Distribution
Eurasia: Black Sea, Sea of Azov and Caspian Sea, entering all main rivers that empty into them (Don, Kuban, Danube, Dnieper (rare), Dniester) (Ref. 9953). Introduced throughout Europe. Considered critically endangered (Ref. 59043). International trade restricted (CITES II, since 1.4.98; CMS Appendix II).