Giant Asian carp
lurk at doorway to Great Lakes
July 15, 2002
By Sabrina Eaton
Say hello to the giant
Asian carp, the latest foreign invader to menace the Great
They're big, sometimes
exceeding 100 pounds. They've crowded other fish out of
the Mississippi River and its tributaries. Scientists
fear they will infiltrate Lake Michigan within a year
and spread throughout the Great Lakes unless an experimental
barrier outside Chicago stops them.
"They are a huge threat
to the Great Lakes and could disrupt the food chain in
ways that would be very difficult to predict," said Gary
Isbell, who heads the Ohio Department of Natural Resources'
fisheries management program.
But local scientists
are less certain.
"As with zebra mussels
and every other foreign species, it's very difficult to
predict what impact it will have and very difficult to
control once it's introduced," said Rich O'Neal a fisheries
biologist with the Michigan Department of Natural Resources.
"It can't be good to
have them in Lake Michigan, but we don't know yet if they
would be a curiosity or a disaster," said Chuck Pistis,
an agent for Michigan Sea Grant.
Although Asian carp
have been caught twice in Lake Erie, biologists believe
those specimens do not signify an infestation because
they probably were set free by people who bought them
at Asian food markets. A 47-pound sample caught last year
in the Ohio River also was an isolated find, said Isbell,
who believes it swam all the way from the Mississippi
"They're strong swimmers,"
Asian carp are several
fish species native to China and Siberia that were imported
by fish farms in the southern United States. They escaped
into the Mississippi River during floods in the 1980s,
and rapidly spread north into tributaries such as the
Illinois River. A U.S. Fish and Wildlife survey conducted
last month found them just 55 miles south of Lake Michigan.
"They tend to eat almost
everything in their path," said Dick Munson, executive
director of the Northeast Midwest Institute think tank
in Washington, D.C. Already, he said, 97 percent of fish
in some sections of the Mississippi River are now Asian
Lake Erie Commission
Executive Director Jeff Busch said the fish aren't tasty
and don't make good sport fish. If many got into Lake
Michigan, he said, they'd certainly spread to Lake Erie.
"It's all one big, connected
waterway," said Busch. "It might happen quickly, or it
could take a long time."
the monster fish will crowd out local species by eating
huge amounts of the tiny plankton they rely on for food.
They say one type of the fish eats mollusks and could
devastate endangered native shellfish already being pushed
aside by zebra mussels.
But there's a way they
threaten humans directly: acrobatics.
The giant fish leap
out of the water for no apparent reason and land on people
and watercraft, said Pam Thiel of the U.S. Fish and Wildlife
Service office in La Crosse, Wis.
Thiel said one recently
struck an unsuspecting commercial fisherman on Illinois'
Kaskaskia River and broke his nose. A research biologist
in Illinois was hit four times by jumping carp, once so
hard that he filed a worker's compensation claim. In the
St. Louis area, the fish often land on the canopy of an
Army Corps of Engineers boat.
"When you're dealing
with something that size, it's shocking," said Marc Gaden
of the Great Lakes Fishery Commission in Ann Arbor.
Biologists hope an electronic
barrier recently built across a canal that separates the
Mississippi River water system from Lake Michigan will
contain the invaders. It cost more than $1 million, and
Great Lakes activists are requesting federal money to
install improvements such as a backup power system.
of Natural Resources biologist Rich Hess said the barrier
consists of cables on the bottom of the Chicago Sanitary
and Ship Canal that sends electric current through the
water to discourage fish from crossing.
While the system worked
well in laboratories, Hess said, it has never been field
tested. Researchers plan to place transmitters on other
species of test fish to determine whether the barrier
blocks them, he said.
Hess said it is uncertain
whether the barricade would stop larvae that might flow
through the canal.
, and whether the current
it supplies would be enough to turn the fish away without
stunning them. A stunned fish might float through the
canal and recover on the other side of the barricade.
The fish also might
be spread by anglers who unwittingly pick up small fry
to use as bait and later dump them in different waterways,
"We may have to go through
some novel experimental regimes," said Hess. "It's a real