertheless,theassessmentshowedconsistentdeclinesinstockabundanceinrecentyears,andmostmodelprojectionspredictedfurtherdeclinesatcurrentlevelsoffishingmortality.TheWCPFCSCconcluded

bRoADbiLL SWoRDfiSh

ta b l e 2 2 .7 Biologyofbroadbillswordfish


Range 50°S–60°Nwithaworldwidedistribution,includingtheMediterranean.Highlymigratorypelagicspecies;large,solitaryadultsaremostabundantat15–35°NorthandSouthoftheequator.Distributionvarieswithsex—largefemalesmorecommonathigherlatitudes,andmalesintropicalandsubtropicalwaters.Geneticstudiessuggestseveralsemi-independentstocks(anorthernstock,asouth-westernstockandtwoorthreeeasternPacificOceanstocks)

Depth Duringthedayindeepwaters(downto700m,maydiveto1000m).Atnight,movetosurfacewaterstofeed

Longevity ~20years

Ageatmaturity OffeasternAustralia,femalesmatureat~150cmorbitalforklength(OFL);malesmatureat~90cmOFL

Spawningseason Spawnbroadlyacrosstheoceans—includingtropicalwatersoftheETBF—whenseasurfacetemperatureexceeds24°C.Batchspawner;highreproductivecapacity

Size Maximum:~455cmTL;536.15kgwholeweight;theaverageweightofbroadbillswordfishcaughtbyAustralianlonglinersis~62kgwholeweight

SOURCES:Nakamura(1985);(Youngetal.2003);Campbell(2008);Pepperell(inpress).

ETBF:Catchesofbroadbillswordfishincreasedin2008to1483t,from1353tin2007(Fig.22.7).ItisimportanttonotethattheTACissetonafinancial-yearbasis;catchesinthe2007–08financialyearwerebelowtheTACof1400t.In2008,CPUEremainedconstantatapproximatelythreefishper1000hooks.

WCPFC convention area: Thetotalcatchforswordfishfor2007was23704t,whichisthehighestonrecordfortheWCPFC



Furtherresearchintostockstructurewaslistedasapriority;furthertaggingstudiesinthesouthPacificOceanareongoing.IftheswordfishharvestedintheETBFarealocalstock,thedropincatchratesislikelytobeduetolocaliseddepletion,andreplenishmentwilldependonlocalrecruitment.Thecomplexmigrationpatternsofswordfishandsexualdifferencesingrowthratesmeanthatsize-compositionmonitoringshouldalsorecordcatchlocationandswordfishsex.Thiswouldrequiremonitoringatseabecauseswordfisharelandedgilledandgutted.

StRiPeD MARLiN

ta b l e 2 2 . 8 Biologyofstripedmarlin


Range 46°N–47°S,19°E–69°W;highlymigratorypelagicspecies;distributedthroughouttropicalandsubtropicalwatersofthePacificOcean.Stockstructureisuncertain.Preliminarystudiessuggestgeneticdifferencesbetweenstripedmarlininthesouth-westernPacificOceanandthoseinthenorth-centralandeasternPacificOcean

Depth 0–200m

Longevity ~16years

Ageatmaturity ~2–3years

Spawningseason

November–Decemberinthesouthernhemisphere.Looseaggregationsoccurduringspawningperiods.Highlyproductive.Widelyseparatedspawninggrounds

Size Maximum:244kgwholeweight;theaverageweightofstripedmarlincaughtbyAustralianlonglinersis~90kgwholeweight

SOURCES:Nakamura(1985);Campbell(2008); Pepperell(inpress).

thatanyfurtherincreasesinfishingmortalitywouldprobablymoveswordfishinthesouth-westernPacifictoanoverfishedstate.

