Accuracy and Choice in Risk Estimation for Fisheries Assessment

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Abstract
Risk analysis has been used recently to enhance scientific advice to managers by providing estimates of risk to the fishery of different management strategies. However, little consideration has been given to the accuracy of these estimates. We present a reformulation and generalization of the risk analysis procedure of Francis (1992. Can. J. Fish. Aquat. Sci. 49: 922–930) and use simulation methods to examine the properties of a number of alternative risk estimators for two of New Zealand's main fisheries. It is shown that the choice of estimator can strongly affect the final estimates of risk and that the risk estimators can be alarmingly inaccurate. The accuracy of estimates is also shown to vary according to the type of risk being estimated, so analysts may improve the accuracy of their estimates by choosing the type of risk they estimate.