Ever since the discovery of gender-bending fish in the Potomac River,
scientists have wondered what could be changing the sex of large numbers of fish
in the waterway outside Washington, D.C.
They may not have to wonder much longer.
A recent U.S. government study has found large quantities of chemicals in the
river and its tributaries?pollutants that are known to cause sex change in
These chemicals, from both residential and industrial sources, may be linked to
the unnatural fish, says the U.S. Geological Survey (USGS) report, which was
released late last month.
Males With Eggs
The discovery of the abnormal fish "was largely accidental," said Douglas
Chambers, a USGS scientist who led the study.
"In 2002 we were looking at stream-water chemistry to understand the large fish
die-offs at these sites. It was then that we found smallmouth bass with intersex,
a condition where male fish develop premature egg cells."