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Invasive 'jumping carp' found in Mississippi River near La Crosse

The infamous silver carp, or "jumping carp," has been found in the Mississippi River near La Crosse.

This is the first confirmed identification of a silver carp upstream of Clinton, Iowa, and the first identified in Wisconsin waters.

Fisheries supervisor Ron Benjamin of the Wisconsin Department of Natural Resources said a single silver carp was among three species of invasive Asian carp discovered late last week in a commercial fishing net deployed in the Mississippi River near La Crosse. It was not immediately identified.

Two grass carp and one or two bighead carp were also pulled from the net.

Biologists from Wisconsin and Minnesota are working together to determine the extent of the problem. It is not yet known if more silver carp are in the river, or whether there are enough of them to support reproduction. Nor is it known whether the habitat in the northern Mississippi River will support a reproducing population of silver carp.

Silver carp have been known to cause injury to boaters. The vibration of a spinning propeller excites these large fish and boaters have been struck when they leap out of the water. Invasive carp also damage aquatic plants important to native fish species.

"A common question is to ask what will be the impact of Asian carp to the river that we love," said Benjamin. "The short answer today is it clearly isn't good. Aquatic invasive species are detrimental to native aquatic ecosystems."

Asian carp were imported by the aquaculture industry for vegetation removal, snail control and as a source of protein.

The four species imported were grass carp, bighead carp, silver carp and black carp. All have to some extent escaped into the wild, typically when flood waters carried them out of commercial ponds.

Grass carp are currently stocked in Iowa for vegetation control. Bighead and silver carp are abundant below Lock and Dam 19 at Keokuk, Iowa, and they are common below the Quad Cities. Bighead carp are present south of Dubuque and are rare south of St. Paul. Silver carp had not been reported north of the Quad Cites.

In the Wisconsin portion of the Mississippi River, grass carp have been found in low numbers since 1987. Bighead carp were caught by commercial fisherman at the mouth of the St. Croix River in 1998, in Lake Pepin in 2003 and 2007, and now in Pool 8 for the first time.

Black carp have not been reported in Wisconsin to date.

Benjamin said it is likely these invasive species moved north during the record floods this past spring. Lock and dam structures are a barrier to upstream migrations, but when flood waters topped the dams there was nothing to stop fish from swimming upstream.

Interestingly, Benjamin said, biologists have been finding Skipjack herring, an endangered native fish, in Pool 8 of the Mississippi River at La Crosse. These fish were previously found only farther to the south. So the flood waters helped re-introduce a native species to Pool 8.

The upper Mississippi River is already one of the most well researched rivers in the world. Biologists from Wisconsin, Minnesota and the federal government have been working together for decades to monitor the health of the river and to restore river habitat for fish, birds and mammals.

The invading carp will be closely studied, but in a river the size of the Mississippi management options are limited.

"Invading carp will be closely studied," Benjamin said, "but this is a good reminder to all who use our waters to help us stop the spread of invasives."

Benjamin asked boaters to take the following steps:

  • Inspect your boat, trailer and equipment and remove visible aquatic plants, animals and mud.
  • Drain water from your boat, motor, bilge, live wells and bait containers.
  • Do not move live fish from one water to another.
  • Dispose of leftover bait in the trash, not in the water or on land.
  • Buy your minnows from Wisconsin bait dealers or catch your own and use it to fish the water you caught it from.
  • Wash your boat and equipment with high pressure or hot water, or let it dry for five days.