Sea Lamprey: Petromyzon marinus

A Primative Fish

The Sea Lamprey belongs to a group of fishes called Lampreys.  They are by far some of the most primitive fish, along with hagfish.  They are called cyclostomes, meaning 'round mouths' which refers to their lack of jaws.  Instead of jaws, sea lamprey have a round sucker mouth full of many grasping teeth.  Sea lampreys also lack bone.  Instead they hae a skeleton of cartilage. 

Anadromous Fish

Just like Salmon and Alewives, the Sea Lamprey is a fish that swims into freshwater to breed.  There are lampreys though that never migrate to the ocean.  

An Invasion

In 1835 the fish was introduced to Lake Ontario. In 1921 the Sea Lamprey invaded Lake Erie via the Welland Canal.  They rapidly conlonized the lake and are causing big problems with the fisheries. They have large infestations now in Lake Michigan and Lake Huron and reports by scientists are that one lamprey can eat up to 40 pounds of fish in a year.

Control of the Sea Lamprey

Sea Lampreys reached peak numbers in the 1950s and scientists were working to find a way to control them.  In 1958 they found the chemical TFM which selectively kills sea lamprey larvae in the spawning grounds.  This chemical has now decreased the numbers of lampreys to about 10 percent of their peak poplulation. The worry today, however, is that the surviving lampreys may develop a resistance to the chemical or begin breeding in deeper wates, where the lampricide is not effective.

More information

Alien Profile: Sea Lamprey
Wisconsin Department of Natural Resources

International Sea Lamprey Management on the St. Mary
’s River: Everyone Wins…But the Sea Lampreys
Great Lakes Fishery Commission

Sea Lamprey: The Battle Continues
Minnesota Sea Grant

Sea Lamprey: A Great Lakes Invader
Great Lakes Fishery Commission

Sea Lamprey Assessment: Improving Control
Through Better Understanding
Great Lakes Fishery Commission

Sea Lamprey Barriers: New Technologies Help Solve an Old Problem
Great Lakes Fishery Commission

Sea Lamprey Control
Great Lakes Fishery Commission

Sea Lamprey in the Great Lakes Region
Great Lakes Information Network

Sterile-Male-Release-Technique: An Innovative
Sea Lamprey Control Method
Great Lakes Fishery Commission

TFM and Sea Lamprey Control: A Success Story
Great Lakes Fishery Commission