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News Release

Virginia Investigators Prepare for Possible Fish Kills

Richmond, VA — The Department of Environmental Quality and the Department of Game and Inland Fisheries are directing ongoing scientific studies this year in preparation for potential fish kills. Spring 2009 investigations will focus on weekly observations, continued fish health evaluations and in-depth study of possible bacterial causes of the kills.

Since 2004, unexplained fish kills have occurred in the Shenandoah River basin. During 2007 and 2008 similar events took place in the upper James and Cowpasture rivers. No kills have been observed in these rivers in 2009, though April and May are the most likely time for occurrences.

The kills are most severe among smallmouth bass and sunfish, but other types of fish also have been affected. Many of these fish develop skin lesions before dying. Other fish, though, have only fungal infections and many have died without any visible skin lesions. The fish kills have begun in the spring when water temperatures rise above the mid-50s and generally have run from early April until mid-May.

A detailed summary of findings through the 2008 fish kill season is available on the DEQ website at www.deq.virginia.gov. Fish health studies indicate that fish in the affected rivers are subjected to multiple stresses and reveal significant damage to the skin, gills and internal organs. The fish being studied also contain a large number of parasites, but scientists have not been able to connect this condition directly to impairment or fish kills. Biological pathogens, or fish diseases, have received more attention in the past two years and suggest a strong relationship between certain fish bacteria and the springtime fish kills.

Scientists at the U.S. Geological Survey's National Fish Health Lab in Leestown, West Virginia, recently have found a link between Aeromonas salmonicida – a bacterium found in the diseased river fish – and lesions and deaths of experimentally infected laboratory fish.

A significant focus of current investigations is to determine the source of this bacterium and how it is transmitted, and to determine why certain fish appear to be more susceptible than others. Scientists will continue to collect water and fish samples this spring from the Shenandoah and upper James rivers before, during, and after any disease or fish kill outbreaks.

State agencies and their partners have led multiple investigations into these fish kills. In 2005, DEQ and DGIF formed the Shenandoah River Fish Kill Task Force, which includes university and government scientists, environmental groups, fishing guides, other state agencies and volunteer monitors – all with a common goal of finding the cause of the kills. This group has helped identify, conduct and evaluate research into possible causes of the fish kills.

Studies by state and federal scientists and university researchers have centered on water chemistry, fish diseases, and general health of fish and other aquatic life. Water quality studies have not identified any specific chemicals at levels that would be expected to cause the fish kills.

Many of the contaminants found in the rivers have not been studied, and there is no information on the levels at which they could affect aquatic organisms. A second group at USGS is studying whether combinations of contaminants could increase their strength, or whether they cause problems with immune system function that could help explain the fishes' susceptibility to diseases. Scientists also are trying to determine whether there is a correlation among contaminants that could cause the intersex condition that is prevalent among smallmouth bass and sunfish.

Researchers have credited the public with providing significant assistance in the investigation. Many of the outbreaks were reported by fishermen, landowners and other river users. Knowing the timing and location of these events allows scientists to concentrate on the areas where fish kills are active. This information also allows DEQ and DGIF to collect current information on locations and severity of fish kills, and to share this information with the public through periodic updates on the agency websites.

DEQ and DGIF ask the public to continue to report observations of diseased or dead fish. Key information includes types and numbers of fish, location, and any unusual circumstances. Digital photographs are particularly helpful. Anyone with information on dead or dying fish is encouraged to contact the DEQ regional office in Harrisonburg at (540) 574-7800 or toll-free in Virginia at 1-800-592-5482. Information and photos also can be emailed to DEQ at fishreports@deq.virginia.gov.