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dc.contributor.authorLarsen, Lena Inger
dc.contributor.authorÖberst, Rainer
dc.contributor.authorMaxwell, David
dc.contributor.authorPennington, Michael
dc.contributor.authorSparholt, Henrik
dc.contributor.authorLassen, Hans
dc.date.accessioned2007-11-16T14:46:02Z
dc.date.issued2006
dc.identifier.urihttp://hdl.handle.net/11250/100853
dc.description.abstractAbstract The basic data from several ICES coordinated trawl and beam trawl surveys in the Baltic Sea, the North Sea, the area west of Scotland and France are stored in the DATRAS database in the ICES Secretariat; every year and for each survey member countries report data to the database. The DATRAS system offers facilities for the calculation of fish stock abundance indices, these indices are fed into the routine fish stock assessment work. The indices should be supplemented by an estimate of their uncertainty and the present paper suggests a bootstrap algorithm for implementation in DATRAS to calculate such estimates of variation for each stock/area index in a given year. The procedure is a two-step bootstrap routine whereby the length compositions and age-length key are bootstrapped independently, i.e. the uncertainty estimate is based on variability between catches in individual hauls in that year. The goal is to supplement the routine indices with uncertainties estimates in the future.en
dc.format.extent282827 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoengen
dc.publisherICESen
dc.relation.ispartofseriesICES CM documentsen
dc.relation.ispartofseries2006/M:10en
dc.subjecttrålingen
dc.subjecttrawlingen
dc.subjectstock assessmenten
dc.subjectbestandsberegningen
dc.subjectcatch
dc.subjectfangst
dc.titleMeasuring uncertainty in trawl surveys: implementation in DATRASen
dc.typeWorking paperen
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Catch: 925
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924
dc.source.pagenumber17 s.en


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