Acipenser oxyrinchus

Acipenser oxyrinchus Mitchill, 1815

Languages: English

Overview

Comprehensive Description

"Gulf sturgeon, also known as the Gulf of Mexico sturgeon, are "anadromous" fish, inhabiting coastal rivers from Louisiana to Florida during the warmer months, and the Gulf of Mexico and its estuaries and bays in the cooler months. Sturgeon are primitive fish characterized by bony plates, or "scutes," and a hard, extended snout; they have a heterocercal caudal fin (their tail is distinctly asymmetrical with the upper lobe longer than the lower). Adults range from 4-8 feet (1-2.5 m) in length, females attain larger sizes than males. They can live for about 60 years; usually 20-25 years."

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

The Atlantic sturgeon is a long-lived, estuarine dependent, anadromous fish. Atlantic sturgeon can grow to approximately 14 feet (4.3 m) long and can weigh up to 800 lbs (370 kg). They are bluish-black or olive brown dorsally (on their back) with paler sides and a white belly. They have five major rows of dermal "scutes".

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm)

Author(s): Hammock, Jen
Rights holder(s): Hammock, Jen

Conservation and Management

Management

The Atlantic sturgeon is managed under a Fishery Management Plan implemented by the Atlantic States Marine Fisheries Commission (ASMFC). In 1998, the ASFMC instituted a coast-wide moratorium on the harvest of Atlantic sturgeon, which is to remain in effect until there are at least 20 protected age classes in each spawning stock (anticipated to take up to 40 or more years). NMFS followed the ASMFC moratorium with a similar moratorium for Federal waters. Amendment 1 to ASMFC's Atlantic sturgeon Fishery Management Plan also includes measures for preservation of existing habitat, habitat restoration and improvement, monitoring of bycatch and stock recovery, and breeding/stocking protocols.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm)

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Threats

Gulf sturgeon number initially declined due to overfishing throughout most of the 20th century. Habitat loss was exacerbated by the construction of water control structures, such as dams and "sills", mostly after 1950. Other habitat disturbances such as dredging, groundwater extraction, irrigation, and flow alterations also threaten the Gulf sturgeon. Poor water quality and contaminants, primarily from industrial sources, also contribute to population declines.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

Historical overharvest led to wide-spread declines in Atlantic sturgeon abundance. A large U.S. commercial fishery (100,000 - 250,000 lbs/yr) existed for Atlantic sturgeon from the 1950s through the mid-1990s; the origin of the fishery dates back to colonial times. Since a 1998 harvest moratorium there have been few surveys to assess status and abundance. "Bycatch" of sturgeon in fisheries targeting other species is a current threat in the ocean environment.

In their estuarine and freshwater habitats, Atlantic sturgeon face additional threats, including habitat degradation and loss from various human activities such as dredging, dams, water withdrawals, and other development. Some populations are being impacted habitat impediments including locks and dams (e.g., Cape Fear and Santee-Cooper Rivers ) and ship strikes (e.g., Delaware and James Rivers). Although there are no known diseases threatening Atlantic sturgeon populations, there is concern that non-indigenous sturgeon pathogens could be introduced through aquaculture operations.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm)

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Trends

Total number of mature individuals throughout their range is unknown. However, among coastal rivers of the Gulf of Mexico, the Suwannee River supports the most viable subpopulation, which was estimated at 7,650 adults. The subpopulation estimate for mature Gulf sturgeon in the Choctawhatchee River ranges from 1,700-3,000 fish; estimates in the Apalachicola, Pascagoula and Pearl rivers range between 50-350 fish.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm and references cited)

Studies have consistently found Atlantic Sturgeon populations to be genetically diverse and indicate that there are between 7 and 10 populations that can be statistically differentiated. However, there is some disagreement among studies, and results do not include samples from all rivers inhabited by Atlantic sturgeon. There are only two Atlantic sturgeon populations for which size estimates are available - the Hudson River and the Altamaha River populations. In 1995, sampling crews on the Hudson River estimated that there were 9,500 juvenile Atlantic sturgeon in the estuary. Since 4,900 of these were stocked hatchery-raised fish, about 4,600 fish were thought to be of wild origin. The mean annual spawning stock size (spawning adults) was estimated at 870 (600 males and 270 females). The Altamaha River supports one of the healthiest Atlantic sturgeon populations in the Southeast, with over 2,000 subadults captured in research surveys in the past few years, 800 of which were 1 to 2 years of age. The population appears to be stable. 

