AUTHORS: Ryan Eastman, Wisconsin Cooperative Fishery Research Unit; Jason Breeggemann, Wisconsin Department of Natural Resources; Robert Davis, University of Wisconsin - Madison Center for Limnology; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit; Daniel Isermann, U.S. Geological Survey
ABSTRACT: Green Bay and its tributaries support a world-class fishery for trophy muskellunge that attracts anglers from across North America, but there has been little evidence of natural recruitment and the population remains reliant on stocking to sustain the fishery. Previous efforts to document natural recruitment have focused on the Fox and Menominee rivers where spawning is known to occur. Results of these assessments suggest that hatching success in these rivers is limited. However, recent telemetry-based research indicates that approximately half of Green Bay muskellunge spawn in non-tributary locations. These locations could represent important yet unconsidered sources of natural recruitment in southern Green Bay. Furthermore, anecdotal observations suggest spawning occurs in the Sturgeon Bay area but it is unknown if these fish contribute to the broader southern Green Bay population. Our objectives for this project are to determine if: (1) successful hatching is occurring at open-water locations in Green Bay, including locations in the Sturgeon Bay area, (2) presence of eggs or larval muskellunge at a location is related to a suite of habitat characteristics including distance to shore, bottom slope, depth, dissolved oxygen, substrate type, and aquatic vegetation, and (3) muskellunge spawning in the Sturgeon Bay area contribute to the overall population in southern Green Bay. We are integrating intensive egg and larval fish sampling and acoustic telemetry to address our objectives. We will present preliminary results related to spawning and hatching in non-tributary locations based on sampling efforts during the 2024 field season. We will also discuss the framework of our acoustic telemetry approach to assess the contribution of muskellunge spawning in the Sturgeon Bay area to the broader Green Bay population.
