The changes of Russian sturgeon stocks in the southern Caspian Sea was studied by measuring and considering different population parameters such as fish length, weight and age and also fluctuation of catch and catch per unit effort. Amount of catch and biomass showed an descending trend during last 3 decades. In 1971-72 catch and CPUE of Russian sturgeon had been 837 tons and 602 kg/boat/day and was decreased up to 57 tons and 0.34 kg/boat/day in 1999. The abundance of young fishes was decrease during last decade and older fishes have been dominated at present. Because of a sharp decrease of sea ranching of Russian sturgeon fingerlings and consequently decrease of young fish abundance, therefore it is predicted that amount of catch will be considerably declined in the future.