The European Sturgeon (Acipenser sturio) is a critically endangered species and the last population is located in the Gironde Dordogne Garonne system (South west of France). Since autumn 2007 a European restoration plan on this species has been adopted under the aegis of the Berne convention. Thanks to recent successful assisted reproductions, more than 90 000 larvae were stocked in this system in 2007 and 2008. In this context field experiments were initiated in 2008 to assess stocking success and to document fish spatial behaviour and habitat use. Different methods and techniques are implemented to achieve these goals. Trawling sampling in the estuaries is planned to estimate fish abundance and to locate their habitats. Telemetry studies were initiated in 2008 and in 2009 to document individual movement patterns and habitat use. Knowledge acquired from these experiments is intended to bring a help to the management programme and to the conservation of this species.