http://www.theage.com.au/world/pollution-makes-male-fish-more-feminine-than-ever-20090915-fpmj.html
Pollution makes male fish more feminine than ever WASHINGTON September 16, 2009 US SCIENTISTS believe 20 per cent of male black bass in river basins have egg cells growing inside their sexual organs, a sign of how widespread fish feminising has become. The findings come from the US Geological Survey in its first comprehensive examination of intersex fish, a problem linked to women's birth control pills and other hormone treatments seeping into rivers. The agency looked at past data from nine river basins, which cover about two-thirds of the United States - and found that about 6 per cent of the nearly 1500 male fish had a bit of female in them. The study looked at 16 species, with most not affected. The fish most feminised are two of the most sought-after freshwater sport fish: the largemouth and smallmouth, which are part of the black bass family. Those two species also were the most examined, with nearly 500 black bass tallied. ''It's widespread,'' said biologist Jo Ellen Hinck, author of the study published online this month in Aquatic Toxicology. She said 44 per cent of the sites where black bass were tested had at least one male with egg cells growing inside. Studies have linked the problem to endocrine-disrupting hormones, such as estrogen from women's medicines. While the fish can still reproduce, studies have shown they do not reproduce as well, Ms Hinck said. AP
