Six species of sturgeon once migrated in the Danube River for spawning: the anadromous species beluga, Huso huso; Russian sturgeon, Acipenser gueldenstaedtii; stellate sturgeon, A. stellatus, and the European Atlantic sturgeon, A. sturio, and the river resident ship sturgeon, A nudiventris and sterlet, A. ruthenus (Bacalbasa-Dobrovici 1997). Although considered as critically endangered, beluga – Russian – and stellate sturgeons still survive in the North-Western Black Sea and enter for spawning in the Lower Danube River (LDR), while the resident sterlet is considered only as vulnerable (Suciu 2013).