The Caspian Sea is one of the most significant lakes of the world that produces 90% of the world's caviar and is thus popularly known as the Sea of Black Pearls. During the upper Miocene period about 17 million years ago this sea was considered a Samartian basin. About 6 million years ago the Samartian basin was converted into the Black Sea and Pannonian Sea as a result of tectonic processes. Three million years ago during the mid Miocene period the Black Sea and Caspian Sea separated from each other. Today it is about 15 thousand years since the Caspian Sea has turned into a closed water body (Klige and Myagkov, 1992). The biodiversity of the Caspian Sea includes 854 species of animals and more than 500 species of plants. Fishes are considered the commercially valuable species of this sea. The aquatic species of the Caspian Sea are divided into three groups: freshwater, brackish water and marine species. The marine species have three origins. Some of these species have found their way to the Caspian Sea from the Black Sea (Zenkevitch, 1963) and include animal species (belonging to 374 genera), 538 plankton species (belonging to 30 genera), 170 parasitic species (belonging to 67 genera) and 23 aquatic species (belonging to 14 genera). Several marine species of the Caspian Sea have originated from the Azov, North and Arctic Seas. The fishes of the Caspian Sea belong to 65 genera and 21 families of which 114 species, 35 sub species and 13 races have been identified (Zenkevitch, 1963). The family Gobiidae that includes 27 species consists of the maximum number of species. The family Cyprinidae is made up of about 19 species. On the whole about 25 species of the Caspian Sea are economically important and are exploited commercially.

In general it is supposed that chondrosteans as a group originated in the freshwater basin of northern Asia in early Triassic from ancient ancestors belonging to the paleoniscoid fishes (Berg, 1948; Schaeffer, 1973; Yakovlev, 1977) and acipenserids became widespread in the Northern Hemisphere in the late cretaceous era (Grande and Bemis, 1991).