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A mystery of fish mortality

Something in the Shenandoah River is making fish weaken and die, leaving the river bottom flecked with white bellies. is doing all this. After five years of tests, more than $600,000 in government money and uncounted numbers of dead fish, that's still as much as anybody knows.
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Something in the Shenandoah River is turning the smallmouth bass thin and listless and causing sunfish to break out in blisters that look like cigarette burns. Something in the water is making both species weaken and die, leaving the river bottom flecked with white bellies.

Something is doing all this. After five years of tests, more than $600,000 in government money and uncounted numbers of dead fish, that's still as much as anybody knows.

Since 2002, fish have been dying in the Shenandoah and other western tributaries of the Potomac River, and scientists have been racing to find the cause. They have considered viruses, oxygen-depleted "dead zones" and runoff from chicken farms, but they have found nothing definitive. At the same time, the search has been complicated by die-offs this year in two rivers outside the Potomac watershed: the Cowpasture and upper James.

At the center of the mystery is the Shenandoah, whose easy fishing and picturesque setting have long attracted visitors from the Washington area. Here, the impact has been ecological, economic and emotional, as locals try to understand how this beloved waterway became something that kills fish.

"It was such a beautiful river and everything," said Chuck Kraft, a longtime fishing guide from Charlottesville, who has stopped bringing clients to the Shenandoah. "It's kind of sad, you know. It's like losing a friend or a family member."

This spring and summer, dead fish have been reported in six waterways that begin in the mountains near the Virginia-West Virginia border. Four are part of the Potomac River watershed: the North Fork of the Shenandoah, the South Fork of the Shenandoah, the main body of the Shenandoah and the South Branch of the Potomac. The other two are part of the James River watershed.

Often, dead fish have large blisters on their sides or patches of fungus that look like cotton balls. Sometimes, the gills are so inflamed that they can no longer filter oxygen out of the water.

"You don't see a lot at one time, but you see some everywhere you look," said Bill Hayden, a spokesman for Virginia's Department of Environmental Quality.

The kills are not thought to signal a threat to human health. No risk is seen to people who swim in the affected rivers or Washington area residents whose drinking water is drawn from the Potomac downstream. But it troubles scientists that the same types of fish, with the same problems, have been dying in the region since 2002.

"We can't say it's the same thing," Hayden said. "But it is very similar."

Weakened immune systems
A 2002 fish kill occurred in the South Branch of the Potomac in West Virginia. Beginning in 2004, die-offs followed in the Shenandoah and its two main tributaries, which wiggle through mountain valleys just beyond Washington's western suburbs.

In each case, scientists have looked for the usual suspects in any fish kill -- a toxic algae bloom, a malfunctioning sewage treatment plant, an overturned chemical truck -- and found none of them. Instead, some of the fish were being killed by bacteria that they would normally be able to fend off. Something, apparently, was weakening their immune defenses.

What that something is, though, remains elusive. In January, a report from two university professors listed more than 20 theories that might explain the problem. The suspected causes include a virus, pesticides and the dumping of illegal drugs. None of the theories has been proved.

Vicki S. Blazer, a researcher with the U.S. Geological Survey, said a major factor could be manure washed down from the chicken and cattle farms that dot the Shenandoah Valley. Animal waste carries hormones, such as estrogen, that can cause immune problems in fish.

"It overwhelms the fish, is my feeling. But we don't have any proof of that yet," Blazer said.

'Intersex' fish
One piece of evidence supporting this theory is the "intersex" fish found in some of the same rivers: male bass are growing eggs, possibly because of hormone-rich pollution.

A new wrinkle was added to the mystery this year when fish died in the Cowpasture and upper James Rivers in far western Virginia. Both of those waterways are unconnected to the others. For now, nobody can say whether it is the same problem or, if it is, how it traveled overland.

The affected rivers seem significantly changed. Although some fish species, including catfish and carp, have come through unharmed, others, including smallmouth bass and redbreast sunfish, have been devastated. After the 2006 fish kills, state scientists estimated that in sections of the Shenandoah, 80 percent of the smallmouth bass had died.

"I think we're talking millions of fish," said Jeff Kelble, an environmental advocate who is called the Shenandoah riverkeeper.

State officials said they have no way of estimating the total number of fish killed

Even the bass that remain can seem weak and ill. One morning this week, Kelble, a former Shenandoah fishing guide, launched an inflatable boat here into a shallow, deep-green section of river. The scene was pastoral: hayfields on the banks, mountains in the background and great blue herons skimming the surface. But when Kelble reeled in a bass, something was wrong.

"That fish should have a belly," Kelble said, but the stomach, which should have been fat from spring feeding, seemed caved-in and gray. "You see how that's concave? That fish should have a belly there."

Parasites or diseases might have taken advantage of the fish's poor health, Kelble said.

Economic impact
The Shenandoah's famous bass fishery is not officially dead. The president of a local chamber of commerce declared last week, "We are open for business, and the fishing's good."

But the kills have made an economic dent. Last year, a James Madison University researcher estimated that the gruesome kills had scared 2,100 fishermen from the Shenandoah area, at a cost of $686,000 to the local economy and the state.

At Mossy Creek Fly Fishing in Harrisonburg, Va., Colby Trow said many clients -- once drawn by the Shenandoah's famous bass -- had stopped coming.

"They basically just said, 'We'll keep in touch, but we won't be back until that river's clean,' " Trow said.

Instead of driving a few minutes to the South Fork of the Shenandoah, Trow goes 120 miles each way to bring clients to a section of the James River.

Bob Cramer, a fishing guide in Dayton, Va., had been taking clients from Northern Virginia out on the Shenandoah for $300 a day. Now he's helping a friend install invisible pet-control fencing for $75 a day.

But Cramer said the loss was more than financial: It is a sin, he said, that this rural stream seemed to be more toxic than big-city rivers.

"To me, it's just an embarrassment," Cramer said. "We live in such a beautiful place, and we have such terrible water quality."