Using Side-Scan Sonar to Assess Habitat Use of Sub-Adult Lake Sturgeon in the Wolf River, Wisconsin

Little is known regarding habitat use of sub-adult lake sturgeon in riverine portions of the Lake Winnebago system located in central Wisconsin.  Understanding habitat use by sub-adult fish will improve lake sturgeon assessment by allowing biologists to better evaluate recruitment dynamics and identify critical habitat.  Characterizing habitat and substrate in aquatic environments using traditional transect-based methods can be difficult, time consuming, and expensive.  However, the availability of small, portable, and inexpensive side-scan sonar devices now offers a more efficient means of mapping physical habitat in aquatic systems. Our objective is to determine if sub-adult lake sturgeon selectively occupy certain habitats in the lower Wolf River based on substrate, depth, and presence of coarse woody debris.  Habitat availability in the lower Wolf River will be mapped using side-scan sonar.  Twelve sub-adult lake sturgeon were implanted with radio transmitters in fall of 2013. These fish will be located approximately every 2 weeks and habitat variables will be recorded at each location.  Selectivity will be evaluated by comparing habitats occupied by fish to habitat availability assessed from side-scan images.