Biology, Management, and Culture of Walleye and Sauger

Chapter 5: Walleye and Sauger Habitat

Michael A. Bozek, Timothy J. Haxton, and Joshua K. Raabe


Habitat is a fundamental cornerstone of all fish populations and is broadly defined herein as those physical and chemical features of aquatic systems that affect survival, growth, reproduction, and recruitment. Simply stated, it is where fish live and the conditions that occur there. Interestingly, despite widespread interest in managing habitats and considerable money spent by agencies on habitat restoration and enhancement, knowledge of specific habitat requirements and quantitative relations between habitat quality and quantity relative to population performance parameters lags our understanding of other aspects of fish species’ life history and management. This knowledge gap often results in failed habitat projects (Smokorowski et al. 1998). Walleye is a species that has a moderate amount of basic habitat and life history information (e.g., spawning substrate sizes, water depth and velocity, yet there is a serious lack of quantitative information on the functional linkage between fish abundance and habitat quantity and quality in a predictive sense. Moreover, basic habitat information and information on the functional link between abundance and habitat quantity and quality for populations of sauger is even more depauperate.

When identifying habitat, biologists may commonly focus on physical features (e.g., substrate, macrophytes, water depth) while water quality characteristics (e.g., temperature, dissolved oxygen, pH, metals) may be considered only as an afterthought. However, both components of habitat are crucial characteristics of aquatic environments that influence the distribution and abundance of walleye and sauger populations and may even preclude their occurrence altogether. Although less often thought of as habitat directly, biogeographic characteristics are a third and equally important aquatic habitat component since they influence overall access to suitable habitats for completing life histories, colonizing new habitats, or recolonizing habitats where extirpation may have occurred. For example, biogeographic characteristics may allow or obstruct fish passage (i.e., movement, migration) and influence colonization or recolonization processes (from source populations) in water bodies. From a habitat standpoint, biogeographic processes differ in that fish do not respond to them directly, but rather respond to the physical and water quality conditions that they can access through the presence of movement corridors, or are precluded from accessing in their absence.