Résumé
Many fish and crustacean stocks in the Bay of Biscay suffer from over exploitation despite the application of quota regulations. Among the reasons put forward to explain this management failure, the two main are the single species approach and the choice of a constraint on outputs of the fishery system instead of a constraint on inputs, e.g. fishing effort limitation. The establishment of such fishing activity regulation requires taking into account spatial and seasonal heterogeneities of the populations and fishing activity distributions to achieve a sustainable level of exploitation. In this regard, several alternative management measures to quota regulations such as marine protected areas (reserve, spatial restriction to non selective gears, closed area during the reproduction season), should prove more efficient. Various options of protected areas have been under discussion in recent year, but none was implemented due to lack of convincing analyses of consequences. The purpose of this paper is to compare the impact of different options on the dynamics of the mixed Hake and Nephrops fishery in the Bay of Biscay. We carry out this assessment using ISIS-Fish, a simulation tool of mixed-fishery dynamics aimed at evaluating the impact of spatial and seasonal management measures. This requires to parameterize the populations' dynamics, the fishing activity dynamics and the fishers' reactions to management measures. First, we review the existing parameters and estimate the missing ones. Then, we perform a numeric simulation to measure the sensitivity of simulation results to various parameters and to test several hypotheses regarding fishers' reactions to the simulated marine protected areas.