This work identifies and characterizes the zones of essential habitats for juveniles of Acipenser sturio in the Gironde estuary. It is also attempts to identify the reasons for sturgeons’ preferential habitat utilization. For this purpose, results from monthly surveys in the Gironde estuary carried out between 1995 and 2000, as well as telemetric surveys of 16 sturgeons in 1999, are used. Additionally, results from investigations on the diet of juvenile sturgeons, as well as biotic and abiotic characterization of habitat, are utilized. Three zones where sturgeon concentrate are distributed along a salinity gradient. They show common denominators in the subtidal area as far as depth, muddy or sandy sediment are concerned, and similar current velocity. These habitats constitute an important feeding ground rich in tubedwelling polychaetes (Polydora sp. and Heteromastus filiformis), which have been identified as the dominant prey items of European sturgeon juveniles.