Population dynamics of muskellunge in Wisconsin waters of Green Bay, Lake Michigan, 1989-2005

Muskellunge, Esox masquinongy, were an important component of the Green Bay ecosystem prior to mid 1900s, but were extirpated by over-fishing, pollution, habitat degradation, and the introduction of exotic species. The Green Bay ecosystem improved after the passage of the Clean Water Act, and the Wisconsin Department of Natural Resources (WI DNR) started a muskellunge reintroduction program in 1989. Monitoring the results of reintroduction efforts is necessary to achieve the program goal of establishing a self-sustaining population. We used available data to provide a 2005 spawner abundance estimate for a Green Bay tributary, estimates of contributions to that spawning stock from fall fingerling and yearling stocking, a weight–length relationship, a growth analysis, and a description of size and age at maturity. Our results indicate that stocking efforts have been successful in producing an adult population, with yearlings contributing to the spawning stock at a higher proportion than fingerlings (14.69:1). Our weight–length and growth analyses suggest that Green Bay muskellunge are unlikely to reach record length, but that it is possible for females to achieve record weight. The rapid growth of Green Bay muskellunge results in their maturing at larger sizes than other stocks, but the relationship between age and maturity is not well understood. Reintroduction efforts in Green Bay have created stocked populations capable of supporting trophy fisheries, but evidence of successful natural reproduction has not been observed. Future research should focus on the reproductive requirements of muskellunge reintroduced into altered habitats.