Multi-objective assessment of conservation measures for the European eel (Anguilla anguilla): an application to the Camargue lagoons

The European eel (Anguilla anguilla) stock has declined since the early 1970s and is presently considered outside safe biological limits. The European Commission proposed a regulation (COM 2005/472 final) to establish measures for the recovery of the stock, with the aim to achieve the escapement to the sea of a 40% of adult eel biomass (with respect to undisturbed conditions) from each river basin. The proposed regulation imposes an effective reduction of fishing activities until implementation of an approved eel management plan. We use a demographic model, explicitly accounting for age, length and sex structure and for the peculiar features of the continental phase of eel life cycle, to assess the effectiveness of the regulation proposal. We explore alternative management options with reference to the Camargue (Southern France) eel population. Using multi-criteria methods we compare different fishing policies with respect to two potentially conflicting objectives: preserving a sufficient spawner escapement and guaranteeing an acceptable harvest to fishermen. We show that the current fishery is inefficient and that appropriate management policies (like limiting the fishing season and increasing the mesh size of the fishing gears) are likely to have a doubly positive effect, by achieving the conservation target of the regulation and increasing fishermen revenues.