2008 update

TheMULTIFAN-CLsoftwarewasusedtoconducttherevisedassessment,whichformedthebasisofthestockstatussummaryin2008(kolodyetal.2008).Importantchangesfromthe2006assessmentincludedarefinedspatialstructure,two–threeyearsofnewcatchandeffortdata,revisedestimatesofmigrationfromtaggingdata,andrecognitionofincreaseduncertaintyingrowthratesandageatmaturity.RecentincreasesinCPUEintheAustralianandNewZealandfleets,combinedwithsubstantiallydecreasedcatchandeffort,improvedthesignalinthedataavailablefortheassessmentandsuggestedthatthestockmayberebuilding.Estimatesof2008referencepointsaremoreoptimisticthaninthe2006assessment:Fcurrent/FMSYis0.44,whileBcurrent/BMSYis1.57.Thekeyconclusionsofthemodelsindicatethatswordfishinthesouth-westPacificisneitheroverfishednorsubjecttooverfishing.


ThereisstillsomeuncertaintysurroundingstockstructureofswordfishinthesouthernPacificOcean,whichimpactsontheinterpretationofthestockassessmentresults.Theapparentfidelityofswordfishtoparticularareas(i.e.seamounts)isamatterforconcernasthiscanleadtolocaliseddepletion.Sometrendsincatchratesmaybemisleading(withrespecttobiomass/abundancetrends)duetooperationalfactorsthatcouldinfluencecatchability.Thereisuncertaintyaboutthegrowthofswordfish,inpartduetodifferentmethodsusedindifferentlaboratoriesforestimatingagesforswordfish.Hence,thecurrentassessmentincludesmodelsthatspanthisuncertaintyingrowthandsizeatmaturity.Thestockassessmentattemptedforthesouth-centralPacificOceanwasunabletodeterminethecurrentstatusofswordfishinthisarea,largelyduetoconflictingtrendsinCPUEfromdifferentfleets.


1984 1988 1992 1996 2000 2004 20080.0

0.2

0.4

0.6

0.8

Catch: striped marlin, ETBF


Cat

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F i g u r e 2 2 . 8 Stripedmarlincatchhistory,1984 to2008

previous assessment

ETBF:ThereisnospecificstripedmarlinassessmentfortheETBF.

WCPFC convention area:Thefirst,andmostrecent,assessmentonstripedmarlinwasundertakenin2006bytheBureauofRuralSciences(BRS)andtheSPC(Langelyetal.2006).Thisassessmentwasconsideredtobepreliminaryastherewasagreatdealofuncertaintyregardingkeyparametersintheassessment,particularlynaturalmortalityandgrowth.Theassessmenthighlightedsignificantdeclinesinabundance,particularlyinthelate1950s,whenJapaneselonglinerstargetedthespeciesintheCoralSea.Itwasuncertainwhetheroverfishingwasoccurringorwhetherthestockwasoverfished.However,severaloftheplausiblescenariosindicatedthatcurrentfishingmortalityequalledorexceededFMSY,andcurrentspawningbiomasslevelsequalledorwerebelowthelevelthatwouldsupportMSY.TheWCPFCSCsubsequentlyrecommendedthat,asaprecautionarymeasure,therebenoincreaseinstripedmarlinfishingmortalityinthesouth-westernPacific,particularlyintheareaencompassingtheCoralandTasmanSeasasthesefisheriesaccount forthemajorityofthestripedmarlincatchinthisarea.

ETBF:Catchesofstripedmarlinincreasedin2008to425t,from359tin2007(Fig.22.8).LonglinersfishingfortunaandswordfishtakesubstantialcatchesofstripedmarlininthePacificOcean.Mostarecaughtincidentally,butsomefleetstargetstripedmarlinincertainhigh-abundanceregionsandseasons.Otherlonglinefleets,suchasthoseofFiji,alsocatchstripedmarlin.AtsashimimarketsinJapan,stripedmarlinfetcheshighprices—attimescomparablewithbigeyeprices—andithasagrowingdomesticmarketinAustralia.Stripedmarlinhavesurpassedblackmarlinasthebillfishspeciesmostfrequentlycaught,taggedandreleasedbyanglers.

