Résumé
We developed ISIS-Fish V2.0, a simulation tool aimed at evaluating the impact of spatial and seasonal management measures on the dynamics of mixed fisheries. ISIS-Fish V2.0 is generic software that elaborates on the previous version by explicitly considering and modeling the short-term economics dynamics of mixed fisheries. Effort allocation may be altered through fishers behaviors, which depend on economic conditions, management options implemented, and other factors influencing fishers decisions. Economic conditions are modeled through short-term cost and revenues. Decision rules and other endogenous behaviors may be modeled through a Script language that is integrated in ISIS-Fish V2.0. Statistical simulation designs coupled to linear models are defined to run simulations and quantify the impact of management scenarios on fishery dynamics. An application of ISIS-Fish V2.0 to a demersal mixed fishery of the Bay of Biscay is proposed. This fishery is actually managed through mono-specific-TAC, minimum-landing sizes, mesh size, and fishing ban for large boats within the 12 miles area. All these management measures are inefficient to protect the main target species, Nephrops, Hake, Anglerfish and Megrim. Since several years, spatial closures of the nephrops area and the hake nursery have been envisaged. We propose to assess this management measure and to compare it to traditional ones.