Title - Schoolyard Habitat

Male fish, with immature female eggs.

Yes…that’s right.

Last year, researchers with the U.S. Geological Survey found male fish with immature female eggs, right here in the Potomac River .

What’s in the water?

These fish, called intersex fish, may occur as a result of chemicals in the water that mimic or antagonize hormone levels. Known as endocrine disruptors, these substances can interfere with an organism’s normal hormone functions. Endocrine disruption has the potential to compromise proper development, leading to reproductive, behavioral, immune system and neurological problems, as well as the development of cancer.

Endocrine disruptor compounds can enter a waterway from sewage outfalls, industrial and municipal pollution, and agricultural runoff. Endocrine disruptors may be entering the Potomac River watershed through synthetic estrogen, such as those in birth control pills and hormone replacement therapy, or from those hormones associated with livestock operations.

Current Research

Federal agencies are now investigating the effects of organic pollutants and endocrine disrupters on hormone activity in fish in the Potomac River watershed. The U.S. Fish & Wildlife Service and our partners at U.S. Geological Survey, Maryland Department of Natural Resources and D.C. Department of Health, collected water samples and fish at various sites in the Potomac River watershed.

Smallmouth and largemouth bass were selected as the target fish because they are sensitive to pollution and frequently display the physical symptoms of intersex. Biologists measured concentrations of endocrine disruptor chemicals in the water and sampled bass from the Monocacy River and Conococheague Creek in Washington County , Maryland , and the Potomac River in Washington , D.C.

Preliminary results are not yet complete, but researchers will continue to examine bass sex abnormalities in a laboratory while they await the results.

For more information, please contact Chris Guy at (410)573-4529.


Students find joy in environmental stewardship
Scientists with the U.S. Geological Survey process small mouth bass to determine if endocrine disrupters have affected sex tissue

Completed Schoolyard Habitat project
U.S. Fish & Wildlife Service biologist Pete McGowan collects water samples in the Potomac River watershed to measure organic pollutants and endocrine disrupters in the water

Getting down and dirty
Volunteers and staff with state and federal government agencies electro-shock and catch fish in the Potomac River watershed.

USFWS photos

Back to On the Wild Side!

Back to CBFO home page