Asian carp, a large non-native fish species that has invaded U.S. waters, may have spread to southwestern Michigan's Kalamazoo River.

Officials said today that while no live fish have been found, genetic material left by Asian carp has been discovered in the river, the Associated Press reported.

"While we don't have evidence of a live fish in the water, we treat this finding very seriously," Michigan DNR senior water policy adviser Tammy Newcomb told the AP.

Wildlife officials don't yet know if the Asian carp DNA, which could come from the fish's scales, excrement or mucous, was left by live fish or if it entered the river from boats, fishing gear or bird droppings.

The carp species, which reproduce quickly and can grow up to 100 pounds each, would cause serious damage to fish in the Great Lakes if the non-native creatures make their way up the Kalamazoo River.

We are definitely concerned," Newcomb told MLive and other media. "We need folks to be vigilant. We need to keep the fish out of the Great Lakes."

Discovered by the DNR and U.S. Fish and Wildlife Service, the sample that tested positive for Asian carp genetic markers was just one out of 200, according to MLive.

The carp have become an invasive species since being brought to America in the 1970s to clean up fresh water. Breeding in the long Illinois River, the fish were leaping onto boats by the dozens over the summer to become easy prey for local fishermen, who compared being struck by a flying carp to "getting hit with a brick."

Asian carp pose a threat to the Great Lakes ecosystem and its fishery, which is worth $7 billion. Officials are working with local bait shops and area fishermen to keep tabs on any sightings of the silvery fish.

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