Fish on ‘the pill’

2 min read

Estrogen playing havoc with fish reproduction

Human birth control pills are creating problems in the sex lives of fish.

Reporting results of a seven-year research study at the annual meeting of the American Association for the Advancement of Science in Boston, Karen Kidd, a biology professor at the University of New Brunswick, said
that the synthetic estrogen contained in birth control pills are ruining the fishes’ reproductive system.

Kidd said that even the miniscule amounts of estrogen in municipal wastewater discharges can destroy wild fish populations living downstream. Male fish are producing egg protein normally synthesized by females, and female fish are experiencing delays in sexual maturation.

“We’ve known for some time that estrogen can adversely affect the reproductive health of fish,” Kidd said, “but ours was the first study to show the long-term impact on the sustainability of wild fish populations. Estrogen can wipe out entire populations of small fish — a key food source for larger fish, whose survival could be threatened in the long term.”

The study was conducted by adding small amounts of synthetic estrogen — the type used in birth control pills — to an experimental lake in northwestern Ontario to re-create concentrations of the hormone found in municipal wastewater. After a few years, scientists discovered that chronic exposure to estrogen led to near extinction of fathead minnows and population declines in pearl dace and lake trout.

Researchers also discovered that halting the addition of estrogen normalized conditions. “Once you take the stressor out the system,” Kidd said, “we now have ample evidence that suggests affected fish populations will