Magazine article Science News

Fish Free Fall: Hormone Leads to Population Decline

Magazine article Science News

Fish Free Fall: Hormone Leads to Population Decline

Article excerpt

Trace amounts of natural and synthetic estrogens released into the environment by wastewater-treatment plants are known to cause reproductive abnormalities in fish. Researchers have now found an even more dramatic consequence of exposure to the synthetic estrogen used in birth control pills--the near extinction of a fish population.

Women taking birth control pills excrete the synthetic estrogen 17alpha-ethynylestradiol along with natural estrogens. Male fish exposed to estrogens at concentrations of only a few parts per trillion (ppt) can become intersexual, displaying male and female tissues in their gonads (SN: 3/10/07, p. 152).

"A big question remained," says Karen A. Kidd, an ecotoxicologist at the University of New Brunswick in Canada. "Can these males still successfully reproduce, or are fish populations at risk?"

In 1999, Kidd, then at Fisheries and Oceans Canada in Manitoba, and her colleagues began a study at the Experimental Lakes Area, a facility in northwestern Ontario set aside for whole-lake experiments. For 2 years, the team gathered data on species in one study lake and in two reference lakes. During the summers of 2001 through 2003, the researchers added 17alpha-ethynylestradiol to the study lake three times per week, maintaining a concentration of 5 to 6 ppt.

The researchers focused on a common species offish, the fathead minnow, which they collected from the lakes at regular intervals from 1999 through 2005. They examined changes to its reproductive system and monitored its population. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.