Inventory and assessment of coregonine spawning locations in lakes Erie and Ontario, including connecting channels

Edward Roseman (USGS, eroseman@usgs.gov), Dimitry Gorsky (USFWS), Hannah Schaefer (USGS), Robin DeBruyne (USGS)

This project involved two phases. First, to identify locations of key habitats for coregonines in lakes Erie and Ontario and their respective connecting channels, we conducted a literature review of historical spawning, nursery, and adult habitat sites where coregonines have been observed. Second, we used these sites as a reference for weekly larval sampling at six locations across the southern shore of Lake Erie during spring 2017 (U.S. waters) to explore for evidence that coregonine spawning occurred based on presence of early life history stage larvae. Weekly egg sampling was conducted at two locations in western Lake Erie during the 2016-2017 and 2017-2018 incubation periods and additional spatially distant locations were sampled for eggs to evaluate the spatial extent and magnitude of spawning. We also conducted one week of exploratory sampling in southern Lake Ontario. In 2017, USFWS performed weekly larval sampling from March 27 to April 19. Biologists sampled seven sites in both the upper Niagara River and the lower Niagara River for a total of 76 sample collections. Along the south shore of Lake Ontario, USFWS completed weekly larval surveys at six sites in Irondequoit Bay, a historic cisco spawning embayment, for a total of 17 sample collections. Only two coregonines were collected by USFWS sampling, both located at sites near the mouth of the lower Niagara River.