Using an ecosystem modeling approach to assess the management of a Mexican coastal lagoon system

The Huizache-Caimanero coastal lagoon system supports an economically important artisanal shrimp fishery and a less valuable finfish fishery. We analyze the response of the fisheries and the ecosystem to changes in fishing effort. To do this we use Ecosim - a dynamic version of Ecopath, which is a steady-state model emphasizing natural rates of growth and consumption of marine populations. We examine changes in each group's biomass and determine which fishing strategies optimize yields on the basis of economic, social, and ecological criteria. We find that two of the four exploited fish groups, centropomids and gerreids, are underutilized; the other two, ariids and mugilids, are near the maximum sustainable yield. We find that the shrimp resource is overexploited. Our simulations suggest that the optimal management strategy occurs with a small increase in effort in the finfish fishery (1.24 times) combined with a small reduction of effort (0.8 times) in the shrimp fishery. This strategy enhances fishery yields of centropomids and gerreids, thereby decreasing the biomass of finfish and resulting in fewer (lower biomass of) shrimp predators. Simulations suggest that applying the optimal fishing strategy increases economic profits by ten percent.