Sturgeons are restricted to bodies of flowing water in the Northern Hemisphere. Their distribution spans the coasts of the Atlantic and the Pacific, the Mediterranean, the Black and Caspian seas, and also to large rivers like the Danube as well as some lakes.
The Atlantic sturgeon (Acipenser sturio) is already extinct, while the Ship sturgeon (Acipenser nudiventris) is close to extinction. The Danube sturgeon (Acipenser gueldenstaedti), the Beluga (Huso Huso) and the Stellate sturgeon (Acipenser stellatus) are highly endangered and extremely rare, while the Starlet (Acipenser ruthenus) is dependent on stocking programmes for survival.
Sturgeons can become very old and are sexually mature at a late age; the Beluga reaches sexually maturity at the age of 15. During the spawning season, from spring to summer, sticky, brownish-green eggs are laid. After 2 weeks, the young sturgeon are ready to feed, and they migrate to the ocean between their 1st and 3rd years.