High Levels of Contaminants Creating Intersex Fish

(Photo: C. Yamashita/Pennsylvania Fish and Boat Commision)

Biological studies, conducted by the U.S. Geological Survey (USGS) since 2003, have found small- and large- mouth bass with immature eggs within various sections of the Potomac River.

These studies have found abnormal concentrations of compounds found in herbicides and veterinary medicines (most likely due to runoff from farms and sewage system overflows) near smallmouth bass nesting sites in the Potomac. Compounds such as these are considered endocrine-disrupting and can alter physiological processes in the bass that regulate hormones and the reproductive system. So far there has not been a consensus on a single chemical that is responsible for causing these male fish to partly develop female reproductive functionality.

Estrogen products are washed down drains contaminating water in urban areas, while natural animal hormones (highly concentrated in estrogen) are excreted in manure and washed into the rivers during storms. Findings from the Environmental Monitoring and Assessment, and a report from the Environmental Integrity Project agree that there is far more nitrogen and phosphorus pollution in the Chesapeake Bay than the states and EPA are leading residents of the area to believe. A major concern is the probability that these contaminants that lead to intersex fish are also affecting people in ways we may have yet to recognize and understand.

Read the full article: As More Male Bass Switch Sex, A Strange Fish Story Expands