Scientists baffled by massive spring fish kills on the Shenandoah River over several years now have additional confusing information: several hundred dead fish in December.

An environmentalist counted at least 300 dead northern hogsuckers on a 10-mile stretch of the main branch of the Shenandoah in Clarke and Warren counties in early December, said Don Kain, a state Department of Environmental Quality biologist. An accurate count was impossible because many had sunk the bottom, DEQ spokesman Bill Hayden said.

About a dozen more dead fish were found later, but they were of different species and in different parts of the river. Most of them were sunfish except for one smallmouth bass, Kain said. Half were found on the North Fork of the Shenandoah and half on the South Fork.

“That’s been the toughest thing about this fish kill,” Kain said. “There really aren’t any concerted patterns.”

None of the fish killed recently bore the cigar-burnlike lesions that afflicted fish in previous kills.

Other kills on the river prized by anglers occurred in the spring, but the species have varied. Last spring, northern hogsuckers died on the mainstem Shenandoah in Clarke County, and a number of smallmouth bass and sunfish bearing lesions died on the North Fork.

In 2005, 80 percent of the smallmouth bass and redbreast sunfish in the South Fork developed lesions and died. The kill was similar to one in 2004 on the North Fork of the Shenandoah.

Scientists have been unable to determine the cause of the fish kills, and the state’s Shenandoah River Fish Kill Task Force that was formed to investigate those kills will look into the recent incidents.

Kain, the task force’s co-chairman, said he’ll be out on the river looking for fish samples that scientists can study. A fish must still be alive and in distress or freshly dead to be useful to scientists. The fish found so far had been dead for a longer period.

Fish that died in previous kills showed signs of stress, and some males had female characteristics, a condition called “intersex.”

Development caused the Shenandoah River to make American Rivers’ 10 most endangered waterways this year for the first time.

Workshop will address fish health issues in the watershed

A workshop, “Fish Health in the Chesapeake Bay Watershed: Synthesis and Evaluation of Current Knowledge,” will take place Jan. 23–25 at the U.S. Fish and Wildlife Service’s National Conservation Training Center in Shepherdstown, WV.

The workshop will bring together experts in fish health, fisheries biology, ecology, water quality and toxicology.

The first day is open to the public and will be an opportunity to learn what is known about major fish health issues in the watershed. For information, or to register to attend on Jan. 23, go to www.cbf.org/fishworkshop.