Sea lamprey populations in the Great Lakes are at near-historic lows in Lakes Ontario and Michigan. They are holding steady just above targeted population levels in Lake Huron, and declining but above targets in Lakes Erie and Superior, according to the Great Lakes Fishery Commission 2019 report on sea lamprey numbers.
“It’s a pretty good report card,” said Scott Grunder, Fish and Wildlife Administrator, Interior Region 3-Great Lakes, U.S. Fish and Wildlife Service Sea Lamprey Control Program.
The report compares estimated sea lamprey populations in each Great Lake to targets for each lake. The numbers used to compare conditions to target are a three-year average of annual assessments so they are more reliable than a single year’s numbers.
Lake Erie and Lake Superior remain above their target level of the fish-killing parasite, but sea lamprey populations have significantly dropped from near-record highs in 2017, according to the report.
Grunder works out of the Ludington Biological Station currently based in Manistee. He said poor conditions on the U.S. side of Lake Erie during trapping surveys means the population estimates might be suspect. Until lamprey control teams have a couple good years of trapping, he said, crews will continue to hit Lake Erie. Two areas of special concern are being addressed. A permanent fix is being sought the Springvale Dam on Cattaraugus Creek in western New York. Rebuilding of the Harpersfield Dam on the Grand River near Ashtabula, Ohio, is nearing completion. It will better block lamprey than the old dam. New trap nets at the site should also help with more reliable surveying, Grunder said.
Lake Michigan will get a lot of lamprey control attention next year, Grunder said.
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