As their name suggests, Asian carp are not indigenous to the United States, yet these invasive fish have become the subject of a Supreme Court lawsuit. Introduced in the US in 1831, carp were originally intended for consumption although today they are not widely eaten. Populations have flourished in the Mississippi and Illinois Rivers since the 1970s, when it is thought that they escaped from Midwestern fish farms during heavy flooding. Carp consume only plankton, although vast amounts of it, and some species of Asian carp can grow to over one hundred pounds. Not only are the fish a hazard to recreational boaters, they also compete with native species for food and space. Environmentalists fear that carp will infiltrate the Great Lakes, via locks connecting the Mississippi to Lake Michigan, where they would damage the ecosystem. Anti-carp activists also fear that by crowding out species such as salmon, Asian carp would also be detrimental to the Great Lakes’ sports fishing industry. The US government currently spends $80 million per annum on Asian carp control, using methods such as toxins and underwater electric barriers designed to repel carp. Evidence of carp in Lake Michigan, however, has led anti-carp activists to call for stronger measures, such as blocking off the locks on the Chicago canal. Business interests strongly oppose the closure of this major shipping lane for economic reasons, also arguing that forcing canal traffic onto the roads will cause pollution.