For fifty years Canada and the U.S. have been battling an eel-like creature across the Great Lakes. Sea lampreys are parasites that drill holes in fish to feed on blood and body fluids. They often kill the fish. The sea lamprey was one of the first invasive species to arrive in the lakes, and it’s the only invasive to be successfully controlled by humans.
But in recent years, the lamprey has been getting the upper hand in the struggle. As Peter Payette reports there might be more setbacks in the near future:
If you’re on a lamprey control team you get to see all the prettiest streams and rivers in the Great Lakes. That’s because lampreys like clean water.
“Part of our problems recently have been some of the streams that were too dirty to harbor lampreys have been cleaned up and now we have lampreys in parts of the Saginaw River. We never had lampreys in that up until 15 or 20 years ago.”
Ellie Koon supervises one of the U.S. Fish and Wildlife treatment teams. They spend the warm months killing young lampreys by the thousands.
They treat rivers using a chemical called lampricide. It’s a poison that rarely hurts other fish. In fact, during a treatment the fish get a feast they normally wouldn’t. Young lampreys look a bit like worms at this stage and stay in the mud. But when they’re poisoned they swim out where fish can grab them.
Ellie Koon and one of her team members, Hank Cupp, say fish and other animals in the river pig out.
“You can almost hear the fish burping the day after we treat. You can see them swimming around with lampreys hanging out of their mouths that they can’t swallow.”