ABSTRACT
I used the Pacific Salmon Commission Chinook Model to help define equivalent exploitation rate reduction policies for endangered Snake River fall chinook salmon Oncorhynchus tshawytscha. This stock is harvested in gauntlet fashion by a number of mixed-stock fisheries from Alaska to California. The overall exploitation rate on Snake River fall chinook can be reduced by various means, each having different economic consequences for the individual fisheries. I consider eight general types of policies. Four reduce harvests in single geographic regions: Alaska, British Columbia, Washington, and Oregon ocean fisheries, and the Columbia River. Two policies reduce harvests in all regions in equal or scaled amounts, and two policies reduce harvests only in U.S. waters by equal or scaled amounts. Scaled policies reduce each fishery’s legal harvests in proportion to that fishery’s estimated share of the total adult equivalent fishing mortalities of Snake River fall chinook during the period 1979–1993. Policies are deemed equivalent when the overall adult equivalent exploitation rate on Snake River fall chinook is reduced by the same percentage. Under equilibrium conditions equivalent policies are shown to be independent of assumptions about Snake River fall chinook productivity, thus eliminating a major source of uncertainty in recovery planning. The methodology described in this chapter can be incorporated into recovery plans for other depressed fish stocks.
