Fish on the pill: Birth control has negative effect on lake ecosystems

Introducing the birth control pill to Canada’s waterways nearly killed all the freshwater fish, a study found. Researchers introduced small amounts of estrogen to a lake and the fathead minnow nearly became extinct because of its inability to reproduce. The fathead minnow was reduced to one per cent of the population. Led by Karen Kidd of the University of New Brunswick, the study has been ongoing since the late 1990s when U.K. researchers found that introducing estrogen led to a habitat led to male fish beginning to produce eggs.

Right away, the male fish started to respond to the estrogen exposure by producing egg yolk proteins and shortly after that they started to develop eggs.

Karen Kidd

When fathead minnow numbers declined, they had a domino effect on the rest of the ecosystem. The population of lake trout, the main predator of the fathead minnow, also saw a sharp decline in numbers. Insects are the fathead minnow’s main prey and because of the experiment, their numbers grew. Kidd said many areas in Canada have feminized male fish because of the municipal waste water sewage being released into waterways in Saskatchewan and Southern Ontario. After removing the estrogen from the environment, Kidd said the ecosystem quickly recovered.

It’s evidence that removing these chemicals from our effluents will have downstream benefits for the fish population.

Karen Kidd

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