Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

30.  HABITAT SELECTION OF JUVENILE SHOVELNOSE STURGEON. 

Elise R. Irwin, USGS, Alabama Cooperative Fish and Wildlife Research Unit, Auburn, Alabama; 119 Swingle Hall, Auburn University, Auburn Alabama, 36849; Phone: 334-844-9190; E-mail: irwiner@auburn.edu

Marilyn Taylor, Katie Mickett, and Peter Sakaris; Alabama Cooperative Fish and Wildlife Research Unit, Auburn, Alabama.

Conservation plans for the endangered Alabama sturgeon Scaphirhynchus suttkusi include future stocking of juveniles into riverine systems known historically to be within its range.  Therefore, we examined habitat use of juvenile shovelnose sturgeon S. platorynchus as a surrogate experimental fish for the Alabama sturgeon to identify appropriate habitats for stocking.  We designed and constructed a 7-m serpentine stream tank where multi-variable habitats (i.e., depth, substratum, cover, and velocity) were manipulated, and specific availability in the tank was measured.  Using video recordings from two digital video cameras (transferred to video cassettes), fish (212-353 mm standard length, SL) distributions relative to habitat types were quantified.  We used a 4 x 4 Latin square experimental design, and blocked on time and tank position, to determine differences in habitat use among the following treatments: sand; sand with cover; gravel/pebble mix; and gravel pebble mix with cover.  Time was not a significant factor; however, tank position was.  We determined that shovelnose sturgeon selected sand and sand with cover treatments over the gravel/pebble treatments.  In the presence of flow, fish selected for the most downstream position in the tank and avoided the most upstream position.  In the absence of flow, sand treatments were selected regardless of tank position.  Behavioral observations indicated that shovelnose sturgeon often aggregated and oriented into the flow.  In addition, fish avoided touching gravel/pebble when swimming to and from treatments; whereas, fish settled on sand substrata.  We hypothesize that selection of sandy habitats is related to foraging behavior and that velocity of habitats is also critical for habitat selection.  These data provide a baseline for selection of stocking areas and potential collection areas.