An Asian carp was found for the first time beyond electric barriers meant to keep the voracious invasive species out of the Great Lakes, state and federal officials said Wednesday, prompting renewed calls for swift action to block their advance.

Commercial fishermen landed the 3-foot-long, 20-pound bighead carp in Lake Calumet on Chicago's South Side, about six miles from Lake Michigan, according to the Asian Carp Regional Coordinating Committee.

Officials said they need more information to determine the significance of the find.

"The threat to the Great Lakes depends on how many have access to the lakes, which depends on how many are in the Chicago waterway right now," said John Rogner, assistant director of the Illinois Department of Natural Resources.

But environmental groups said the discovery leaves no doubt that other Asian carp have breached barriers designed to prevent them from migrating from the Mississippi River system to the Great Lakes and proves the government needs to act faster.

"If the capture of this live fish doesn't confirm the urgency of this problem, nothing will," said Andy Buchsbaum, director of the National Wildlife Federation's Great Lakes office.

Scientists and fishermen fear that if the carp become established in the lakes, they could starve out popular sport species and ruin the region's $7 billion fishing industry. Asian Carp can grow to 4 feet and 100 pounds and eat up to 40 percent of their body weight daily.

Rogner, from the Illinois Department of Natural Resources, estimated that the male carp was about 3 to 4 years old. It was caught live but has since been killed and will be sent to the University of Illinois to determine if it was artificially raised or naturally bred.

The fish was sexually mature, but Lake Calumet's conditions aren't conducive to reproduction because the water is too still, Rogner said. Even so, the lake is the ideal living environment for the fish because it's quiet and near a river system, he added.

"It fits the model to a T," he said. "They may be concentrated in that area."

Officials said they'll use electrofishing and netting to remove any Asian carp from the lake.

They have been migrating up the Mississippi and Illinois rivers toward the Great Lakes for decades.

There are no natural connections between the lakes and the Mississippi basin. More than a century ago, engineers linked them with a network of canals and existing rivers to reverse the flow of the Chicago River and keep waste from flowing into Lake Michigan, which Chicago uses for drinking water.

Two electric barriers, which emit pulses to scare the carp away or give a jolt if they proceed, are a last line of defense. The Army corps plans to complete another one this year.

"Is it disturbing? Extraordinarily. Is it surprising? No," Joel Brammeier, president of the Alliance for the Great Lakes, said of the carp's discovery beyond the barriers.

He said the capture highlights the need to permanently sever the link between the Mississippi River and the Great Lakes. The Army Corps is studying alternatives, but says the analysis will take years.

"Invaders will stop at nothing short of bricks and mortar, and time is running short to get that protection in place," Brammeier said.

In Michigan, officials renewed their demand to shut down two shipping locks on the Chicago waterways that could provide a path to Lake Michigan. The U.S. Supreme Court has twice rejected the state's request to order the locks closed, but state Attorney General Mike Cox said he was considering more legal action.

"Responsibility for this potential economic and ecological disaster rests solely with President Obama," Cox said. "He must take action immediately by ordering the locks closed and producing an emergency plan to stop Asian carp from entering Lake Michigan."

A Chicago-based industry coalition called Unlock Our Jobs said the discovery of a single carp did not justify closing the locks. Doing so would damage the region's economy and kill jobs without guaranteeing that carp would be unable to reach the lakes, spokesman Mark Biel said.

"A few isolated incidents of Asian carp in this small section of the Illinois Waterway does not mean existing barriers have failed," said Biel, also executive director of the Chemical Industry Council of Illinois. "Additional regulatory controls and river barriers should be explored before permanent lock closure is even considered."