Fixed -Location Split-Beam Hydroacoustics for Assessing Lake Sturgeon Spawning Runs in Lake Superior

Lake sturgeon (Acipenser fulvescens) are a biologically important and culturally significant species in the Great Lakes. Populations are well below historic levels due to past over exploitation, habitat loss, and reduced water quality. Several rehabilitation efforts have been initiated and agencies continue to better describe the current status of lake sturgeon populations throughout the Lake Superior basin. Lake sturgeon populations are often sampled during annual spawning migrations into Great Lakes tributaries during the spring, however some of these riverine systems can be difficult or inefficient to sample with traditional gears. We tested the efficacy of a fixed-location split-beam hydroacoustics system as a tool to enumerate adult lake sturgeon in the Bad River, a tributary to Lake Superior in Wisconsin. Severe flooding events prevented estimation of the entire spawning run in multiple years of sampling; however the initial hydroacoustic data collected showed great promise for successfully discriminating adult lake sturgeon in the river among other fish species and as a rapid assessment tool for other Great Lakes spawning populations. Future work will focus on ground-truthing hydroacoustic estimates of lake sturgeon with annual mark-recapture surveys conducted in the Bad River.