Midwest Fish & Wildlife Conference 2016

AUTHORS: Nick Kalejs*, Purdue University; Tomas Höök, Purdue University; Mitchell Zischke, Purdue University; Jay Beugly, Purdue University; Edward Roseman, Great Lakes Science Center, United States Geological Survey; Robert Hunter, Great Lakes Science Center, United States Geological Survey; David Fielder, Alpena Fisheries Research Station, Michigan Department of Natural Resources

ABSTRACT: Saginaw Bay is a shallow, nutrient rich embayment in Lake Huron that supports species-rich and abundant fish communities. Historically, Saginaw Bay had a complex network of rocky reefs that were used as preferred spawning and nursery habitats for a variety of fish species, including walleye Sander vitreus and lake whitefish Coregonus clupeaformis. These rocky reefs likely provided a number of benefits to spawners including protection from egg predation. Decades of land-use related sedimentation caused many of these reefs to be lost or severely diminished in size. In recent years, with seemingly decreased sedimentation, there has been increased momentum towards reef restoration in Saginaw Bay and reestablishment of the bay’s traditional spawning habitat diversity. The purpose of this study was to analyze current spawning regimes of two key Great Lakes fish species (walleye and lake whitefish) to ascertain whether reef restoration would provide suitable spawning habitat likely to be used by these species. To accomplish this, we evaluated four sites with different levels of reef degradation. We evaluated environmental conditions, abundances of actively spawning fish, egg deposition, and egg predation. Halfway through the two-year study, we have documented actively spawning walleye and lake whitefish and egg deposition at multiple sites, suggesting that some individuals would be able to take advantage of future improved reef spawning habitat. However, spawner and egg densities were very low and various fishes were documented to prey on both walleye and whitefish eggs. We suggest that reef restoration may provide better protection from these egg predators and attract additional fish to spawn.