WCPFC convention area: The2007catchofstripedmarlin(3802t—8%oftotalbillfishcatch)wasthelowestrecordedsince1983(WCPFC2008).CatchesofblueandblackmarlinareretainedbyothernationsfishingintheWCPFCconventionareas.The2007catchofbluemarlinin2007(20118t—40%oftotalbillfishcatch)wasthelowestsince2002.The2007catchofblackmarlin(2163t—4%oftotalbillfishcatch)hasalsodecreasedcomparedwithrecentyears.Thevastmajorityofmarlins(blue,blackandstriped)arecaughtbylongliners.

Longline vessel making way PHOTO:QUENTINVARDY,CUSTOMS


fleet;betterestimatesofcatches,retentionanddiscardingratesofstripedmarlinbytheNewZealandlonglinefleet;andincorporationofhistoricalsizedatafromthecommercialcatch.ThereisalsoarecentFisheriesResearchandDevelopmentCorporation(FRDC)projectlookingatthepopulationbiologyandhabitatpreferencesofstripedmarlinineasternAustralia(duetobecompletedinlate2009).

2 2 . 5 e c o n o m i c s tat u s

information availableTheAustralianBureauofAgriculturalandResourceEconomics(ABARE)hasregularlysurveyedcommercialoperatorsintheETBFsincethemid-1990sandreportssurveyresultsintheAustralianfisheriessurveysreports(Vieiraetal.2008).Estimatesofbothvessel-levelfinancialperformance(whichrepresentanaveragefisher’saccountingstatement)andfishery-levelneteconomicreturns(NER,whichtakeintoaccounteconomiccostssuchastheopportunitycostofcapital)aregenerallyreported.Themostrecentresultsavailableareforthe2005–06and2006–07financialyears(Vieiraetal.2008).Collectedsurveydatahavealsobeenusedtocalculateproductivityindicesandprofitdecompositionsforthefishery(kompasetal.2009).Estimatesoftheleveloflatentpermitsinthefisheryarealsoavailable.Thereiscurrentlynobioeconomicmodelforthefishery.

LittleinformationexistsabouttheeconomicstatusoftherecreationalsectoroftheETBF.WorkbyGaleanoetal.(2004)assessedtheeconomicvaluesassociatedwithrecreationalandcharterfishingintheETBFforthe2001–02financialyear.TheirfindingsshowedthatNERatthetimewererelativelylowinbothcomponentsofthesector.Morerecentinformationisnotavailableforthesectorand,therefore,itseconomicstatusisnotdiscussed.

2008 update

NonewstockassessmentwasundertakenforWCPOstripedmarlinin2008.Therefore,thestockstatusdescriptionandthemanagementrecommendationsfromthe2006assessmentandWCPFCSCarestillcurrent.


Thereisconsiderableuncertaintysurroundingsomeofthekeyinputstothemodel—inparticular,naturalmortalityandgrowth.However,fromamanagementperspective,currentcatchlevelsfortheWCPOarecomparabletotherangeofMSYestimatescalculated.


Thestockassessmentidentifiedthefollowingresearchareasforfutureassessments:ageandgrowthstudiestoimproveestimatesofgrowthandnaturalmortality;verificationofthecurrentassumptionsregardingageatmaturityandspawningfrequency;improvedestimatesfortheparametersofthelength–weightrelationship;increasedunderstandingofmovementdynamicsinthesouth-westPacific;amorecomprehensiveanalysisofcatchandeffortdata,particularlyvariationsintargetingandfishingpoweroftheJapaneselongline

