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Acipenser oxyrinchus oxyrinchus Mitchill, 1815
Atlantic Sturgeon
Federal Protection: Listed Endangered
State Protection: Endangered
Global Rank: G3T3
State Rank: S3
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 7
Habitat Summary for element in Georgia: Estuaries; lower end of large rivers in deep pools with soft substrates; spawn as far inland as Macon, GA on the Ocmulgee
The Atlantic Sturgeon is a member of family Acipenseridae, within order Acipenseriformes. A total of 27 sturgeon species can be found across the northern hemisphere; nine species are native to North America, and four were historically found in Georgia. Like other sturgeons, Atlantic Sturgeon are characterized by large, heavy, almost cylindrical bodies. They have five rows of bony scutes along their lateral and dorsal surfaces. The mouth is located on the underside of the flattened, shovel-like snout, behind 4 long barbels. Atlantic Sturgeon have no teeth, and the mouth is fleshy and protrusible. The upper body color varies from dark brown to gray; the underside of the body is usually white or light gray. Female Atlantic Sturgeon may attain total lengths of 2.7 m (8.9 ft) in the southern portion of their range, but historically reached > 4.6 m (15.1 ft) in northern rivers. Males are somewhat smaller than females. In Georgia, Adult Atlantic Sturgeon can weigh up to 200 lbs. In the northern portions of their range, Atlantic Sturgeon may have lifespans >60 years, but in the southern portion of their range, Georgia, the species’ lifespan is not known to exceed 30 years.
The Shortnose Sturgeon (Acipenser brevirostrum) has a similar appearance, although it is smaller at adulthood than the Atlantic Sturgeon. The two species are easily distinguished by size, length of snout, color, and several other characteristics. Shortnose Sturgeon reach a maximum size of about 1 m (3.3 ft). The snout (rostrum) of the Shortnose Sturgeon is only 25-40% of head length, whereas the snout of the Atlantic Sturgeon is approximately 30-50% of head length. Atlantic Sturgeon generally have a narrower mouth relative to rostrum width, compared Shortnose Sturgeon. Colors are variable, but Shortnose Sturgeon are typically brown or bronze and Atlantic Sturgeon are grey with a white underside. Atlantic Sturgeon also have a larger anal ray count (usually 26-28 rays) than Shortnose Sturgeon (usually 19-22 rays). Atlantic Sturgeon have two ventral scutes posterior to the vent, and Shortnose Sturgeon have one.
Atlantic Sturgeon are anadromous, meaning that adults reside in the ocean, but return to their natal river to spawn. Adults inhabit large areas of the coastal ocean, and may even leave the continental shelf. Adults and subadults from different populations mix offshore, and fish originating from Georgia are observed coastwide. Spawning occurs near the fall line, in habitat featuring hard substrates such as gravel or cobble. Larvae gradually migrate downstream to the upper estuary. River-resident juveniles reside in nursery areas below the head of tide, and marine migratory juveniles inhabit coastal marine waters.
The diet of juvenile Atlantic Sturgeon consists of benthic animals, including insect larvae, bivalves, isopods, and amphipods, which they extract from the muddy substrate. Adults feed on a variety of freshwater and marine invertebrates, including molluscs, crustaceans, isopods, amphipods, and polychaetes. They will also opportunistically consume small fishes, such as capelin.
Each stage within the Atlantic Sturgeon’s anadromous life cycle has different habitat requirements and behavioral patterns. In northern populations, spawning occurs in the spring, but recent studies have indicated that at least some central and southern populations spawn in the fall. In Georgia, spawning likely occurs only in the fall, when water temperatures begin to decline from their summer maxima. Atlantic Sturgeon are intermittent spawners; males typically spawn every 1-4 years, and females every 3-5 years. Each spawning female can produce 800,000 to 2.4 million eggs, which are sticky and adhere to the substrate. Eggs incubate for 4-7 days, depending on water temperature. Upon hatching, larval sturgeon begin to drift downstream. By age 1, juveniles occupy habitats below the head of tide, near the freshwater-saltwater interface. These “river-resident” juveniles remain in the estuary, where they grow quickly. Beginning the winter of age 2, some individuals outmigrate to marine habitats, transitioning to the marine migratory life stage. Other river-resident juveniles may not leave their natal estuary until age 3 or 4. Marine migratory juveniles disperse coast-wide through nearshore marine habitats, although they may occasionally return to estuarine or riverine habitats. Age at maturity varies with latitude, but females typically mature at 7-20 years and males mature at 5-13 years. Females continue to grow steadily after maturation, but growth in males usually slows. Atlantic Sturgeon are intermittent spawners; males may spawn every 1-3 years, while females spawn every 3-5 years.
