Two of the biggest challenges facing fisheries managers and policy makers are how to effectively manage multi-sector fisheries and how to design harvest strategies for fisheries with highly variable productivity. The ‘western’ snapper (Chrysophrys auratus) stock is Victoria’s most important finfish fishery, and harvesting occurs by both recreational and licensed commercial fishers. To add complexity, the stock’s productivity is highly variable, owing to the influence of biotic and abiotic features of the stock’s primary breeding grounds. These effects lead to large fluctuations in annual recruitment, and years later, to corresponding changes in the productivity of the fishery.
Here we describe the development of a Management Strategy Evaluation (MSE) framework built upon Stock Synthesis (SS3) and the ss3sim package in R, allowing for the exploration of multiple alternative harvest strategies. Tested strategies aim to balance total yield from the fishery, sustain the spawning biomass above some target reference point, and also deal with changes in productivity owing to highly variable recruitment success.
The MSE framework is an objective quantitative tool to help managers, policy makers, and other stakeholders understand the performance, implications, and trade-offs associated with alternative management strategies. This in turn aids the decision making process with regard to management controls that affect both the recreational and commercial aspects of the fishery, while still meeting the overall requirements of resource sustainability.