MARQUETTE, Mich. (WLUC) - The United States Fish and Wildlife Service (USFWS) conducted sea lamprey control measures on Bismark Creek in Marquette on Tuesday.
The creek, which is part of the Harlow Lake system, was treated last year for lamprey but the treatment was unsuccessful due to a large beaver dam. Instead of flowing down the river, the lampricide was held up by the dam.
Bodies of water are usually treated every three to four years due to the life cycle of the destructive species.
"This beaver dam created a lot of problems for the treatment. A larval assessment unit came in with backpack electrofishers and they found residual sea lamprey in this area and downstream,” said USFWS Biologist, Christopher Gagnon.
The treatment consists of a chemical called “3-trifluoromethyl-4-nitrophenol “ or “TFM” which kills sea lamprey larvae but has little to no effect on other wildlife. The chemical was first used in the 1950s and remains the primary lampricide used by the USFWS.
Gagnon said killing the larvae in streams and rivers is more efficient than trying to kill adult sea lamprey, since adult lamprey tend to reside in large bodies of water like the Great Lakes. Larger bodies of water are more expensive and more difficult to treat.
By targeting larvae in rivers and streams, sea lamprey are killed at the source.
"We specifically target the larval lamprey stage just because we know they're in the river here, we know that we can have an effective treatment and really dent their overall populations here on the stream level,” Gagnon said.
He added that treating a body of water, including smaller ones like Bismark Creek, requires a lot of data collection and processing. Things like the population density of lamprey, the water’s pH level, and the water’s alkalinity are collected and recorded.
"The amount of lampricide that we put in is really dictated by the amount of water there is, and also the pH and also the alkalinity. The pH affects how well the chemical works on the lamprey. We measure those at least several days before the treatments,” Gagnon said.
Though very involved and expensive, the TFM treatments have been largely successful.
"We estimate over 90 percent reduction in the adult population out in the Great Lakes," Gagnon said.
For more information on the Sea Lamprey Control Program, click here.
For more on the USFWS, click here.