The latest population of European sturgeon a diadromous fish is known to reproduce in the Gironde Garonne Dordogne river basin. Young sturgeons migrate downstream through the Gironde estuary. Their life cycle depends on this essential area. This endangered species is stricktly protected in Europe but french gravel extraction projects threat the integrity of the Gironde estuary. So, speedy special conservation areas have to be taken. Studies shown the existence of two zones of high densities in sturgeons distant 20 km from each other. The fist one is located in the oligohaline sector and the second one in the polyhaline sector. In order to determine what kind of factors are involved in such a distribution, we decided to study the feeding behaviours and locations of these fishes.