Giant Carp Invade Chicago, Authorities Bring Out the Zappers!

May 19 (Bloomberg) -- Richard White, a charter-boat captain in Waukegan, Illinois, makes a living hooking 10-pound (4.5- kilogram) salmon and trout from Lake Michigan. There's a fish 10 times that size he hopes never to catch.

Asian carp, an invasive species as big as 100 pounds, has migrated up the Mississippi River to within 50 miles (80 kilometers) of Lake Michigan, leading the U.S. Army Corps of Engineers to try to stop the carp with an electric barrier in a Chicago shipping canal. ``Those fish get into the Great Lakes, we'll be out of business in a few years because they eat everything,'' says White, 59.

For the $4 billion fishing industry in the Great Lakes, the world's largest fresh-water ecosystem, Chicago is the final line of defense from an Asian carp invasion. The start-up of the $9.1 million barrier, the largest ever built, has been delayed until later this month after electric current strayed too far and threatened to ignite ships in the channel connecting Chicago with the Mississippi River and Gulf of Mexico.

The carp, native to rivers in China, are squeezing out other fish because of prolific appetites and breeding, says Marc Tuchman, a scientist in Chicago with the U.S. Environmental Protection Agency. A 40-pound female produces as many as 2.2 million eggs in a spawning season, more than the 46,000 eggs for bluegills, a common U.S. river fish.

Some types of carp eat as much as 20 percent of their body weight daily, making them more disruptive than other aquatic invaders such as the zebra mussel or the round goby bottom- dweller from Asia that has become established in Great Lakes waters in recent years, Tuchman says.

Discouraging Fish

Asian carp were imported by catfish farmers in the U.S. South to eat algae from ponds, according to the EPA. Catfish ponds overflowed during floods in the early 1990s, releasing fish into local waterways. The carp worked their way into the Mississippi River, crowding out native fish in some stretches.

The EPA and the fishing industry are counting on Chuck Shea of the U.S. Army Corps of Engineers, who leads the project to build the electric barrier on a section of the Chicago Sanitary & Ship Canal, about 30 miles southwest of Lake Michigan in Romeoville, Illinois.

The 28-mile canal, dug in the late 1890s to reverse the flow of the Chicago River to protect the city's drinking water by carrying sewage away from Lake Michigan, links the Mississippi River and Great Lakes for barge traffic.

``We're confident it's going to work,'' Shea, 36, says of the barrier. ``We're plugging the biggest hole by stopping the direct pathway for these fish.''

The barrier, comprised of two electrified zones about 220 feet (67 meters) apart, will generate as much as 1 volt of electricity per linear inch (2.54 centimeters) of water to discourage fish from swimming further and turn them around unharmed, Shea says.

`Some Challenges'

To build the barrier, crews threaded bundled cables through holes bored in bedrock lining the canal and connected them to steel bars along the channel bottom to create the electrical field. A second stage will be completed next year, and the system will cost the state of Illinois about $20,000 a month to run, Shea says.

A temporary barrier 800 feet closer to the lake is running until the new system is working.

Similar barriers have been used in other parts of the U.S., typically in small streams and fish farms, Shea says. The Chicago project, at a combined 260 feet long, will be the largest of its kind in the world, he says.

``It is a one-of-a-kind project, and that does lead to some challenges,'' Shea says.

White, the Waukegan charter boat captain, says his industry is pulling for Shea. Unimpeded Asian carp would wipe out demand for his Dell V Charters because they can't typically be lured to bait on a rod and reel, and their bodies are bonier and have less flavor than salmon or trout, he says.

``They're no good to eat,'' says White, a former Golden Gloves boxer who takes ``Punch'' as his nickname. ``They're garbage fish. It would be like chewing on an old tire.''