To understand the trophic functioning of continental shelves, it is necessary to evaluate the factors that drive production at different levels. For bentho-demersal fish, one such factor is spatial variability in the biomass of their macrobenthic prey. In this study, we investigated the distribution of the macrobenthos in the northern part of the continental shelf of the Bay of Biscay in order to determine how variability in these prey resources might affect the bentho-demersal fish that feed on them. Due to the scarcity of available field data, an empirical graph model and a biochemical model were used to produce different indices of macrobenthic biomass, which were then used to generate three maps illustrating the distribution of this biomass in the Bay of Biscay. In general, values from these maps showed high Spearman correlations with the limited data available, but also discrepancies at greater depths where field data are quite poor. Globally, a pronounced decline in macrobenthic biomass was observed from the coast to offshore, but with particularly high values in deeper muddy sediments. Among eight fish species analyzed, the four most known for their strongly benthivorous diet demonstrated positive relationships between body condition and the macrobenthic biomass indices, with the strongest associations detected for smaller-sized fish. This suggests that biomass index maps may be i) indicative of the availability of benthic prey at the level of the continental shelf along a major coastal-offshore gradient, and ii) useful for studying spatial variability in the transfer of energy or matter along the food chain within this ecosystem. However, there is a clear need for macrobenthic data from field surveys at the shelf scale, notably in deep circalittoral areas, to confirm or improve the accuracy of the spatial biomass trends estimated by models.