Wisconsin Fishery Project
Determining spawning locations of Green Bay walleyes
July 2017 - June 2021
- University of Wisconsin-Stevens Point
- Fox River/Green Bay natural Resource Trustee Council
Walleyes are native species that are both ecologically and economically important to the Lower Green Bay-Fox River (LGB-FR) ecosystem. Management of walleyes in Green Bay is complicated because walleyes spawn in many locations within Green Bay and its tributaries, but the importance of these different locations or regions to the overall population and fishery have not been determined. Specifically, walleyes spawning in the Fox River and southern Green Bay may contribute a substantial proportion of the fish to the overall population. Our primary objective is to determine if the walleye population in Green Bay is largely comprised (≥ 90%) of fish spawning in the Fox, Oconto, Peshtigo, and Menominee rivers or, if fish spawning in other locations within southern or northern Green Bay are important components. Additionally, we want to determine if walleyes spawning in Wisconsin waters contribute to the walleye population in Michigan waters, as the population as a whole is jointly managed by Wisconsin and Michigan DNR. Determining the extent to which walleyes spawn within certain tributaries or open-water habitats will help DNR biologists determine where habitat protection is needed to maintain spawning stocks and where habitat improvement and restoration might be used to increase abundance of some stocks. Our work may also help identify spawning habitats that were not previously known to biologists. Understanding walleye behavior and movement within Green Bay is also critical in determining whether current WDNR sampling of adult walleyes in these four tributaries provides useful estimates of abundance that can be used in determining predator-prey ratios within the LGB-FR ecosystem, as AOC delisting targets include recommended predator-prey ratios between 1:10 and 1:20. If some walleyes spawn outside of these four rivers, then current sampling may not provide accurate estimates of walleye abundance needed for determining predator-prey ratios.