Fisheries, Midwest Region
Conserving the Nature of America

Sea Lamprey Control Program
Two sea lampreys parasitize a lake trout.

Sea lamprey control in the Great Lakes is truely one of the most complex and astounding Stories in the History of North American Fisheries Management.

Historically, Lakes Huron, Michigan, and Superior were the source of large, high quality cold water fish for markets of the Midwest and east coast. Lake trout alone accounted for an average annual commercial catch of 7000 tons in the 1940s. The season closed in 1962 with the lake trout population collapse brought on by the invasion of parasitic sea lampreys introduced to the Upper Great Lakes through shipping canals.

The sea lamprey is a predatory fish that attaches to host fish and feeds on the blood and body fluids. A single sea lamprey kills 40 or more pounds of fish in its life as a parasite. It is native to the Atlantic Ocean and existed throughout the St. Lawrence Waterway and Lake Ontario but was prevented from moving up into the Upper Great Lakes by Niagara Falls. The canal system used to provide boat transport through the eastern states and ultimately, the construction of the Welland Canal in the late 1800s to provide a shipping route bypass around Niagara Falls, allowed sea lamprey to gain access to the Great Lakes. By the mid-1900s sea lamprey had colonized each of the the Upper Great Lakes.

U.S. Fish and Wildlife Service  employees lift a trap filled with sea lamprey.
The U.S. Fish and Wildlife Service (USFWS), acting as an agent through the Great Lakes Fishery Commission, implemented a massive chemical control effort in the 1950's and by the early 1960's had reduced the abundance of sea lampreys by 90 percent. This effort paved the way for recovery of self-sustaining populations of native lake trout in portions of the Upper Great Lakes. See Aquatic Species Conservation Poster.

While total elimination of sea lamprey populations from the Great Lakes in unlikely, continued chemical treatments along with new technologies and techniques such as mechanical and electrical barriers, and application of phermones to attract lampreys to traps are leading to increasingly healthier fish populations and an economic powerhouse fueled by the resulting recreational fishery. Sea lamprey control will continue and become more important as lake trout restoration activities expand in the Upper Great Lakes.

The Great Lakes Fishery Commission contracts and funds sea lamprey control in the Great Lakes. The Canadian Department of Fisheries and Oceans conducts sea lamprey control in Canadian waters of the Great Lakes and has partnered with the U.S. Fish and Wildlife Service on large projects.