A Management Strategy Evaluation of Harvest Control Rule Performance

In the revised National Standard 1 under the Magnuson-Stevens Fishery Conservation and Management Reauthorization Act (MSFCMRA 2006), the Statistical and Scientific Committees (SSC) of each of the eight regional management councils have been tasked with recommending acceptable biological catch (ABC) that will prevent overfishing.  A number of harvest control rules exist, and new rules have been developed in response to the new legal mandate to prevent overfishing, but it is not understood how these control rules perform relative to one another, nor is it clear how uncertainty in the status of a stock affects the risk of overfishing associated with a particular control rule.  We performed a management strategy evaluation (MSE) of several F-based harvest control rules currently in use (or in development) by the regional management councils, as well some catch-based rules that may be used when information is limited.  The operating model included recruitment stochasticity and measurement error in stock status, resulting in imperfect knowledge of stock status and associated biological reference points.  In measuring the performance of a particular ABC rule we considered a number of management (e.g. minimizing the risk of overfishing) and fishery objectives (e.g. a high, steady catch), and identified the trade-offs in meeting these objectives for a particular control rule.  Preliminary results suggest there is considerable variation in the performance of different ABC control rules, and that there are often important trade-offs among objectives.  For example, some risk-averse control rules result in a low probability of overfishing, but also had large inter-annual changes in the ABC, which may not be desirable to many stakeholders.  Our work suggests that care is needed when selecting a particular ABC rule because not all objectives can be met with any single ABC control rule.