Temperature-dependentgrowthratesofAlaskan‘shallow-water’

flatfishspeciesTomHurst,MicheleOttmar,CliffRyerFisheriesBehavioralEcologyProgram

AlaskaFisheriesScienceCenterNOAA-NMFSNewport,OR

FlatfishesinAlaska

• 24SpeciesrecordedinAlaskanwaters

• ~15speciescommoninGulfofAlaskaand/orBeringSea

• 14speciescommerciallyharvested• 2011– 2015average >250,000MT/y ~$225M/y

• MostimportantspeciesYellowfinsole– largestlandingsofanyflatfishinworldRocksole(northern+southern)– secondlargestlandingsPacifichalibut– mostvaluable– over$130M/ycommercial

+importantrecreational+subsistencefisheries

Compiledfrom:Mecklenburgetal.2002.FishesofAlaskaNOAACommercialfisherystatisticswebsiteNMFS2014.FisherieseconomicsoftheUnitedStates

Speciesdistributions– “shallowwatercomplex”

Northernrocksole Yellowfinsole

Pacifichalibut Alaskaplaice

Englishsole Longheaddab

AdultdistributionsfromMatarese etal.2003LHDdistributionfromMecklenburgetal.2002

Allsixspeciesresideinshallowcoastalnurseriesasjuveniles.

Temperature-dependentgrowthrates.

Temperature-dependentgrowthratesofjuvenilesmeasuredbyRyer,Hurst,&Boersma.2012

Northernrocksole

Pacifichalibut

Englishsole

Objectives:Measuretemperature-dependentgrowthratesof

YellowfinsoleAlaskaplaiceLongheaddab

Comparethermalresponsesamong6Alaskanflatfishes

Contrastyellowfinsoleandnorthernrocksolethermalsensitivity,habitat,distribution,andclimateresponses.

Fishcollections

Collectionlocations:YFS:Kodiak,AKAKP:Nome,AKLHD:Nome,AK

NRS:Kodiak,AKPH:Kodiak,AKES:Newport,OR

Fishcollectedfromnearshore waters3-20mdepthOttertrawl&beamtrawlHeldforseveraldaysatcollectionsite

OvernightshipmenttoAFSClaboratoryoncampusofOSUinNewport,OR

ExperimentalfacilitiesBecauseoflogisticalconstraintsassociatedwithfishnumbersandquarantinerequirementsforsomespecies,wehadtodoexperimentsintwodifferentsetsoftanks.

“large”roundtanks,n=15

Usedfor:NRS,PH,ES,LHD Usedfor:YFS,AKP,PH

Crossover:LHDmeasuredintanksusedforearlierstudiesAdditionalPHexpt insmalltanksat9°C

“small”rectangletanks,n=32

Experimentalprotocols

Tankmeangrowthratesusedinallanalyses

Numberofindependenttanks=10-16perspecies

Fishacclimatedtolaboratorycultureforatleast2monthsprioruseinexperiments.

Extendedlowtemperaturerangeto2°C forAKP,YFS,LHD.

Fishacclimatedtotesttemperaturesatapprox.1.5°C/day

Acclimatedfor2weekspriortomeasuringgrowthrates.

Fishfedadlibitumonceperday;“gelfood”

Measured3-5timesat2weekintervals

Individualfishidentifiedthroughsize-rankdifferences

exceptYFS&SupplementalPHexperiment;RFIDPITtagsinbodycavity

Analysesbasedontankmeangrowthrates

Growthandsurvival

Highsurvivaltotemperatureswheregrowthdropsoff.

Alaskaplaice

Growthandsurvival

Highsurvivaltotemperatureswheregrowthdropsoff.

Survivaldeclinedabovetemperatureofmaximumgrowth.

Alaskaplaice Yellowfinsole

Growthandsurvival

Highsurvivaltotemperatureswheregrowthdropsoff.

Survivaldeclinedabovetemperatureofmaximumgrowth.

Lowsurvivalattemperaturesabove10°C,butsurvivingfishhadhighgrowth.*Notsize-dependent.

Alaskaplaice Yellowfinsole Longheaddab

Comparisongrowthratespatternsacrossstudies

Ryeretal.2012.

