TRAVERSE CITY, Mich. (AP) — Asian carp could find enough food and breeding
areas to reach all five of the Great Lakes within 20 years if allowed to
gain a foothold, a scientific report said Thursday.
The risk analysis by U.S. and Canadian researchers said just 10 mature
females and even fewer males could establish a population in the lakes,
assuming they find rivers suitable for spawning. Previously, some officials
have said hundreds of the carp probably would be needed to launch a
Their likeliest pathway to the lakes is a network of canals and rivers in
the Chicago area, where their DNA has been detected just 6 miles from Lake
Michigan, the report said. If they evade an electric barrier and reach the
lake, they could proliferate in bays and tributary rivers, eventually moving
north to Lake Huron and then south into warm, shallow Lake Erie, which has
the region’s most abundant fish population and would be ideal carp habitat.
It would take longer for them to infest Lakes Superior and Ontario. But they
could survive in both, the report said, contrary to some experts who contend
Superior would be too cold. The analysis, released by Canada’s Fisheries and
Oceans ministry after a 16-month study, is “sobering,” said Michael Hansen,
chairman of the Great Lakes Fishery Commission. “It concludes that arrival
of Asian carps is looming, and should the fish become established in the
Great Lakes, that their effects on the ecosystem would be severe.”
Bighead and silver carp have migrated northward on the Mississippi River and
its tributaries since escaping from Southern sewage lagoons and fish farms,
where they were imported in the 1970s. Researchers are studying their impact
on native fish.
The U.S.-Canadian report says the carp, which gorge on tiny plants and
animals called plankton, would reduce the food supply for small Great Lakes
fish, causing them — and eventually bigger fish that feed on them — to
decline. The carp also could gobble larvae of prized sport fish such as
walleye and yellow perch, it said.
these non-native fish first escaped and began to breed prolifically in the
rivers of the Midwest, the questions everyone has been asking are: ‘Can a
breeding population survive in the Great Lakes and would it be a significant
problem if they did?’” said Marcia McNutt, director of the U.S. Geological
Survey. “Now we know the answers and unfortunately they are ‘yes and yes.’"