A watershed community of scientists will conduct spawning abundance estimates for a remnant population of lake sturgeon in the grand river, MI

The Department of the Interior Fish and Wildlife Service Region 3 awarded a $250,107.59 Project Grant under the Fish and Wildlife Management Assistance Program (CFDA 15.608) to the Grand Rapids Public Museum to conduct spawning abundance estimates for a remnant population of lake sturgeon in the Grand River, MI. The museum will use two methodological approaches - hydroacoustic imaging and genetic analysis of age-0 sturgeon - to establish baseline data on annual spawning abundance, effective spawning size, and genetic diversity of the Grand River's lake sturgeon population. This data will inform management prescriptions by the Michigan Department of Natural Resources. The museum will pilot the use of fixed-location hydroacoustic technology to assess annual spawning runs and collect genetic samples through nighttime visual surveys to calculate effective population size and parental contribution. This project aims to evaluate efficient survey methods for obtaining population-level data on a large river system that could be replicated to address knowledge gaps about lake sturgeon in the Great Lakes region.

Two methodological approaches will be used and include the piloting of hydroacoustic imaging of spawning sturgeon and genetic analysis of age-0 sturgeon. The two methods will provide annual spawning abundance and effective spawning size estimates that will establish a baseline to be used for evaluating and refining detailed management prescriptions. The grand river lake sturgeon population is one of the last in the lake michigan basin where basic population data is absent. The void comes from difficulty in sampling a large river system and investment to understand feasible survey methods. This has inhibited knowledge of a population trajectory, a primary metric which michigan department of natural resources (midnr) bases management prescriptions. This project aims to evaluate hydroacoustic methodologies in a large river system that could provide an efficient option for obtaining population-level data on a large river system. A multi-organizational collaborative has begun to address lake sturgeon knowledge gaps in the grand river and has collected lake sturgeon recruitment data through visual nighttime surveys conducted over six years. Index sites have been established and recruitment documented. In 2022, project partners measured lake sturgeon habitat in the grand river and evaluated locations for deploying fixed-location, hydroacoustic technology to quantify the annual number of sturgeon migrating to spawn. This study will expand upon the current effort and provide estimates on annual spawner abundance, effective spawner size(parents contributing to spawning), genetic diversity, and recruitment. The fixed-location, split-beam hydroacoustic technology will be piloted during the first season of the project and then the refined methodological process will be redeployed to assess annual numbers of lake sturgeon in the spawning run. Nighttime visual surveys will be used to collect genetic samples from age-0 sturgeon to calculate effective population size, parental contribution, and genetic diversity (scribner ET AL. 2022). The use of acoustics techniques holds great promise for rapid-assessment of lake sturgeon populations and have been used for assessing fisheries in the northwest although only a single lake sturgeon spawning assessment has been conducted in the great lakes. This study will pilot acoustic methods which may be the most feasible technique for assessing lake sturgeon spawning populations in large rivers with turbid waters. The information collected from both methods will provide the baseline information that will be needed to make informed management decisions for the grand river lake sturgeon population.