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Great Lakes Article:


An old enemy persists
By John Myers
Duluth News Tribune
Published September 12th, 2004


ALONG THE NEMADJI RIVER - For all the talk of freakish foreign creatures invading the Great Lakes in recent decades, none has come close to the devastation caused by an unwelcome pest that's been present more than 80 years.

The sea lamprey swam through the Welland Canal shortly after it was built in 1919. It began an infestation of the upper Great Lakes that continues to wreak havoc today.

Lamprey have cost millions of dollars to fight, cost billions in lost revenue from depleted fisheries and upset the Great Lakes ecosystem like no other invader.

And while giant, leaping carp, snake head fish, zebra mussels and spiny water fleas all worry scientists, none has come close to having the impact on Lake Superior and most other Great Lakes as the sea lamprey has.

But Dale Ollila is fighting that.

Ollila, of Marquette, Mich., is part of the U.S. Fish and Wildlife Service's team that hunts down and kills lamprey before they leave spawning streams and head into the Great Lakes.

On a recent late summer morning, Ollila and his crew partner, Rob Katona, were wading into the Nemadji River south of Duluth. With batteries and power converters on their backs, they sent periodic charges of low-voltage electricity through long probes into the river.

The charge stunned nearby lamprey, which floated to the surface and were scooped up.

"I've been doing this for 34 years," Ollila said. "I never dreamed this would happen... but I've made a career out of lampreys."

NEVER-ENDING SEARCH

On this day, crews were searching the Blackhoof and the Nemadji Rivers, probing likely spawning areas and collecting their find.

"Here's one!" Ollila said as he probed along a steep bank not far from the Minnesota Highway 23 bridge.

Ollila showed his four-inch catch to some onlookers, saying he couldn't be sure if it was a harmless, native lamprey or a young sea lamprey preparing to head out to Lake Superior.

"I'd say it's a native... but you really can't be sure until you get them back to the lab. It's almost impossible to tell with the naked eye at this size," he said.

A few minutes later, Katona hollered that he had found a very small lamprey upstream. Like Ollila, he carefully placed the catch in a container and went back to searching the stream. This one, Ollila thought, may well be a sea lamprey.

There are ten, two-person teams spread across the upper Great Lakes, looking for concentrations of young lamprey. The other crews are fanning out on streams already found to hold large lamprey populations and are using the chemical toxin TFM to kill them. Developed in the 1950s, it still is the primary weapon in the fight to keep lamprey numbers in check.

This winter, when assessment crews return to their Marquette headquarters, they'll feed their findings into a computer. All streams with lamprey will be ranked based on the density of young invaders. Only the 50- or 60-most-heavily infested streams will get treated.

It's a $16 million battle every year, but it's protecting a fishing industry worth billions. So far, the governments of Canada and the United States have supported the cost because of the payback.

"We only have a limited amount of money. So we have to focus our efforts where they can do the most good," treating the most-heavily infested rivers, said Terry Morse, supervisory biologist for the U.S. Fish and Wildlife Service.

This summer, crews chemically treated the Nemadji, Amnicon and Red Cliff rivers along the South Shore. Colder water, fewer nutrients and more natural waterfall barriers leave North Shore streams with fewer lamprey.

But tributaries of the St. Louis River are a recurring problem. It's clear that lamprey are spawning in the tiny Red River, the Blackhoof and probably the Nemadji. It's likely some of those streams will have to be treated with TFM soon.

It's part of the never-ending fight to keep lamprey numbers at levels low enough to allow Great Lakes fish to survive. It's estimated that lamprey numbers in the lakes have been cut by more than 90 percent since the 1950s thanks to efforts by Ollila and others.

On some rivers, like Wisconsin's Brule, lamprey barriers are built to stop their upward migration and to allow trappers to remove them from the ecosystem. In other places, sterile male lamprey are used to foil reproduction. And scents are being developed to fool female lamprey to spawn their way into traps.

"We'll never get rid of all of them. But we're knocking their numbers back to where we can have fish in our Great Lakes," Morse said.

SURPRISING TURNAROUND

That didn't seem possible a half-century ago.

Less than 40 years after their introduction to the upper Great Lakes, lamprey had devastated native fish populations. The blood-sucking creatures, along with toxic chemicals like PCBs, helped eliminate native Great Lakes lake trout in all but Lake Superior, where a remnant population hung on.

In Lake Huron, the lake trout catch dropped from 3.4 million pounds in 1937 to nothing by 1961. The Lake Superior lake trout harvest dropped from an average of 4.5 million pounds annually to just 368,000 pounds by 1961.

Now, thanks to the constant fight against lamprey, fish populations have rebounded in all of the Great Lakes. Fishing, mostly sport angling, is now a $4 billion industry.

Lake Superior is considered fully recovered, with natural reproduction replenishing the lake's stock. Lake trout are reproducing on their own in Lake Michigan, too. And for the first time in a half century, trout are starting to spawn on Lake Huron, considered the lake hardest hit by lamprey.

"We're seeing increasing numbers of (naturally reproducing) lake trout. Their numbers are doing well," said Steve Johnson, a Duluth charter fishing captain with 22 years of experience on Lake Superior.

But Johnson is warning fishery biologists that there seems to be an increasing number of lamprey on Lake Superior's western tip.

"We're seeing more small lamprey than we've ever seen before... It's hasn't affected the fishing yet, but we're worried what it means" for the future, Johnson said.

That's why Ollila and crews are probing Northland streams now, trying to find which rivers are serving as lamprey nurseries.

"If we didn't do this, lamprey numbers would bounce back, and the fish populations would disappear. It would probably take less than 10 years before we didn't have any sport fish, any salmon or trout, at all," Morse said. "It's not like we've solved the problem. But we're fighting them to a draw... The problem is, we can never stop, and that gets expensive.

"The fact a lot of people don't realize lamprey are still a big problem means we're doing our job, I guess," Morse added. "But I sure hope people don't think the fight has been won."


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JOHN MYERS covers the environment, natural resources and general news. He can be reached at (218) 723-5344 or at jmyers@duluthnews.com.

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