November 20, 2006

Flying Fish Unwelcome in Nebraska Rivers

By David Hendee, Omaha World-Herald, Neb.

Nov. 19--Chris Kelly was puttering around the confluence of the Platte and Missouri in a flat-bottom riverboat when a silver missile practically fell into his lap.

Thwack!

Then again.

Thunk!

There were near-misses against the side of the vessel . . .

Thud! Thud!

. . . and into the river.

Splash! Splash! Splash!

The brief airborne assault from Asian silver carp is an increasingly common encounter near the mouth of the Platte River south of Omaha.

Scientists wonder how long it will be before the riparian raiders strike deep into Nebraska, reaching Columbus up the Platte or moving into the Loup River.

Regardless of how many times they witness these surprise attacks, Kelly and other boaters have the same reaction.

Shock and awe.

Kelly, a University of Nebraska-Lincoln authority on invasive species, has a front-row seat to the flying-fish phenomenon that threatens Nebraska and Iowa's multimillion-dollar sport-fishing industry.

The bottom-feeding, high-flying carp are leaping onto lists kept by Kelly and other scientists of exotic, invasive species that jeopardize the ecology of an aquatic system, where they compete with native fish for food and space.

Silver carp have been on scientists' radar screens for about two decades. Now boaters, anglers and water skiers are coping with the flying fish.

"It doesn't feel good to get clobbered by one of those guys," said Mark Pegg, a UNL fisheries ecologist who saw his first silver carp a decade ago in the Missouri River near Nebraska City.

A 20- to 25-pound silver carp can be about 4 feet long.

"It's a sizable projectile," Pegg said.

The frenzied, torpedo-shaped carp react to motorboats by leaping as much as 6 to 10 feet in the air, sometimes striking people or tumbling onto boat decks.

They've knocked out teeth and bloodied noses. Their fins have cut people.

The U.S. Geological Survey says water skiing on the lower Missouri is "exceedingly dangerous" because most silver carp jump behind fast-moving boats, creating high-velocity fish flak in the path of skiers.

"It's dangerous when they leap into a boat," said Jeff Jackson, a Nebraska Game and Parks Commission fisheries manager, noting the risk they pose to passengers. "They bleed from the gills and there's blood everywhere. It's a mess."

Kelly, an environmental biologist at UNL, will feature the fish at an Omaha workshop next month for the annual Midwest Fish & Wildlife Conference.

"We're still trying to raise people's awareness of silver carp," Kelly said. "We know they're there. Now we need the technology and research to stop them before they destroy our waters and we have to sound the ecological alarm."

Southern aquaculture farmers imported silver carp -- and their seldom-leaping cousins, bighead carp -- from Asia in the 1970s to control algae and plankton in fish farms. By the early 1990s, the carp had been released into the wild or had escaped from the fish ponds.

They flourished, spreading to much of the Mississippi River drainage, including the Missouri, Ohio and Illinois Rivers and their tributaries.

Pegg said silver carp have been found 200 miles up tributaries of the Illinois River. A 15-minute boat ride on the Illinois River can stir up thousands of leaping carp.

"If there's an open channel, they're probably in it," Pegg said. "They could make it up the Platte to Columbus here in Nebraska, and possibly into the Loup River."

They've been caught near Gretna in the Elkhorn River, a Platte tributary.

"If there's not a dam, it's likely they have been -- or soon will be -- in any waterway connected to the Missouri River," Pegg said.

Studies on the Illinois River found silver carp moving 40 to 50 miles a day, Pegg said.

They grow quickly -- 9 to 12 inches a year -- and reach more than 50 pounds. Scientists say Asian carp may be the most abundant large (over 5 pounds) fish in the lower Missouri.

They compete with native fish for food and space, said Schuyler Sampson, a Nebraska Game and Parks Commission biologist.

Sampson, who wrote his master's thesis on the diet of Asian carp, encounters the fish during his work with a pallid sturgeon recovery program.

Asian carp are big eaters. They consume zooplankton and phytoplankton, tiny organisms at the bottom of the aquatic food chain. Other native larval fish also need that plankton, Sampson said.

"We're not sure what their natural predator is," Sampson said. "They may not have a natural predator."

Pegg said the numbers and size of the carp pose problems in the Missouri, although their impact so far is difficult to measure.

It was 2003 before the first silver carp was caught in South Dakota, and the fish still isn't often seen in the Missouri north of the Platte, Pegg said.

Around Omaha, they tend to cluster at the mouth of the Platte or on the lee side of the Missouri's wing dikes, where they find protection from the swift current, Pegg said.

Bow anglers build platforms on boats for standing and shooting arrows at swimming or leaping carp.

A silver carp is considered tasty. Pegg said the bony, light meat is flaky, like crappie.

So why do silver carp leap?

Pegg said it's believed to be a combination of the noise of a boat motor and the pressure change created by the surge of water from the moving vessel.

"They can hear very well for fish. They might suspect that the noise is a predator coming after them," Pegg said, "although we don't have anything in North America that can eat a 2- or 3-pound silver carp."

Until they reach nuisance status, silver carp probably will be an interesting anomaly in the central Missouri, Pegg said.

"But they're pretty well despised by everybody downstream from Nebraska," he said.

Commercial fisherman hate them because they replace market fish.

Anglers hate them because they compete with native and sport fish for feed.

Boaters hate them because they're a danger.

"It's a lose-lose-lose situation," Pegg said. "It's sort of sad that it's come to this. They're a fish nobody wants."

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Copyright (c) 2006, Omaha World-Herald, Neb.

Distributed by McClatchy-Tribune Business News.

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