Land use tied to ‘intersex’ smallmouth bass in Bay rivers

"Scientists are still trying to sort out exactly what’s causing sexual abnormalities among smallmouth bass in Chesapeake Bay rivers, but they may be getting closer to figuring out how to reduce them.

Prompted initially by disturbing fish kills in the Potomac and Susquehanna rivers, researchers have been on a quest for nearly 20 years to understand what’s impacting the health of smallmouth bass, a popular freshwater recreational catch throughout the Bay watershed.

While studying die-offs, skin lesions and infections seen in both adult and juvenile bass, scientists began noting “intersex” conditions in Potomac and Susquehanna fish. They’ve found cells in the sex organs of males that are usually found only in females, as well as a protein that’s produced by females to form the yolk around an egg.

Extensive water sampling in Bay rivers has also documented the presence of hormone-disrupting chemicals, which have been linked to the development of intersex traits in bass.

There appears to be no one source of those chemicals in Bay tributaries, but a pair of new research papers suggest that efforts to reduce nutrient and sediment pollution also could help reduce chemical contaminants — and possibly the intersex abnormalities.

After conducting a statistical analysis of water and fish samples collected at multiple sites over several years, a team of U.S. Geological Survey scientists found that land use nearby or upstream was linked to the levels of hormone-disrupting contaminants measured in the water. . ."

Read the full article in the Bay Journal

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