Five US states sue over Asian carp invasion
Five US states have sued the federal government and Chicago's water authority seeking action to stop Asian carp invading the Great Lakes.
Scientists are afraid the fish may overrun native species like salmon, which inhabit the freshwater lakes on the border of the US and Canada.
The large fish have no natural predators.
The five states are asking the US Army Corps of Engineers to use nets to stop the carp from entering Lake Michigan.
The lawsuit filed in the US District Court in northern Illinois also asks for a study to be conducted on whether the Great Lakes can be separated from the US's Mississippi River and seeks to close Chicago shipping gates and locks - which may be providing an entrance to Lake Michigan for the fish.
Asian carp have proliferated in the Mississippi River and can grow to weigh as much as 100lb (45kg). Some boaters have reported collisions and even injuries from run-ins with the species.
The US Supreme Court has rejected three previous requests for court action from Michigan, Wisconsin, Minnesota, Pennsylvania and Ohio.
The most recent lawsuit was prompted by the discovery of a 20lb (9kg) Asian carp last month on the wrong side of electronic barriers designed to contain the fish.
"President Obama and the Army Corps of Engineers have failed to fight Asian carp aggressively," said Michigan Attorney General Mike Cox, a Republican running for governor.
He added: "Asian carp will kill jobs and ruin our way of life."