Ecological Significance, History and Range
Sturgeons are an ancient group of fish dating back about 200 million years. Worldwide there are 27 known sturgeon species and two closely related paddlefish species.
The Gulf sturgeon, also known as the Gulf of Mexico sturgeon, is a subspecies of the Atlantic sturgeon, differing in genetic makeup and size.
Historically, the Gulf sturgeon occurred from the Mississippi River to Charlotte Harbor, Florida. In 1991, the species was listed as federally threatened, and today its current range is limited from the Suwannee River in Florida to the Pearl River in Mississippi and Louisiana.
Ideally, the best river habitat for Gulf sturgeon is a long, spring-fed free-flowing river with steep banks and a hard bottom. River systems with viable populations include the Pearl, Pascagoula, Escambia, Yellow, Choctawhatchee, Appachicola, and Swannee rivers. The Gulf sturgeon rarely migrates far into the Mississippi River due to a natural lack of spawning habitat.
Total number of mature individual Gulf sturgeon is unknown, but scientists estimate that the Suwannee River supports about 7,650 adults. Estimates for Apalachicola River in Florida and Mississippi’s Pascagoula and Pearl rivers range between 50 and 350 mature sturgeon.
As months get warmer (usually between February and April), Gulf sturgeon, an anadromous species, move from the saltwater estuaries and bays of the Gulf of Mexico to the upper reaches of their natal freshwater rivers to spawn in areas with clean substrate of rock and rubble.
After spawning, the sturgeon spends the summer in mid to lower reaches of the river before moving back to the Gulf in the fall.
The Gulf sturgeon began to decline in the late 1900s due to over-fishing for food and caviar.
The construction of dams on major rivers and tributary systems like the Pearl in Mississippi, the Alabama in Alabama has had a severe effect on sturgeon and other anadromous fish. These structures block access to key upstream spawning areas.
Dredging, removal of in-channel woody debris, habitat loss, poor water quality and spoil deposition to maintain and improve navigation routes as well as to promote floodplain development also impede upstream spawning migration. Incompatible floodplain and shoreline development have also contributed to declining sturgeon habitat.
- can live for about 60 years, but average 20 to 25 years;
- can grow longer than 9 feet and weigh in excess of 300 pounds, with females tending to be larger than males;
- have rows of armored plates along their sides and back (called scutes;
- range in color from a light neutral color to dark brown and have a white underbelly;
- use sensitive barbels and a tube-like mouth to detect and siphon tiny bottom-dwelling sea invertebrates, crustaceans, and marine worms;
- can jump 6 feet out of the water;
- adults feed in brackish or marine waters of the Gulf of Mexico and its estuaries rather than in rivers because searching for food requires excessive amounts of energy saved for spawning; juveniles forage in freshwater habitat;
- cannot reproduce until they are between 8 and 12 years old;
- spawn sticky, negatively buoyant eggs that adhere in clumps to snags, outcroppings or other clean surfaces.
What The Nature Conservancy Is Doing
The Conservancy is working with landowners, agencies and other partners to ensure the Pascagoula and Pearl rivers – essential habitat for spawning Gulf sturgeons – remain healthy, free-flowing rivers with well-managed upland areas to protect against pollution runoff and erosion that can impact water quality.
In addition to helping to protect nearly 70,000 acres of bottomland forests and swamps in the Pascagoula River, the Conservancy helped establish the Pascagoula River Basin Alliance, a coalition of public, private and individual stakeholders working to ensure the Pascagoula remains one of the nation’s best preserved river systems.
In the lower Pearl River basin, the Conservancy owns and manages 5 preserves totaling more than 6,400 acres and assisted in protecting 35,971 of habitat to sustain the ecological integrity of the system.
In 2002, the Conservancy’s Mississippi and Louisiana programs collaborated with state agencies to create the Lower Pearl Partnership which works with public and private stakeholders to restore and protect ecologically significant areas along the Pearl and its tributaries.