It’s a species of fish that’s survived at least four major extinction events and remained largely unchanged for over 300 million years and now work is underway to contain a spike in sea lamprey across the Great Lakes.
The Great Lakes Fishery Commission says since the pandemic, the prevalence of sea lamprey has increased in all five Great Lakes thanks to control efforts largely being suspended at the height of COVID-19.
“Control effort in 2024 continued at pre-pandemic levels, but elevated and variable adult sea lamprey abundances should be expected over the next year or two before turning back downward,” said Ethan Baker, the chair of the commission.
The Invasive Species Centre in Sault Ste. Marie, Ont., says this species may have been here since the 1800s, at one point even collapsing the commercial fishing sector for years in the 1950s.
“Actually in their native range, which is in the Atlantic Ocean, these are parasites that don’t actually kill their hosts but in the Great Lakes we don’t have that kind of co-evolutionary link so they do act as predators,” said Rebecca D’Orazio, an Aquatic Invasive Species Specialist with the Centre. “I think the number is that each individual can kill up to 40 pounds of fish over their 12-month feeding period.”
According to D’Orazio, the vampire-like fish uses the suction cup portion of its mouth to attach itself to a fish and then uses its raspy tongue and teeth to dig into the flesh of the fish. Once they’re latched on, they rasp through the fish’s scales with their tongue and feed on the fish from the inside out.
While sea lamprey has a particular taste for lake trout it is also known to eat salmon, brown trout and even lake sturgeon. The good news is they do not attack humans.
Drew Purvis is a vessel captain and co-owner of Purvis Fisheries on the northern end of Lake Huron. He says fishermen across the Great Lakes have noticed the increase in sea lamprey and are watching the situation closely.
“The flesh in the fish will turn really, really white because all the blood has been removed from the fish,” he explained. “They wiped out the lake trout in the 1940s, and we’ve got a lake full of lake trout again now so the potential could be bad if the numbers get to be too high.”
While this invasive species is not expected to be eradicated, efforts to control sea lamprey which were suspended during COVID-19 have returned and both the Great Lakes Fishery Commission and Invasive Species Centre say there are some early indicators that those populations are coming back down.
