After years of consistently low numbers, the invasive parasite known as the sea lamprey is on the rise once again in Lake Superior — and action needs to be taken, an expert says.

Alex Gonzalez, of the U.S. Fish and Wildlife Service, in Luddington, Mich., told CBC News that — after years of holding the parasite at a relatively low population with a chemical that kills larva — numbers in Lake Superior have been on the rise.

He said recent lamprey control efforts have been largely focused on Lake Huron and Lake Michigan and they have worked well.

But Gonzalez said the blood sucking lamprey are killing lake trout and other fish in Lake Superior and will get some attention using chemical treatments this summer.

"We are coming back here, to Lake Superior, in 2016. To hit the Lake Superior tributaries very,very,very hard," he said.

Death by lampricide

Gonzalez said the Great Lakes Fishery Commission oversees lamprey control, and uses a chemical based lampricide known as TFM (3-trifluoromethyl-4-nitrophenol) in the spawning rivers.

Money for the multi-million dollar lamprey control program is collected from both the U.S. and Canada.

Mother and son look at sea lamprey

Sea lamprey are an invasive species, and they are controlled solely by human intervention. Tanks of lamprey are always a draw with kids at the sports and trade shows. (photo credit: Gord Ellis/CBC)

Gonzalez said between 40,000 and 60,000 lamprey are estimated to live in Lake Superior — and they'd like to see that population cut in half.

At a booth set up by the Department of Fisheries and Ocean at a recent Thunder Bay outdoor show, Gonzalez said children need to know not only what a lamprey looks like, but the harm they do to fish.

The booth featured an aquarium with live lamprey and offered various activity books for youngsters.

"Some of these children will end up owning land, where we have to apply lampricide into rivers," he said. "And we need to get permission to access their properties to do these treatments."

Gonzalez said lamprey are always a draw with kids at the sports and trade shows.


  • A previous version of this story referred to sea lampreys inaccurately as lamprey eels.
    Mar 04, 2016 2:44 PM ET