On November 20, 2009, the Corps of Engineers announced a single sample of DNA from Asian carp had been found above the electric barrier constructed in the canal in an attempt to prevent carp from migrating into the Great Lakes. The silver carp, also known as the flying carp, displace native species of fish by filter feeding and removing the bottom of the food chain. It migrated through the Mississippi River system, and could make its way into the Great Lakes, through the man-made canal. Carp were introduced to the U.S. with the blessing of the Environmental Protection Agency (EPA) in the 1970s to help remove algae from catfish farms in Arkansas. They escaped the farms.