Predicting the Response of the Macquarie Island Patagonian Toothfish Population to Fisheries Management Strategy Using a Simulation Approach
The Macquarie Island fishery for Patagonian Toothfish is managed uner sets of pre-agreed rules for selecting management actions based on the annually assessed population size. These actions are implemented in the hope of achieving specified management objectives. The components of the management strategy are:
• The management objectives,
• the sampling program,
• the assessment and
• decision rules that translate the data from the sampling program and information from the assessment into an annual Total Allowable Catch (TAC).
A management strategy evaluation (MSE) is applied to the toothfish fishery at Macquarie Island using data collected up to 2006. Many of the uncertainties about the dynamics of the population can be incorporated into the simulation framework by outlining alternative population dynamics assumptions under differing operating model scenarios. The resource and fishery dynamics are simulated from 1995 and projected through to 2040 using the operating model to represent the future ‘true’ dynamics of the system. Alternative feedback management strategies can then use the annual estimated current status to set catch quotas. For each management strategy and model scenario the future of the fishery is predicted several hundred times using Monte Carlo simulation and a range of performance statistics is produced.
The performance statistics are tabulated to provide a summary of the performance of each particular management strategy and model scenario. These summaries provide a means of comparing alternative management performance against competing management objectives and allowing for uncertainty in population dynamics. Results suggest that it is possible to find satisfactory management strategies that are robust across the uncertainties in the population dynamics of Macquarie Island Patagonian toothfish.