Though a September 7 Associated Press article noted an unusually high percentage of inter-sex fish in the Potomac and Shenandoah rivers, local experts say they’d need more research to determine if male fish growing eggs are cause for alarm in the increasingly developed and polluted Shenandoah watershed.
“We’re not convinced,” Julia Dixon, spokesperson for the Virginia Department of Game and Inland Fisheries (DGIF) says. “We have not ruled out that [the inter-sex fish] could be naturally occurring.”
Scientists aren’t sure because the control study, done in a supposedly cleaner river with no chemical runoff, showed similar numbers of inter-sex small-mouth bass. Scientists say bass are susceptible to developing inter-sex traits. “It’s not something that is known to occur just here in this area,” Steve Reeser, a fish biologist with the DGIF and the Shenandoah Fish Kill Task Force says. “It has been found or documented throughout the world and in other places in the United States. The one question that comes to mind—what are the natural background levels of this?”
But the inter-sex fish are part of a larger trend of unhealthy fish in local waters. Scientists on the Shenandoah Fish Kill Task Force discovered inter-sex fish when studying the health of other fish that have been dying off in large numbers since 2004. Fish kills are associated with pollution. “What’s causing this is what they call hormone-disrupting compounds, or endocrine-disrupting compounds. Some of them have been known to induce inter-sex, some are suspects,” Reeser says.
Waste water treatment plants currently don’t remove the compounds, which are in everything from pharmaceuticals to herbicides to feed additives and hormones for livestock. The Shenandoah watershed includes the Shenandoah Valley, with agricultural areas and growing residential and commercial impacts. The EPA doesn’t regulate the amounts of endocrine-disrupting compounds left in water.
Though it would seem that where there is pollution, there are inter-sex fish, Reese says his team isn’t ready to draw that conclusion. “We’ve had pretty drastic fish kills, and I think that just shows that we’ve got a whole river system that’s stressed to the point where it doesn’t take much to push those fish over the edge…It’s just been really perplexing.”
