How has exposure to chemical contaminants in the Chesapeake Bay region led to intersex characteristics in fish?

Fish biologist Vicki Blazer with the U.S. Geological Survey (USGS) brings her team to the Shenandoah River in Front Royal, Va., to collect and study smallmouth bass, a species in which intersex characteristics have been linked to chemical contaminants in the Chesapeake Bay region.

Intersex conditions occur when exposure to chemicals disrupts the hormonal systems of an animal, leading to the presence of both male and female characteristics in an animal that should exhibit the characteristics of just one sex in its lifetime. In the case of smallmouth bass, male intersex fish are found with immature eggs in their testes, which indicates exposure to estrogenic and anti-androgenic chemicals.

“The sources of estrogenic chemicals are most likely complex mixtures from both agricultural sources, such as animal wastes, pesticides and herbicides, and human sources from waste water treatment plant effluent and other sewage discharges,” says Blazer, who first discovered intersex characteristics in fish while studying fish kills in the South Branch of the Potomac River and the Shenandoah River.

  • Produced by Will Parson
  • Music/Audio: “A Moment of Jazz” by Ancelin

Comments (4)

Lawrence Olsavsky
January 05, 2020

The same thing is happening to smallmouth bass in the Susquehanna River (a major polluter of the Chesapeake Bay) in Pennsylvania on a large scale.  The Pennsylvania state legislature has refused the Pennsylvania Fish & Boat Commission’s recommendation to declare the Susquehanna River an “Impaired Waterway,” the result being less required pollution abatement.

January 08, 2019

This is scary and great info.

November 19, 2018

This is very interesting data, and if some of the males can give birth, would the babies be the same as them or different, and would they help boom the fish population. Do they have oil in their bodies?

Yana ravskanbeknova garasimova- Shea Radman
October 04, 2018

This is great info. Thanks for sharing.

This article is really intresting and a little scary.


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