Great Lakes beware, the Asian carp
By Jeremy Grant
Published July 17, 2004
Chicago has battled fire and flood since its founding
in 1837. A more dangerous menace now looms: an invasion
of alien fish.
The Asian carp, a species hitherto unknown in the Great
Lakes, has found its way from fish farms in the southern
state of Arkansas and is threatening to enter Lake Michigan.
Local conservationists and politicians fear disaster.
They say that the fish, which can grow to four feet and
can weigh 100 pounds, could seriously deplete native stocks
of salmon and whitefish and become the dominant species
in all five Great Lakes. The fish is a voracious eater,
feeding on animal and plant plankton that is the staple
food for the young native fish in the lakes.
"Based on the havoc these carp have wreaked on the
Mississippi river, we have every reason to believe they
would devastate the Great Lakes ecosystem as well, should
they enter the lakes," says Gerry Barnhart, chairman
of the Great Lakes Fishery Commission, founded 50 years
ago by the US and Canada to combat "invasive species".
The prospect has resonance beyond Chicago: the Great
Lakes are the largest surface freshwater system on earth,
containing more than 90 per cent of the surface fresh
water in the US.
The Great Lakes Commission, another US-Canadian body
involved in the management and protection of the lakes,
says that as many as 160 non-indigenous aquatic species
have invaded the Great Lakes from around the world.
Many, like the zebra mussel that first appeared in the
early 1990s, were carried to North America in ballast
water by ships sailing from the Caspian Sea. Zebra mussels
have spread across the Great Lakes, clogging industrial
water intakes, encrusting the keels of boats and costing
millions of dollars of damage to business.
The Asian carp was originally introduced into the US
from Asia in the early 1970s to control algae growth in
aquaculture ponds. The fish, capable of covering 40 miles
in a year, have made it to within 20 miles of Chicago
along a canal fed by Lake Michigan.
The only thing standing between the fish and Lake Michigan
is an electrified barrier built in 2002 whose electrodes
are expected to wear out within eight months.
Last Monday the US army corps of engineers broke ground
on the first stage of a two-stage project to build a second
barrier, funded by the US army and the state of Illinois.
But there is a $1.8m ( 1.6m, £1m) funding
shortfall and the second stage is under threat. Officials
say it is only six months before the carp reach the barrier.
Phil Moy, a specialist in non-indigenous species at the
University of Wisconsin and chairman of the barrier project,
says the carp are a threat even to humans. "These
are large fish and not very pretty," he says. "They
respond to the sound of boat motors and can leap six feet
out of the water and collide with people. We really have
to stop them."
Officials at a conference yesterday in Chicago organised
by the International Association of Great Lakes and St
Lawrence Mayors appealed for legislation to help combat
But with dozens of national and local agencies responsible
for Great Lakes policy, there is a fear that bureaucratic
gridlock means funding will come too late, if it comes
at all, for the Chicago barrier.
"These things are coming up the canal. They're not
worried about federal or state or local governments,"
says Richard Daley, Chicago's mayor. "If we don't
stop them now, they will destroy the Great Lakes."