Researchers are finding more intersex fish and in more widespread parts of the Chesapeake Bay watershed, says the Washington Post. “In the latest study, smallmouth bass and white sucker fish captured at 16 sites in the Delaware, Ohio and Susquehanna rivers in Pennsylvania had crossed over into a category called intersex, an organism with two genders.” Intersex fish also have been found in the Columbia, Colorado and Mississippi river basins.
“Scientists have yet to identify a single chemical responsible for causing male fish to become part female,” says the Post. One researcher believes a mixture of chemicals may be responsible. Says the Post, “In urban areas, estrogen products are often flushed down drains, contaminating water. In rural areas, natural animal hormones, much of it estrogen, is excreted in manure, which is spread on fields and washed into water by rain.”
The U.S. Geologic Service site for Chesapeake Bay information, including information about intersex fish, is available here.