Post-spawning dispersal and open-water spawning locations for Green Bay walleye

NGBWE

April 2025 - April 2029

Spatial variation in walleye recruitment is evident within Green Bay. Recruitment failure has been documented in northern Green Bay where stocking is occurring. Conversely, sustained natural recruitment is occurring in the south where no stocking occurs. The Sturgeon Bay area appears to fall between these two scenarios because inconsistent recruitment has been documented, but stocking occurred until 2012. Recent telemetry research supported by GLFWRA funding showed that 40% of 58 walleye spawning in Little Bay de Noc in northern Green Bay moved into southern Green Bay (south of Chambers Island) and 48% moved into Lake Michigan, with these migrations repeated annually. Our initial findings suggest that walleye recruitment occurring in northern Green Bay (which includes Michigan DNR stocking) may be “outsourced” to other areas as fish reach sexual maturity. However, previous telemetry research included few walleye that spawned in the Whitefish or Rapid rivers. Fish spawning in these two rivers could represent a large proportion of the walleye population in northern Green Bay and may be less likely to leave the area. Additionally, only 25 fish from the Escanaba River were tagged during spawning, and this river represents another potential source of recruitment in northern Green Bay. The previous configuration of receivers in Green Bay (e.g., lines at key transition zones) did not allow us to determine where northern Green Bay walleye went after they crossed into southern Green Bay or Lake Michigan. The current configuration of the open-water receiver array in Green Bay (8-km grid) and the GLFWRA-funded addition of receivers along the lakeside of the Door Peninsula provides the opportunity to better understand post-spawning dispersal of northern Green Bay walleye. In southern Green Bay, previous telemetry showed that most walleye spawned in tributaries, but 21% of fish appeared to spawn outside of tributaries, including the Sturgeon Bay area, although we could not determine specific locations. Spawning outside of tributaries may occur at locations where significant investment in habitat improvements has occurred and confirming walleye spawn at these locations is important in determining whether project objectives have been met. Spawning in Sturgeon Bay could represent a source of recruitment if hatching occurs and spawning fish disperse at a bay-wide scale. We will verify walleye egg deposition and hatching at select locations in southern Green Bay and use telemetry to describe the extent of post-spawning dispersal for walleye spawning in Sturgeon Bay (e.g., local, bay-wide, mostly south vs. mostly north). This is a tag-only project.

• Daniel Dembkowski (University of Wisconsin Stevens Point) - dan.dembkowski@uwsp.edu

• Wisconsin Cooperative Fishery Research Unit
• Wisconsin Department of Natural Resources
• Michigan Department of Natural Resources