A probability-based approach to setting annual catch levels

The Magnuson–Stevens Fishery Conservation and Management Reauthorization Act of 2006 (MSRA) requires that each Fishery Management Plan in the United States “establish a mechanism for specifying annual catch limits . . . at a level such that overfishing does not occur in the fishery . . .” (MSRA, 2006). This requirement, which ref lects an increased emphasis on conservation, is new in the sense that prevention of overfishing is mandated to be through annual catch limits (ACLs), rather than only through such less restrictive measures as trip limits, size limits, or days allowed at sea. Because the statute requires ACLs to be implemented by 2011 in all fisheries (by 2010 for fisheries where overfishing is occurring), discussion has begun on ways to compute them. Accompanying the discussion of ACLs is the discussion of corresponding annual catch targets (ACTs), levels of catch set as quotas in the fishery. In this study, we propose a method for setting annual catch levels that are treated as targets, but equally well could serve as limits. The method is based on stochastic projection with uncertainty in population dynamics. It extends usual projection methodology by including uncertainty in the limit reference point and in management implementation, and by making explicit the overfishing risk that managers consider acceptable. This probabilistic approach was devised specifically to satisfy the U.S. statute, but we expect it should be A probability-based approach to setting annual catch levels