It may be bad news that it’s the spawning season for the parasitic sea lamprey again, which means they’re moving up the New Brunswick River in crowds.
But the good news is that they are so focused on spawning that their digestive system shuts down.
“They couldn’t eat if they wanted to,” said Mark Gadden, communications director of the Great Lakes Fisheries Commission.
“They have only one thing on their mind once they reach this spawning phase, and that is to find a mate and spawn successfully.”
WATCH Sea lampreys build their nests underwater near Belail Bay
Blood-sucking, snake-like fish arrive to spawn
Underwater footage of lampreys spawning and nesting in a stream in Midland, about 58 kilometers northeast of St. John
Sometimes mistakenly called the eel, the sea lamprey is a fish with a powerful suction cup in its mouth, filled with many round rows of horn-shaped teeth and a tongue that digs into the host’s body to liquefy its tissues and feed on will.
These lampreys spend much of their lives at sea, attached to and feeding on the blood of other fish. But at this time of year, adults return to inland streams and rivers to spawn.
Oana Bircianu, an assistant professor at Western University in Ontario, has been studying sea lampreys for years.
“I have worked with sea lampreys for so many years, but I have never seen them make their nests in the wild,” Bircianu said.
The Big Lakes Fisheries Commission’s website describes the lamprey’s mouth as “a large oral suction disk full of sharp, horn-shaped teeth surrounding a razor-sharp scraper.”
That’s why she was fascinated by a video shot by Mike Sherwood near his home in the Belaile area. These are underwater shots of several lampreys building nests in a stream in Midland.
“It’s fascinating,” Bircianu said after watching the video.
Sherwood’s video shows an adult lamprey capturing moving stones around – some larger than softballs.
Other parts of the video show them clinging to even larger rocks with their powerful suction cups.
At one point, he even caught two fish spawning in one of the crescent-shaped nests they were working on.
The life cycle of lampreys
Bircianu said males usually leave the Atlantic first and make their way to spawning grounds.
She said pheromones released from larvae from previous seasons that are still in the area help guide them. The females then follow these pheromones and those released by the males, which begin working on the nests before the females arrive.
She said sea lampreys are looking for rocky places to spawn because the rocks help protect the newly laid eggs. Ideally, they look for rocky terrain upstream and muddy bottom downstream.
The eggs develop into worm-like creatures that make their way to where they can bury themselves in the sandy bottom. They usually remain in this state, feeding on algae and decaying matter for three to seven years – and even 14 years in some cases, Bircianu said.
A head of a sea lamprey with its mouth closed, covering the dreadful inside.
Once they reach about 120 millimeters in length, they stop eating and go through a metamorphosis, where they transform into their adult bodies. This approximately two-month transformation even changes the way they breathe so that they can continue to breathe while fully attached to the host.
Once the transformation is complete, these young specimens head out to sea, where they attach to the host fish and then feed at will while the host goes on with its life.
Then, when it’s time to spawn, the lampreys return to inland waters to begin the cycle again. But when it’s over, both males and females die.
“They put all their energy into this spawning phase and die after spawning,” Gaden said.
Same fish, different story
Sea lampreys are native to Atlantic Canada. They are part of the ecosystem and other species have learned to evolve with them. They are even useful for fish such as salmon, returning valuable nutrients to the environment when dozens of them die after spawning.
But elsewhere they are an invasive species that has changed the ecosystem and destroyed other fish populations.
The Great Lakes were particularly hard hit after new canals opened a new habitat for sea lampreys in the mid-1900s.
Gaden said the scientific name for sea lampreys means stone sucker.
“The power of this suction cup is also what makes the sea lamprey so deadly in the Great Lakes,” he said.
Mark Gadden is Director of Communications and Legislative Relations for the Big Lakes Fisheries Commission. (Submitted by Mark Gaden)
They catch fish and their tongue pierces their host’s scales and skin and feeds on blood and tissues, usually killing the host.
“Very often in its home range in the Atlantic, the sea lamprey will be a real parasite. That is, it may be able to feed on fish and not kill the host, and then it may switch to another species.”
But in the Great Lakes, native species are not large enough to survive their parasitic hitchhikers, and millions of fish have been killed in the process.
Gaden said a sea lamprey could feed and kill about 40 pounds of fish in about two years.
For decades, the Great Lakes Fisheries Commission has been working to gain control over the lamprey population. Each year, they spread lampudicide in waterways to kill millions of larvae.
According to Alex Gonzalez of the USFish and Wildlife Service, sea lamprey populations in Superior Lake are returning. (photo credit: T. Lawrence GLFC)
Without such vigilant and sustained efforts, Gaden said it would not be long before sea lampreys thrived again. After all, every female is able to lay between 50,000 and 120,000 eggs. And without any natural predators, the return would be quick.
“Sea lampreys are very opportunistic. If you ease control even for a short time, they will come back in a few years.”
The Commission maintains an ongoing calculation on its website of how many sea lampreys have been killed so far this year. The number is currently over 2.5 million.
As their numbers peaked, Gaden said eradication efforts had reduced sea lampreys by 95 percent, “and that saves more than £ 110 million in fish from the Great Lakes a year.”
“Great salon trick”
Gaden is helping run the commission’s public awareness campaign, bringing live lampreys to the road. He said they were doing a “great salon trick” and had lost count of how many times he had attached one to his flesh.
He said it was a demonstration of how powerful sucking is, but because lampreys do not feed on warm-blooded animals, they do not pierce humans with their tongues.
Gaden said it was impossible to remove the fish once they were fastened. This shows how impossible it would be for the host fish to shake off itself. He said it took some effort to squeeze the sides of his mouth until the suction was interrupted by a loud pop.
Hamilton Mountain MP Lisa Hepfner with a sea lamprey attached to her arm, along with Niagara Center MP Vance Badawi on Parliament Hill in April. (Submitted by Mark Gaden)
“You have to break the seal. You can’t just take it off. I’ve heard it’s described as powerful as a store vacuum cleaner.”
Gadden recently took his lamprey show to Parliament Hill and prompted several members of parliament to ask for a lamprey to be attached to their hand.
With all the attributes of lampreys on the horror show, one legend is not true. Lampreys do not travel through land, Gaden said. Although they are able to make their way through and around barriers, they do not leave the water, unlike some species such as the snake’s head, another invasive species in Canada that can travel over land short distances.
The video
Birchanu said Sherwood’s video showed the males building the nest. She said the men had a “vein-like” spine on their backs. They are also more silvery than females.
She said at one point in the video that the female releases her eggs at the same time as the male releases his semen.
“The male and female are intertwined and have this trembling behavior and then they release eggs and the males release the sperm,” Bircianu said.
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