06/12/2006

By SUE LINDSEY  / Associated Press

Fish bearing cigar-burnlike lesions are continuing to die in Virginia's Shenandoah River, and similar kills have been reported this spring no more than 50 miles away in the Potomac River in West Virginia. The fish show signs of stress and some males have female characteristics, but scientists so far are at a loss to explain why.

Complicating Virginia's investigation is the fact that recent kills involved a new species on a stretch of the river not affected previously. Dead northern hogsuckers were reported on the main stem of the Shenandoah in Clarke County.

"I think everybody wishes it would just go away," said Don Kain, of the state Department of Environmental Quality's Shenandoah Valley office. "It appears it's not going to."

The kills in the Shenandoah this spring have not been as extensive as last year, when 80 percent of the smallmouth bass and redbreast sunfish in the South Fork developed lesions and died. That may be partly because so many fish have already died, the DEQ official said.

This year, a number of smallmouths and sunfish developed lesions and died in the North Fork, Kain said. About 20 percent of the two species in the South Fork developed lesions, but none died. The hogsuckers that died on the main stem had no lesions, but they have been found on redhorse suckers.

About the same time as the Shenandoah hogsucker deaths late last month, a number of northern hogsuckers and golden redhorse suckers turned up dead on the South Branch of the Potomac, said Bret Preston, of the West Virginia Division of Natural Resources. Some rock bass and smallmouth bass also died.

The kills were similar to ones in 2002 on the South Branch and in 2004 on the North Fork of the Shenandoah.

Maryland had a kill of about 1,000 golden redhorse suckers this spring on the north branch of the Potomac below Harpers Ferry, W.Va., where the Potomac and Shenandoah rivers meet, but Department of the Environment spokeswoman Julie Oberg said the deaths were not unusual.

Following the 2002 kill, West Virginia began a joint research project to study water quality and fish with a U.S. Geological Survey laboratory in Leetown, W.Va., Preston said. Virginia scientists also have been conducting more extensive analyses of the Shenandoah's water, and both states have sent dying fish to the USGS lab for examination.

Scientists in both states said the Leetown studies may be key to the investigation.

"We're relying on the fish health experts to try to help us understand," Preston said.

The USGS scientists who examined fish tissue and organs found that the fish apparently had weakened immune systems, pathologist Vicki Blazer said. Their skin was infected by a variety of bacteria and fungi that are commonly found in the rivers and wouldn't normally harm them.

"My feeling is that what we're seeing is fish that are stressed," she said. "What we don't know is what are the stressors."

Blazer said scientists should look more closely at "emerging contaminants" such as hormones and other pharmaceuticals that increasingly are showing up in waterways. Drugs such as Prozac are found in fish tissue, she said, and estrogen from birth control pills and hormone replacement drugs is found in the water downstream from wastewater treatment plants.

Estrogen, she said, was responsible for the "intersex" fish that the lab has discovered. The fish were males, she said, but the female hormone had caused development of immature eggs in their testes.

The condition isn't toxic, Kain said, but could make fish more susceptible to disease.

The West Virginia laboratory is conducting additional tests on the fish tissue, and Virginia's DEQ is still looking at water quality. Scientists won't rule out finding a cause for the kills, but they're not holding their breath for an "Aha!"

"Rarely do we have a real nice cut and dried 'Oh, they died of this,'" Blazer said.

The character of the Shenandoah Valley has not changed much in recent years, Kain noted. Development caused the Shenandoah River to make American Rivers' 10 most endangered waterways this year for the first time, but the DEQ scientist said that is unlikely to have caused the fish kills of recent years.

"Development is one of those things that creeps along," he said.

Still, Kain hopes scientists will soon identify factors that are harming the fish.

"Sunfish are almost nonexistent in some stretches of the North Fork now," he said. "The cumulative effect of repeated fish kills has hurt."

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On the Net:

http://www.deq.virginia.gov

http://www.wvdnr.gov