By Sally Voth
The Shenandoah River has reclaimed its status as a "legendary" fishing venue, Shenandoah Riverkeeper Jeff Kelble says.
Less than a decade after widespread fish kills involving smallmouth bass, red-breasted sunfish and rock bass in 2004 and 2005, fish populations are back in force.
"[The fish kill]'s something that I think lasts in people's minds here in the valley, particularly people who either use the river or pay attention to what's going on in the river," Kelble said.
He doesn't know the exact numbers of fish that died on the whole stretch of the North and South forks of the Shenandoah River, but said it was in the many thousands. Kelble said the Virginia Department of Game and Inland Fisheries estimated about 80 percent of the population was wiped out.
"That was kind of a general estimate," Kelble said, adding that he was a fishing guide at the time, and depending on the area, he thought 40-95 percent of the population was affected.
It's still not known for certain what caused the fish kills, he said. There is a possible link between early exposure to hormone-mimicking chemicals and later susceptibility to those chemicals.
The Shenandoah Riverkeeper, a nonprofit organization, worked with the U.S. Geological Survey to study issues with fish, and "a strong correlation" was found between two pesticides and levels of intersex in smallmouth bass, according to a news release from the organization.
Those pesticides had been found to impact immune system function in previous studies, according to the release.
Kelble explained that intersex refers to male fish producing both eggs and sperm in their testicles. Those eggs are not mature and aren't laid by the fish, he said.
It's not known if the intersex phenomenon was related to the fish kills, Kelble said.
While there is some evidence of birth-control pill residue in the river, the areas of the intersex condition had no human effluent, he said.
Upstream of any agricultural operation, up to 100 percent of the male fish were intersexed, while the density of egg clusters was greater downstream of sewer plants, Kelble said.
He said a link had been discovered between plant hormones and intersex fish. In March, Kelble discussed an algae problem on the Shenandoah.
"Algal blooms are caused by excessive nutrients running off of farm and urban lands as well as from sewer treatment plants," the release states. "It's possible that the chemicals and plant hormones act together to accentuate their individual effects."
Kelble said that in his opinion, the reason so many fish were lost because their immune system dropped.
"There are probably a lot of reasons it dropped," he said. These could include fast-rising temperatures, big storms, algal blooms, bacteria and fungi.
Regardless of the cause of the kills, fish have rebounded, according to Kelble.
"The smallmouth bass made the fastest recovery, followed by the sunfish," he said. "The rock bass has still not recovered by all sort of measures, so, we don't know if they ever will."
But, the river is known for its smallmouth bass, Kelble said.
"It was really a big deal when a legendary river lost of most of the fish people knew it for," he said.
Now, the smallmouth bass population "is the best I've seen it since I started guiding" in the late 1990s, Kelble said.
He started counting male nests in 2002, and this year recorded the highest number yet, Kelble said.
"We've got recovery in terms of mature fish," he said. "There's lots of fish in the river again."
Contact staff writer Sally Voth at 540-465-5137 ext. 164, or firstname.lastname@example.org