Great Lakes sea lamprey treatments proceed after earlier doubts about US participation

When Thunder Bay fishing guide and angler Gord Ellis describes sea lampreys it sounds like a nightmare that would keep Ridley Scott awake at night.

"The worst part of them is they have this rasping mouth that has a series of teeth inside of it," Ellis told CBC News. "They'll cling on to a fish, they'll rasp a hole in it."

"If you've ever seen it, it's an awful thing to see. The fish has a huge hole in it, and it's been drained... All the fluids are out of it and it's just literally bone dry."

By the middle of the last century, according Ellis, lampreys had almost devastated the fishing industry in the Great Lakes. 

"Your average lamprey kills 40 pounds of fish, which is why they just about wiped out the Great Lakes. In the '60s and early '70s they just ate them all, killed them all. I remember as a kid in the '70s that you couldn't catch a lake trout in Lake Superior, there just weren't any," Ellis says. 

Maintaining control

Back in 1957, a compound was discovered that is lethal to lamprey. Since then, the deployment of lampricides into the tributaries around the Great Lakes became a regular occurrence, with the goal being to kill larval sea lampreys before they can mature. 

A large scale lampricide resumed around Lake Superior tributaries on August 5 and will continue until August 22. Treatment in other parts of the Great Lakes have already happened, or are set to take place in the coming weeks. 

But keeping the Great Lakes free of sea lamprey requires cooperation with U.S. through the Great Lakes Fishery Commission which runs an annual program that treats streams and rivers with targeted chemical applications to kill sea lamprey larvae.

That cooperation was in doubt earlier this year when the Trump administration fired probationary federal workers and implemented a freeze on seasonal hiring. Those moves jeopardized the program's operation, which typically runs from April to October. 

The administration reversed the seasonal hiring freeze, and a court ruling reinstated the probationary employees, allowing this year's lampricide to proceed.

The compound used specifically kills lamprey while leaving other animals unharmed due to a quirk in the fish's biology, according to Great Lakes Fishery Commission legislative affairs and policy director Greg McClinchey. 

"Lamprey are a 360 million year old species of fish and they have not evolved certain enzymes in their body to process this compound," McClinchey says. "If you introduce this compound to a lake trout, they simply metabolize it and away it goes. If you introduce it to a sea lamprey, they die."

"They put only the minimum dose in that they need to to be lethal to lamprey," McClinchey says. "It's a constant process where they monitor downstream, they do water quality samples... [The compound] doesn't just become diluted, it actually degrades in sunlight and only kills sea lamprey."

Historic success

Since 1955, the Great Lakes Fishery Commission has been a binational body monitoring these bodies of water. 

Because the Great Lakes encompass both the Canadian and United States borders, there has been an effort on both sides of the border to control lamprey levels. 

If you take your foot off them for a second, they spring back.- Greg McClinchey

As a professional angler in the region, Ellis says the work done by the commission has been effective. He has noticed the difference in lamprey numbers in his decades of fishing. 

"They're incredibly good at keeping track of how many lamprey there are," Ellis says. "If the program wasn't there, it wouldn't take very long for the Great Lakes fishery to collapse."

McClinchey agrees, stating that "if you take your foot off them for a second, they spring back."

Then COVID-19 came, a time that revealed the incredible strength with which lampreys spring back. 

"In the year 2020 and 2021 we had to reduce sea lamprey control," McClinchey recalls. "Our data shows us that it will have cost the economy of the Great Lakes about $2 billion just from that reduction in sea lamprey control."

"We can't rest on our laurels in that fight."

Sea lamprey efforts could be unifying

As the relationship between Canada and the U.S. becomes more tumultuous, lamprey control works as a quiet antidote to friction at the border. 

"During Prime Minister Pierre Trudeau's tenure as Prime Minister and President Richard Nixon's tenure as president, they didn't like each other... They didn't care much for each other and things in the national relationship were pretty rocky," McClinchey says. "During that time period, at the Great Lakes Fishery Commission, every single thing we did during that time period was unanimous."

As treatment continues across borders, the Great Lakes Fishery Commission still wants to reduce lamprey populations to 10,000 in Lake Superior, which currently stand at approximately 50,000.

Ellis says that there is still a way to go as far as anglers are concerned. 

"It's way down from where it was three or four decades ago, [but] 50,000 lampreys is way too many."