Sturgeon

Sturgeon are large, ancient bony fish belonging to the family Acipenseridae, one of the oldest surviving fish lineages, with a fossil record dating back over 100 million years. The genus Acipenser includes many species distributed across freshwater rivers and coastal waters of the Northern Hemisphere, with the European or Atlantic sturgeon (Acipenser sturio) serving as the classic representative and type species of the family. Sturgeon are anadromous, migrating from the sea into large rivers to spawn, and are notable for their armored, shark-like appearance despite being true bony fish rather than cartilaginous ones. Most sturgeon species today are critically endangered due to habitat loss, river damming, and historical overexploitation.

Sturgeon are large, elongated fish that can reach well over a meter in length.

• Body: torpedo-shaped with five longitudinal rows of bony armored plates called scutes instead of typical fish scales
• Head: flattened, shark-like snout with four sensory barbels hanging in front of a small, toothless, tube-like mouth used for suction feeding
• Tail: asymmetrical, heterocercal tail fin with an elongated upper lobe
• Coloration: grayish-brown to olive dorsally, paler below

The row of bony scutes and barbeled, shark-like snout readily distinguish sturgeon from true cartilaginous sharks, which lack scutes and bony skeletons, and from other large freshwater fish.

Sturgeon are anadromous fish, spending much of their adult life in coastal marine or estuarine waters before migrating into large rivers to spawn over gravel or rocky riverbeds. Historically distributed across major river systems of Europe, the Atlantic sturgeon (Acipenser sturio) once ranged from Scandinavia to the Mediterranean and Black Sea, though its range has contracted drastically and it now survives mainly in the Gironde-Garonne-Dordogne river system of France. Sturgeon generally require cool, well-oxygenated water and unobstructed river passage to complete their spawning migrations, making them highly sensitive to dams and habitat fragmentation.

Sturgeon are slow-growing, long-lived fish that can take a decade or more to reach sexual maturity and may live for several decades. They are bottom-oriented feeders, using their sensitive barbels to locate invertebrates, worms, and small crustaceans in soft river or estuarine substrate, then sucking prey into their toothless mouths. Adults undertake long migrations between marine or estuarine feeding grounds and freshwater spawning rivers, typically spawning over gravel beds in flowing water. Because of their late maturity and dependence on free-flowing rivers, sturgeon populations are highly vulnerable to overfishing and dam construction, and most species are now subject to strict conservation protections.