TRAVERSE CITY, Mich. — Canadian and U.S. scientists announced Tuesday the launch of a joint study that will look at the likelihood that Asian carp will spread across the Great Lakes and decimate the fish populations if allowed to gain a foothold.
The 18-month study will be the first joint effort by the two nations to evaluate possible consequences of an invasion by bighead and silver carp – Asian species threatening to enter Lake Michigan through Chicago-area rivers and canals.
"We have seen the destructive behavior" of Asian carp in parts of the Mississippi and Illinois rivers, where they have disrupted the food web by hogging the plankton on which many fish depend, said Becky Cudmore, senior research scientist for Fisheries and Oceans Canada. "We are not taking the threat to the Great Lakes lightly."
Canadian researchers produced an initial assessment in 2004 and U.S. experts did likewise the following year. The new project will aim to resolve differences between them while yielding new information about the carp threat, said Marc Gaden, spokesman for the Great Lakes Fishery Commission.
Asian carp were imported in the early 1970s to cleanse algae from Southern fish farms and sewage treatment plants. They escaped into the Mississippi River and have migrated northward ever since.
The carp have advanced to within about 25 miles of Lake Michigan, where their path is blocked by two electronic barriers on the Chicago Sanitary and Ship Canal. Their DNA has been detected in numerous spots above the barriers, although just one actual Asian carp has been found there.
Scientists have differed on what is likely to happen if a sizable number breach the barriers and slip into Lake Michigan.
Some say the voracious, hardy carp, which can reach 4 feet in length and 100 pounds, could become established in large sections of the Great Lakes, where they would starve out competitors for plankton and jeopardize the region's $7 billion fishing industry.
Skeptics say a carp invasion, if it happens at all, probably will be limited. They say the lakes might be too cold or have too few tributary rivers where the carp can spawn – and their food supply could run short because zebra and quagga mussels have devoured much of the plankton.
The U.S.-Canadian study will focus on such issues. It also will look at other potential doorways to the lakes for the carp and the possible effects of a full-scale invasion on the region's environment and economy.
It will bring together top scientists in the field and will be peer-reviewed, said Nick Mandrak, a Fisheries and Oceans Canada research scientist.
"With this risk assessment, we will have a vastly improved understanding about where Asian carps might establish a population within the basin," said David Ullrich, the fishery commission's U.S. chairman.
The study will help regulators and natural resource managers devise strategies for keeping carp out of the lakes or controlling their numbers if some get in, Cudmore said.
"It's far easier, more cost-effective, to prevent an invasive species from getting in than dealing with it after it arrives," she said.