Some of the same pollutants that apparently cause male fish in the Potomac and Shenandoah rivers to exhibit female characteristics may also leave them vulnerable to disease and large-scale fish kills, according to a new study. The study points to a possible link between the occurrence of intersex fish and fish kills in the rivers in recent years.

Fish are dying once again in western Virginia. Each spring since 2004, an unknown ailment has sickened and killed fish, mainly in the Shenandoah River but also in the upper James River and other streams. This year, people have been reporting dead and dying fish since mid-May. “This is very mild compared to what we’ve had in previous years,“ said Bill Hayden, a spokesman for the state Department of Environmental Quality.