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 lobs ter (Panulirus argus) in Exuma Sound Bahamas, was used to investigate the j oint effects of marine reserve design and larval dispersal via hydrodynamic currents on an exploited benthic invertebrate. The effects of three hydrod ynamic scenarios tone diffusion-only and two advection-diffusion cases), on e 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 o ver broad spatial scales; in contrast, the advection-diffusion scenarios re presented realistic hydrodynamic patterns and :introduced broad spatial var iation. Both advection-diffusion scenarios were based on empirical measurem ents of near-surface flow in Exuma Sound. Catches were sensitive to interac tions between reserve configuration and pattern of larval dispersal. A give n reserve configuration led to enhancement or decline in catch, depending o n the hydrodynamic scenario, reserve size, and reserve location. Larval pro duction increased linearly with reserve size, when size was expressed as th e population fraction initially protected by the reserve, but when reserve size was expressed as the fraction of coastline protected, larval productio n decreased for some reserve configurations under the two advection-diffusi on hydrodynamic scenarios. Use of a simple reserve-design rule (e.g., prote ct 20% of a coast) would in the latter cases, lead to a false sense of secu rity, thereby endangering-not protecting-exploited stocks. The optimal desi gn of marine reserves therefore requires attention to the joint effects of larval dispersal, reserve location, and reserve size on fishery yield and r ecruitment.