Sex-change fish and factory chickens: Update

Lakes in the chicken-raising country south of Philadelphia are producing mutant largemouth bass, with male sex organs - and female eggs. Lots more "intersex" fish have also turned up in the Susquehanna, Chesapeake and Potomac.

"We find it in every lake that we look," Daniel J. Fisher, senior research scientist at the University of Maryland's Wye Research and Education Center in Queenstown, MD, told the Baltimore Sun here. "Intersex" fish at lakes in central Delaware and Maryland's Eastern Shore range "from 33 percent of fish we sampled to 100 percent."

"In separate laboratory tests, the UM researchers said, they found the sex and development of certain juvenile fish were affected when exposed to water contaminated with poultry waste," says the Sun.

"Fathead minnows displayed changes in their gonads, or sex organs, and larval minnows experienced "pronounced feminization." By contrast, mossbunkers put through similar tests didn't change sex, but they still showed a reaction to elevated female hormones, if I'm reading the summary of their original report correctly.

Fisher, Lance T. Yonkos, and their colleagues reported their findings in October's Environmental Toxicology and Chemistry journal.  More from the US Fish and Wildlife Service here.

UPDATE: Don't blame hormones or runoff from the Peninsula's millions of avian residents for the she-male fish, says industry lobby Delmarva Poultry Council 's Bill Satterfield: It's still "speculation at best, and unproven" to associate the "feminization" of male fish to runoff from hormone-treated poultry farms.

"At best, this report is a weak link between fish estrogenicity findings and poultry-associated litter contaminants," Satterfield says. The cause of the egg-bearing male fish "could have been crop chemicals, common household products... or other pollutants, and not poultry manure; we simply don't know... Keeping little fish in tanks in continuous, long-term exposure" to poultry runoff "is not representative of what happens in nature."