Midwest Fish & Wildlife Conference 2018

AUTHORS: Christopher J. Sullivan, Wisconsin Cooperative Fishery Research Unit, College of Natural Resources, University of Wisconsin-Stevens Point; Holly Embke, K. Martin Perales, Steve Carpenter, M. Jake Vander Zanden - Center for Limnology, University of Wisconsin- Madison; Zach J. Lawson, Wisconsin Department of Natural Resources; Daniel A. Isermann, U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit, College of Natural Resources, University of Wisconsin-Stevens Point

ABSTRACT: Walleye Sander vitreus are one of the most economically important fish species within the state of Wisconsin where they support both recreational and tribal fisheries.  Over the last decade or more, recruitment of Walleyes has declined in many northern Wisconsin lakes.  Evidence suggests that populations of Largemouth Bass Micropterus salmoides have expanded and this may be true of centrarchid species in general (e.g., Bluegill Lepomis macrochirus, Black Crappie Pomoxis spp., and Rock Bass Ambloplites rupestris). Consequently, potential inter-specific interactions such as competition and predation could be affecting Walleye reproductive success.  During 2017-2021, we will be evaluating population- and ecosystem-level responses following the removal of centrarchid species populations from a northern Wisconsin lake and comparing these responses to trends observed in a reference lake. Specifically, we will determine if Walleye recruitment improves following removals.  In addition, we will evaluate both population dynamics and demographics of Walleyes and centrarchids before and after removals occur. We will discuss the lake selection process, our proposed sampling design, and insights from preliminary data collected from the two lakes this spring.  We believe our assessment will provide insights into the mechanisms regulating Walleye recruitment and could guide future management initiatives aiming to improve Walleye recruitment.