TRAVERSE CITY — A parasitic fish's days may be numbered in one Grand Traverse County stream system.
The U.S. Fish and Wildlife Service scheduled pest control treatments from June 4-9 to kill sea lamprey larvae burrowed in the Mitchell Creek stream bottoms. The creek flows through Traverse City State Park before entering into the East Arm of the Grand Traverse Bay.
Alex Gonzalez, a fish biologist with the U.S. Fish and Wildlife Service's Ludington office, said the treatments are between 95 and 99 percent effective in killing the devastating lake parasite.
"The larval sea lamprey in these rivers is at its most vulnerable life stage," Gonzalez said. "For us to get the adult lamprey in the lakes would be impossible."
Like salmon, sea lamprey swim from larger bodies of water into rivers and streams to spawn and die. Their larvae grow to become parasitic adults that migrate back into the Great Lakes to kill native lake trout, salmon and walleye by sucking their blood.
Gonzalez said the lamprey control program has helped control the parasite's Great Lakes populations for 50 years and keep native fish populations viable. Treatments are typically done every three to five years.
Heather Hettinger, a fisheries biologist with the Michigan Department of Natural Resources' Traverse City office, said most local tributaries that connect with Lake Michigan — such as the Betise and Platte Rivers — have been regularly treated for sea lamprey for decades. She said she hasn't yet received any notices for other upcoming treatments in the area.
The lampricides have been found to pose no unreasonable risk to humans or the larger environment, but people are encouraged to limit their exposure as the treatments are underway. Hettinger said the chemicals biodegrade quickly.
"They post notifications as they do treatments and they'll be up until they biodegrade," she said.
Gonzalez said other fish species in their spawning stage — such as darters, salmon or walleye — are sensitive to lampricide in their stressed conditions. He said mayflies and certain agricultural plants also may be sensitive to the treatments.
"If we saw there was a large (mayfly) hatch going on we may reschedule treatment," he said. "Plants that would be sensitive would be agricultural plants like peppers and cucumbers."