The Associated Press reports the U.S. Supreme Court on Monday refused to hear an appeal filed by Minnesota and other Great Lakes states. The states asked the court to order the closure of shipping locks in the Chicago area to prevent the invasive Asian carp from spreading farther north.

Last month Congress made changes to shorten the timeframe for developing a federal plan to prevent the invasive fish from spreading to the Great Lakes. But Minnesota and four other states that are suing the federal government over the issue say they won't withdraw the lawsuit.

The Obama administration's point man in the fight against invasive Asian carp says his agency is focused on protecting the Great Lakes. But he doubts the plan Sen. Amy Klobuchar is pushing is a viable way to keep the fish out of the upper Mississippi River.

A risk analysis by U.S. and Canadian researchers finds the food supply and breeding areas in the Great Lakes would allow Asian carp to spread rapidly. The report says just ten breeding females and a few males would be enough of a foothold for the invasive fish to populate all five of the Great Lakes.

A biologist from the United States Geological Survey says the Mississippi and Illinois rivers have more Asian carp than anywhere else on the planet -- including more than China, where the species came from.

The U.S. Army Corps of Engineers says it will come up with a short list of options for blocking the spread of the invasive fish by the end of next year. The Corps had earlier said the process would take until 2015. Asian carp have already invaded the Mississippi River watershed. Officials hope to keep them from migrating into the Great Lakes.

State and federal officials are pushing a bill in Congress that would close the lock and dam at St. Anthony Falls if the invasive fish is found nearby. They say if Asian carp get any farther up the Mississippi River, they would threaten Minnesota's $11 billion tourism industry.