00000nam 2200000za 4500 9.805565 CaOODSP 20221107135700 cr ||||||||||| 150406s1999 oncdb ob f000 0 eng d CaOODSP eng eng fre n-cn--- Fs70-1/1999-168E-PDF Tanasichuk, Ronald W. Natural mortality rates of adult Pacific herring (Clupea pallasi) from southern British Columbia [electronic resource] / R.W. Tanasichuk. Ottawa : Fisheries and Oceans Canada, 1999. 34 p. : fig., graphs, maps, tables. Canadian Stock Assessment Secretariat research document, 1480-4883 ; 99/168 Includes bibliographic references (p. 11-12). Data for over 904000 Pacific herring (Clupea pallasi) seined or gillnetted in British Columbia between 1951 and 1998 was used to estimate age- and year-specific adult natural mortality rates. Apparent sampling bias precluded using data for all stocks before 1980 and for northern British Columbian stocks since then. For the southern (West Coast Vancouver Island, Strait of Georgia) stocks, the instantaneous natural mortality rate (M) for adult herring is an increasing exponential function of age. Surplus energy requirements for gonad recrudescence and overwintering appear to cause the death of adult herring. It was found that, based on an experiment using a hypothetical herring population and assessment model or regression estimates of M, the escapement model overestimates survival, relative to the age structured model and the predictive regression, for west coast Vancouver Island herring; the three mortality estimates generate similar abundance trajectories for Strait of Georgia herring. It is suggested that the described sampling bias be considered by herring stock assessment models. gccst Fisheries resources gccst Salt water fish gccst Fishing area gccst Fisheries management Canada. Department of Fisheries and Oceans. Canada. Canadian Stock Assessment Secretariat. Canadian Stock Assessment Secretariat research document, 1480-4883 ; 99/168 (CaOODSP)9.507740 PDF 435 KB https://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-1-1999-168-eng.pdf