There’s some bad news in the Great Lakes regarding the sea lamprey -- an eel-like creature that literally sucks the life out of fish. They do a lot of damage and now they’re on the rise in some lakes. The trend has stumped scientists.

The eel-like threat

A jar thuds on a table in Helen Domske’s office at the University at Buffalo. It’s a clear, large, one gallon container, just like the ones found in grocery stores, filled with crisp, green, dill pickles. But, in this case it’s filled with a liquid solution, and a preserved gray corpse of a sea lamprey.

“They’re pretty gnarly looking. Here’s one you can see the teeth on it. It actually has teeth all over its mouth. And they’re pretty fierce. They really do a number."

Domske is an educator for New York Sea Grant. She travels to schools and to public events to raise awareness about invasive species like the lamprey.

A 70 percent jump

'It's kind of a two-edged sword. ... As we really focus on water pollution ... we've really created more habitat for them.'

She’s concerned about a new report from the Great Lakes Fishery Commission.

It says sea lamprey numbers jumped nearly 70 percent in Lake Erie in the last three years. The trend is the same in Lake Superior, though in the other Great Lakes, their numbers are dropping.

Marc Gaden is with the fishery commission in Michigan and works with the lamprey-control program.

“Lamprey is probably the worst of the invaders that have come into the Great Lakes, there’s no question about that,” he said.

Each adult can kill about 40 pound of fish in its lifetime. They burrow their tongues into fish and drain out blood. They especially hit lake trout.

Before lamprey control began in the 1950s, more than 100 million pounds of fish were lost in the Great Lakes every year. Now that’s dropped to about 10 million pounds.

Does habitat restoration let the lamprey settle in?

So far, Gaden says, scientists haven’t pinpointed a reason for the uptick in Erie and Superior. But, there are a few theories. One is that sea lampreys have more nesting sites—due to habitat restoration in the Lake Erie watershed.

“It’s kind of a two-edged sword. As we clean up the environment it makes it more hospitable,” Domske said. “Some of these creeks maybe didn’t have lamprey in them. But now as we really focus on water pollution and trying to control the pollution levels we’ve really created more habitat for them.”

Harsh weather could be a factor as well – making it harder to spawn.

“The lamprey numbers went down significantly after those two very cold winters 2014 and 2015,. ... So the numbers may have gone down just because, in the spring the streams were so cold,” she said.

Spreading their range

But the past two winters have been mild – leading to a better spawning season. Gaden said there’s still more work to do, to keep the creature at bay.

“The problem with Lamprey is that they are resilient, they work very hard to spread their range they will find new habitat and infest it,” Gaden said. “There’s lots of fish in the lakes for them to eat and there’s nothing keeping them in check except for us.”

His group is working with the U.S. Fish and Wildlife Service to get the lamprey numbers back on target.

Great Lakes Today is a collaboration of ideastream, WBFO Buffalo, and WXXI Rochester.