Influences of Environmental Conditions on Distance Moved By Shovelnose Sturgeon in the Lower Mississippi River

Shovelnose Sturgeon Scaphirhynchus platorynchus have been described as both highly migratory and sedentary by previous studies, though these behaviors are not well documented in the lower Mississippi River.  Distance between weekly detections along with environmental variables were recorded for 32 individual Shovelnose Sturgeon throughout a 27-km reach of the lower Mississippi River.  We recorded 221 locations of Shovelnose Sturgeon during a 6-month period over a range of river stages and water temperatures.  More than 75% of the fish traveled at least 150 m and 25% traveled more than 1 km between weekly relocations suggesting limited movement.  We used a linear mixed model with individual as a fixed effect to determine influences on distance moved by fish.  Distance traveled was influenced by river stage and surface current velocity but not change in river stage, water temperature, or depth.  Distance traveled increased with surface current velocities and declining river stage.  Decrease in habitat availability at low river stages and therefore searching for suitable habitat, along with high energy expenditure in high surface current velocities may cause Shovelnose Sturgeon to move greater distances.  This type of analysis can support a greater understanding of habitat selection cues that Shovelnose Sturgeon use when changing locations.