Rock Island Ecological Services Office
Midwest Region


Scaphirynchus alba

Background Information

The Pallid Sturgeon (Scaphirynchus alba) was listed as an endangered species on September 6, 1990. It inhabits the Missouri River and and the Mississippi River below the mouth of the Missouri. Little is known of the basic biology, life history and habitat utilization of this species which makes conservation difficult at best. Furthermore, it makes Section 7 compliance frustrating for the Service, states and Federal action agencies working on the river.

Although wide ranging, catch records for the pallid sturgeon are extremely rare. The species hybridizes with the shovelnose sturgeon (S. platyrynchus ), making identification difficult. A recent genetics study has conclusively separated the pallid and shovelnose sturgeon from the Alabama sturgeon (S. suttkusi) but was inconclusive in separating the pallid from the shovelnose. The degree of difference in mitochondrial DNA haplotypes in these two species suggest that they only recently diverged, about 33,000 years ago.

Large-scale modification of the Mississippi River for navigation system maintenance and flood control is being effected through such activities such as dredging, construction of dikes and weirs, and bank stabilization; and through Section 10 permit issuance for sand and gravel mining throughout the river. Resources at risk include valuable main channel border habitat. Commercial fishing may be affecting the species to an unknown degree.

Recovery Activities

In telemetry studies of pallid sturgeon on the Middle Mississippi River conducted by Dr. Robert Sheehan of Southern Illinois University, Carbondale, IL, a positive selection for main channel border and downstream islands tips was found and also for depositional areas between wingdams and deep holes off of wingdam tips. Sheehan speculated that between wingdam areas and downstream island tips may be used as velocity refugia and/or feeding stations. Study sturgeon were found most often in main channel habitat, however, they exhibited selection against this habitat type. Their occurrence in such habitat was not surprising considering main channel comprised approximately 65% of the available habitat in the study reach.

Last updated: July 17, 2008