Potential effects of marine spatial regulations on the Florida snook fishery

Background/Question/Methods Much scientific literature on the effects of marine protected areas is devoted to the potential benefits of small protected areas within a large overfished stock. The reverse idea, remediation of small overfished areas within a large sustainably managed stock, seems of less immediate concern. However, this scenario is of potential interest in recreational coastal fisheries where the spatial distribution of fishing activity may lead to high local mortality. With many aspects of the management of coastal recreational fisheries being the responsibility of local agencies, government organizations and stakeholder groups, it is important to understand the potential benefits, uncertainties and caveats of local interventions in fisheries management. We look for evidence of local depletion in the Common Snook, a coastal recreational fishery in Florida that is not generally considered overfished, but subject to high local fishing pressure, and use a spatially explicit age-structured population simulation model to test the potential impact of fisheries closures in such areas.

Results/Conclusions

Our simulations show that fish within the closed area will grow to a larger size and attain a higher abundance, assuming that movement is negligible, which is an expected result consistent with general fisheries management and experience with Marine Protected Areas. The increase in spawning biomass within the closed area is attributable not only to a longer lifespan but also to the age-dependent sex change found in this species. Dispersal from the closed area does not lead to additional recruitment outside the closed area unless dispersal of effort leads to a very high increase in mortality outside the protected area. Our simulations also indicate that local depletion may be wrongly attributed to excessive fishing pressure, and that changes in the fishing mortality alone may not lead to the desired recovery. Where local depletion is due to a combination of excessive fishing pressure and low recruitment, closures combined with habitat restoration appear promising.