A scientist places an acoustic tracking tag onto a walleye while on a research boat.

Chris Vandergoot, director of the GLATOS at Michigan State University, places an acoustic tracking tag onto a walleye. Credit: Tyler Funnel

Populations of walleye (Sander vitreus) in Saginaw Bay in Lake Huron have rebounded over the last decade because of water quality and habitat improvements. As a result, management goals for these populations have now shifted to ensuring a sustainable harvest. Unfortunately, not much is known about where these fish are spawning or where they are coming from – some walleye are residents of the bay while others migrate into Lake Huron to spawn. This information is needed to ensure better management and habitat protection. 

Chris Vandergoot, director of the Great Lakes Acoustic Telemetry Observation System (GLATOS) at Michigan State University, is leading a team to identify walleye spawning sites and their relative contributions in Saginaw Bay. In addition to funds Michigan Sea Grant, the Great Lakes Fishery Commission is also helping to support this project. This project will help determine how the fish are using 14 known tributary spawning aggregations; if off-shore rock reefs are a source of reproduction; and whether migrant and resident walleye aggregations differ in spawning locations or timing.

The team are placing 355 acoustic tags on walleye and installing acoustic receivers in the mouth of each river and on the reefs. The receivers will record the presence of the fish by tracking the tags using sound to determine where they are spawning. These findings also will shed light on any differences in spawning between resident and migratory walleye. 

A researcher releases a walleye back into Saginaw Bay from a boat.

Chris Vandergoot releases a walleye back into Saginaw Bay, Lake Huron, after tagging to ensure tracking. Credit: Tyler Funnel

Ultimately, this project will identify individual walleye spawning aggregations and determine their relative importance to the Saginaw Bay population – one of the last key missing pieces of information in understanding and helping to manage the newly recovered population and fishery. Determining the relative importance of each river and reef for spawning can help fisheries managers better identify and prioritize areas for habitat improvement, fish passage projects, off-shore reef creation, dam removals, or other initiatives. 

One unique aspect of this project is that the team is working with recreational anglers to help gather the data. Team members worked with anglers to catch the fish, and the scientists then tagged them. During the first year of the project, not many fish were caught; fortunately, 2023 was a good year for tagging fish and gathering data. The team is hoping to gather data for at least another year. The project began in March 2022 and will end in December 2026. 

“One of the things we are particularly interested in with these fish is spawning site fidelity,” said Vandergoot. “We want to know if these fish are returning to the same spawning sites each year, information that will help ensure sustainable management.” 

Partnering organizations include the Michigan Department of Natural Resources, Michigan State University – Department of Fisheries and Wildlife, United States Geological Survey – Hammond Bay Biological Station, and the Ohio Department of Natural Resources – Division of Wildlife.