An improved knowledge of habitat utilization by demersal species is a pre-requisite for their spatial management. Based on scientific survey data collected over the period 1994-2010, the present study investigates relationships between 4 environmental factors and 10 demersal species in the Gulf of Lions (northwestern Mediterranean Sea). Generalized linear models provided statistically satisfying results in terms of both model explanatory and predictive powers. The 'biological zone' factors, based on the percentage of light penetration to the sea bottom and bottom temperature, were the most important factors, while sediments and benthic macrofauna were only significant for a few species. The type of associations varied among species, resulting in different spatial predictions among species. The spatial structures of species distributions appeared to be due more to habitat preferences that are spatially auto-correlated than to intra-specific population dynamics. The use of a spatial optimization procedure on the predicted species distributions allowed the detection of a set of 7 zones covering 17% of the studied region, that included at least 20% of each species' abundance and that reflected the diversity of the species' habitats. This preliminary result illustrates the potential of further analyses on Marine Protected Areas as a tool for the conservation of the demersal community in this region.