Mississippi flooding may have spread invasive fish

MARY FOSTER

Asso­ci­ated Press

NEW ORLEANS — While sci­en­tists have been bat­tling to keep a rav­en­ous, inva­sive fish species out of the Great Lakes, some worry that spring floods along the Mis­sis­sippi River may be spread­ing the Asian carp downstream.

Duane Chap­man, a U.S. Geo­log­i­cal Sur­vey biol­o­gist and Asian carp expert, says the fish are likely to show up in places where Mis­sis­sippi flood­wa­ters intruded. They can weigh up to 100 pounds, grow 4 feet long and live for 25 years.

They could be crowd­ing out food sources of native species for decades.

“I think there is a very seri­ous issue here,” said Chap­man. “We may now be find­ing them in lakes, ponds, bay­ous, any­where the river water went. Those things will be full of carp now.”

Asian carp is a term applied to sev­eral related species of carp that were brought to the United States in the 1970s to con­trol algae in cat­fish farms in the South. Floods washed them into the Mis­sis­sippi River in the 1980s.

Since their escape into the wild, the carp have estab­lished them­selves in the Mis­sis­sippi and Mis­souri river basins. They endan­ger native fish by greed­ily eat­ing aquatic veg­e­ta­tion and rob­bing local species of their food supply.

The bat­tle to keep them out of the Great Lakes includes the use of under­wa­ter cam­eras and sonar to mon­i­tor the effec­tive­ness of the Army Corps of Engi­neers’ elec­tronic barriers.

The Mississippi’s spring floods inun­dated an esti­mated 6.5 mil­lion acres along a 1,000-mile stretch of wind­ing river from Cape Girardeau, Mo., to the Mississippi’s mouth in Louisiana, said corps spokesman Bob Anderson.

In Mis­souri, the corps blew up a levee to send some of the river water into a flood­way at Birds Point-New Madrid; it also opened the Mor­ganza and Bon­net Car­rie spill­ways in Louisiana.

“That entire area could see carp spread­ing to for­merly vir­gin areas,” Chap­man said.

In Mis­sis­sippi, ponds hold­ing farmed cat­fish have taken a heavy toll from back­wa­ter flood­ing. The indus­try says it may take a year to scrub out the ponds and remove much that was left behind, includ­ing Asian carp. They also will have to restock because their crop either swam away in the flood or died because of muck and foul water enter­ing the ponds.

The carp thrive in fast-moving water, said Ruben Keller, a lec­turer in envi­ron­ment stud­ies at the Uni­ver­sity of Chicago who has worked exten­sively on Asian carp with the National Inva­sive Species Council.

“They spawn in high water events like the flood,” Keller said. “This will pro­duce many more carp.”

Greg Lutz, pro­fes­sor of aqua­cul­ture at the Louisiana State Uni­ver­sity Agri­cul­ture Cen­ter, said that means big pres­sure on the food sup­ply for fish. “There’s a rule of thumb for fish size and food con­sump­tion. You can say a 1-pound carp has eaten at least 10 pounds of plank­ton to get that size. So if you have hun­dreds of thou­sands of pounds of carp they are eat­ing mil­lions of pounds of plankton.”

The Yazoo River in Mis­sis­sippi and the Atchafalaya River in Louisiana could be espe­cially sus­cep­ti­ble. Flood­ing has been exten­sive along the Yazoo as the Mis­sis­sippi backed up into farm­land and cat­fish farms.

Mike Kaller, an LSU biol­o­gist, said Asian carp have been found for sev­eral years in the south­ern end of the Atchafalaya basin, but not on its mid­dle and north­ern segments.

But that may change now because the open­ing of the Mor­ganza spill­way west of Baton Rouge could bring fresh carp stocks into the wet­lands that make up the north­ern part of the basin.

Mis­sis­sippi water flow­ing through the Bon­net Car­rie spill­way near New Orleans is expect to spread the species into Lake Pontchar­train and Lake Mau­repas and their tributaries.

The lakes are brack­ish — a mix of fresh and salt water.

Most fresh­wa­ter species can­not sur­vive in a salty envi­ron­ment. But the carp can.

“Asian carp unfor­tu­nately are the excep­tion that can do fairly well in high-salinity water,” Chap­man said.

How far the fish may spread because of the flood won’t be known for some time, he said.

“At this point we have to wait until after the flood dis­si­pates before we can eval­u­ate and see how bad it is.”

Posted by AP News on Jun 10 2011. You can follow any responses to this entry through the RSS Feed. Comments can be made below.