barrier to invasive bighead carp
By Dan Egan
Milwaukee Journal Sentinel
May 2, 2004
When the Army Corps of Engineers announced earlier this
year that it couldn't find enough money to complete a
$6 million carp-zapping barrier on the Chicago Sanitary
and Ship Canal, Great Lakes politicians pounced.
At a congressional hearing in February, Michigan congressman
Vernon J. Ehlers told John Paul Woodley Jr., assistant
secretary of the U.S. Army for civil works, that his "head
would be on a platter" if the food chain-destroying
bighead carp make their way up the canal and into the
The fish are believed to have escaped southern fish farms
more than a decade ago and have since been migrating steadily
up the Mississippi and Illinois rivers toward the Great
The day after the hearing, all 21 members of the Illinois
congressional delegation fired off a letter to Army Corps
staff calling the decision not to fund the barrier "unacceptable."
Army Corps brass buckled under the pressure, and construction
on a state-of-the-art invasive species "lock"
on the Great Lakes' front door should begin this spring.
But what about the back door?
Dennis Schornack, President Bush's handpicked point-person
for U.S.-Canadian Great Lakes issues, appeared before
the Canadian Parliament's Standing Committee on Fisheries
and Oceans in Ottawa last year with a special guest -
a live bighead carp that he purchased just a few blocks
away at a fish market. Bighead are popular food in some
Asian cultures, and the worry is people will take the
exceptionally fecund fish and drop them into a Great Lake
instead of a fryer.
"Only my good conscience and knowledge - no rule,
no regulation, no ordinance, no anything stops me from
putting this live fish into the river," Schornack,
the U.S. chairman of the International Joint Commission,
a binational organization charged with helping to shape
policy for U.S. and Canadian waterways, recalls telling
Ontario is working on a provincial law preventing the
live sale of bighead, but it has yet to pass. Wisconsin
tried to do the same thing earlier this year, and the
legislation went nowhere. The Wisconsin bill also would
have held anyone who releases a bighead liable for the
environmental damage they inflict.
"I don't know why," says Sen. Rob Cowles (R-Green
Bay), one of the bill's sponsors. "We have to have
additional penalties for releases . . . if some of these
things get in the lake system, it's devastating."
Wisconsin isn't alone in what some see as a lack of legal
protections to keep the bighead and other troublesome
carp species from slipping into the Great Lakes.
The city of Chicago blocked the sale of live bighead
a year ago, but live ones are still legal in the rest
of the state, says Marc Gaden, spokesman for the Great
Lakes Fishery Commission.
A newspaper ad last fall, in fact, featured live bighead
at the Food Harbor grocery store in Addison, Ill., for
$1.29 a pound. Cheap. Especially considering what they
could do to the Great Lakes' $4.7 billion recreational
A clerk at the fish counter at the Food Harbor recently
said that his boss' policy is to kill the bighead before
they leave the store's front door, but some want to rely
on more than middle managers' policies to protect the
Great Lakes - they want severe federal restrictions on
the transport of the species.
The U.S. Fish and Wildlife Service is mulling a move
to list bighead as an "injurious species" under
the Lacey Act. That would make it illegal to transport
live bighead across state lines, but so far nothing has
"It is mind-boggling that at a time when we are
working around the clock to keep these fish from swimming
into the Great Lakes through the Chicago Sanitary and
Ship Canal that there is still the trade of these live
Conservationists say the stakes couldn't be higher.
"If these things get into the Great Lakes en masse,
it will cause a biological meltdown," says Cameron
Davis, executive director of the Lake Michigan Federation.
"These things clean out ecosystems when they move
They do it not by eating all the other fish. They do
it by attacking the food chain at its most vulnerable
point - the bottom.
Bighead eat the plankton that smaller fish need. That
squeezes out the little fish, and that leaves big predatory
fish such as lake trout and salmon with no little fish
to eat. The damage to the ecosystem can happen in a matter
of years, and the cold, fresh water of the Great Lakes
is considered the ideal habitat for a species that importers
brought over from Asia three decades ago to clean the
bottoms of fish farm ponds.
If even a small breeding population of bighead makes
it into the Great Lakes, Schornack says, "Then it's
just a matter of time before we end up with a carp pond."
Loose in Lake Erie?
Wisconsin and Illinois do require permits to stock a fish
species, but fears of illegal bighead carp releases are
legitimate. Last summer, a 38-pound bighead was caught
in Chicago's McKinley Park Lagoon, just a few miles from
the Lake Michigan shoreline. The lagoon is not linked
to Lake Michigan, and to date no bighead have been found
in the lake.
Lake Erie is a different story.
Ontario biologists report that three bighead carp have
been taken there to date, including a 3-foot-long one
snagged in a fisherman's net on Oct. 16, 2000.
There is evidence more fish are swimming in the lake.
A doctor snorkeling in Lake Erie's main tributary in
August 2003 identified two bighead carp lurking just off
the riverbed, said Andy Cook, a biologist with the Ontario
Ministry of Natural Resources. Cook takes the report seriously.
"He has seen this species in the Missouri River
previously," he says.
The U.S. Geological Survey also reports that a fourth
bighead was taken from Lake Erie in 2002.
