Engaged in a war that will never see an ultimate victory, the federal government will fight another battle next week in its efforts to control the invasive sea lamprey.
The work will be performed at four pre-selected sites on the Grand River and was conducted by the U.S. Fish & Wildlife Service with the cooperation of the joint U.S.-Canada Great Lakes Fisheries Commission. The former provided the expertise and muscle power while the latter furnished the bucks.
And those dollars are extensive, too. For the entire Great Lakes, the cost for sea lamprey control is $9 million annually from which the expense for the Grand River this year being about $200,000.
Yet the outlay is worth it, says Jenna Tews, the Fish and Wildlife Service’s Station Supervisor for its Sea Lamprey Control Program in Ludington, Michigan.
Without treating the Grand River with what’s called a “lampricide,” approximately 3,400 juvenile sea lampreys would eventually grow into adulthood. At that stage the adults would migrate into Lake Erie where each would feast on – and kill – approximately 40 pounds (about 28,000 pounds total) of such fish species as steelhead, lake trout, bass, and walleye, Tews says.
“Those are significant number for Lake Erie,” Tews said. “The thing is, the Grand River is the fifth latest producer of sea lampreys for Lake Erie, the largest being the St. Clair River.”
Tews says the Grand River has perfect habitat and water quality for sea lamprey spawning and as a nursery water. Thus it qualifies for regular treatment of the lampricide, “TFM,” Tews said.
Besides the Grand River, Conneaut Creek also is periodically treated. Meanwhile, western New York’s Cattaraugus Creek will receive a jolt of TFM this month; a process that costs $488,000, Tews says.
“Lake Erie has 842 tributaries, 30 tributaries have records of larval sea lamprey production, and of these, 18 tributaries – seven in Canada and 11 in the U.S.. - have been treated with lampricides at least once during 2012-2021,” Tews said additionally.
Since 1958, the program has used TFM to control sea lamprey in the Great Lakes. It was discovered in 1957 after more than 6,000 compounds were tested to uncover a selective sea lamprey control method. TFM is fully registered with the U.S. Environmental Protection Agency and with Health Canada as a safe and effective pesticide, Tews says.
This chemical works by killing sea lamprey juveniles, called larvae, which hatch from eggs, burrow into the river’s bottom where they live for several years before emerging as adults with eyes and the suction-cup mouth fitted with circular rows of hooked teeth.
At that point the adults make their way into Lake Erie where they feast on fish for 12 to 18 months before returning to a stream to spawn and die, repeating the cycle. They do this by using those circular rows of teeth to clasp onto a fish and then employ their rasping tongue to consume a fish’s flesh.
“So you can have several year classes of lampreys in a stream,” Tews said as well.
With TFM, Tews explains, the Great Lakes sea lamprey population has been reduced by 90 percent, helping to protect the system’s fisheries, estimate to be worth $9 billion annually, Tews says.
“The Grand River was last treated in 2017 so we are a little behind in our three- to five-year scheduling for it to be treated, partly as a result of COVID,” Tews said.
Treated will be a 32-mile long stretch of the Grand River, beginning at the Ashtabula Metro Parks’ Harpersfield Dam unit. Other sites included the confluence with the river at Mill, Paine, and Big-Kellogg creeks, all in Lake County and each associated with the Lake Metroparks’ system.
“We try to treat when the Grand River has a stream flow of 200 to no more than 1,000 (cubic feet per minute) stream flow. If the stream flow is too low than the TFM doesn’t move and the risk is greater for non-targeted species,” Tews also said.
And if the stream flow is too great than the lampricide becomes diluted and just washes downstream,” Tews also says.
Those non-targeted species include such species as mud puppies stonecats, and some fish species such as darters which could be spawning and consequently “are under greater stress,” Tews said.
For this reason part of the Fish & Wildlife Service’s work includes monitoring for any loss of non-target species as well as how the lampricide is being distributed.
What the Fish & Wildlife Service has found also, says Tews, is that the more frequently a stream is treated the greater is the public’s support for a project that for all practical purposes is the salvation of the entire Great Lakes fisheries.
“We have some people who are upset because of the non-targeted species losses but other people can see the bigger picture as to how the work is necessary for the protection of the Great Lakes fisheries,” Tews said.
By Jeffrey L. Frischkorn
JFrischk@Ameritech.net
JFrischk4@gmail.com
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