Proceedings of the Pacific Region Science Advisory Process for Spiny Dogfish (Squalus acanthius) in British Columbia, Canada; May 17, 2010
Chairperson: G. Workman
A regional advisory process meeting was held May 17, 2010 in Nanaimo, British Columbia (BC) to conduct a science peer review of the status of spiny dogfish (Squalus acanthius) in British Columbia, Canada. The science review was conducted in response to a request from DFO Fisheries and Aquaculture Management (FAM) for advice regarding the current stock status and appropriate fishery reference points for the inside (Groundfish Management Area 4B) and outside (GMA 3C, 3D, 5AB, 5CDE) stocks. This species has recently been reviewed by the Committee on the Status of Wildlife in Canada (COSEWIC) and the fishing industry has expressed interest in pursuing eco-certification for the directed longline hook fishery.
A generalized Schaefer and Pella-Tomlinson surplus production model was applied to the inside and outside stocks to estimate the current biomass and equilibrium BMSY and FMSY reference points. Inputs to the models included annual landings data beginning in 1935 and discard data beginning in 1966. Available stock indices varied by stock but included catch per unit effort (CPUE) data available from the commercial longline hook and trawl fisheries. Fishery-independent indices included spiny dogfish CPUE derived from a targeted spiny dogfish longline hook survey, the Hecate Strait trawl survey, the International Pacific Halibut Commission longline hook survey, and the National Marine Fisheries Service trawl survey. A suite of 16 model fits was performed for each stock to evaluate the impacts of various choices of fixed or estimated leading parameters which included the intrinsic rate of increase, r, carrying capacity, K, and the shape parameter, m, of the surplus production model. Freely estimated parameters tended towards their upper constraint bounds in most cases for fits of the model to the outside stock data. Similar estimation behaviour was obtained for the intrinsic rate of growth parameter for the inside stock.
Model results suggested there is insufficient contrast in the stock index data to provide productivity and scale information for the two stocks when using a surplus production model formulation. Consequently the results of the modeling were not recommended as the basis for advice to fishery managers. Advice to fishery managers for the inside stock was provided based on average long-term catch history consistent with the Sustainable Fisheries Framework policy. No changes to current management for the outside stock were identified.
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