Walleye Habitat Use, Spawning Behavior, and Egg Deposition in Sandusky Bay, Lake Erie

Understanding habitat selection in fish can reveal areas critical for a population’s continuation in the ecosystem. In systems experiencing habitat alterations or reductions in population sizes, identifying habitat use takes on increased importance. To facilitate our understanding of potential factors limiting the success of walleye (Sander vitreus) in Sandusky Bay, Lake Erie, we combined walleye locations determined from radio telemetry with habitat predictor variables to model habitat use and reveal sex-specific patterns of habitat use throughout the spawning season (Chapter 2). Models revealed that the presence of preferred walleye spawning substrate, gravel and cobble, was an important predictor of walleye locations during the entire spawning season, and depth and distance from shore were important particularly prior to the spawn. In examining sex-specific patterns of habitat use, we discovered that males were more likely to occur over gravel and cobble substrates than females. We hypothesize that males establish position in these areas in anticipation of spawning females. Only a small proportion of walleye tagged in Sandusky Bay migrated to upstream spawning grounds (2 of 197; 1%). To confirm whether walleye spawning occurs in Sandusky Bay and to analyze how spawning substrate might affect egg deposition rates and viability, we compared eggs collected using spawning mats from gravel/cobble and sand/silt substrates (Chapter 3). Egg deposition and egg viability were not significantly different between substrates, and the majority of walleye eggs were collected from one site that contained gravel and cobble. The combined results of this investigation reveal that the Sandusky Bay is a spawning ground for walleye and that preferred spawning substrate is an important factor predicting the location of walleye during the spawn. Because the amount of spawning habitat in this system has declined by an estimated 92% during the past century, we recommend that conservation and restoration steps be taken to preserve this walleye spawning population.