Pallid Sturgeon Migration and Spawning Habitat Use On the Yellowstone and Missouri Rivers

We used a suite of hydroacoustic tools to map habitats used by telemetered reproductive pallid sturgeon in the Yellowstone River in Montana and North Dakota and the channelized Lower Missouri River in Nebraska, Iowa, and Missouri.  Migratory habitats used by reproductive pallid sturgeon were assessed using an acoustic Doppler current profiler (ADCP) to map depths and velocities at transects located at telemetry locations along migratory pathways.  Probable spawning locations were identified on the using intensive telemetry of gravid female pallid sturgeon.  Spawning reaches approximately 1-2 kilometers in length were mapped using an ADCP, a high-resolution multibeam echosounder, and side-scan sonar.  Patterns of habitat use and availability differed by river segment.   Depth and velocity use was similar to availability on the Yellowstone River and the Lower Missouri River in Nebraska and Iowa whereas pathways with lower velocities and a wider range were selected on the Lower Missouri River in Missouri.  Spawning generally occurred on outside bends on or adjacent to bank revetment or bedrock outcrops.  Depths, depth gradients, velocities, and velocity gradients at spawning telemetry locations were greater than those available over the entire reach.  Spawning occurred in regions of greater depth, higher velocity, and harder substrate compared to migratory pathways.