Officials say an Asian carp has been found for the first time beyond the electric barriers constructed to keep the dreaded invasive species out of the Great Lakes. State and federal officials said Wednesday that commercial fishermen found the 3-foot-long, 20-pound carp in Lake Calumet on Chicago’s South Side, about six miles downstream of Lake Michigan.

The single carp is the first to be found in a Chicago waterway above the Army Corps of Engineers’ electric barrier system. Officials say they’ll use electrofishing and netting to remove any carp from the lake.

Scientists and fishermen fear that they if the carp become established in the Great Lakes, they could starve out popular sport fish such as salmon and walleye. They can grow to 100 pounds and 4 feet.