Multi-Scale Habitat Assessment of Larval and Young Sturgeon Habitat in the Lower Missouri River

We examined potential larval- and young-sturgeon habitat at the patch, reach, and segment scale in the Lower Missouri River.  At the patch scale we surveyed three sites believed to provide habitat for young-of-the-year sturgeon over a range of flows.  These surveys were conducted in coordination with U.S. Fish and Wildlife Service Columbia Fish and Wildlife Conservation Office trawling efforts from June to September 2011.  Patches were mapped around the region of the trawl lines with a single-beam echosounder and an acoustic Doppler current profiler (ADCP) where flow expansion has created shallow-water habitat accessible to larval and young-of-the-year sturgeon.  We performed surveys at the reach scale (0.5-2 km in length) during the summer 2011 high flows to investigate the dynamics of confluence and side-channel habitats for larval and young sturgeon.  Eight sites were mapped to access the dynamics of larval drift and exchange between the main channel, off-channel, and tributary habitats.  These reach-scale sites were mapped at a high-resolution using a multibeam echosounder paired with an ADCP.   At the segment scale we conducted a GIS analysis of Missouri River habitats to test the hypothesis that regions of flow expansion and secondary flow may create habitats favorable to larval and young fish.  Measurements of channel width, wing dike location and width, thalweg sinuosity, and bend curvature are being used to develop a model of where regions of flow constriction, expansion, and shallow water habitat occur.  We hypothesize that segment-scale indicators will be predictive of young and larval sturgeon occurrence.