dc.contributor.author Toresen, Reidar dc.date.accessioned 2012-07-03T09:08:20Z dc.date.available 2012-07-03T09:08:20Z dc.date.issued 1986 dc.identifier.citation This report is not to be cited without prior reference to the author no_NO dc.identifier.uri http://hdl.handle.net/11250/103967 dc.description.abstract The age and length at maturity is calculated for the six year-classes, no_NO 1973-78. The age at maturity is also calculated for the year-classes 1959-61. The two periods are caracterized by great differences in stock abundance and recruitment. The proportion of mature herring in an age group is estimated as it's proportion in the spawning stock while maturing (at 3, 4 and 5 years) relative to it's proportion of mature fish in the spawning stock when fully recruited (mean proportion at 6, 7 and 8 years). The length at maturity for an age group is calculated as follows. The length distributions of the recruiting yearclasses while still maturing is back calculated from the length distribution of the fully recruited age group (at 6, 7 or 8 years). To find the length at maturity, the relative proportions of mature fish in the early age groups are used directly in these length distributions assuming the maturation to be length dependent. According to the growth rates of the different year-classes, the age at maturity vary from 3 to 5 years in the investigated period. However, the length at maturity is found to be fairly constant. dc.language.iso eng no_NO dc.publisher ICES no_NO dc.relation.ispartofseries ICES CM Documents;1986/H:42 dc.subject herring no_NO dc.subject sild no_NO dc.subject maturation no_NO dc.subject modning no_NO dc.title Length and age at maturity of Norwegian spring-spawning herring for the year-classes 1959 -61 and 1973 -78 no_NO dc.type Working paper no_NO dc.subject.nsi VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921 no_NO dc.subject.nsi VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fish health: 923 no_NO dc.source.pagenumber 8 s. no_NO
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