Photo by Ron Sinfelt

In any given fishing forecast, inevitably, there is both good and bad news. Unfortunately, some major news on the Virginia smallmouth bass front last year was very much of the negative kind -- and it was news that will have repercussions this year and likely in the years to come. Once again, a fish kill rocked the Shenandoah and Potomac system -- likely killing over 80 percent of the adult smallmouth bass on the South Fork of the Shenandoah.

"The fish kill on the South Fork of the Shenandoah appears to be following the same pattern as the one we had on the North Fork of the Shenandoah in 2004 and that West Virginia experienced on the South Branch of the Potomac in 2002," said Don Kain, water monitoring and compliance manager for the Department of Environmental Quality (DEQ) office in Harrisburg. "In each case, low numbers of dead fish began appearing around early April. The situation continued for four to six weeks. Nearly all the dead fish had skin lesions and sores."

Many live fish have been observed with these same lesions, greater than 50 percent of the smallmouth bass and sunfish in some cases. Other species have been affected only in very low numbers, if at all.

"Even though only low numbers of dead fish have been seen at any place and at one point in time, the overall effect of this situation has been very significant," Kain said. "While we can't provide exact numbers, we probably lost over half of the adult smallmouth bass and sunfish during each episode. The fish kill seemed to end by mid-May on the North Fork in 2004. The kill in the South Fork seems to have persisted longer, possibly because of the extended cool spring weather."

Kain noted that these are not classic fish kills like those that occur from a spill, chemical release, or even low dissolved oxygen. Most fish kills from pollution events occur quickly and in a well-defined area. With a typical fish kill, there is generally an upstream zone with no problems, then a severe impact zone at the point of pollution, followed by a gradual recovery downstream. However, these fish kills have been river-wide. In the North Fork, the kill began upstream of Broadway and extended to beyond Strasburg. In the South Fork, there have been reports of dead fish from the head of the river at Port Republic to Front Royal and beyond.

Kain stated that the DEQ and Virginia Department of Game and Inland Fisheries (DGIF) have responded to every report of dead fish, many times visiting the site and other locations upstream and downstream. They have periodically sampled fish to determine numbers and density of live fish and the percentage with lesions. A review of the ongoing water quality data (both current and historic) has taken place and nothing has been found that suggests a clear cause for these events.

The DEQ has also tried to determine what the kills on the South Branch and North and South Forks have in common.

"We have looked for common threads in these three fish kills," Kain said. "All three watersheds are highly agricultural, with poultry predominating. These rivers have relatively high levels of nutrients. Our water quality analyses do not show any recent trends that would correlate with the fish kills, however. In our ongoing North Fork Shenandoah River water quality study, we sample monthly at eight or nine sites. We also sample weekly at two of these sites in hopes of identifying any short-term variability that might not be detected in our monthly sampling."

Interestingly, Kain reported that the benthic data from the North Fork looked quite good through the fish kill and continues to do so. There were very strong insect hatches during the spring of 2005 on both the North and South Forks. Using the insects as water quality indicators does not suggest that the cause of the kill is water quality, Kain added.