Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

47.  FOOD HABITS OF THE ALABAMA STURGEON, SCAPHIRHYNCHUS SUTTKUSI WILLIAMS AND CLEMMER, A ENDANGERED SPECIES.

Christopher Haynes, Department of Biology, Shelton State College, Tuscaloosa, AL 35405.  Phone 205-391-2202; chaynes@sheltonstate.edu

Richard L. Mayden, Department of Biology, St. Louis University, 128 Macelwane Hall, 3507 Laclede Avenue, St. Louis, MO 63103-2010; Phone 314-977-3494; FAX 314-977-3658; maydenrl@slu.edu

Bernard R. Kuhajda*, Department of Biological Sciences, University of Alabama, Box 870345, Tuscaloosa, AL 35487-0345; Phone 205-348-1822; FAX 205-348-6460; bkuhajda@bama.ua.edu

The Alabama Sturgeon is a critically imperiled species endemic to the Mobile Basin of the southeastern United States.  Very few individuals of this species have been captured within the last decade and only a few specimens have been vouchered in museums, leading to it listing as an Endangered Species under the USA Endangered Species Act.  Little is actually known about the biology of this species aside from the correlated decline of the species following the completion of some hydroelectric dams on the Alabama River and alterations of the Tombigbee River in Mississippi and Alabama.  Habitat association of this species is an area of increasing importance given that it is hoped that the Alabama Sturgeon population will recover from its current state of imperilment.  In this study we examined gut contents of 12 specimens of the Alabama Sturgeon from available museum materials at the University of Alabama Ichthyological Collection. A total of 25 identifiable taxonomic units were found.  From these 25 taxa, 7 taxa were represented by only a single individual, and 6 taxa were represented by only 2 individuals. Five insect families composed the bulk of stomach contents, being both the most frequently occurring among the different stomachs, and the most abundant taxa per stomach.  These families were the Heptageniidae (Ephemeroptera), Gomphidae (Odonata), Hydropsychidae (Trichoptera), and the Ceratopoginidae and Chironomidae (Diptera).  In terms of frequency, the Ceratopogonidae was the most frequently encountered, occurring in 83% of the stomachs.  Heptagenids occurred in 67% of the stomachs.  Both Chironomids and Gomphids occurred in 58% of the stomachs, and Hydropsychids occurred in the 50% of the stomachs. In addition to insects, small fish occurred in 42% of the stomachs.  Plant material (root, stem, leaf pieces, and seeds) occurred in 33% of stomachs.  In addition to the organic material, gravel (3-8 pieces <1 cm dia.) was found in 25% of the stomachs, and sand was present in 75% of the stomachs. The most abundant food organisms per stomach were the Ceratopogonidae and Chironomidae, each with over 50 organisms per stomach.  The Heptageniidae averaged 5.25 organisms per stomach.  Small fish averaged 2.0 organisms per stomach; the Hydropsychidae averaged 1.50 organisms per stomach; Gomphidae averaged 1.33 organisms per stomach. Based on the family assemblage present in the specimens examined, the feeding habitats of these individual sturgeon specimens shortly before they were captured would have included relatively shallow, sandy bottom (low silt), moderate current areas as well as deep swift water areas with a stable substrate.