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm)

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Description

Lookalikes

Atlantic sturgeon are similar in appearance to shortnose sturgeon (Acipenser brevirostrum), but can be distinguished by their larger size, smaller mouth, different snout shape, and scutes.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Ecology

Habitat

"Gulf sturgeon are anadromous: adults spawn in freshwater and migrate into marine waters in the fall to forage and overwinter. Juvenile Gulf sturgeon stay in the river for about the first 2-3 years. Gulf sturgeon return to their natal stream to spawn. Riverine habitats where the healthiest populations of Gulf sturgeon are found include long, spring-fed, free-flowing rivers, typically with steep banks, a hard bottom, and an average water temperature of 60-72° F. Gulf sturgeon initiate movement up to the rivers between February and April and migrate back out to the Gulf of Mexico between September and November."

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

Atlantic sturgeon are "anadromous"; adults spawn in freshwater in the spring and early summer and migrate into "estuarine" and marine waters where they spend most of their lives. In some southern rivers a fall spawning migration may also occur. They spawn in moderately flowing water (46-76 cm/s) in deep parts of large rivers. Sturgeon eggs are highly adhesive and are deposited on bottom substrate, usually on hard surfaces (e.g., cobble). It is likely that cold, clean water is important for proper larval development. Once larvae begin migrating downstream they use benthic structure (especially gravel matrices) as refuges. Juveniles usually reside in estuarine waters for months to years. Subadults and adults live in coastal waters and estuaries when not spawning, generally in shallow (10-50 m depth) nearshore areas dominated by gravel and sand substrates. Long distance migrations away from spawning rivers are common. 

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Hammock, Jen
Rights holder(s): Hammock, Jen

Distribution

Gulf sturgeon are found in river systems from Louisiana to Florida, in nearshore bays and estuaries and in the Gulf of Mexico.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

Historically, Atlantic sturgeon were present in approximately 38 rivers in the United States from St. Croix, ME to the Saint Johns River, FL, of which 35 rivers have been confirmed to have had a historical spawning population. Atlantic sturgeon are currently present in approximately 32 of these rivers, and spawning occurs in at least 20 of them. 

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Trophic Strategy

"Gulf sturgeon are bottom feeders, and eat primarily macroinvertebrates, including brachiopods, mollusks, worms, and crustaceans. All foraging occurs in brackish or marine waters of the Gulf of Mexico and its estuaries; sturgeon do not forage in riverine habitat."

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

Atlantic sturgeon are benthic feeders and typically forage on "benthic" invertebrates (e.g. crustaceans, worms, mollusks) (Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Hammock, Jen
Rights holder(s): Hammock, Jen

Cyclicity

Following spawning, male Atlantic Sturgeon may remain in the river or lower estuary until the fall; females typically exit the rivers within four to six weeks. Juveniles move downstream and inhabit brackish waters for a few months and when they reach a size of about 30 to 36 inches (76-92 cm) they move into nearshore coastal waters. Tagging data indicate that these immature Atlantic sturgeon travel widely once they emigrate from their natal (birth) rivers.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Life Expectancy

Atlantic sturgeon have been aged to 60 years. There is generally faster growth and earlier age at maturation in more southern populations. For example, Atlantic sturgeon mature in South Carolina rivers at 5 to 19 years of age, in the Hudson River at 11 to 21 years, and in the Saint Lawrence River at 22 to 34 years.

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm).

Author(s): Shapiro, Leo
Rights holder(s): Shapiro, Leo

Reproduction

"Gulf sturgeon migrate into rivers to spawn in the spring; spawning occurs in areas of clean substrate comprised of rock and rubble. Their eggs are sticky, negatively buoyant and adhere in clumps to snags, outcroppings, or other clean surfaces."

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/gulfsturgeon.htm)

Spawning adult Atlantic Sturgeon migrate upriver in spring, beginning in February-March in the south, April-May in the mid-Atlantic, and May-June in Canadian waters. In some areas, a small spawning migration may also occur in the fall. Spawning occurs in flowing water between the salt front and fall line of large rivers. Atlantic sturgeon spawning intervals range from 1 to 5 years for males and 2 to 5 years for females. "Fecundity" of female Atlantic sturgeon is correlated with age and body size and ranges from 400,000 to 8 million eggs. The average age at which 50% of maximum lifetime egg production is achieved is estimated to be 29 years, which is approximately 3 to 10 times older than for other bony fish species. 

(Office of Protected Resources, http://www.nmfs.noaa.gov/pr/species/fish/atlanticsturgeon.htm)

Author(s): Hammock, Jen
Rights holder(s): Hammock, Jen

Taxonomic Children

Total: 1

Acipenser oxyrinchus desotoi