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."
On this day, crews were searching the Blackhoof and the
Nemadji Rivers, probing likely spawning areas and collecting
"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
"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
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
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
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
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.
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
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
"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
"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
That's why Ollila and crews are probing Northland streams
now, trying to find which rivers are serving as lamprey
"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."
JOHN MYERS covers the environment, natural resources and
general news. He can be reached at (218) 723-5344 or at