00000nam 2200000za 4500 9.806277 CaOODSP 20221107135845 cr ||||||||||| 150406s2000 oncd ob f000 0 eng d CaOODSP eng eng fre n-cn--- Fs70-1/2000-155E-PDF Schnute, Jon. Estimating stock biomass from tow-by-tow data for Pacific groundfish [electronic resource] / J.T. Schnute, R. Haigh. Ottawa : Fisheries and Oceans Canada, 2000. ii, 32 p. : fig., graphs, tables. Canadian Stock Assessment Secretariat research document, 1480-4883 ; 2000/155 Includes bibliographic references (p. 11-12). This paper describes an analytical technique for estimating groundfish biomass from swept area density measurements. Conceptually, the idea is simple. Tows give estimates of biomass density. Bathymetry, locations of fish capture, and other sources of information give estimates of habitat area. Multiplying the density by the area gives an estimated biomass, which might be interpreted as an absolute measure or a relative index. A rigorous description of the method is presented, along with a bootstrap technique for assessing uncertainty. Illustrations from Pacific groundfish commercial fisheries and research surveys demonstrate various limitations and advantages to this approach. The analyses highlight issues of scientific importance, such as the need to obtain better habitat definitions. Comparisons between surveys and commercial fisheries provide some insight into the underlying processes. Despite their limitations, biomass estimation methods play an important role in groundfish stock assessment. Patterns in the analysis of a particular data set may reflect a variety of factors, such as biomass trends, response by fishermen to regulation, and measurement error. gccst Fisheries resources gccst Salt water fish gccst Biomass gccst Fisheries management Haigh, Rowan, 1959- Canada. Department of Fisheries and Oceans. Canada. Canadian Stock Assessment Secretariat. Canadian Stock Assessment Secretariat research document, 1480-4883 ; 2000/155 (CaOODSP)9.507740 PDF 695 KB https://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-1-2000-155-eng.pdf