Seegenerallysimilarpatterns.Extendedexperimentstolowertemperatures.Strongereffectsobservedatthehighesttemeratures.

Comparisongrowthratespatternsacrossstudies???

Aretheremethodologicaldifferencesthatcanexplainthelowerratesobservedinthecurrentstudy.

ButoverallslowergrowthobservedinAKP,YFS,LHDthanNRS,PH,ES

Halibutexperimentcomparison

Anexperimentonjuvenilehalibutconductedin2016,atthesametimeastheYFSexperimentallowedustoevaluatethepotentialforproceduraldifferencesbetweenexperiments.

Ryer etal.2012tested5,9,13,16°“large”roundtanks7fishpertanknottaggedmean69.5mmTL

HurstandPlanas,unpublished*tested2and9°C“small”tanks5fishpertankinternalRFIDtagsmean66.7mmTL

<10%differenceinSGR

Growthat9°C

*TalkbyPlanas andHurst,Tuesday11am.

Sizeeffects?

LHD16°

AKP13°

YFS13°

PH16°ES

16°NRS13°

Notenoughsizevariationwithineachexperimenttodescribesize-dependentvariationingrowth.

But,likelynotenoughtoberesponsiblefortheobserveddifferencesinmeasuredrates.

Sizeeffects? Age effects?

Age0

Age1

But,becauseofdifferencesinthetimingofspawningandsettlement:

NRS,PH,ESwerecollectedasage-0AKP,YFS,andYFSwerecollectedasage-1

Isthereanageeffectongrowthpotential,independentofthegeneraldeclineinSGRwithincreasingsize.

H0:age-0(pre-firstwinter)fishare“different”thanage-1(post-firstwinter)?

LHD16°

AKP13°

YFS13°

PH16°ES

16°NRS13°

Similarpatternsobservedamongjuvenilegadids.

Laureletal.2016

Comparingtemperaturesensitivityamongspecies

CalculatetemperatureofmaximumSGR

Calculatetemperaturerangeto50%SGR

DeltaT

Eurythermic

Stenothermic

LHDRepresentative?Highmortalityatthesetemps.

Implicationsforclimatechange

The“Blob”– extensiveareaofwarmwatersovertheN.Pacific&BeringSea

Yellowfinsolemaybemostsensitivetoclimatechangebecauseoftheirhighthermalsensitivity.

Alreadyhavefieldevidenceofsensitivity.

Interannual variationingrowthreflectsthermalsensitivity

Mattaetal.2010.MEPS.

CollectedNRS,AKP,andYFSfromBeringSeawherethespeciesdistrubutions overlap.

Lookatsynchronyandclimatedriversofannualgrowthrates.

Otolithringwidthindexbasedonwithinindividual,acrossyearvariation.

Interannual variationingrowthreflectsthermalsensitivity

Eurythermic

Stenothermic

Eurythermic

Stenothermic

Whataboutotherpartsofthedistribution?

Yellowfinsole

NorthernrocksoleNorthernmostrange

Generalmodelswouldpredictthatwarmingwouldallownorthernrocksoletoexpandfarthernorth,occupyingwaterscurrentlyinhabitedbyYFSandAKP.

But,coastaltemperaturesdonotfollowlatitudinaltrends.

Warmingmayreducehabitatsuitabilityforthehighlatitudespecieseveninthenorthernpartoftheirrange.

X

Summary

Differencesamongspeciesinthermalsensitivity.YFShavehighthermalsensitivityandliveinthemostthermally

variableenvironments.GrowthresponsesdidnotmatchsurvivalpatternsinLHD.

YFSwillbemoresensitivetoclimatechanges.Climatechangemayalterhabitatusethroughouttheirrange.

Future:1.Repeatexperimentsacrossagestoclarifysizeandageeffects.2.Performtemperaturepreferenceexperiments

– linkperformancetopreference.3.Spatiallyexplicitmodelofseasonalgrowthpotential.

Broader:Explorehowtointegratefieldandlaboratorystudiestoimproveunderstandingofclimateandhabitatinteractionsonfishdistributionsandproductivity.