Predators of the Great Lakes


The Great Lakes contains 21 percent of the entire planet’s freshwater supply. The region also accounts for one-third of our industry’s retail boat sales. Protecting its $7 billion annual fishery from the menacing sea lamprey is a top priority for marine dealers there.

Never heard of a sea lamprey? It’s an eel-like fish that grows up to 20 inches long, features an ugly round, suction mouth circled with rows of horn-shaped teeth and a razor-sharp rasping tongue. We’re talking one ugly creature!

Sea lampreys are the Great Lakes' biggest predators. They attach to valuable fish and feed on their victims blood and body fluids. Their meal of choice is the much sought-after lake trout. But they can suck the life out of most other species of large Great Lakes fish including brown trout, sturgeon, whitefish, walleye, Chinook and Coho salmon, and rainbow trout — all prized fish by the anglers who buy our boats.

Each individual lamprey is capable of killing up to 40 pounds of desirable fish over a 12-18 month feeding period. And, they really look like they’ve come out of a horror movie. I recall more than once boating a nice lake trout in Lake Erie with a sea lamprey still attached (they usually drop off before the fish is netted) and having it slithering on deck, much to the chagrin of our kids until I skewered it.

It was man’s progress that really triggered the problem. Sea lampreys were actually first observed back in the 1830’s but only in Lake Ontario which connects to the Atlantic Ocean via the Saint Lawrence River, according to Sea Grant at the University of Minnesota that continues to study the lamprey’s impact. Niagara Falls — between Lake Ontario and Lake Erie — was the natural barrier that prevented them from ever invading the other four Great Lakes.

Enter man. The construction of the Welland Canal in 1833 bypassed Niagara Falls and opened an excellent new navigation route. Ships could now get to the interior of the nation all the way to the western end of Lake Superior in Minnesota. But by 1938, so could the sea lampreys — which were confirmed swimming in all five Great Lakes.

Minnesota Sea Grant reports: “The sea lampreys’ impact on the Great Lakes fishery was staggering. Before they entered the Great Lakes, the U.S. and Canada harvested about 15 million pounds of lake trout in lakes Huron and Superior each year. By the early 1960s, the catch was down to about 300,000 pounds.” The once-thriving fisheries were devastated along with thousands of jobs.


Since the early 1970s, to combat the lamprey, the Great Lakes Fishery Commission, formed by a U.S./Canada Treaty, has installed and operated sea lamprey barriers in many strategic locations to keep them from desirable reproduction backwaters. In addition, there is some controlling impact from thousands of hydro-dams and other barriers built for other purposes that also help control lamprey.

Another critically successful deterrent used by the agency is the strategic application of lampricides to tributaries where lamprey are in their larval stage before changing into their adult form to prey on sportfish in the open lakes. A single female can produce as many as 100,000 eggs!

I witnessed the application of lampricides treatments during the many years we docked our boat on the Chagrin River east of Cleveland. It happened periodically because the Fishery Commission has to designate annually where to devote strong attention to reducing the lamprey. It’s also notable that these chemical treatments, while controlling sea lamprey larvae, are considered otherwise safe for people and the environment by the U.S. Environmental Protection Agency.

If you’ve never been aware of all this, you’re likely not alone. Often critically important programs that benefit our marine industry go about their mission without much fanfare. But their impact on boating and fishing is immeasurable. Truth is, if you’re a dealer in any of these states that border the Great Lakes — Wisconsin, Illinois, Indiana, Michigan, Minnesota, New York, Ohio and Pennsylvania (and Ontario) — and sold a boat to any angler that fishes these big lakes, you’ve benefited.

The Fishery Commission is supported with both U.S. and Canadian federal funds. Moreover, in 1996 the Fishery Commission also wisely established trust funds in the U.S. and Canada. The purpose of the funds is to provide enhanced support for lamprey control and fishery research programs, the same reasons for which the commission was formed.

Donations are fully tax deductible. To learn more about this remarkable success, go to Sea Lamprey Control Program — a well-deserved salute to the Fishery Commission.


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