Cooperative Fish and Wildlife Research Units Program: Wisconsin Fishery
Education, Research and Technical Assistance for Managing Our Natural Resources

The Lake Winnebago System (LWS) in east-central Wisconsin supports one of the largest lake sturgeon populations in the world. Lake sturgeon spawn in many locations within the LWS, and many fish make extensive spawning migrations into the Fox and Wolf Rivers and their tributaries. The contribution of different spawning locations to the overall lake sturgeon population is unknown at this time and this information is critical in developing management strategies. Specifically, identifying the contribution of different spawning locations to spearing harvest would allow managers to determine if this harvest differentially affects certain spawning groups or “stocks”. Furthermore, little is known about the relative number of recruits that are produced at different spawning locations and this information could help guide efforts to increase recruitment at some locations through habitat improvement. Additionally, whether adult characteristics such as size and sex affect reproductive success remains unknown. This information could have important implications for harvest management, if the probability of producing offspring varies among fish of different sizes. Our objectives are to determine if: 1) otolith microchemistry can be used to identify larval and juvenile lake sturgeon hatching at different locations within the LWS (e.g., Fox vs. Wolf rivers, tributary vs. main river); 2) if differences in chemical signatures are consistent between otoliths and fin rays; 3) abundance of larval sturgeon varies among spawning locations; 4) if contribution to spearing harvest varies among spawning locations; and 5) probability of producing offspring varies in relation to size and sex of adult fish captured at individual spawning locations.