Carp spreading up the Mississippi River

Imported fish raise fears among naturalists of ecological havoc

August 26, 2002|By NEW YORK TIMES NEWS SERVICE

VICKSBURG, Miss. - Grass carp, bighead carp and the silver carp - giant, prolific species all originally imported by catfish farmers in Mississippi and Arkansas two decades ago - have escaped in floods into the Mississippi, and have begun showing up as far north as Iowa and Illinois.

"They are thick as fleas in Mississippi tributaries," said Bill Reeves, chief of fisheries for the state of Tennessee.

Now a more recent arrival, the black carp, is stirring alarm from New Orleans to Ontario. Also known as the snail carp and the Chinese roach, the black carp is a bottom-sucking ogre that can grow 5 feet long and up to 150 pounds. It gorges on mollusks, including parasite-infested ram's horn snails that can populate ponds and infect the catfish with wormy yellow grubs.

The various carp species, imported from China, Russia and Vietnam, were intended to control detritus and unwanted plant and animal life in fish farm ponds. They are banned from fish farms in several states. They are edible but largely uneaten here, except by some Asian immigrants for whom they are a dietary staple.

But as the grass, silver and bighead carp already in the river grow and proliferate, conservation agencies are finding them difficult to control. Carp hug the bottom of the muddy Mississippi, and nobody knows how many there are.

As they head north, said John Chick, director of the Illinois Natural History Survey's Great River field station near Alton, Ill., some have been seen up around Iowa and Wisconsin. Their next stop could be the Great Lakes, he said.

Marc Gaden, spokesman for the Great Lakes Fisheries Commission in Ann Arbor, Mich., a U.S.-Canadian organization that seeks to prevent pollution and ecological damage to the Great Lakes, said the fish were "scratching at our door."

To thwart carp that escaped from the Mississippi, and any other fish heading from there to the lakes along the Chicago Sanitary Canal, the Corps of Engineers has installed an electric barrier in the canal that should turn back fish.

With relatively few species established in the rivers, it is hard to tell which of the carp, if any, will become bearable nuisances, or whether any could become something much worse, like the zebra mussel. As big, gluttonous feeders, carp compete with other fish for food and spawning ground.

Richard Wehnes, fisheries unit chief at the Missouri Department of Conservation, said, "The silver carp has taken off exponentially." The carp compete with largemouth bass, bluegills, redears and crappie for plankton, Wehnes said, adding, "Our concern is, what are they pushing out?"

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