UW-Green Bay

Master of Science in Environmental Science & Policy

Population Dynamics of Self-Sustaining Muskellunge in Northern Wisconsin Lakes

Lawrence D. Eslinger

The muskellunge is a vital fish species throughout Wisconsin and many other parts of North America. Ecologically, the muskellunge sits atop the aquatic food chain within many freshwater systems, and helps to maintain ecosystem balance and health. Economically, muskellunge fisheries provide important monetary revenues to many local communities. Unfortunately, many naturally-reproducing, self-sustaining muskellunge populations have become, or are at risk of being, unable to sustain themselves.

The muskellunge is a relatively long-lived, low-reproducing species that is susceptible to environmental degradation and changes in fish community composition. They are commonly managed as a trophy fish species with high minimum length limits and low daily bag limits. Despite these restrictive regulations, fishing popularity for muskellunge continues to increase, and most anglers have adopted the practice of live catch-and-release of legal-sized fish. Muskellunge typically occur in relatively low abundances, and therefore, information regarding population dynamics along with factors affecting their recruitment is limited. Therefore, the analysis of a large database, collected over a continuous number of years, is needed to provide insight on muskellunge population dynamics in response to changing environmental, biological, and angler conditions.

The Escanaba Lake Fisheries Research Area, operated by employees with the Wisconsin Department of Natural Resources, has been in operation since 1946. For over 60 years, a large database has been developed for a number of fish species, including muskellunge, as well as quantifiable information on angler statistics. This study uses data collected between 1987 and 2008 to analyze information on muskellunge population dynamics, fish community structure, environmental parameters, and angler statistics on four lakes in northern Wisconsin that contain naturally-reproducing, self-sustaining muskellunge populations.

Results from this study show that natural muskellunge recruitment is most influenced by forage fish species availability, May water temperatures, and the structure (abundance and/or size structure) of the adult muskellunge population. The research also implies that muskellunge populations, and aspects of the fisheries they provide, are most influenced by biological characteristics of the aquatic ecosystems they reside in. However, findings do show that changes in angler behavior can contribute greatly to modifications in the population dynamics within some muskellunge populations.

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