Assuming that appropriate state and federal permits are obtained, this species is best surveyed with anchored gill and trammel nets set during a slack tide. Drifted gill nets may also be useful for sampling adult Atlantic Sturgeon. The potential for sampling mortality should be minimized by limiting net sets to 30 minutes or less at temperatures ≥27 °C (81 °F) and eliminating sampling altogether at temperatures > 28 °C (86 °F). Captured sturgeon should be kept in a floating net pen until biological data are collected. Handling time of sturgeon should be minimized to decrease the potential for mortality.
The historic range of the Atlantic Sturgeon extends from the St. Lawrence River in Canada to the St. Johns River, Florida. Within Georgia, the species can be found in the Savannah, Ogeechee, Altamaha, Satilla, and St. Marys Rivers. Atlantic Sturgeon also use the Atlantic Intracoastal Waterway, and can be found in all of Georgia’s marine waters.
Throughout the 19th and 20th centuries, Atlantic Sturgeon populations suffered major declines due to a variety of anthropogenic factors. Historically, they were over-harvested for both their meat and roe (caviar). Additionally, the construction of impoundments in spawning rivers impeded access to historic spawning sites and modified natural hydrologic flow and temperature regimes. Although Atlantic Sturgeon are protected from harvest, they may still be caught as bycatch in commercial fisheries, including the riverine American Shad fishery and in coastal trawl and net fisheries. In some areas, sturgeon are threatened by poaching. The species is also at risk of being struck by ships while migrating through busy ports and shipping channels. It is possible that non-native catfish (such as blue and flathead) may prey upon larval or juvenile sturgeon. Habitat modifications also pose a threat to sturgeon conservation and recovery. Dredging and construction may directly or indirectly impact sturgeon. These activities may result in habitat damage, sedimentation, or altered flow patterns that negatively affect spawning habitat or holding areas. Dredging related to the Savannah Harbor Expansion Project will affect Atlantic Sturgeon nursery areas, and is predicted to increase salinity and decrease dissolved oxygen throughout the estuary. Deadhead logging is also likely to disturb river sediments, and may have a negative impact on sturgeon. Water quantity and quality are also important for Atlantic Sturgeon. Reduced flow may negatively impact recruitment. Water pollution adversely affects many fish populations, including sturgeon. In southern rivers, naturally poor water quality resulting from high temperatures and low dissolved oxygen pose a threat to conservation and recovery of Atlantic Sturgeon, and these problems may be exacerbated by climate change.
Atlantic Sturgeon were federally listed under the Endangered Species Act in 2012. The Savannah and Altamaha Rivers host the most robust Atlantic Sturgeon populations within the South Atlantic Bight. Those rivers consistently produce hundreds to thousands of age 1 sturgeon every year, and sturgeon populations there appear to be stable or recovering. Much smaller Atlantic Sturgeon populations exist in the Ogeechee and Satilla Rivers. Recruitment in those rivers is relatively low (dozens to hundreds of fish per year), and does not occur every year. Although the species was once thought extirpated in the St. Marys River, a remnant population of Atlantic Sturgeon persists there – recruitment is very low and infrequent. Georgia’s sounds and lower estuaries appear to be important habitat for non-natal Atlantic Sturgeon as well, and migrant adults have been documented between September and May. Recent telemetry studies in Georgia have detected Atlantic Sturgeon originating from many different populations, including fish from as far north as the New York Bight.
