Proceedings 2011/011

Regional Science Advisory Process on the Pacific Review of Yelloweye Rockfish (Sebastes ruberrimus); September 22, 2010

Chairperson: Greg Workman

Summary

A regional advisory process meeting was held September 22, 2010 in Nanaimo (BC) to conduct a science peer review of the status of the inside population of yelloweye rockfish (Sebastes ruberrimus) 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 of the inside population of yelloweye rockfish, primarily located in Groundfish Major Area 4B which encompasses protected waters to the east of Vancouver Island. Advice was requested on recommended limit reference point (LRP), upper stock reference point (USR) and target reference point (TRP), and the supporting rationale for their application to management of the inside yelloweye rockfish population. An assessment of the status of the inside population of yelloweye rockfish relative to recommended reference points was requested, as was an evaluation of the impacts of varying harvest levels on future population trends.

Population dynamics were modeled using two variants of a Bayesian surplus production model. The first model explicitly incorporated changes in predation of yelloweye rockfish by pinnipeds (PBSP), while the second formulation was a standard Bayesian surplus production (BSP) model without pinniped predation. Working paper results suggested that pinniped predation is a plausible cause of the decrease of this yelloweye rockfish population over the last few decades and constrains population rebuilding. Review of the working paper identified (i) problems in the definition and application of MSY-based reference points, and (ii) large uncertainties in pinniped diet and population index assumptions. Consequently, conclusions regarding the applicability of management advice were deferred pending re-assessment of data inputs, additional model sensitivity tests, and development of the MSY-based reference points in the presence of removals due to pinniped predation. The revised working paper will be re-examined via a regional advisory process in 2011.

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