Research Document - 2010/105
Assessment Framework for Sea Cucumber (Parastichopus californicus) in British Columbia
By N.M.T. Duprey, C.M. Hand, J. Lochead, and W. Hajas
Abstract
The Pacific sea cucumber (Parastichopus californicus) fishery in British Columbia has been undergoing a rigorous period of data collection, analysis and review since 1995, with the objective of developing a biologically-based stock assessment program and risk-averse fishery management. Here we describe how sea cucumber stocks were historically assessed and document how current assessments are carried out. Methods and protocols for estimating sea cucumber densities for both surveyed and unsurveyed areas of the coast, and for calculating mean weight estimates, are described. Procedures for measuring and calculating shoreline length are described, along with conventions for applying baseline densities to differing classes of shoreline exposure. The precision and accuracy of density estimates is presented, with a comparison of the accuracy of two different methods of calculating density; linear and spatial. The new harvest rates, modelled from the results of the long term Experimental Fishing Areas (EFA) data are reviewed, as well as the recommended Limit Reference Point of 50% Bo. Reserves, or no-take areas, are discussed in detail especially in regards to the sea cucumber fishery and to future development of a network of reserves throughout the British Columbia coast. Research and stock assessment needs are listed, including defining the priority for future surveys, determining the optimal sample size for density estimation, developing methods to include error in shoreline length and cucumber weight estimates into biomass calculations and investigating recruitment and re-colonization dynamics. Finally, recommendations to fishery managers are made regarding the fisheries in low-density areas fisheries in non-productive areas.
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