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common pool of larvae, distributed proportionately into reserve and nonreserve areas. The value of the reserve depends on the redistribution of fishing effort into the nonreserve area and the level of fishing pressure.

Multispecies and Trophic Models

A great majority of marine reserve models focus on the population dynamics of single species. Even though they are complex in their treatment of fishing mortality rates and population subdivision, in most cases, the population size of only one species is considered. Recently, trophic simulations based on the Eco-Path model have begun to incorporate fishery reserves (Walters et al., 1997). Such models try to estimate the impact of reserves on biomass at all trophic levels in an ecosystem, by estimating the flow of biomass from one trophic level to the next with and without fishing pressure. So far, these models do not allow a complex mosaic of fishing efforts and do not include terms to describe the connectivity among different marine populations. They also focus on biomass rather than number of individuals or individual size, so the relationship between these results and typical fishery theories is not yet well known. However, it is clear that single-species models, no matter how complex they are in habitat structure and dispersal capacity, will not capture the community-wide effects of reduced fishing pressure and that efforts to develop multispecies models are one of the next frontiers in modeling the biological properties of marine reserves.



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