Habitat Use and Selection by Adult Pallid Sturgeon in the Lower Mississippi River

The Pallid Sturgeon Scaphirhynchus albus is an endangered riverine sturgeon with historical distribution restricted to the Yellowstone, Missouri, Mississippi, and Atchafalaya rivers. Although not abundant, Pallid Sturgeon in the lower Mississippi River appear to be naturally recruiting, and information about habitat use is important to conserve this species. Thirty-four adult Pallid Sturgeon (612-1,013-mm FL) were tagged with acoustic transmitters and relocated a total of 272times in a 40-km reach of the lower Mississippi River from April 2009 through December 2012. Pallid Sturgeon strongly selected island tip and natural bank habitats, and, to a lesser degree, revetted bank habitat. Although frequently used, Pallid Sturgeon exhibited negative selection for the expansive main channel habitat. Secondary channel habitat was seasonally available and excluded from habitat selection analysis, but this habitat was frequently used in the spring when available. Fifty percent of Pallid Sturgeon detections were in relatively narrow ranges of depths (6.2-13.6m) and surface current velocities (0.64-1.05m/s). Use of different habitats was related to river stage and water temperature, suggesting use of some habitats was seasonal. Results suggest that maintaining natural bank habitat and secondary channel-island complexes will benefit conservation of this endangered species in the lower Mississippi River. Received April 12, 2012; accepted July 29, 2013