Lake Ontario Bloater restoration: hints of success: contributed by Brian Weidel

Posted 11-12-19: Bloater (Coregonus hoyi) are a pelagic fish species native to Lake Ontario that inhabited deep, offshore habitats. Commercial fishery records suggest the species was historically abundant in Lake Ontario, but by the 1970s, was rare. Lake Ontario restoration began in 2012 by stocking Bloater raised from eggs collected from Lake Michigan by the U.S. Fish and Wildlife Service in Green Bay WI. From 2012 – 2017, only two Bloater were captured in annual bottom trawl surveys but in 2018 a three individuals were captured in the April survey and another two in the October survey (Weidel et al., 2019). Bloater reared at the USGS Tunison Laboratory and stocked in U.S. waters are batch marked with calcein, a non-antibiotic compound that produces a visible mark on fish scales and bones (Chalupnicki et al., 2016). Initial examinations of calcein marks suggest the April caught fish were stocked in 2017 near Oswego, NY. This means these fish moved at least 114 and 203 kilometers (71 and 126 miles) from the stocking site in fall of 2017 to their capture locations in April 2018 (Niagara River, Hamlin Beach). To date, three individuals were captured in spring and summer trawl surveys of 2019. Observed trawl catches, while relatively small, are similar to predicted catches and suggests the current trawl surveys may track the restoration success at the current Bloater stocking levels (Weidel et al., 2019). Lake Ontario Bloater restoration is a collaborative effort involving state, provincial and federal partners and additional information can be found in the annual Lake Ontario reports of New York State Department of Environmental Conservation and the Ontario Ministry of Natural Resources and Forestry.

USFWS and USGS contract technicians holding an ~10” female Bloater from the 2018 October collaborative trawl survey. This was the largest Bloater captured to date and contained developed eggs. Photo B. Weidel USGS

Bloater being stocked in Lake Ontario in 2017 near Oswego, NY. Photo: USGS

Calcein in the scale of a stocked Bloater fluoresces under ultraviolet light identifying its stocking origin. Photo M. Chalpunicki USGS