Tuna on longline PHOTO:MIkEGERNER,BRS


ta b l e 2 2 . 9 Vessels,permits,hooksandshotsintheETBF

YearActive vessels

Total permits

(per calendar

year a)Hooks

(millions) Shots

1986–87 62 n.a. 0.3 760

1987–88 68 n.a. 1.1 1618

1988–89 94 n.a. 1.1 2099

1989–90 98 n.a. 0.8 2300

1990–91 101 n.a. 1.6 2864

1991–92 109 n.a. 1.8 3252

1992–93 91 n.a. 1.9 2975

1993–94 79 202 2.4 3664

1994–95 98 227 3.4 4509

1995–96 112 229 4.0 5552

1996–97 123 217 5.3 7645

1997–98 150 222 7.5 9270

1998–99 156 220 9.9 10762

1999–2000 147 220 9.9 11070

2000–01 136 220 10.1 11529

2001–02 143 220 11.8 12874

2002–03 140 220 12.7 13535

2003–04 131 220 11.1 11766

2004–05 113 220 9.4 9869

2005–06 92 218 9.3 8976

2006–07 71 109 8.9 7314

2007–08 57 109 8.2 6543

n.a.=notavailablea Totalpermitsissuedincalendaryear;forexample,1993–94

representsthe1994calendaryear.SOURCES:AFMArecordsandlogbookdata;Evans(2007).

Net economic returnsAfallinthenumberofactivevesselssince1999coincideswithaperiodofgenerallylowornegativeNER(Fig.22.9).Ofthelast13surveyedyears,positiveNERwasestimatedononlythreeoccasions.Theincreaseinrevenuethroughoutthe1990swasalmostalwaysaccompaniedbyproportionalincreasesincosts,leavingtheNERtothefisherylargelyunchanged.TargetingofswordfishoffMooloolaba(Queensland)inthelate1990sledtomodestaggregatenetreturnsbeing

Level of latent effortManyvesselshavemorethanonepermitattachedtothem.Thismeansthatitishardtodeterminehowmanypermitsarefishedagainst,eventhoughinformationaboutthenumberofactivevesselsisobtainable.Table22.9showsthat,in2002–03,12.7millionhooksweresetunderthe220issuedpermits.By2005–06,only9.3millionhooksweresetunderasimilarnumberofpermits(218).Underthisscenario,theabilityofoperatorstovarytheleveloffishingeffortappliedtothefisherymeantthateffortcouldfluctuatedependingontheNERofthefishery.PositiveNERcouldthereforebedissipatedquicklywiththeactivationoflatenteffort.FollowingthebuybackofpermitsthroughtheFisheriesStructuralAdjustmentcomponentoftheSecuringourFishingFuturepackage,permitnumberswerehalvedto109in2006–07,whilethenumberofhookssetremainedrelativelystableat8.2million.Thissuggeststhatalargereductioninlatentefforthasoccurred.

Tuna on longline PHOTO:MIkEGERNER,AFMA


freightandmarketing($96000)andrepairsandmaintenance($83000).Vesselcashincomeremainedrelativelyconstantataround-$18000pervesselin2005–06and-$19000pervesselin2006–07.

Forthetwosubgroups(broadbillandnon-broadbill)inthefishery,averagetotalcashreceiptsin2006–07wereestimatedat$828000fortheaveragebroadbillvesseland$411000fortheaveragenon-broadbillvessel.Thefourmajorcostitemsmentionedaboveaccountedfor69%and74%oftotalcashcostspervesselinthebroadbillandnon-broadbillsubgroups,respectively.Vesselcashincomewasnegativeinbothsectorsin2006–07(-$9800inthebroadbillsectorand-$25200inthenon-broadbillsector).

Basedonthisinformation,afewkeyfactorscanbeidentifiedthatwerelikelytohavedrivenNERin2007–08,including:

arelativelyslightdecline(5.2%)inreal•GVPin2007–08adecline(26.8%)inthenumberofvessels•activeinthefisheryfrom71in2006–07 to52in2007–08anincrease(21.3%)infuelpricefrom•81.2centsperlitrein2006–07to98.5centsperlitrein2007–08.ItisdifficulttodeterminewhetherNER

increasedordecreasedin2007–08,giventhepositiveandnegativeimpactsofthesefactors.ta b l e 2 2 .1 0 FinancialperformanceofvesselsintheETBF(averagepervessel)

All vessels

2005–06 ($) 2006–07 ($)

Total cash receipts 501 405 570 574

Crewcosts 117817 137086

Freightandmarketingexpenses

83830 96376

Fuel 96796 104168

Repairsandmaintenance

60847 82523

Othercosts 159684 169748

Total cash costs 518 974 589 901

Vessel cash income -17 569 -19 327

SOURCE:Vieiraetal.(2008).

generated,butthesehadbeendissipatedby2001–02asinterestinthisspeciesincreased.Sincethen,substantialneteconomiclosseshaveoccuredinthefishery.

