Sea Lamprey

What do Sea Lampreys look like?

Sea lampreys are members of an ancient family of "jawless fishes" that were around before the time of the dinosaurs. They are 12-20 inches long and eel-like. They have dark brown to black backs and light yellow to pale brown bellies. Look for a feathery fin from their midsection down and under the tail. Their mouth is circular with circular rows of teeth. They have large reddish eyes.
Sea Lamprey
It is important to recognize the distinguishable features of Sea Lamprey because there are several native freshwater lamprey species found in the Great Lakes region. Some are parasites and some are not. These lampreys live in balance with their natural food chain and don't deplete fish populations.

Sea Lamprey The four native lamprey species include:

  1. Silver lamprey (parasitic); found in the Mississippi River and Chippewa, Embarrass Rivers. It feeds on carp, catfish, walleyes, northern pike, suckers, sturgeons, and paddlefish.
  2. Chestnut lamprey (parasitic); found in the Upper Mississippi River, Wisconsin River, Chippewa River, St. Croix River, Namekagon River (‘74-’86 records).
  3. Northern brook lamprey (not parasitic); found in the Brule River, Red Cedar River & tributaries, Peshtigo River tributaries.
  4. American brook lamprey (not parasitic); found in the Red Cedar River & tributaries, Buffalo River, Trempealeau River, La Crosse River, Kickapoo River, Wisconsin River, Menominee River.

Why are Sea Lampreys considered to be a nuisance?

  • Direct Predation– Sea lampreys attach themselves to other fish and suck on their blood and body fluids. They leave rounded scars on the fish. When they first arrived on the Great Lakes scene, they killed large numbers of predatory sport fish. People began to notice the lack of large fish and the scars on others. Lampreys preyed on whitefish, lake trout and chub populations in lakes Superior and Michigan. The lamprey invasion made it hard on the people who fished the Great Lakes to make a living.
  • Ecological Impacts - One sea lamprey can upset an ecosystem and food chain by eating an estimated 40 pounds of fish or more in its lifetime. Multiply that times 22,000 lamprey found in just one river and you have a lot of dead fish. Because of lower large fish populations, small fish, like the alewife, were able to increase in numbers.

How do Sea Lampreys affect recreational users?

Anglers – Recreational anglers who fish for lake trout, salmon, rainbow trout (steelhead), brown trout, whitefish, yellow perch, burbot, walleye, and catfish are affected by sea lamprey. This parasitic fish attach themselves to popular gamefish and effectively destroy them.

Where are Sea Lampreys currently found?

Sea Lamprey are found throughout the Great Lakes and clear, cold streams in the region. Construction and improvements on the Erie and Welland Canal (between Lake Ontario and Lake Erie) around 1921 allowed sea lampreys to get through the canal to the next lake.

Sea Lamprey Map

What is the potential for Sea Lamprey to spread elsewhere in U.S.?

Due to the leadership of the Great Lakes Fishery Commission and its partners, Fisheries and Oceans Canada and the U.S. Fish & Wildlife Service, these organizations undertake sea lamprey control on the Great Lakes. The control program uses several techniques to attack sea lampreys during different stages of the life cycle including:
  • the chemical application of Lampricide,
  • the use of barriers to block the upstream migration of spawning sea lampreys; and
  • a technique known as the Sterile-Male-Release that reduces the success of sea lamprey spawning and trapping.
This multi-faceted approach has been tremendously successful. Ongoing control efforts have resulted in a 90% reduction of sea lamprey populations in most areas, creating a healthy environment for fish survival and spawning. Although it is impossible to completely rid the Great Lakes of sea lampreys, through continued cooperation and support, we can keep their populations at levels that lessen the impact to our fishery. Sea lamprey control is an investment in our fishery and our future. It means more quality fish and fishing opportunities for ourselves and for future generations! (From Sea Lamprey: the battle continues working together to protect our great lakes fishery. A publication for the Great Lakes Fishery Commission by the Ontario Federation of Anglers & Hunters ©1998).

Sea Lamprey

How can I prevent the spread of Sea Lampreys?

Learn about Sea Lamprey and support your governmental agencies that are collaborating to control this nuisance species.

What else can I do?

This infomation was provided by the U.S. Fish and Wildlife Service. For more information, go to their campaign website