Boy Fish Are Girl Fish?

With scores of television programs and every conceivable lure and fish-finding device designed to help enthusiasts deceive their scaly nemeses, black bass sport fishing has become an American industry unto itself. As Carl Hiaasen wrote in his sport-fishing spoof, “Double Whammy:” “Bass fishing is an immensely profitable business, the fastest-growing outdoor sport in America. Of course, the tournament circuit is in no way a sport, it’s a cutthroat enterprise.”

But it may surprise a few good old boys that when they hook one of those surly lunkers, that gender-bending boy fish just might have ovaries tucked behind his nads. According to a new USGS study, scientists have discovered female eggs in the genitalia of a third of all American male smallmouth bass and a fifth of their largemouth cousins. Meanwhile, female bass will occasionally show signs of male testes in their reproductive organs.

Back in 2003, scientists began putting the tissues of smallmouth bass under the microscope. When probing through samples, they were surprised to find oocytes – the precursors of female eggs – in male testicles. Since then, more intensive studies of intersex fish have been undertaken.

A USGS press release about a similar 2008 study stated that the prevalence of intersex fish “has been associated with known or suspected endocrine disrupting compounds in wastewater effluent, which are not removed during standard sewage treatment, and in runoff from farming operations. These compounds can include estrogen from birth control pills and hormone replacements, pesticides and fertilizers used on crops, and hormones from livestock operations.”

With a documented shrinking sperm count and earlier occurrence of adolescence, recent studies are finding similar anomalies in America’s human population.

Will once-embarrassed men be joining their wives on those journeys through the feminine hygiene aisle in some future decade? Some might call it evolution, but only time will tell.

Photos, top: courtesy Marshall Astro via Flicker. Bottom: USGS researcher examining bass for abnormalities in Alabama, by Jo Ellen Hinck, courtesy U.S. Geological Survey.