A Spatial Model of the Mixed Demersal Fisheries in the Eastern Channel

Abstract

In the Eastern Channel, a diversity of fleets targets a large variety of species with various gears. The complexity of the fishery makes it difficult to develop and predict the effects of the new management measures promoted by the new Common Fisheries Policy, in particular harvest control rules and landing obligation. The evaluation of the impact of these new measures on fishing activities and resources requires a model which can capture the main features of the fishery. Here, we conduct an analysis of the Eastern Channel demersal fishery to collect information and identify the important aspects that need to be included in the model. The analysis shows the importance of six main species restricted to the Eastern Channel in the French demersal fleet’s revenues: scallops, sole, plaice, red mullet, squid, and cuttlefish. Landings are very mixed which does not allow the identification of a main target species at the fishing trip level. We also noticed a strong spatial structuration of effort in space, mainly due to the characteristics of the boats and the distribution of fish. Effort is also structured in time because of the seasonality of species and of management constraints. The spatially and seasonally explicit model ISIS-Fish is consequently chosen to integrate this information and to allow simulating the evolution of the fishery under a new management regime. The spatial resolution and the definition of the fleets are selected in accordance with the results of the descriptive analysis. Métiers are described and catchability parameters are assessed. Spatially explicit population dynamics models are developed for each of the six species. Finally, a fishing behavior model is proposed to allow predictive simulations to account for changes in species distribution, management, and economic conditions.