Listing Status
- Federal Status: Endangered
- FL Status: Federally-designated Endangered
- FNAI Ranks: G3/S1 (Globally: Rare/State: Critically Imperiled)
- IUCN Status: VU (Vulnerable)
Appearance
The shortnose sturgeon is one of seven species of sturgeons found in North America. Sturgeons are prehistoric species that date back to the time of dinosaurs. They are popular in the food industry as a source of caviar. Their physical features separate them from other kinds of fish, such as a spiral valve stomach and a cartilaginous skeleton (like sharks and rays) but, they have scutes (hard, protective, large individual body plates) instead of denticles like sharks have or scales like other fish have. Shortnose sturgeon have barbels located on the underside of the snout, no teeth, rubbery lips, and a suctorial mouth for vacuuming food off the bottom. The sturgeon's coloring typically is dark brown along the upper (dorsal) side, shading to a creamy white-colored belly (Wakeford 2001). The shortnose sturgeon is one of the smallest sturgeons with a body length of three to four feet (.9-1.2 meters) and a weight of up to eight pounds (3.6 kilograms).
Behavior
Sturgeons are benthic feeders consuming organisms on, in, or near the bottom of a water body. Preferred prey includes worms, crustaceans, insect larvae, and molluscs (National Marine Fisheries Service 1998).
Spawning times differ geographically due to the fact that shortnose sturgeon require specific water temperatures to spawn. Shortnose sturgeon migrate from estuarine waters to fresh water to spawn. Spawning begins when the water reaches temperatures of 44.6-50°F (7-10°C) (Friedland and Kynard 2004). Females can lay from 27,000 to 208,000 eggs per spawning act. Sturgeon eggs have a sticky surface, which enables them to stick on objects on or near the bottom of the water body. Eggs hatch 13 days after spawning at 44.6-50°F (7-10°C). The fry (young fish) are very poor swimmers and will drift with the current down river. Sexual maturity is reached at different times in their geographical range. Males reach sexual maturity by age three in Georgia, age five from South Carolina north to the New England states, and age 11 in New Brunswick. Females reach sexual maturity by age six in Georgia, age seven from South Carolina north to the New England states, and age 13 in New Brunswick. Males will first spawn around two years after reaching sexual maturity, while females will first spawn around five years after reaching sexual maturity. Males can spawn every year, while females usually spawn every three years (National Marine Fisheries Service 1998).
Habitat
Shortnose sturgeon are classified as anadromous, living in the estuarine reaches of most Atlantic seaboard rivers and ascending to flowing freshwater to spawn. They tend to congregate in the main river channels and only use smaller tributaries to a lesser extent. While shortnose sturgeons only occasionally frequent marine habitats, they can tolerate full seawater, and do migrate between rivers. The shortnose sturgeon can be found from New Brunswick Canada, to the St. Johns River in Florida (National Marine Fisheries Service 1998).
Threats
Now that rampant overharvest has been stopped, the main threat to shortnose sturgeon survival is the dams located on Atlantic seaboard rivers, which prevent sturgeon from reaching historic spawning areas, therefore decreasing the spawning rate of the species. Habitat destruction is also a threat to the sturgeon population. Shortnose sturgeon habitat has increased vulnerability because they inhabit areas that are at risk of dredging. The dredging of river channels is a practice that can destroy or suffocate sturgeon eggs located on objects in the benthic layer (bottom, sediment layer) of the river. Dredging of rivers also affects the food source of sturgeons as they are benthic feeders. Other threats to the sturgeon population include lethal by-catch and declining water quality. Water quality can be affected by pollution reaching the floodplains of the river, and excessive water withdrawals from the rivers. Sturgeons are slow breeders, which makes any loss of breeders or spawning habitat a serious problem for the species (Wakeford 2001).
Conservation and Management
The shortnose sturgeon is protected as an Endangered species by the Federal Endangered Species Act and as a Federally-designated Endangered species by Florida’s Endangered and Threatened Species Rule. Shortnose sturgeon habitat is also protected by the Federal Clean Water Act.
References
Friedland, K.D. & Kynard, B. 2004. Acipenser brevirostrum. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.1. <www.iucnredlist.org>. Downloaded on 09 June 2011.
National Marine Fisheries Service. 1998. Recovery Plan for the Shortnose Sturgeon (Acipenser brevirostrum). Prepared by the Shortnose Sturgeon Recovery Team for the National MarineFisheries Service, Silver Spring, Maryland. 104 pages.
Virginia Polytechnic Institute & State University. The Virtual Aquarium. Retrieved June 9, 2011. from: http://cnre.vt.edu/efish/families/acipenseridae.html.