Time-varying natural mortality in fisheries stock assessment models: identifying a default approach

Autor: Katyana A. Vert-pre, Curry J. Cunningham, Juan L. Valero, Kotaro Ono, André E. Punt, Carey R. McGilliard, Cody S. Szuwalski, Kelli F. Johnson, Cole C. Monnahan, Athol R. Whitten, Sean C. Anderson, Felipe Hurtado-Ferro, Roberto Licandeo, Melissa L. Muradian
Rok vydání: 2014
Předmět:
Zdroj: ICES Journal of Marine Science. 72:137-150
ISSN: 1095-9289
1054-3139
Popis: Center for the Advancement of Population Assessment Methodology, 8901 La Jolla ShoresDrive,La Jolla, CA 92037, USA*Corresponding author: tel: +1 206 543 4270; fax: +1 206 685 7471; e-mail: kfjohns@uw.eduJohnson,K.F.,Monnahan,C.C.,McGilliard,C.R.,Vert-pre,K.A.,Anderson,S.C.,Cunningham,C.J.,Hurtado-Ferro,F.,Licandeo,R.R.,Muradian,M.L.,Ono,K.,Szuwalski,C.S.,Valero,J.L.,Whitten,A.R.,andPunt,A.E.Time-varyingnaturalmortalityinfisheriesstockassessmentmodels:identifyingadefaultapproach. – ICESJournalofMarineScience,doi:10.1093/icesjms/fsu055.Received4 September 2013; revised 1 March 2014; accepted 3 March 2014.A typical assumption used in most fishery stock assessments is that natural mortality (M) is constant across time and age. However, M is rarelyconstant in reality as a result of the combined impacts of exploitation history, predation, environmental factors, and physiological trade-offs.Misspecification or poor estimation of M can lead to bias in quantities estimated using stock assessment methods, potentially resulting inbiasedestimatesoffisheryreferencepointsandcatchlimits,withthemagnitudeofbiasbeinginfluencedbylifehistoryandtrendsinfishingmor-tality. Monte Carlo simulations were used to evaluate the ability of statistical age-structured population models to estimate spawning-stockbiomass,fishingmortality,andtotalallowablecatchwhenthetrueMwasage-invariant,buttime-varying.Configurationsofthestockassessmentmethod,implementedinStockSynthesis,includedasingleage-andtime-invariantMparameter,specifiedatoneofthethreelevels(high,medium,andlow)oranestimatedM.Themin–max(i.e.mostrobust)approachtospecifyingMwhenitisthoughttovaryacrosstimewastoestimateM.The least robust approach for most scenarios examined was to fix M at a high value, suggesting that the consequences of misspecifying M areasymmetric.Keywords: model misspecification, natural mortality,population models, reference points, simulation, Stock Synthesis, time-varying.
Databáze: OpenAIRE
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