After testing 20 streams and rivers throughout North Carolina, researchers have reported a disturbing trend of male fish growing eggs in their testicles.

Black bass and sunfish have shown the highest rate of intersex characteristics. Of the 81 black bass tested by researchers, 60 percent were found to have eggs in their testicles; of the 815 sunfish tested, 10 percent were found to have eggs in their testicles.

A black bass. (Photo Credit: Béotien lambda / WikiMedia Commons)

A black bass. (Photo Credit: Béotien lambda / WikiMedia Commons)

The investigation of intersex fish in the state’s waterways is part of a study that was partly inspired by a US Geological Survey study in 2009. Then, intersex male fish were discovered in nine US river basins, with the highest percentage (80 percent) identified in the Pee Dee River basin that spans North and South Carolina.

The prevalence of intersex fish in North Carolina may be due to endocrine disrupting compounds that have contaminated the water. These compounds can include hormones, industrial chemicals and pesticides, all of which can influence the biology of marine creatures with the same effect as estrogen hormones. As Environmental Health News reports, these chemicals enter the state’s waterways via “permitted effluents, stormwater and agricultural runoff, and wastewater treatment plants, where excreted birth control and natural estrogens pass through relatively un-altered.”

During this latest study, as yet unpublished, researchers detected 43 percent of the 135 contaminants they’ve been hunting for.

Ph.D. student at North Carolina University Crystal Lee Pow is leading the work and told EHN that some of the contaminants may be sourced to livestock operations in the state. “There are also a lot of concentrated animal feeding operations in North Carolina,” she said. Pig waste, which is stored in toxic waste lagoons, “is chock-full of estrogens,” she added.

Vicki Blazer, a U.S. Geological Survey fish biologist who was not involved in the study, has said that bass seem more prone to intersex mutation than other fish. The reason may be due to their particular biology or the timing/location of where they spawn.

The prevalence of intersex fish in these waterways could have disastrous impacts on the marine ecology, as males build and guard spawning nests for their young. If their behavior becomes altered by endocrine disrupting compounds, it may endanger the fish population.

Where riparian contamination is concerned, North Carolina is not an isolated case. Last year, the Virginia Department of Environmental Quality reported that more than 16,000 miles of the state’s rivers are polluted with fecal bacteria, mercury and PCBs.

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