Slope rockfish assessment for the west coast of Canada in 1999 / J.T. Schnute, N. Olsen, and R. Haigh. : Fs70-1/1999-184E-PDF

This year's report does not provide a new assessment, but rather a series of steps essential for future assessments, based on industry-sponsored surveys for slope rockfish. The research follows a strategic plan for collaborative work with the groundfish industry. The report presents the latest available data and makes the following major advancements on past work. First, a bathymetric database has been developed, cross-referenced with the observer data, from which bottom area available to fishing as well as actual bottom areas swept and impacted can be calculated. Estimates of biomass for each slope rockfish species have also been provided by extrapolating observed estimates of density at depth to all available coastal bathymetry. Second, in collaboration with the Canadian Groundfish Research and Conservation Society, the development of an industry-sponsored slope rockfish survey has been initiated, independent of the fishery. To date, maps have been developed that record fishermen's impressions of trawl characteristics of the ocean floor. These classifications and preliminary estimates of fish density provide essential prior information in designing a survey that minimizes the variance of biomass estimates for a given level of available resources. Third, biological data has been used to calculate rough estimates of key reference points for the slope rockfish species. The report presents the complete mathematical framework for calculating reference point values from underlying biological parameters.

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