Male Fish Turning Female Due to Pollution

Canadian researchers who studied fish in Alberta’s Red Deer and Oldman rivers found a peculiar effect of pollution on a native minnow called the longnosed dace. Males they sampled contained elevated levels of a protein marker normally only found in females. Also, “…up to 44 per cent of the male fish had eggs in their testes.” In normal circumstances only females produce eggs. One of the study’s co-authors Lee Jackson said, “… it tells us the fish are exposed to estrogen or something that looks like estrogen to the fish.” Mr. Jackson is the executive director of a research facility which creates new approaches for treating wastewater.

The researchers also analyzed water samples from the river locations where they examined the minnows. They found synthetic estrogens from birth control pills and hormone therapy drugs in the river water. In addition, synthetic and natural hormones were found in the water, which could be from agricultural run-off and cattle ranching. The researchers took samples at 15 locations along 600 kilometers of river. Their study indicated the disruptive chemicals could be present in a span covering the entire 600 kilometers of river water.

The ratio of females to male minnows in the rivers could also be shifting much toward greater numbers of females. If this ratio remains unbalanced, fewer numbers of new fish will be born, as there will not be enough males to fertilize fish eggs. With so many chemicals in the minnow’s habitat, it could be difficult to pinpoint exactly which chemical is causing the gender bending, or if it is a combination of all of them.

The effect, called fish feminization, is not unique to the Alberta minnows. In fact, it has been documented in Europe, and the United States as well.

The Canadian researchers are going to continue their studies to deepen their knowledge of what is taking place in the Red Deer and Oldmans rivers, with the ultimate goal of perhaps influencing policy decisions that can stop the problem.

Longnosed dace eat aquatic insects and are prey for larger fish, so they are an important part of the food chain.

Recently in Colorado a similar situation was partly remedied by upgrading a wastewater treatment plant. Fish exposed to the water previously had been feminized in about seven days, but after the treatment plant’s upgrade, it took more than 28 days.

One of the researchers involved in the Colorado study said that it is not only about changing wasterwater technology, it is also about modifying consumer behavior, “We excrete natural and synthetic estrogens and use shampoos, detergents and cosmetics containing a variety of hormone disrupters that wind up in waterways. All of these different chemicals we are putting into the environment have the potential to alter the biology of animals and to affect ecosystems.”

He said consumers can refuse to buy milk made with growth hormones and antibacterial soaps. Also they can reduce their use of shampoos and detergents.

Image Credit: Public Domain


Julie Botsch
Julie Botsch3 years ago

Thank you for the article.

Rhonda B.
Rhonda Bruce7 years ago

"a similar situation was partly remedied by upgrading a wastewater treatment plant. Fish exposed to the water previously had been feminized in about seven days, but after the treatment plant’s upgrade, it took more than 28 days."

Philippa P.
Philippa P7 years ago

Pollution will produce some incredibly strange things.

Petra Luna
Petra Luna7 years ago

Stop flushing down meds. Hormone and other pills don't belong going into the water shelf.

Laurie H.
Laurie H7 years ago

We have to inquire as much as possible about everything we consume these days and take nothing for granted. Thanks Jake!~

Melinda M.
Past Member 7 years ago

It makes you wonder what those drugs are doing for us if we are peeing them out. This polution needs to stop.

Anja N.
Justin R7 years ago

Much is our fault for believing all the BS advertisers tell us.
We should question more and accept less.

Lika S.
Lika P7 years ago

Thank you for the article.

Past Member
Past Member 7 years ago

plastic toxins produce residue that mimics estrogen and other harmful chemicals which then change fish genders...what do u think this is doing to humans?....

Gita Sasi Dharan
Gita Sasi Dharan7 years ago

Polluting pure water, clean air and fresh food has become the order of the day. If only, those who are careless and irresponsible and cause this destruction of the planet should reap the rewards and turn in to females and lead the rest of their lives , like half male and half female and should face a wretched, lonely life.