Evaluation of harvest control rules: simple one-parameter vs. complex multi-parameter strategies
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Harvest control rules (HCR) are sets of well-defined rules that can be used for determin-ing annual fish catch quotas. If a management policy can be expressed as a HCR, then the HCR provides means to determine the total allowable catch unambiguously. In order to improve certain aspects of the performance for these rules, rules of increasing complexity have been suggested for fish stocks both in Europe and in North America. But is this complexity necessarily better? Are simple strategies outdated? “Traditional” harvesting strategies (i.e. constant harvest rate, fixed quota and constant escapement strategies) are simple HCRs with only one control parameter (i.e. target harvest rate, catch and escape-ment, respectively). “Complex” harvest control strategies are here defined as a multi-parameter HCR. In this study, three criteria (average catch and its coefficient of variabil-ity and risk of population abundance below a minimum acceptable level) are used to judge the performance of traditional and complex HCRs, utilizing a set of stochastic age-structured population models that mimic dynamics of fish populations. The traditional and complex HCRs are then evaluated against each other, paying particular attention to the trade-offs among the performance criteria.
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