Single large or several small marine reserves for the Caribbean spiny lobster?

Abstract

The ‘SLOSS’ debate—Single Large Or Several Small protected areas—remains unresolved. We used a heuristic model based on population dynamics of Caribbean spiny lobster in Exuma Sound, Bahamas, to compare impacts of regional reserve designs that configured 20% of available coastal habitat as either a randomly located single large reserve or a network of six small, randomly located reserves on three performance indicators (fishery yield, larval production, population growth rate) for a hypothetical overexploited lobster population. Two additional management strategies were considered: one reduced effort by 20% (without protected areas), and one did nothing. Effects were evaluated for two levels of hydrodynamic variability. In general, performance indicators ranked the management strategies, independent of hydrodynamic variability, from best to worst in the order (1) single large reserve (2) several small reserves (3) reduced effort (4) no management action, but differences were not always significant. Therefore, for the model regional system investigated here, a single large reserve is preferable to several small ones. We propose that this conservation strategy is most suitable at the regional scale (~100s of kilometres) and that such single, large regional reserves would function most effectively within a broadscale (~1000s of kilometres) reserve network, barring local catastrophes.