Male fish becoming females because of family planning drugs flushed down household drains

Naturally, a fish is either male or female. When the female fish lays eggs, the male fish fertilises them by releasing sperm on the eggs.

However, according to a study, a fifth of male fish are now said to be transgender because of chemicals from the contraceptive pills being flushed down household drains.

Being transgender denotes a person whose sense of personal identity and gender does not correspond with the sex they are born with. In the case of the fish, a fish that was hatched as a male now shows more characteristics of female fish, and vice versa.

The researchers note that male river fish are displaying traits peculiar to feminine fish and are even producing eggs, the study found.

Some now have reduced sperm quality and display less aggressive and competitive behaviour, which makes them less likely to breed successfully, researchers say.

They note that the chemicals causing these effects include ingredients in the contraceptive pill, by-products of cleaning agents, plastics and cosmetics, according to the findings.

Professor Charles Tyler, of the University of Exeter, explains that the offspring of such “transgender” or “intersex” fish can also be more sensitive to the effects of these chemicals in subsequent exposures.

Tyler said: “We are showing that some of these chemicals can have much wider health effects on fish than we expected.

“Using specially created transgenic fish that allow us to see responses to these chemicals in the bodies of fish in real time, for example, we have shown that oestrogens found in some plastics affect the valves in the heart.”

Tests showed 20 per cent of male freshwater fish, such as roach, at 50 sites had feminine characteristics.

More than 200 chemicals from sewage plants have been identified with oestrogen-like effects and drugs such as antidepressants are also altering fish’s natural behaviour, his study found.

“Other research has shown that many other chemicals that are discharged through sewage treatment works can affect fish, including antidepressant drugs that reduce the natural shyness of some fish species, including the way they react to predators,” Tyler said.

Professor Tyler presented his findings in the opening lecture of the 50th Anniversary Symposium of the Fisheries Society in the British Isles at Exeter University, holding from July 3 to 7.

Dr. Steve Simpson, who organised the symposium, said the week of talks would give “fish biologists from around the world a chance to exchange ideas and discuss how to protect dwindling fish populations in rapidly changing seas and rivers, before it is too late.”

Other research being discussed at the event includes how the destruction of coral reefs and their distinctive sounds means fish are getting lost in the water, how fish are shrinking because of climate change and how power cables can disrupt how fish find sexual partners.

Source: Punchng
Male fish becoming females because of family planning drugs flushed down household drains

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