Asian carp were first introduced to North America by fish farmers in the southern U.S. They imported the carp to control plant growth in fish ponds. But the big fish with no natural enemies soon escaped the ponds and began eating -- and leaping -- its way north. And east and west. Carp have been found in Lake Pepin and in lower reaches of the St. Croix River.
Unsuspecting boaters up and down the Mississippi have been injured when 25-to-50-pound silver carp, excited by the boat's motor, jump high in the air and sometimes land in the boat.
Asian carp is the generic term for one of four species of fish that are posing threats. The silver carp is the most notorious, for its acrobatic antics. It's a YouTube favorite.
And the carp are causing as much havoc underwater. Phil Moy studies Asian carp at the University of Wisconsin Sea Grant Institute.
"These things are robbing everything else that depends on the productivity of the water -- the tiniest fish, the minnows that then feed larger fish that then feed us, all rely on plankton -- and here we have a great big fish, and a lot of them, taking the food from everyone else," said Moy. D: