PRESENT STATE OF ICHTHYOFAUNA OF MIDDLE AND LOWER STREAM OF THE RIVER SURA
It is shown that at the present time 39 species of fish inhabit the middle and lower reaches of the river Sura. After the construction of cascade of HPS on the Volga River and the river pollution a number of species disappeared from the fauna of the river. These include the Caspian lamprey Caspiomyzon wagneri, black backed shad Alosa kessleri, Russian sturgeon Acipenser güldenstädtii, whitefish Stenodus leucichthys leucichtys and beluga Huso huso, stellate sturgeon Acipenser stellatus and spiny sturgeon A. nudiventris. All the considered views rose to spawn from the Caspian Sea. However, during the XX century, in the river Sura several new species: Black and Caspian Sea sprat Clupeonella cultriventris, eel Anguilla anguilla, Chinese sleeper Perccottus glenii and goldfish Carassius auratus appeared. In the lower reaches, part of which is the Gulf of Cheboksary reservoir, species diversity is somewhat higher. Rheophils share on average is above, the opposite picture is observed with limnophils.