MAN: Big ones. Big one.
TOM BEARDEN: These are the invaders, large fish that leap high out of the water when disturbed. They are called Asian carp. The Chinese have been growing them for food for 1,000 years. But, to Americans, they are an invasive species, destroying the habitat of native fish in the Mississippi River and its tributaries, all the way from the Gulf of Mexico to Chicago.
The fear that they will do the same to the Great Lakes has set state against state, with Michigan filing suit, along with five other Great Lakes states, to force Illinois and the federal government to stop these fish in their tracks.
JIM ROBINETT, vice president of animal regulation, Shedd Aquarium: This is a bighead carp right here, and this is a little guy. I have collected them on the Illinois River, where they are easily twice that length. They would weigh upwards of 50 pounds. I have been told they will hit 100 pounds. But these guys will eat probably at least half their body weight in plankton every single day.
TOM BEARDEN: Eating that much plankton scares Jim Robinett, vice president of animal regulation at the Shedd Aquarium in Chicago. Plankton consist of several species of tiny plants and animals in the water. They are the foundation of the entire food chain.
JIM ROBINETT: It is an issue that is a potential time bomb, I would say. It would have a devastating affect on the Great Lakes if the Asian carp were to get in there and be able to reproduce in huge numbers. It could wipe out the upwards of $7 billion fishery in the Great Lakes by just outcompeting all the desirable fish.
TOM BEARDEN: One hundred and twenty-five miles across the lake, in Muskegon, Michigan, commercial fishermen Paul Jensen is worried the carp could destroy his business. He spent decades trying to cope with the more than 180 invasive species already in Lake Michigan.
PAUL JENSEN: I am quite certain that the commercial fishing business in Michigan and in all the Great Lakes States has been driven down by the invasive species arrival, because it keeps changing the game.
And fisherman are adaptive creatures, but, you know, the -- the adaptions cost money and time and -- and create big issues. And we get worried about the next one, just like the carp.
TOM BEARDEN: One path for invasive species was the Chicago Sanitary and Ship Canal. Hailed as an engineering marvel when the city opened it in 1900, the canal reversed the flow of the Chicago River and established a water link between Lake Michigan and the Mississippi River system. The canal made Chicago an important port, and it also carried sewage away from the city.
To stop the carp from using the canal to enter Lake Michigan, the U.S. Army Corps of Engineers built an underwater electric barrier in 2002. A second larger installation followed, and a third is planned.
MIKE COX, attorney general, Michigan: There's been DNA found here of both kinds of carp, both kinds of carp found here.
TOM BEARDEN: But when small traces of carp DNA showed up beyond the barriers, Michigan Attorney General Mike Cox asked the Supreme Court to order Chicago to close the locks that link the river to the lake.
MIKE COX: They are ecological and economic danger to the Great Lakes. And, quite simply, they are biological terrorists. And if they get in our Great Lakes, and hit, impact the ecology and the economy of eight different states, two different Canadian provinces, it could cost billions.
TOM BEARDEN: On Tuesday, the court issued a one-sentence statement denying Michigan's request to immediately close the locks. While the preliminary injunction was denied, Cox says the Supreme Court could order the larger case back to a lower court, appoint a special master to oversee a settlement, or order the waterway to be permanently closed.
Henry Henderson works for the Natural Resources Defense Council that supported Michigan's lawsuit. Henderson says the only real solution is to physically wall off the lake from the river, as it was in the 17th century.
HENRY HENDERSON: The barrier has not been adequate. It never has been adequate. And it's not going to be adequate. They are going to be very, very hard to eradicate. And we -- I think we -- we can't eradicate them. That is why we need to figure out and institute a permanent barrier, so they don't get into the Great Lakes.
JOHN KINDRA, Kindra Lake Towing: I was amazed this morning how many salt trucks are lined up.
TOM BEARDEN: But John Kindra and Del Wilkins, who run barge companies, say closing the locks would destroy their industry.
JOHN KINDRA: Well, the first thing is that it would put us right out of business. If we don't have barges coming through the locks, we don't have any activity at all.
DEL WILKINS, Illinois Marine Towing: On the Chicago Sanitary Ship Canal system, which we are standing right in front of, 16.9 million tons move through that system. If you equate that to trucks, that is 1.3 million truckloads and close to 280-some-odd-thousand railcars. The infrastructure in this area couldn't handle that kind of capacity overnight.
TOM BEARDEN: John Kindra even doubts whether closing the locks would accomplish anything.
JOHN KINDRA: With regard to the locks, you know, the locks are not necessarily designed to be watertight. I mean they come through, they hold water, but they -- they are all designed to leak a little bit. So, that may not be the effective method, if they do choose to close the locks.
DICK LANYON, executive director, Metropolitan Water Reclamation District of Greater Chicago: The walls are like three feet thick.
TOM BEARDEN: Dick Lanyon is the executive director of the Metropolitan Water Reclamation District of Greater Chicago, the agency that operates the canal system. He says, if the court orders the locks closed in the future, thousands of homes would flood during a severe storm; the metro train tracks would be under water; sewage would back up in thousands of basements.
DICK LANYON: Our last big storm was in September 2008. We had nine inches of rain across the whole Chicago area. We ended up discharging 11 billion gallons of water to Lake Michigan for flood relief.
TOM BEARDEN: So, these are not rare occurrences?
DICK LANYON: These are not rare.
MIKE COX: In terms of flooding, they have only had to open any of the locks nine times since 1995 or the past 25 years. In our pleadings, we -- we don't ask the Supreme Court not to allow them to open the locks for flooding. Obviously, we want a provision in the order for that. We're trying to be eminently reasonable.
TOM BEARDEN: Paul Jensen worries that, while the states battle it out in court, businesses like his might get eaten alive.
PAUL JENSEN: Well, we're obviously the small guys. But whether we are going to get eaten by Chicago, I don't know. If they would eat our fish, we would be happier.
TOM BEARDEN: On Tuesday, the Army Corps of Engineers announced it had found traces of carp DNA in Lake Michigan itself, indicating the fish may have already reached the lake. But scientists say that doesn't necessarily mean that a breeding population has been established -- yet.