In Lake Superior, an invasive species success story
With all the attention placed on destructive invasive species like Asian carp and zebra mussels, non-natives that are still completely uncontrolled - it's easy to forget about the one exotic species in the Great Lakes that scientists have largely outsmarted.
On All Things Considered Friday I reported on the sea lamprey control program, a $20 million dollar effort of the U.S. and Canadian governments. A few decades ago lake trout were nearly extinct from the Great Lakes. Now, thanks in large measure to the program that's cut 90 percent of the sea lamprey population, there's a small commercial lake trout fishery along the North Shore.
Lamprey use their many teeth to latch onto the side of lake trout and suck their body fluids until the trout die. It's estimated that each lamprey kill between 10 and 40 pounds of lake trout during their lifespan, which is estimated at 18 months. (Derek Montgomery for MPR)
The main component of the sea lamprey control program is a chemical called TFM that's applied to streams where sea lamprey swim to spawn. The chemical binds to a lamprey's oxygen uptake and suffocates the larval lamprey before they mature and go out into the Great Lakes and prey on fish. Barriers and traps in the streams also help control their population.
But scientists are also researching alternative ways to control the lamprey, in part because, as Don Schreiner, Area Fisheries Manager with the Minnesota DNR put it, "nobody likes to use pesticides" in the streams. Marc Gaden, spokesman for the Great Lakes Fisheries Commission, which oversees the lamprey control program, said biologists are on the cusp of putting lamprey pheromones and repellants into the field to basically trick lamprey into changing their behavior during spawning season.
Pheromones are natural attractants that male lamprey emit to to lure females to spawn. Scientists are experimenting with using pheromones to lure lamprey into traps or into streams that don't have suitable spawning habitat.
Similarly, last year researchers at Michigan State University observed that lamprey are repelled by the scent of their own dead. Gaden said "the scent of death," as researchers have dubbed it, could be used to keep lamprey away from good spawning habitat, like the Brule River and other streams in northern Wisconsin.
Researchers at the University of Minnesota and elsewhere are exploring using pheromones to try to control invasive carp, which are steadily migrating up the Mississippi River. The hope is to soon add more critters to the very short list of invasive species success stories.