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Great Lakes Article:

Alien invaders creep in


Sunday, July 28, 2002


Daniel Manyen was "kind of shocked" by what he saw.

A 4-inch-long sea lamprey hung off the fin of a walleye fished from the Tittabawassee River near Dow Chemical Co.'s dam in Midland County last April.

Normally, the Essexville charter fishing captain would spot the parasitic lamprey -- which feeds mostly on trout and salmon -- on the high seas of northern Lake Huron.

But the tax-paid war against the parasitic eel now occurs on inland rivers and streams, often many miles away from the open waters of the Great Lakes and its more than $2 billion a year sport fishery industry.

"They're a multimillion-dollar problem in Lake Huron," said James P. Baker, fisheries supervisor of Bay City office of the state Department of Natural Resources. "They prey on desirable fish."

That's a concern for charter captains such as Manyen, 50, and Larry Lienczewski, 52, of Linwood, who depend on fishing excursions for their livelihood.

Anglers have reported "quite a few" lampreys scarring salmon this season near Oscoda, "which is really unusual," Lienczewski said. "Usually they don't come down that far."

Officials have no estimates of how much damage the predator causes.

Still, Manyen and Lienczewski said encounters with sea lampreys are uncommon.

Lampricide treatments have proven effective, although it's not realistic to expect the annihilation of the species in the lakes, said Paul H. Wendler, a former Saginaw mayor and adviser to the Great Lakes Fisheries Commission.

One lamprey can lay thousands of eggs.

"We have knocked the lamprey down, but we will never, never eliminate the lamprey," he said.

An alien invader

Sea lampreys, ancient creatures that invaded the four Great Lakes that border Michigan with the completion of the Welland Canal in the 19th century, spawn locally in Saginaw River tributaries and use the waterway as a highway to Lake Huron.

Lampreys "decimated" lake trout by the 1950s, and they recovered only because of restocking programs, Baker said. The U.S. Fish and Wildlife Service dumps more than a million trout yearlings and more than 3 million salmon annually into Lake Huron.

Typically greenish or gray, sea lampreys usually flourish in clear-water rivers and creeks that have gravel beds. The predators hunt in outer Saginaw Bay and Lake Huron for smooth-scaled fish such as trout and salmon, anglers say.

The toothy vampire-like creatures suck blood and fluids from their prey, consuming 40 pounds of fish in an adult lifespan of roughly 18 months.

It's not surprising sea lampreys were found near Dow Dam, where 500 were caught in a trap this spring, said Dennis S. Lavis, a sea lamprey expert at the U.S. Fish and Wildlife Service biological station in Ludington. The Chippewa River, a known lamprey spawning ground, joins the Tittabawasee near the dam. Federal officials treat the Chippewa every few years to keep the predator population from exploding.

Saginaw County predators

Federal wildlife workers took a survey of the muddy brown Cass River near Frankenmuth this summer, but did not find enough larvae to justify a lampricide treatment, Lavis said.

Workers last treated the river in 1984.

"They need clean, clear water to reproduce," Manyen said. "I hate to say this, but it's almost a compliment to the river system if you do see them."

The St. Mary's River connecting Lake Superior and Lake Huron acts as a hotbed for lamprey spawning, officials said.

In mid-Michigan, federal wildlife workers also fight the predators in the Big Salt River, Carrol Creek, and Little Salt Creek in Midland County.

Workers don't treat the Saginaw River because lampreys don't spawn in the waterway.

That wasn't the case in the Shiawassee River near Chesaning, where crews poured 2,260 gallons of trifluoromethyl nitrophenol -- a lampricide -- to kill an estimated 12,800 larvae this spring.

Treatments have caused "a little controversy" in some areas because they have on occasion killed unintended targets -- namely, fish, Manyen said.

In 1997, the lampricide killed a large number of white suckers and carp on the Shiawassee because the restricted-use pesticide reacted with the changing acidity of the river, said Alex Gonzalez, a supervisor at the U.S. Fish and Wildlife Service in Ludington.

"It was substantial enough where we had to go back and pick up the dead fish," he said.

Biologists test a river's acidic content before adding the lampricide. They must wear rubber gloves, aprons and rubber boots when handling it, he said.

"We have not had any report of any problems with humans or mammals because of this chemical," he said.

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