Anadromous Sturgeons, Acipenser spp.
Two species of sturgeon inhabit the inshore estuaries and offshore waters of the east coast of the United States. Both of these species, Atlantic sturgeon (Acipenser oxyrinchus) and shortnose sturgeon (Acipenser brevirostrum), are anadromous, which means they make a migratory spawning run from the ocean to spawning grounds in freshwater rivers. Both species of sturgeon are long-lived and reach maturity at a relatively late age (approx 6-10 years). These factors are important to biologists working with the species. At smaller sizes, it is difficult to distinguish the two species, however Atlantic sturgeon are known to exceed 13 feet in length, while the shortnose sturgeon grows to only about 4 feet in length. Both species are considered ‘species of concern’ with shortnose sturgeon being listed as endangered. This is due to a variety of factors including an intensive fishery that once existed for their prized caviar and flesh, by-catch in existing fisheries that target migratory shad and herring, pollution, and habitat degradation including construction of dams that hinder or prohibit natural migrations.
Since 1985, Bears Bluff National Fish Hatchery (BBNFH) has worked on the development of techniques to spawn adult shortnose sturgeon. By developing conditioning regimes for adult sturgeon, biologists can now produce large numbers of shortnose sturgeon fry for stock enhancement and research efforts. Studies conducted at the BBNFH include development of tagging and marking methods, spawning protocols, and improved diets for rearing larvae, juveniles, sub-adults, and adults.
Bears Bluff National Fish Hatchery once boasted the largest captive population of shortnose sturgeon broodstock in the United States. In 2007, the anadromous sturgeon program at Bears Bluff National Fish Hatchery changed its focus to the Atlantic sturgeon, A. oxyrinchus. As a result, the shortnose sturgeon program was transferred to the Orangeburg National Fish Hatchery in Orangeburg, SC. In the fall of 2008, BBNFH began receiving wild-caught adult Atlantic sturgeon. These massive fish are currently held in large circular tanks in a facility that allows researchers to investigate spawning techniques for adult Atlantic sturgeon. Current efforts include transitioning wild-caught adults to captivity, diet development and development of dependable spawning techniques in an effort to restore, protect and enhance Atlantic sturgeon populations throughout their range.