Fish kill hits fewer in James River this year

The springtime phenomenon causing fish to develop lesions or die from illness may have been tempered this year in the upper James River by the cold, wet spring.

The problem, which was first seen in the James River in 2007, was only about half as bad as in years past and didn’t travel downstream past Buchanan, said Scott Smith, a Department of Game and Inland Fisheries biologist working primarily on the upper James.

However, Smith added, it was tough to tell for sure because during the weeks that traditionally had the worst effects, the river was so high and muddy that anglers, who provide many reports of sick or dead fish, weren’t out fishing.

Smith and other DGIF biologists did survey the river and found some sick fish up around the Buchanan area, but found none near Big Island or Lynchburg. “Whatever issues we did have seem to be confined to really far up river,” Smith said.

In previous years, 30 to 40 percent of the fish were found with open sores or dead, but this year that number, Smith estimates, is between 10 to 20 percent. Additionally, most of the lesions were smaller than in previous years.

In 2007, the kill was reported as far as just downstream from Lynchburg. Fish were pulled out of the river in front of the fountain bearing large open sores and some had fins almost completely rotted away, exposing bare bone.

Last year, officials attributed the lack of illness near Lynchburg to the lack of rainfall. But that theory didn’t hold this year.

The pattern tends to follow the natural spawn cycle, Smith said. Fish start appearing dead or with lesions in the mid spring, with the highest percentage seen around May. As the water warms above 75 to 80 degrees, the problem disappears — usually by late June.

Years with wetter springs usually had worse fish kills than dryer springs, prompting researchers to assume some sort of connection with runoff.

On the Shenandoah, where the problem has been seen since 2004, conditions this spring allowed for better fishing than on the James. DGIF fish biologist Steve Reeser said the kill there was comparable to ones in past years, but said the good news is it wasn’t worse.

Years with colder and wetter springs, such as this one, usually produce the worst impacts, he said.

“I would have expected this year to have bad kills, perhaps the worst year ever,” said Reeser, who works primarily on the Shenandoah. “Every time we have a path and think we have something figured out, it didn’t hold true and that’s what’s made figuring this out so frustrating.”

Exactly what is causing the problem is still a mystery, but researchers are zeroing in on two theories.

One theory involves a strain of bacteria known to cause disease in fish in a multitude of environments.

The bacteria, mostly known to cause disease in cold-water rivers that sustain trout and salmon, has been found in all streams where the fish kills and illnesses have occurred, Reeser said. It’s been seen in the upper James, Cowpasture, Lower Jackson and throughout the upper Shenandoah. It has not been found in the Maury River, where the fish problem has not been reported.

“To date, it’s the one commonality that links all of these places we’ve had fish kills,” Reeser said. “(The bacteria) is not some mutated strain or some rare thing. It has been documented around the world in multiple species (of fish).”

However, there is curiosity in finding the bacteria causing disease or death in an area where summer stream temperatures are too warm for the bacteria to survive, Reeser said. There are theories that small amounts of the bacteria survive the summer near where cold-water springs enter the rivers or in the very upper reaches of mountain streams that stay below 75 degrees year round, but nothing has been proven. However, another question is “how does it get so widely distributed in the fish population over hundreds of miles of river” and in unconnected watersheds, Reeser said.

Another theory is whether some kind of contaminant is entering the river and stressing the fish and lowering their immunity, so it’s harder for the fish to fight off the illness.

“One of the things we don’t know is that we’re seeing this one bacteria on the fish, but is it just something that’s a symptom of water quality or other problems in the river,” Smith said, “or is it that the fish are perfectly fine other than this bacteria in the river?”

DGIF fish biologists are working with the Department of Environmental Quality, the U.S. Fish and Wildlife Service and the U.S. Geological Survey to get a better grasp on the problem.

One study planned for this summer is to look at why the illnesses occur primarily in adults more so than juveniles, Reeser said. Another is trying to determine whether fish are building up a natural resistance or immunity to the bacteria. “It appears as though it may be these kills aren’t getting worse and in some cases they’re getting better,” Reeser said. “Fish (may be) building up antibodies or resistance, but we need to prove that.”

Angler reports from the Shenandoah River are telling Reeser that the kills aren’t significantly reducing the fish population and may just be weeding out weaker fish. “We know we’re losing some larger adult fish, but on a population level, there haven’t been any observable impacts,” he said. Despite the problem, Reeser said fish in the river have produced strong spawning, which has helped keep the populations up over time.

However, “the jury is still out on the James,” he said. “I think we kind of dodged a bullet this year. What’s going to happen in 2010, I have no idea.”