U.S. Fish and Wildlife Service officers are in Isabella County this week, looking for sea lamprey in the Chippewa River.
One of them, John Ewalt, had a pretty bleak assessment of the critters: “In the Great Lakes, there is really no redeeming quality, in my opinion.”
Ewalt, a biological science technician for the fish and wildlife service, said there are two types of lamprey in Michigan streams: The native creatures, which can coexist with local fish, and the invasive sea lamprey, which Ewalt is out to get.
The sea lamprey live the early stages of their lives in the rivers that feed into the Great Lakes, and they migrate out to the lakes to feed on game fish -- often trout.
Sea lamprey are native to the Atlantic Ocean, Ewalt said conditions in the Chippewa River are perfect for their population to take off.
“We’re in the heartland of Michigan here, where you have a lot of agriculture, so you have a lot of nutrients in this stream,” he said. “They grow a little bit faster here.”
Lamprey are parasites that kill 40 or more pounds of Great Lakes fish during their lives, the fish and wildlife service says.
“They have a rasping tongue and hooked teeth on their oral disk,” said Ewalt. “They’ll attach to the side of a fish, and that tongue will burrow into the side, and it basically drills a hole into the side of a fish, and it basically sucks the lifeblood right out of the fish.”
Ewalt said not every trout that a sea lamprey attaches to dies, “but most of them do. And that’s an issue, because we do spend quite a few dollars in the State of Michigan, and other states in the Great Lakes, stocking for fish, only to have a fish like the sea lamprey that’s going to eat what you’re trying to put there.”
So he and his partner on this job, Allan Keffer, took a boat out on the Chippewa River with lampricide -- like pesticide, but specifically targeted at lampreys.
The chemical stops the lamprey from getting oxygen into their bloodstreams.
When the dying lamprey come up for air, Keffer and Ewalt scoop them up with a net, catalog their size and other characteristics, and enter their findings in a spreadsheet.
After their stay in Isabella County, they’re headed to Midland. Ewalt said there’s a risk that the dam failures on the Tittabawassee River near there last year have allowed invasive lamprey to get further upstream.
He says in some ways, this is a losing battle -- they’ll probably never eliminate all of the sea lamprey in Michigan’s rivers -- but every one they can get to before it kills a native fish is a bit more protection for local ecosystems.