ROCKFORD, Mich. (WOOD) — The U.S. Fish and Wildlife Service will have teams in West Michigan next week to apply lampricides and kill sea lamprey larvae that may have burrowed into the riverbeds.

The USFWS will have crews working on the Rogue River in the Rockford area and Crockery Creek near Nunica. The applications will run between June 6 and June 14 at the two locations. Typically, they take about five days. Days and times may change based on local weather or water conditions.

If not treated, sea lamprey larvae will mature into adults and end up in the Great Lakes to feed on fish. The USFWS says tributaries with known sea lamprey infestations need to be treated every three to five years.

Sea lamprey are native to the Atlantic Ocean but had made it into Lake Ontario by the 19th century. Niagara Falls served as a natural barrier, keeping the lamprey out of the other four Great Lakes. However, changes to waterways around the falls, including the Welland Canal, gave them an opportunity to expand, eventually making their way to all five Great Lakes.

Sea lamprey were first found in Lake Michigan in 1936 and by the 1950s were shown to be a major menace on the ecosystem. At that time, they were killing off an estimated 110 million pounds of fish each year, far more than the commercial harvest. That makes them a threat not only to Great Lakes fish, but also to the fishermen who make their living on the lakes. Marc Gaden, the legislative liaison for the Great Lakes Fishery Commission, called them “incredibly destructive.”

“The people who were fishing the lakes watched in relatively slow motion, a horror as the lamprey wiped out their way of life and their business. By the 1950s, it became apparent that if we wanted to save the Great Lakes fishery, we needed to control the sea lampreys,” Gaden told News 8 last year.

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Lamnpricides have reduced the sea lamprey population in the Great Lakes by up to 95%. (AP file)

After running more than 10,000 experiments, scientists landed on a “silver bullet” — a specific concentration of a chemical that can be safely added to the water that kills lamprey but doesn’t harm other fish.

The common USFWS lampricide is a combination of Lampricid and Bayluscide. A new joint review by the U.S. Environmental Protection Agency and the Health Canada Pest Management Regulatory Agency confirmed in 2003 that the chemicals pose “no unreasonable risk” to the general population.

“We’ve reduced the lamprey populations by about 90% to 95%,” Gaden said. “Basin-wide, we’ve gone from losing about 110 million pounds of fish every year to only about 10 million pounds. … We’ve gone from about 600,000 voracious sea lampreys in Lake Michigan to about 15,000, 16,000.”

Sea lamprey feed on several types of fish, most notably lake trout and lake whitefish, but they also feed on walleye, steelhead and yellow perch. Lamprey aren’t a major threat to ocean fisheries because the fish on which lamprey feed can often survive and work in a symbiotic relationship.