The Great Lakes region has long been heralded for its commercial fishing industry and large hauls. That wasn’t always the case, thanks to a mysterious invasive species that began popping up across the basin more than 100 years ago: the sea lamprey.
It came to the Great Lakes from the Atlantic Ocean and began rearing its literally ugly head by attacking various freshwater fish populations.
One of the first recorded sightings was by a group of youngsters near a popular swimming hole close to Rogers City, Mich.
Lamprey are so pesky and resilient, they even figured out a way to get from Lake Ontario to Lake Erie — bypassing the 51-metre-tall Niagara Falls, swimming upstream through the Welland Canal and shipping channels.
In 1921, a fisherman from Merlin, Ont., in Chatham-Kent, discovered one had latched onto a fish he pulled from Lake Erie. By the late 1930s, lampreys had made their way to Lake Michigan and Lake Superior, too.
Lampreys are blood-sucking eel-like creatures without any bones. They have suction-cup mouths with multiple rows of sharp teeth to pierce the skin, usually of fish, and suck the blood of their prey.
“The fish didn’t even know what hit them, and they feed on pretty much anything in the Great Lakes,” said Marc Gaden, with the Great Lakes Fishery Commission (GLFC).
“The commercial fishing industry, especially in the ecosystem, was quite on the ropes.”
The commission has supported a new documentary, set to release at the end of January, about the lampreys’ devastation across the Great Lakes region. It will be available on its own standalone website, along with other streaming services.
The Fish Thief: A Great Lakes Mystery is directed, produced and written by Thomas Lindsey Haskin, who grew up near Detroit, and now lives in California.
“It was kind of a mystery of what was happening,” he said, until scientists and governments on both sides of the border began investigating.
“The film is about primarily the people in relationship to the Great Lakes, and how important fishing has been historically to the Great Lakes, and how in the middle of the 20th century, the fish that most people cared about nearly completely disappeared.”
Academy Award-winning actor J.K. Simmons narrates the story. The Great Lakes region also holds a special place in his heart, according to Haskin. Simmons was born in Grosse Point, Mich., moved to Ohio when he was 10, and vacationed on the shores of Lake Huron.
Haskin calls the region a “real tie that binds people from all walks of life.”
“No matter their political feelings, no matter their ethnic background, religious background or socioeconomic background — any of those kinds of things — you’ll find people that just love to fish,” he said.
Each female has about 100,000 eggs, he says, and when the eggs hatch, the larvae drifts downstream to a kind of a sandy, silty area and burrow into the bottom of the river. They’ll live in the river bottoms for about four years, and when the time is right, they’ll emerge.
“They’ll metamorphose into that lethal adult and swim out into the lake, and the whole cycle starts all over again,” said Gaden.
Barb Zielinski is a recently retired University of Windsor researcher who specializes in chemosensory systems for species such as sea lampreys.
“They have taste buds just like you and I do,” she said, adding they use their sense of smell for spawning.
“After they feed in the lakes or in the ocean, they they move upstream to streams, and they’re able to locate sort of a good habitat for a spawning because they follow the scent of the larvae.”
Zielinski says lampreys have very strong movement responses in swimming.
“They’re very strong swimmers, and so when they smell an odour or something that’s attractive to them, they can swim to the source. That’s one of their strengths. They’re very adaptable.”
Lampricide, barriers curtail spread of invasive species
Initial attempts to thwart the sea lampreys were seen as “pretty feeble,” according to Gaden. They included things such as mechanical barriers underwater and giant sieves in rivers, attempting to catch them as they migrated out into the lake.
“There was this despair that the lamprey were going to do what they were doing, without there being any way to deal with the problem.”
It wasn’t until the 1950s, he said, that government on both sides of the border got together for a more “uniform approach” at controlling lampreys. This included signing a treaty between the countries in 1954.
New physical barriers were built to keep from lampreys migrating into streams. A focus on finding a pesticide that would kill them and not harm other fish was also prioritized, and eventually proved to be a game changer.
Gaden says “thousands and thousands” of different compounds were tested before the one that is now simply known as lampricide was discovered in 1957.
“It’s a pesticide … applied in streams where the lamprey are living in the stream, at the bottoms, as are most larvae. We actually kill the lamprey before they have a chance to metamorphose into their lethal adult and go out into the lake and slaughter the fish.”
The lamprey control program has killed up to 95 per cent of populations, Gaden said.
“It’s harmless to the fish who can metabolize it, lethal for the lamprey. They can’t. And it’s about as close to a silver bullet as you could possibly imagine.”
WATCH | An up close look at a lampricide field treatment:
During the COVID-19 pandemic, lamprey control programs were significantly reduced, according to Gaden, because of travel restrictions.
That resulted in “huge spikes,” he said, in the number of wounded fish the next two years.
“The sea lamprey are not going to go away.”
“The moment we could get back in the field, we’re getting the data now from the successful treatment seasons of 2022 and beyond, and the numbers are going back down. The lamprey took great advantage of the COVID pandemic for sure.”
