Joint effects of larval dispersal, population regulation, marine reserve design, and exploitation on production and recruitment in the Caribbean spiny lobster

A spatially explicit population-dynamics model for the Caribbean spiny lobster (Panulirus argus) in Exuma Sound Bahamas, was used to investigate the joint effects of marine reserve design and larval dispersal via hydrodynamic currents on an exploited benthic invertebrate. The effects of three hydrodynamic scenarios tone diffusion-only and two advection-diffusion cases), one exploitation level, and 28 reserve configurations (7 sizes x 4 locations) on catch and larval production were simulated. The diffusion-only scenario represented the condition in which settlement did not vary substantially over broad spatial scales; in contrast, the advection-diffusion scenarios represented realistic hydrodynamic patterns and :introduced broad spatial variation. Both advection-diffusion scenarios were based on empirical measurements of near-surface flow in Exuma Sound. Catches were sensitive to interactions between reserve configuration and pattern of larval dispersal. A given reserve configuration led to enhancement or decline in catch, depending on the hydrodynamic scenario, reserve size, and reserve location. Larval production increased linearly with reserve size, when size was expressed as the population fraction initially protected by the reserve, but when reserve size was expressed as the fraction of coastline protected, larval production decreased for some reserve configurations under the two advection-diffusion hydrodynamic scenarios. Use of a simple reserve-design rule (e.g., protect 20% of a coast) would in the latter cases, lead to a false sense of security, thereby endangering-not protecting-exploited stocks. The optimal design of marine reserves therefore requires attention to the joint effects of larval dispersal, reserve location, and reserve size on fishery yield and recruitment