85% Of Male Smallmouth Bass Tested At 19 NWR Sites Across NE US Were Intersex - 27% Of Largemouth

Eighty-five percent of male smallmouth bass tested in or nearby 19 National Wildlife Refuges in the U.S. Northeast had signs of female reproductive parts, according to a new federal study. The study, led by the U.S. Geological Survey and U.S. Fish and Wildlife Service, also reported that 27 percent of male largemouth bass in the testing sites were intersex.

The study is the first of its kind in National Wildlife Refuges and adds to growing evidence that endocrine disrupting chemicals are getting into U.S. lakes, rivers, streams and reservoirs—no matter how protected the waters seem. And such contamination seems to affect the reproductive development of some fish species, which can lead to threatened populations.

In the case of the bass in this study, those considered “intersex” either had a protein that is used to make egg yolk typically found in females, or immature egg cells in their testes, said co author Fred Pinkney, a biologist with the U.S. Fisheries and Wildlife. “The eggs were in the very, very early stages,” he added. But any change to fish reproductive systems could possibly threaten overall fish populations and ability to properly reproduce.

During the fall seasons of 2008 to 2010, the researchers tested a total of 118 male smallmouth bass from 12 locations and 85 percent were intersex. They tested an additional 173 male largemouth bass from 27 sampling sites and 27 percent were intersex. It’s not entirely clear why the bass were intersex as the researchers did not test the waters for specific chemicals, said lead author Luke Iwanowicz, a research biologist with the U.S. Geological Survey. However, the suspected culprits of the sex changes are endocrine disrupting compounds.

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http://www.environmentalhealthnews.org/ehs/news/2015/dec/endocrine-disruption-fish-rivers-national-wildlife-refuge