Decision Analysis of a Large-Scale Fishing Experiment Designed to Test for a Genetic Effect of Size-Selective Fishing on British Columbia Pink Salmon (Oncorhynchus gorbuscha)

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Abstract
Past work suggested that size-selective harvesting of large fish combined with heritability of body size has caused the large (up to 34%) decrease in mean adult weight of British Columbia pink salmon (Oncorhynchus gorbuscha) since 1950. In a companion paper (Can. J. Fish. Aquat. Sei. 49: 1294–1304) we evaluated the statistical performance of a large-scale fishing experiment that could enable managers to test this hypothesis and at the same time increase catch biomass if that hypothesis were correct. In this paper we evaluate the economic performance of the proposed experiment using Monte Carlo simulation and decision analysis under a wide range of conditions that encompasses existing biological uncertainties. We accounted for uncertainties through prior probabilities placed on two key biological hypotheses. We computed the expected economic value of catch biomass for the experimental and current nonexperimental (status quo) management strategies using a 20-yr time horizon and a 10-yr experiment with four spatial replicates. Under a variety of discount rates, the expected economic value of experimentation exceeded that of status quo management in most of the conditions examined, in some cases by as much as 60%.