Although the Savannah and Altamaha River populations of Atlantic Sturgeon appear robust, populations in the Ogeechee, Satilla, and St. Marys Rivers are small and may be fragile. The National Marine Fisheries Service (NMFS) has identified long-term monitoring of each population as an important research need, in order to determine distribution, abundance, and population dynamics. Estimation of spawning abundance will help establish adult population baselines. Additionally, continued monitoring of river-resident juveniles in each Georgia River will help identify any trends in recruitment. Recruitment estimates and trends provide an early measure of recovery status, especially in rivers with small sturgeon populations. Continued monitoring of juveniles in the Savannah River is especially important, given the potential effects of the Savannah Harbor Expansion Project. There is a need for assessments of growth, reproductive success, and environmental tolerances, which are lacking for Atlantic Sturgeon in the southern parts of their range. Successful conservation of Atlantic Sturgeon in Georgia will require the identification and protection of spawning habitats near the fall line – specific spawning locations have not been documented in any of Georgia’s unimpounded rivers. Protection of juvenile nursery habitats in Georgia’s estuaries is also critical. Juvenile Atlantic Sturgeon are constrained by temperature and salinity, and their nursery habitat contracts to its smallest extent during the summer. These summer refugia are very important to the survival of river-resident juveniles, and disturbances to those river reaches should be minimized. Georgia may also provide important overwintering habitat for Atlantic Sturgeon, including those originating in northern populations; a better understanding of migrant sturgeon use of habitats in Georgia will help identify areas that need to be protected from degradation. Minimizing anthropogenic mortality of Atlantic Sturgeon is important to the conservation of the species. NMFS recommends studies to assess the impacts of bycatch in order to better understand this source of mortality and how to reduce it. Additionally, as shipping traffic at Georgia’s ports increases, Atlantic Sturgeon will experience an increased risk of propeller strike. There is currently very little information on vessel strikes in Georgia, and studies quantifying this potential source of mortality may help identify ways to reduce ship-sturgeon interactions. Poaching remains a potential source of mortality that should be investigated. Most Georgia rivers are unimpounded below the fall line and sturgeon are able access most of their historic spawning habitat. There are, however, several dams located on the Savannah River. Fish passage at the New Savannah Bluff Lock and Dam is included as part of the mitigation for the Savannah Harbor Expansion Project, but studies will be necessary to assess how this will affect the Atlantic Sturgeon population there. Water pollution and sedimentation pose a chronic threat to many Atlantic Sturgeon populations, as they do to many other species. NMFS recommends studies to assess toxic contaminant impacts and thresholds, in order to determine how great a threat these contaminants pose to Atlantic Sturgeon.
Atlantic Sturgeon Status Review Team. 2007. Status review of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus), 174 p. Report to Northeast Reg. Off., Natl. Mar. Fish. Serv., Gloucester, MA.
Bahr, D. L., and D. L. Peterson. 2016. Recruitment of juvenile Atlantic Sturgeon in the Savannah River, Georgia. Trans. Am. Fish. Soc. 145:1171–1178.
Bain, M. B. 1997. Atlantic and Shortnose Sturgeons of the Hudson River: common and divergent life history attributes. Environ. Biol. Fish. 48:347–358.
Collins, M. R., S. G. Rogers, T. I. J. Smith, and M. L. Moser. 2000. Primary factors affecting sturgeon populations in the southeastern United States: fishing mortality and degradation of essential habitats. Bull. Mar. Sci. 66:917–928.
Fritts, M. W., C. Grunwald, I. Wirgin, T. L. King, and D. L. Peterson. 2016. Status and genetic character of Atlantic Sturgeon in the Satilla River, Georgia. Trans. Am. Fish. Soc. 145:69–82.
Ingram, E. C., and D. L. Peterson. 2016. Annual spawning migrations of adult Atlantic Sturgeon in the Altamaha River, Georgia. Mar. Coast. Fish. 8:595–606. Schueller, P. and D. L. Peterson. 2010. Abundance and recruitment of juvenile Atlantic Sturgeon in the Altamaha River, Georgia. Trans. Am. Fish. Soc. 139:1526–1535.
Scott, W. B. and E. J. Crossman 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada Bulletin 184. 966pp.
Stein, A. B., K. D. Friedland, M. Sutherland. 2004. Atlantic Sturgeon marine bycatch and mortality on the continental shelf of the Northeast United States. North American Journal of Fisheries Management 24: 171-183.
Adam G. Fox
G. Krakow August 2014 – first draft – skeletal outline
B. Albanese August 2014 – added temporary photo
A. Fox, December 2018: Original account.
