Research Document 1997/137

A discussion paper on reconciling assessment and management of inshore rockfish

By A.R. Kronlund

Abstract

An integrated assessment and management strategy for inshore rockfishes (Sebastes) has eluded biologists and managers along the west coast of North America. Rockfishes are characterized by longevity, low natural mortality, and restricted mobility of adults relative to the capabilities of fishing fleets. A directed hook and line fishery for inshore rockfishes has become significant in British Columbia since the early 1980s, capitalizing particularly on the lucrative market for live fish.

The primary purpose of this paper is to propose a means of reconciling the difficulties of rockfish assessment with the demands of fishery management. Traditional fisheries models are rendered inadequate by discrepancies among the scales of biological processes for rockfishes, the activities feasible for assessment, and the pattern of exploitation. Key to this dilemma is a misunderstanding of the planning horizon required to manage populations that may cycle a single generation during the working career of fisheries biologists. Pragmatic simulation modeling is suggested as a basis for resolving the problems of (1) reconciling the time lag between application of a management tactic and realization of its effects, (2) communication among biologists, managers, and stakeholders, and (3) learning about the consequences of experimental manipulation given model assumptions.

In order to provide context for the proposed simulation modeling, the problems associated with assessment and management of inshore rockfishes are reviewed. A brief account of the history and current status of the directed hook and line fishery for rockfishes in British Columbia is presented, along with a description of available data. Removals of inshore rockfishes by other fisheries and as incidental catch are outlined. Assessment methods applied to inshore rockfishes along the west coast are reviewed. Recommendations are provided that revolve around a combination of large and small scale experiments, based on the results of simulation modeling. In order to refine the assumptions in simulation, increased research priority on rockfish life history is recommended. The evaluation of stock indices that explicitly incorporate life history (e.g. reproductive value) should be conducted in simulation and field research. Stakeholder involvement in planning experimentation and ongoing review of objectives is considered key to successful implementation of the simulation results.

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