During the whole 20^th century and especially in its second half, CaspNIRKH conducted regular studies of sturgeons in the basin: assessed their abundance and distribution in the sea, studied their feeding, growth, spawning, downstream migration of larvae and fingerlings. Many thousands of specimens were examined each year, fish from the control catch and commercial catches were analyzed. And for all those years, there were no cases of finding Siberian sturgeon or other species of this family unusual for the Caspian Sea basin either in experimental or commercial catches (Caspian Sea, 1989; Ivanov, 2000). Sturgeons in the Volga River and sea are studied, besides CaspNIRKH, by a number of research institutes of Russia and Caspian littoral states (Kazakhstan, Azerbaijan, Iran) that have never recorded Siberian sturgeon in catches either.

We have no reason to suggest that the caviar of Siberian sturgeon produced in Siberia can be sold through Astrakhan as that of Russian sturgeon to benefit commercially. Catches of Siberian sturgeon have always been rather small never reaching 100 tonnes since 1990 while in the past five years they may hardly have been more than 50 tonnes (Ruban, 1999).

Thus, the presence of caviar of Siberian sturgeon in batches of Russian sturgeon caviar supplied from Russia and, specifically, from Astrakhan is impossible. Siberian sturgeon was not seen in the Volga River which was witnessed by long-term data of regular investigations. Small quantities of sturgeons, mainly bester, have been reared in fish breeding farms. Catches of Siberian sturgeon have no practical commercial importance.