When Do Marine Protected Areas Pay? An Analysis of Stylized Fisheries
Harold F. Upton and Jon G. Sutinen
Abstract. In this paper, we analyze the bioeconomic consequences of using marine protected areas (MPAs) to manage fisheries. Marine protected area proponents assert that the potential benefits of MPAs include larger population biomass and associated fishery harvests. Most analytical models have considered only direct changes in harvest patterns resulting from decreases in fishing mortality following establishment of an MPA. Yet recent studies show that mobile fishing gear can decrease fish habitat complexity and alter benthic species composition. Protection of the services provided by the environment in which fish live, grow, and reproduce may be the most important fishery benefit associated with MPAs. Our main objective is to examine the conditions under which MPAs are likely to increase net benefits. Our analysis is based on a stylized bioeconomic model in which fishing has an impact on fish habitat. We examine two distinct sub-categories: (1) fishing effort that impacts the habitat of its target species, and (2) fishing effort that impacts the habitat of species targeted by other fisheries. The model incorporates the movements of the fish population between open and closed areas and the response of the fishing effort level in the area remaining open. Equilibrium stock, catch, and profit levels are compared for open access and the level of effort at which net revenue is maximized. Habitat effects are then incorporated and compared to cases where only stock effects occur. Sensitivity analysis was used to examine a wide range of fishing costs, MPA sizes, damage functions, and migration rates. Our model shows that consideration of habitat may be the main reason to use MPAs as a fishery management tool. The curvature of the habitat damage function is also shown to be an important factor when considering the potential use of MPAs.