Spatial extent of contemporary lake whitefish spawning in western Lake Erie

Degradation of lake whitefish (Coregonus clupeaformis) spawning areas in the Detroit River, Maumee Bay, and western Lake Erie reefs and shoals has been identified as a contributing factor to Lake Erie’s population collapse in the 1950s. This decline prompted the United States and Canada to take steps to improve the aquatic ecosystem of Lake Erie. A recent increase in commercial fish harvest and catch of early-life stages of lake whitefish in the western basin of Lake Erie provide evidence that lake whitefish are once again spawning in some of their historical spawning areas, however the extent of use is unknown. To investigate the contemporary distribution of lake whitefish spawning within western Lake Erie, 31 potential spawning locations were sampled for eggs in 2016 and 2017. A subset of sites within Maumee Bay and an open lake reef complex were sampled repeatedly each year to determine the onset of spawning and 17 sites outside these two areas were each sampled once to describe the spatial extent of spawning. Spawned eggs were first detected on 22 November in 2016 and on 18 November in 2017. Viable eggs were collected at 27 of 31 sampled locations, verifying that lake whitefish spawned in Maumee Bay, on the mid-lake reefs, and other locations in 2016 and 2017. These findings confirm that lake whitefish are using historical spawning areas and available spawning habitat in western Lake Erie. The extensive use of available spawning habitat adds spawning stock diversity that is vital for generating population stability and resilience.