Alabama sturgeon

Scaphirhynchus suttkusi

 

SPECIES CODE: E026 V01

 

STATUS:

Listed Endangered on May 5, 2000 (65 FR 26437 26461).

 

Note:All descriptions are from the Federal Register (1994, 1999, and 2000).

 

SPECIES DESCRIPTION:

The Alabama sturgeon is a member of the Acipenseridae family.The species typically grows up to 80cm (30inches) in length, weighs 1 to 2 kg (2 to 3lb.), and may live 15+ years.The species is an opportunistic feeder, preying primarily on aquatic insect larvae, as well as fish eggs, snails, mussels, fish, and plant material.

 

REPRODUCTION AND DEVELOPMENT:

Very little is known of the life history, habitat, or other ecological requirements of the Alabama sturgeon.However, it probably spawns in the spring.Spawning frequency of both sexes is influenced by food supply and fish condition, and may occur every 1 to 3 years.

 

RANGE AND POPULATION LEVEL:

The Alabama sturgeonís historic range once included about 1,600 kilometers (km) (1,000 miles (mi)) of the Mobile River system in Alabama (Black Warrior, Tombigbee, Alabama, Coosa, Tallapoosa, Mobile, Tensaw, and Cahaba Rivers) and Mississippi (Tombigbee River).

 

The species is now restricted to a 216km (130mi) reach of the Alabama River below Millerís Ferry Lock and Dam.The Alabama sturgeon currently inhabits only about 15 percent of its historic range.

 

HABITAT:

The species prefers relatively stable gravel and sand substrates in flowing river channels (Burke and Ramsey 1985).Verified captures of Alabama sturgeon have primarily occurred in large channels of big rivers; however, at least two historic records were from oxbow lakes (Williams and Clemmer 1991).Riverine (flowing water) habitats are required by the Alabama sturgeon to successfully complete its life cycle.

 

PAST THREATS:

The historic population decline of the Alabama sturgeon was probably initiated by unrestricted harvesting near the run of the century.Although the Alabama sturgeonís capture is currently prohibited, the species has and still is affected by incidental capture from commercial and sport fishery.

 

 

Other than harvesting, and more importantly, the decline in the Alabama sturgeonís range is the result of 100 years of cumulative impact to the rivers of the Mobile River Basin as they were developed for navigation, especially during the last 50 years.The deepening and destruction of shoals and shallow runs or other historic feeding and spawning sites as a result of navigation development likely contributed to local and overall historic declines in range and abundance of the Alabama sturgeon.These modifications have also caused siltation, creating an unsuitable habitat for spawning and foraging.

 

Construction of dams and locks fragmented the range and created metapopulations between the dams where migration was inhibited.Fragmentation created metapopulations where all the speciesí habitat needs were not necessarily met, and where the species became more vulnerable to local declines in water and habitat quality caused by riverine and land management practices and/or polluting discharges.

 

CURRENT THREATS:

The species has continues to be affected by over-fishing, loss and fragmentation of habitat as a result of navigation-related development and maintenance, and water quality degradation.

 

CONSERVATION MEASURES:

 

LITERATURE CITED:

U.S. Fish and Wildlife Service. 1994. Withdrawal of Proposed Rule for Endangered Status and Critical Habitat for the Alabama Sturgeon. Federal Register (59) 240: 64794-64809.

U.S. Fish and Wildlife Service. 1999. Proposed Rule To List the Alabama Sturgeon as Endangered. Federal Register (64) 58: 14676-14685.

U.S. Fish and Wildlife Service. 2000. Final Rule To List the Alabama Sturgeon as Endangered. Federal Register (65) 88: 26437-26461.

Williams, J.D., and G.H. Clemmer. 1991. Scaphirhynchus suttkusi, a new sturgeon (Pices: Acipenseridae) from the Mobile Basin of Alabama and Mississippi. Bulletin of the Alabama Museum of Natural History 10:17-31.