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.