Potomac male smallmouth bass have eggs
February 2, 2007
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Male smallmouth bass do not normally create eggs. The United States Geological Study recently found that 80-100 percent of male Bass in the Potomac watershed create eggs or have other intersexed characteristics.In 2003, this percentage was only 25-50 percent. The male smallmouth bass are becoming intersexed. An intersexed fish has the genitals of one sex and attributes of another sex.
USGS and the Fish and Wildlife Service have found the cause to be endocrine disruptors. “Endocrine disruptors are a class of pollutants that are hormonally active, can compete or augment hormonal activity . minute concentrations can cause problems.” said geology professor Angie Moore.
Intersexing of animals caused by endocrine disruptors was first noticed with the Lake Apopka alligators. Lake Apopka was a Superfund sight after being contaminated by high levels of DDT and other chemicals. After cleanup, all but trace amounts of those chemicals had been removed. Those trace amounts of chemicals caused changes in the developmental growth of alligators in the region.
The cause of change in the Apopka alligators was readily apparent. Finding which chemical is causing the intersexing of the Potomac bass is more difficult. In October, USGS released a list of 75 possible endocrine disruptors affecting the Smallmouth Bass.
The list includes pharmaceuticals, fertilizers, steroids, industrial chemicals, plastics and insecticides including DDT. It could be individual chemicals causing problems, or it could be mixtures of these chemicals. “The amounts can be detected, but it’s very small, how much and when the fish have to be exposed is unknown” said biology professor Chuck Smith.
All of these chemicals are found at high enough levels in The Potomac and in other rivers worldwide to conceivably have an effect. Many of the chemicals are not released into the water through carelessness. Pharmaceuticals, both those given to humans and livestock, commonly pass through the body and eventually into the water.
The level of chemicals in the Potomac is considered safe for humans, but many of the chemicals have not been tested on humans, and their long term effects are unknown.
The National Children’s Study believes that children may be affected. “It is hypothesized that in utero and early childhood exposures to EDs may be responsible, at least in part, for decreases in semen quality; increasing incidence of congenital malfunctions of the reproductive organs . increase of testicular cancer; and acceleration of onset of puberty in females.”
Further tests are being done; both to identify which chemicals are causing the changes in male smallmouth bass and what possible effects they could have on humans. Most of the endocrine disruptors being studied mimic Estrogen. Extensive study on the effects of mimicked Testosterone or Progesterone, or the intersexing of female fish, has not been done.