An increasingly popular fisheries management tool, marine protected areas (MPAs or marine reserves) offer an alternative to traditional fisheries management practices such as effort or catch regulations. Studies have shown that MPAs, areas of the ocean where fishing is prohibited, may attain multiple goals simultaneously including maintaining populations and increasing fishing yield. In this study we focus on the second goal, maximizing fishing yield for a mobile species, and compare these reserves with reserves designed simply for persistence of a species. We develop a model of a species with logistic growth and Fickian diffusion that includes spatially-dependent harvest rates.
Results/Conclusions
For a given harvest rate, we find the reserve size that produces the maximum sustainable yield. The optimal size of the reserve increases with habitat size, although the percentage of habitat in reserve decreases with increased habitat size. The optimal size is more sensitive to natural growth rate and less sensitive to fishing pressure, especially for high fishing rates. For higher fishing mortality rates, smaller reserve sizes maximize fishing yield. We compare results from this model with results from a similar model that determines the minimum reserve size for the species to persist. For species with high growth rates or low fishing mortalities or very large habitat sizes, the reserve size that maximizes fishing yields is much larger than is needed for the species to persist. These results also suggest that smaller reserves designed using persistence as a metric may lead to significantly smaller yields.