Great Lakes Asian Carp Invasion Inevitable, Researchers Say

If the right conditions are present, the introduction of fewer than two dozen Asian carp to the the Great Lakes system could be enough to establish a thriving population of an invasive fish notorious for out-competing native fish for food and resources, according to new research published in the journal Biological Invasions.

Researchers from Waterloo University in Canada say the arrival of Asian carp, which are well-established in major waterways like the Illinois and Mississippi Rivers, is inevitable in the Great Lakes system as the fish use the connecting waterways to swim into the system. The best defense, the researchers report, is to focus on intercepting new arrivals.

"It's expected that it's only a matter of time before the population migrates through the many hydrological connections to the Great Lakes," said Waterloo University researcher Kim Cuddington. "Lake Erie, in particular, provides a highly suitable habitat for the fish with very productive embayments for the fish to find food."

Asian carp, which can grow up to 110 pounds (50 kilograms), can eat up to 40 percent of their body weight in a day. Mature Asian carp are at least 2 feet long (61centimeters), giving them a significant size advantage over native fish species in the Great Lakes.

"This species will have a huge impact on the food web," Cuddington said. "Not only is it a fast-growing fish physically, but the population itself grows very quickly. A female can lay well over a million eggs a year, and with no known predators present in the Great Lakes, the Asian carp could dominate the waters and impact fisheries."

Individual Asian carp have been caught in at least two of the five Great Lakes.

Cuddington and her colleagues' research indicates that if just 10 Asian carp establish themselves in one of the lakes, the probability that a population becomes established is 50 percent. If 20 of the fish are present, the probability jumps to 75 percent under the right conditions.

Water temperature will play a key role in whether a booming Asian carp population will become established in the Great Lakes.

The fish are known to reach maturity within three years, so it's expected that it will take about two decades for a moderate population of the Asian carp to become established in the Great Lakes, and between 40 and 50 years for that population to become very large.

But if cooler water slows the fishes' development time to five years, it might take more than 100 years for a population to become established.