1994−95 1997−98 2000−01 2003−04 2006−07−20

0

20

40

60

80

100

Net economic returns, ETBF

Net economic returnsCostsRevenue

2007

−08

A$ m

illion

F i g u r e 2 2 . 9 TotalNERfortheETBFbyfinancialyear,1994–95to2006–07

SOURCE:Vieiraetal.(2008).

Survey-basedestimatesofNERarenotavailablefor2007–08.However,recentvessel-levelfinancialperformanceestimatescanbeused,togetherwithsomekeyeconomicindicators,togainanunderstandingofthekeydriversoffisheryeconomicperformancein2007–08.

Vessel-levelfinancialperformanceresultsfortheETBFarereportedfortheaveragevesselintheentirefishery,theaverage‘broadbillvessel’(vesselsthatcaughtmorethan10tofbroadbillswordfish),andtheaverage‘non-broadbillvessel’(vesselsthatcaughtlessthan10tofbroadbillswordfish).

Fortheaveragevesselintheentirefishery,totalcashreceiptsincreasedfromapproximately$501000pervesselin2005–06toalmost$571000pervesselin2006–07(Table22.10).Similarly,totalcashcostspervesselincreasedfrom$519000in2005–06to$590000in2006–07.Fourmajorcostitemsaccountedfor71%oftotalcashcosts.Thesewerecrewcosts($137000),fuel($104000),


future considerations relevant to economic performanceAmanagementsystembasedonindividualtransferableeffortunitswasinitiallyproposedunderthenewmanagementplanforthefisherybuthasnotyetbeenputintoeffect.Suchasystemshouldbeconsideredasastepintherightdirection.Itintroducestransferablerightstothefishery(otherthanjusttradeinpermits)andbeginsthedifficultprocessofallocatingindividualrightsandresolvingfishers’concernsaboutwhetherthedistributionofrightsisreasonable.Suchamanagementsystemwillalsoallowfishingefforttobeconstrainedmoreeasilythanunderafishingpermit-basedsystem.

However,therearelimitationsassociatedwithsuchaninput-basedmanagementapproach.First,themanagementdoesnothavedirectcontrolovertotalcatchandthespeciescompositionofcatch.Second,underinput-basedmanagement,fishershaveanincentivetofindnewwaystofishwithinthesetrules.Theywilluseunrestrictedinputsinplaceofrestrictedinputstoincreasetheirfishingpower,inaprocessknownas‘effortcreep’.Theendresultisthateachoperator’sflexibilityisconstrainedsothattheycannotuseinputsincombinationsthatminimisecosts.Consequently,vessel-levelefficiencycannotbe

overall economic performanceEvidencesuggeststhattheETBFhastypicallyhadsomeoftheeconomiccharacteristicsofanunmanaged,open-accessfishery,despiteitbeingacontrolledfishery.ABARE’sestimatesofNERforyearsbefore2007–08suggestthatthefisheryearnedonlyverysmallornegativeNER.Increasesinrevenueinthelate1990scoincidedwithsimilarincreasesincosts,leavingprofitsmostlyunchanged.Lowprofitsleadtoalargeproportionofthefishery’spermitsnotbeingfishedagainst.

AlthoughitisdifficulttoestimateinwhichdirectionNERmovedin2007–08,thebuyouthaditsintendedimpactofleavingfewervesselssharinginasimilaramountofcatchandGVP.Sinceasimilarreturnisnowbeingearnedwithfewervessels(andthereforefewerresourcessuchaslabour,fuelandcapital),totaleconomiccostsacrossthefisheryhavebeenreduced.

