Determining the seasonal home range and depth occupancy of round whitefish in Lake Ontario to make recommendations for the design of round whitefish assessment programs.

LORWF

December 2025 - December 2028

Round whitefish are an infrequently encountered native deepwater coregonid in the Great Lakes that have a poorly understood role in the benthic food web and are receiving renewed attention through the Council of Lake Committee endorsed Coregonine Restoration Framework (CRF). The CRF takes an adaptive management approach, iteratively integrating Council of Lake Committee restoration priorities and best available information about coregonines. However, during the planning phase of the CRF, important research needs were identified. These needs include fundamental ecological research into the spatial distribution and habitat of round whitefish and threats to their restoration. In late fall, 20 adult round whitefish will be acoustically tagged (V13TP) near Darlington, where previous surveys reported highest catch-per-unit-effort. We will leverage the existing GLATOS receiver array in Lake Ontario and add additional receivers in strategic locations to detect the acoustic tags at a lake-wide scale year-round. NexTrak receivers will be added in a grid around Darlington (n=10) and individual receivers will be added in the nearshore by Pickering, Peter Rock, and Wesleyville. Detection data will be analyzed using kernel utilization densities and machine-learning habitat models (using temperature logger and open-source environmental data) to determine seasonal home ranges and habitat associations.

• Determine the seasonal home range and depth occupancy of round whitefish in Lake Ontario.
• Determine the factors that influence round whitefish habitat associations (e.g. temperature, bathymetric depth, substrate type) and develop predictive maps of species occurrence.

• Fundamental knowledge about round whitefish spatial ecology and recommendations for the design of round whitefish assessment programs (gear, location, depth, and timing) to generate much needed population and ecological information.

• Emma Bloomfield (Ministry of Northern Development, Mines, Natural Resources and Forestry) - emma.bloomfield@ontario.ca
• Tim Johnson (Ontario Ministry Of Natural Resources)
• Sarah Beech (Ontario Ministry Of Natural Resources)

• Ontario Ministry of Natural Resources and Forestry

• Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health
• Ontario Special Purposes Account - Ontario Ministry of Natural Resources