A recent report from the Great Lakes Fishery Commission (GLFC) reveals that sea lamprey populations have spiked in all five Great Lakes due to a significant reduction in control efforts in 2020 and 2021 during the COVID-19 pandemic.
The commission reports that the number of adult sea lampreys captured in 2024 was 8,619 more than the three-year pre-COVID average of 38,167 (2017-2019). The largest increases were observed in Lakes Superior and Ontario. Although still above target, lakes Michigan, Huron, and Erie have seen flattening trends in abundance since treatments returned to pre-pandemic levels. The report also notes that elevated and variable adult sea lamprey abundances should be expected over the next year or two before turning back downward.
Sea lamprey is a highly invasive and destructive species that were introduced to the Great Lakes through shipping canals in the 1920s. They feed on the blood and bodily fluids of fish, causing significant economic and ecological damage. Before control measures were implemented in 1958, sea lampreys were killing more fish than humans.
Lake-by-Lake Breakdown
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Lake Superior: Adult sea lamprey abundance remains above target, with contributing factors including reduced control effort, changes in distribution, and new infestations.
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Lake Michigan: Adult sea lamprey abundance remains above target, with the Manistique and Big Manistee rivers contributing most to the lake-wide estimate.
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Lake Huron: Adult sea lamprey abundance slightly increased and remains above target, with the Cheboygan River contributing most to the lake-wide estimate.
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Lake Erie: Adult sea lamprey abundance slightly increased and remains above target, with Cattaraugus and Big Creeks contributing most to the lake-wide estimate.
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Lake Ontario: Adult sea lamprey abundance remains above target, with the Humber and Black rivers contributing most to the lake-wide estimate.
The Great Lakes Fisheries Commission was established by the Governments of Canada and the United States in 1955 and is charged with conducting sea lamprey control, formulating a coordinated bi-national research program, and coordinating fisheries management among the jurisdiction in the basin.
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