Lamprey control planned
By Josh Grosteffon
Midland Daily News
Published May 16, 2007
The Fish and Wildlife Service will treat the Shiawassee River and the Carroll Creek in Midland, Saginaw and Shiawassee Counties on or around Thursday for sea lamprey, a parasite that can ravage fish in the Great Lakes ecosystem.
Sea lamprey are the "original invasive species" in the Great Lakes ecosystem according to Dennis Lavis, station supervisor at the Ludington biological station. His crews will be doing the treatments.
The parasite entered the ecosystem when canals made it easier to reach the Great Lakes from the Atlantic Ocean. Once the lamprey came in, they dealt a death knell to the lake trout population, which was already suffering due to overfishing, Lavis said.
"They basically just swam in and once they came in, they found an abundance of lake trout to feed on," he said.
The lampricides (chemicals Lampricid and Bayluscide) the wildlife service uses in treatment aren't dangerous to humans and other mammals if applied properly, studies show. They're diluted to up to six parts per million, but can affect a few other species, Lavis said.
The treatment will destroy an estimated 3,900 sea lamprey larvae in these two streams. Each of these parasites can consume nearly 40 pounds of lake trout and salmon during its life, the wildlife service reports.
Bait fish, such as minnows, or other organisms being raised in creek or river water should be moved to safe waters during treatments. Any irrigation for crops must be suspended for 24 hours during and following treatment.
Residents probably won't notice the Fish and Wildlife Service crews, who apply the chemicals from river crossings via a metered pump, and the crews won't know when they'll be at a specific part of the river until they hit the field.
"Most of the time, we do a treatment and leave and no one knows anything is going on," Lavis said.
The streams are chosen through a complex modeling system that ranks which streams and rivers would be most effective to treat. The services goes down the list until time and money runs out, Lavis said.
Other treatment options are being researched, including a release of sterile male sea lampreys in the St. Mary's River as a control measure. The Great Lakes Fishing Commission is also researching better barriers and traps to help control the pest.
There is other good news. Restocking of trout and pest control have caused Lake Superior to rebound and others are showing some signs of improvement. The wildlife service calls lamprey control programs "highly successful."
"Lake Huron is on its way. We're seeing more and more native lake trout," Lavis said, "but not to the point where they'd be self-sustaining."