Biologists insist that all this doesn't necessarily indicate
a bighead population has established itself in the Great
Lakes. They note that no juveniles have ever been caught,a
promising sign that that carp aren't breeding.
Some believe the bighead are likely isolated creatures
that were dropped into the 9,910-square-mile lake by people.
Another theory is the Lake Erie bighead escaped during
floods from area fish farms, which is how bighead first
colonized the Mississippi River in the southern United
"We'd like to think that maybe there were only four,
five or six in (the lake), but it's probably not reasonable
to think they caught them all," says Phil Moy, fisheries
specialist for the Wisconsin Sea Grant Institute. "But
if you keep their numbers low enough, they may have a
hard time finding each other to reproduce."
Schornack calls the Lake Erie catches "very, very
"It's sort of like mice: If you see one, you've
got 10. But I still have to rely on the scientific opinions
that say there is not a reproducing (population)."
Dan Thomas, president of the Great Lakes Sport Fishing
Council, says as long as the fish are sold alive, there
will be a temptation to release them in open water.
"People have a propensity for wanting to be sympathetic
to anything alive. We swerve our cars rather than hit
a squirrel," he says.
And, at least some of us have a hard time killing fish,
even when they are marketed as food.
Thomas points to the lunker caught last summer in the
landlocked Chicago lagoon.
"It didn't swim there by itself," he says.
"And it didn't fly in."
Bighead carp were imported to the U.S. from Asia in the
early 1970s by southern fish farmers, along with three
other species that fall under the name Asian carp: grass
carp, silver carp and black carp.
Those fish are cousins to the more common species of
carp that found their way into the Great Lakes in the
1800s, but they are much more biologically menacing. Bighead,
for example, can grow up to 100 pounds and consume nearly
half their weight in plankton in a single day.
Bighead and silver carp are the species biologists fear
the most. Bighead have been found in the Illinois River
within 50 miles of the shores of Lake Michigan, and the
only thing right now blocking them from the lake is a
temporary electric barrier set up along the Chicago Sanitary
and Ship Canal, which provides a man-made link between
the Great Lakes and Mississippi River.
The barrier, about 30 miles southwest of Chicago's lakeshore,
is actually 13 electrified cables strung along the bottom
of the 25-foot-deep, 165-foot-wide canal. It is not designed
to kill fish, but to simply turn them back.
But the electrified cables are corroding and could be
useless within the year. Completion of the new barrier,
scheduled for September, can't happen soon enough for
conservationists and biologists alike.
Lake Michigan Federation's Davis savors his sliver view
of the lake from his downtown Chicago office, but he knows
even now loads of trouble lurk under its shimmering silver
"From a pollution standpoint, we've cut the levels
of PCBs and dioxins," he says, "but the biological
pollution of invasive species has gotten worse."
The glacially carved lakes, the world's largest freshwater
system, have been under biological assault since the early
1800s, when the Welland Canal opened the way for boats
- and fish - to bypass Niagara Falls, which served as
an impenetrable barrier to aquatic species invasions for
thousands of years.
The lakes were isolated on the west by a "subcontinental
divide," which separated the Great Lakes Basin from
the Mississippi River Basin. That barrier fell more than
100 years ago when Chicagoans reversed the flow of the
Chicago Riverand carved the canal to create an artificial
link between Lake Michigan and the Mississippi basin.
Since the early 19th century, about 150 foreign species
are believed to have colonized the lakes.
Among the most devastating is the sea lamprey, an eel-like
creature that makes its living attaching itself to big
fish and sucking blood.
By the 1950s, the Lake Michigan lamprey population exploded,
resulting in the crash of Lake Michigan's lake trout population.
That, in turn, led to a surge in the alewife population,
another invader from the Atlantic Ocean. With lake trout
out the picture, the smaller alewives lost a major predator,
and their numbers boomed in the 1950s and the 1960s.
Fisheries experts then introduced salmon to control the
alewife population, and today the salmon are a featured
species in a Great Lakes sports fishing industry that
pulls in nearly $5 billion annually.
Lamprey numbers, meanwhile, are now controlled by the
annual poisoning of their spawning beds in lake tributaries,
a program that costs about $15 million a year. That program
will have to go on forever because it is impossible to
entirely eradicate the species. If the poisoning stops,
biologists say, lamprey numbers will explode.
The lamprey knocked the lakes' natural predator-prey
balance so out of whack that even today annual trout and
salmon stocking is needed to keep the tip of the food
chain from toppling.
More recent invasives include the zebra mussel as well
as the round goby and ruffe, two smaller fish that could
put further pressure on Lake Michigan's native yellow
perch population, which the Wisconsin Department of Natural
Resources estimates has dropped off by about 90% since
All three species are believed to have colonized the
Great Lakes via freighter ballast water, which is yet
another door to invasive species that conservationists
are looking to lock shut.
"The Great Lakes have been so destabilized by the
repeated invasion of non-indigenous species that certainly
many of my colleagues don't consider it to be a stable
ecosystem," says David Reid, a research scientist
with the National Oceanic and Atmospheric Administration's
Great Lakes Environmental Research Lab. "Whenever
you start achieving a stable situation, a new species