Quantitative description of habitat suitability for the juvenile common sole ( Solea solea, L.) in the Bay of Biscay (France) and the contribution of different habitats to the adult population

Abstract

This study describes the spatial distribution of young-of-the-year sole based on autumnal beam trawl surveys conducted in the Bay of Biscay (France) during a 15-y period. Previous studies showed that habitat suitability for juvenile sole varies according to physical factors such as bathymetry, sediment structure and river plume influence. These factors, which are known exhaustively for the entire Bay of Biscay from static maps (bathymetry and granulometry) or temporal maps based on a hydrodynamic model (the river plume), were used as descriptors in a generalised linear model of habitat suitability in order to characterise the distribution of juvenile 0-group sole according to delta distribution. This model was used to identify the habitats in which juvenile 0-group sole are concentrated. The respective areas of these habitats were determined from a Geographic Information System (GIS), and their respective contribution to the sole population in the Bay of Biscay was calculated in terms of the estimated number of young fish (GIS area×density derived from the model). Despite the great variability of survey data, this quantitative approach emphasises the highly important role of restricted shallow, muddy estuarine areas as nursery grounds of sole in the Bay of Biscay and demonstrates the relation between interannual variations of nursery habitat capacity (with respect to estuarine extent) and sole recruitment.