Male smallmouth bass in Pennsylvania’s Susquehanna River are slowly transforming into mutant fish potentially due to sewage and farm runoff into rivers.
Scientists have recently began to notice that some male smallmouth bass in the Susquehanna River are beginning to spout female egg cells in their testes. Many of these fish also have lesions, open sores, and black splotches on their skin.
A recently released United States Geological Survey stated that these mutant fish appear in water with high levels of estrogenic compounds, natural and artificial hormones in animal manure, and untreated sewage.
John A. Arway, the executive director of the Pennsylvania Fish and Boat Commission, says:
We’ve been trying to explain that the river is sick. And the problem is not because of what we’re doing for the water. It’s because of what we’re doing for the land.
Estrogen is naturally occurring in all animal waste and estrogen levels are even higher in manure from milk or egg-producing females. Rivers near farmland with large numbers of domesticated animals often have elevated levels of estrogen due to agricultural runoff.
Smallmouth bass are a sensitive species whose health reflects the state of the river. The areas of the state with the highest levels of intersex fish are in the watersheds that are the most heavily utilized for farmland. A 2013 study found that nearly half of the fish in the Susquehanna river displayed some sort of disease or mutation.
Though the Environmental Protection Agency has begun to take actions aimed at improving the water quality of the Susquehanna River by raising water treatment standards and attempting to limit agricultural runoff into the river, critics say this is not enough.
John Arway, of the Pennsylvania Fish and Boat Commission, suggested state and federal leaders should write a cleanup plan specifically for the Susquehanna River that specifically aims to combat the problem of intersex smallmouth bass.