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Study: Some rivers have majority of male-female fish; chemicals suspected
BALTIMORE - A form of intersex fish, which have both male and female traits, were found more often by researchers in areas with more farming and population density, according to a new study by the U.S. Geological Survey.
So-called intersex fish have been found in U.S. waters over the past decade, including the southern Great Lakes, the Potomac River watershed, which includes the Eastern Panhandle in West Virginia, and the Southern California coast. The cause isn't fully understood, but researchers suspect wastewater and farm runoff polluted with chemicals that stimulate estrogen production are at fault.
U.S. Geological Survey researchers found the frequency of male smallmouth bass with immature female eggs in their testes was highest where farming is most intense and where human population density is highest. The study also found the prevalence of the form of intersex, known as testicular oocytes, was greatest just before and during the spring spawning season.
The results were published in the current edition of the Journal of Aquatic Animal Health.
USGS scientist Vicki Blazer, who led the study, said smallmouth bass were collected from the Shenandoah River, the South Branch of the Potomac, and the Potomac River basin
http://www.msnbc.msn.com/id/23067257/
BALTIMORE - A form of intersex fish, which have both male and female traits, were found more often by researchers in areas with more farming and population density, according to a new study by the U.S. Geological Survey.
So-called intersex fish have been found in U.S. waters over the past decade, including the southern Great Lakes, the Potomac River watershed, which includes the Eastern Panhandle in West Virginia, and the Southern California coast. The cause isn't fully understood, but researchers suspect wastewater and farm runoff polluted with chemicals that stimulate estrogen production are at fault.
U.S. Geological Survey researchers found the frequency of male smallmouth bass with immature female eggs in their testes was highest where farming is most intense and where human population density is highest. The study also found the prevalence of the form of intersex, known as testicular oocytes, was greatest just before and during the spring spawning season.
The results were published in the current edition of the Journal of Aquatic Animal Health.
USGS scientist Vicki Blazer, who led the study, said smallmouth bass were collected from the Shenandoah River, the South Branch of the Potomac, and the Potomac River basin
http://www.msnbc.msn.com/id/23067257/
