An update biomass index of abundance for north atlantic swordfish 1963-2008
2010
Ortiz-de-Urbina-Gutiérrez, José María | Mejuto-García, Jaime | Paul, Stacey | Yokawa, Kotaro | Neves, N. | Idrissi, M.H.
Non age-structured production model analyses of North Atlantic swordfish have been used in addition to age structured virtual population analyses by ICCAT's SCRS to evaluate the status of the resource and to provide a basis for management advice. Production models require a standardized index of relative abundance in terms of biomass. The fleets combined standardized biomass index of abundance developed for the 2006 ICCAT-SCRS meetings for north Atlantic swordfish was revised and updated with data through 2008. Generalized Linear Modeling (GLM) procedures were used to standardize swordfish catch (biomass) and nominal effort (number of hooks) data from longline fleets from the United States, Spain, Canada, Japan, Morocco and Portugal. As in past analyses, main effects included: year, area, quarter, a nation-operation variable accounting for gear and operational differences thought to influence swordfish catchability, a target variable to account for trips where tunas and/or sharks were predominant in the catch or potentially also targeted, and interaction terms for year* area
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