Studying the manner of sturgeon fishes migration to Gorganrud and Tajan rivers

One year study was carried out to understand the sturgeon fish’s migration to Gorganrud & Tajan Rivers from September 1993. Two different catching stations were selected in each river with gillnetting method. The fish were assessed biometrically, labelled and released afterwards the catching was done during Autumn and Spring and no fish was captured in Autumn, but 28 fishes (10 fishes of Acipenser stellatus + 15 fishes of Acipenser persicus + 3 fishes of Acipenser gueldenstaedtii) in Gorganrud and 11 fishes (2 fishes of Acipenser persicus + 9 fishes of Acipenser stellatus) were caught during the catching period, in spring. The result showed that among the labelled fishes at the station NO. 1 in Gorganrud, only 2 labelled fishes were recaptured in the Station No.2 (8 kilometers away from each other). The rest and all the labelled fishes in Tajan River were caught before reaching to the station No.2 by unauthorized fishermen. The main obstacles to sturgeon fish’s migration in both river are: Poaching, Gillnetting near the river estuary and Contamination