Sustainability and economic consequences of creating marine closed areas in a multi-species and multi-activity context

In response to the degradation of marine ecosystems, many scientists and managers support an ecosystem based approach to management. Two key components of ecosystem based management are moving from a single species approach to a multispecies approach and implementing spatial zoning, including marine reserves. The idea of marine reserves can be detrimental to good management if applied without considering other components of the system such as ecological interactions, economic factors etc. It is not at all obvious whether we should expect higher or lower yields, economic rents etc from an ecosystem than would be predicted from the application of single species yield policy. I assert that simple models, embodying the main driving mechanisms, often provide a valuable means of predicting broad-scale general trends in the dynamics. In this context, in the present talk, I would like to give a brief introduction of my present research and some impacts of marine reserves on the interaction between species, stock levels and yields, economic rents based on a simple mathematical model.