Giventhatfuelcostsaccountedfor17.7%oftotalcashcostsfortheaveragevesselin2006–07,thesharpincreaseinthepriceoffuelin2007–08wouldhavehadanegativeimpactonvessel-levelprofitability.Anecdotalevidenceexistsofincreasedinshoreactivityandlowerfueluseasaresult,whichcouldhavemitigatedthisnegativeimpact,butitisdifficulttodeterminetowhatdegree.Inanycase,itislikelythattheimpactontheNERtotheentirefisherywouldhavebeenmuchworsehadthenumberofvesselsinthefisherynotbeenremoved.

Afishery’seconomicperformanceshouldbeassessedaccordingtohowthelevelofNERthatitgeneratesinagivenperiodcompareswiththepotentialNERthatcouldhavebeenearned.InthecaseoftheETBF,eveniffuturesurveyresultsrevealthatNERhavedeclinedduetohighercosts(suchasfuelcosts),economicperformanceislikelytohaveimprovedaccordingtothisdefinition—withfewervesselsoperatinginthefishery,NERarelikelytohavebeenclosertopotential. Tori lines PHOTO:BRADLEYMILIC,AFMA


orcatch.Iftheyare,thefisherywouldmoveawayfromanopen-accesspointwhereNERareclosetozerotowardsapointassociatedwithmaximisingeconomicyield.Ifnot,economicefficiencyisunlikelytoimprovesignificantly,nomatterwhichformofcontrolisused.

2 2 . 6 e n v i r o n m e n ta l i s s u e s

Morethan100marinespecieshavebeenrecordedfromtheETBFlonglinesector,includingtunaandtuna-likefish,billfish,sharks,rays,variousotherfish,andoccasionallyseabirds,seaturtlesandmarinemammals.CommercialmarketshavedevelopedinAustraliaandoverseasforseveralbyproductspecies,suchasmahimahi(Coryphaena hippurus)andwahoo(Acanthocybium solandri).

AFMAhasdevelopedabycatchactionplanforlonglinefisheries(theETBFandtheWTBF)inresponsetoconcernsaboutbycatch.

SharksIn2001,aBRSreporthighlightedhighlevelsofsharkbycatchandthewidespreadpracticeof‘sharkfinning’inAustralia’slonglinetunafisheries(Rose&McLoughlin2001).AFMAhasbannedthepracticeoffinningsharksatsea,prohibitingthepossessionorlandingoffinsseparatefromcarcassesintheETBFsince2005.Since2000,AFMAhasenforcedalandinglimitof20sharkspervesselperfishingtrip.In2005,AFMAalsobannedtheuseofwireleadersor‘traces’onlonglinebranchlinesintheETBF.Themeasureisintendedtoreducesharkmortality;sharksaremorelikelytobitethroughsyntheticfibreleadersandescape.ABRSstudyconfirmedthatbanningwireleadersreducedsharkcatchesandmayincreasecatchratesoftargetspecies,suchasbigeyetuna(Wardetal.2008b).However,thestudyalsohighlightedthepossibilityofunseenor‘cryptic’mortalityamongthemanyanimalsthatareabletoescapebybitingthroughtheleader.

achieved.Finally,ifeffortcreepoccurs,inputcontrolsmustbealteredfrequentlytoensurethatfishingmortalitycoincideswithmanagementtargets.Suchrulechangescanbeexpensiveforfisherswhohavemadeinvestmentsincertaininputs(Rose2002)andalsoinvolvelengthyandcostlynegotiationsbetweenmanagementandindustry.

FollowingadirectioninDecember2005fromthethenMinisterforFisheries,ForestryandConservation,aTACbasedonasystemofindividualtransferablequotas(ITQs)isbeingconsideredforthefishery(Rundle2008).Suchanapproachispreferableasitintroducestransferabilityofrightsinthefishery(asisthecaseunderanindividualtransferableeffortsystem).Itwouldalsoavoidtheproblemsassociatedwitheffortcreepandtheinabilitytocontrolcatchandcatchspeciescomposition.TheincentivesthatITQsmightcreatetodiscard,anddifficultiesinsettinganoptimalTACinafisherytargetingmigratorystockswithunpredictableabundance,havebeenrecognised(Rose2002)butshouldnotbeconsideredanimpediment.Localiseddepletionshavebeenanissueinthefishery’shistoryforbroadbillswordfish.Someformofanarea-basedITQsystemcouldhelpaddressthisissue.

