Diagnostic characters
Body heavy, elongate and subcylindrical in section. Head ending in a hard extendedsnout; a spiracle (small opening above and behind eyes) present in Acipenser; mouth inferior, protrusible, preceded by 4 conspicuous barbels; gill memebranes joined to isthmus, not free.A single dorsal fin set far back on body; caudal fin more or less deeply forked and distinctly asymmetrical, heterocercal, with a fleshy axis bending upward at base of fin and extending rearward to tip of upper lobe, the fin being much wider below than above fleshy axis; pectoral fins set low; pelvic fins abdominal in position; all fins spineless, except for first pectoral-fin ray which is ossified in some species. Skeleton cartilaginous for the most part.Head and body covered with bony plates, shields, or bucklers, those on body in 5 rows, 1 row along midline of back, 1 row along each side, and another along the ventrolateral margin of each side. Colour: variable, light brown to dark brown, almost black or slate grey to blue-black.
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Habitat, biology, and fisheries
Inhabiting lakes, river basins, and coastal marine waters; generally but not always near the bottom, feeding on benthic organisms, insects, molluscs, crustaceans, and occasionally plant material. All sturgeons spawn in fresh water, those species occurring as adults in estuaries or the sea being anadromous. Of the 3 species occurring in brackish and marine waters along the eastern coast of the USA, the Atlantic sturgeon, Acipenser oxyrinchus, is the one which has been most important commercially. It grows to about 267 cm in total length (estimated age at that size is 60 years); adults move upriver for spawning and the young spend 4 years in fresh water before gradually returning to the estuaries or nearby coastal waters. This species is highly tolerant of sharp changes in salinity. The landings today are well below the level of the last century when the Atlantic sturgeon was considered and important commercial fish. The flesh is of good quality and the eggs are sold as caviar.
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