Thetruetestofthenewmanagementsystemwillbewhethercontrols(whetherintheformofatotalallowableeffortoraTAC)aresetatlevelsthatactuallyrestricteffortand/

Longline fishing gear PHOTO:QUENTINVARDY,CUSTOMS


2 2 . 7 h a rv e s t s t r at e g y p e r F o r m a n c e

Theagreedharveststrategy(HS)frameworkfortheETBFisscheduledforimplementationin2009–10.ThepotentialperformanceoftheHSiscurrentlybeingevaluatedand‘tuned’tomeetmanagementandindustryobjectives,usingMSEaspartofadedicatedFRDC–CSIROproject,inconjunctionwiththeEasternTunaResourceAssessmentGroup.

AlthoughITQshavebeenidentifiedasthepreferredmethodofcontrol,thelimiteddataavailablefromthefisheryandtheregionalextentofthekeystockspresentproblemsfortheestimationofscientificallyrobustTACs.Inthiscontext,managementofthefisheryshouldbeadaptive,andallowforupwardordownwardadjustmentofTACswhennewinformationbecomesavailable.Forthisreason,developmentofamanagementstrategywithbiologicalreferencepointsanddecisionrulesmustcontinuetobeamajorconsiderationintheimplementationoftheHSforthefishery.

Marine turtlesPublicconcernoverincidentalcatchesofmarineturtlesresultedinfisheryclosuresforUnitedStateslonglinersinthenorthPacificOcean.IntheETBF,theintroductionofshallowlonglinesetstotargetswordfishmayhaveincreasedthelikelihoodofcatchingmarineturtles,althoughtheavailableempiricalevidencecanneitherconfirmnorrefutethis.TheWCPFCmeetinginDecember2008introducedanewconservationandmanagementmeasure,effectivefrom1January2010,whichrequiresvesselsfishingforswordfishinshallowsetstoimplementoneofthreebycatchmitigationtechniques:theuseoflargecirclehookswholefishbait,amitigationplanoranyotherapprovedmeasure.Circlehookshavebeendocumentedtoreducecatchratesofmarineturtles.Thesecanalsoimprovecatchratesofmosttargetspeciescomparedwithtunahooks(e.g.Wardetal.2008a),althoughincreasedcatchofsomebycatchspecies,includingsharks,mayalsoresult.

SeabirdsSeabirds,suchasalbatrossesandshearwaters,areattractedtolonglinebaitswhenvesselsaresettingtheirgear,andsomebirdsbecomehookedanddrown.Underthebycatchanddiscardingworkplan,allETBFoperatorsfishingsouthof25degreesarerequiredtocarryanddeployanapprovedbird-scaring‘tori’line,andtousealineweightingsystemandthawedbaits.Thereisabanonoffaldischargewhilesetting,anddischargeduringhaulingmustbeavoided.ArecentreportbyBRS(Lawrenceetal.2009)highlightedthecomplexitiesofestimatingseabirdbycatchratesintheETBF.Model-basedestimationmethodsarerecommendedoverusingsimpleobservedseabirdbycatchrates(design-basedestimates),astheeffectofspatialandtemporalbiasinobservercoverageiscateredforinthemodellingprocess.Themodel-basedresultsshowthat,althoughseabirdbycatchrateshavegenerallydecreasedovertime,seabirdbycatchmayexceed0.05birdsper1000hooksinsomeareasandseasons,whichistheperformancemeasurespecifiedinthethreatabatementplan.

Bigeye tuna on longline PHOTO:AFMAOBSERVERPROGRAM


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