Tag: gender

Fish Swimming in Hormones

  • Fish are putting up less of a fight on the line when caught - making them less fun for sport fishing. (Photo courtesy of the National Park Service)

A recent report from the US Geological
Survey confirms past findings that fish
are in trouble. Tanya Ott
reports the hormone estrogen is getting
into rivers and lakes and could reduce
fish populations:

Transcript

A recent report from the US Geological
Survey confirms past findings that fish
are in trouble. Tanya Ott
reports the hormone estrogen is getting
into rivers and lakes and could reduce
fish populations:

The fish have been turning up with lesions and intersexed –
meaning they have both male and female characteristics.

Rob Angus is a fish biologist at the University of Alabama at Birmingham.
He wasn’t involved in the USGS research, but has studied the problem for
more than a decade. The culprit?

“You’re a female? You excrete estrogens. Both natural estrogens,
the estrogenst that are in birth control pills, females that are
on estrogen replacement therapy. All of those end up in the
wastewater stream.”

Wastewater treatment plants clean up about 90 percent of the
estrogen, but the remaining ten percent is a problem.

Fish don’t reproduce as easily. And, for sport fishers, the fish
aren’t as much fun to catch. They don’t put up as much of a fight
on the line. That could affect the 75 billion dollars sport fishing industry.

For The Environment Report, I’m Tanya Ott.

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Water Pollution Feminizing Fish

  • Chemicals in the water are mixing up fish's gender (Photo courtesy of US Fish and Wildlife Service)

Scientists already know estrogen from things like ‘The Pill’ is getting into the water and causing reproductive problems for fish. Male fish are picking up female attributes. Some males are even growing eggs. Now a study finds there are other chemicals getting into water that might be messing with fish gender even more. Rebecca Williams reports:

Transcript

Scientists already know estrogen from things like ‘The Pill’ is getting into the water and causing reproductive problems for fish. Male fish are picking up female attributes. Some males are even growing eggs. Now a study finds there are other chemicals getting into water that might be messing with fish gender even more. Rebecca Williams reports:

This study’s found a group of chemicals that block the male hormone testosterone is getting into rivers.

Charles Tyler is the lead author of the paper in the journal Environmental Health Perspectives.

He says they don’t know exactly where these chemicals are coming from, but some medicines and pesticides can block testosterone. So, add that to the estrogen…

“And so it’s very likely they’re going to have interactive and additive effects, if you like, to induce a double whammy on the poor fish.”

Tyler says they don’t know if what’s happening in fish is also happening in people.

Human male fertility has been declining. But there might be other chemicals contributing to the problem.

And besides, there’s a difference. Fish can’t get away from these testosterone blocking chemicals or the estrogen in the water – they live and swim in them. So Tyler says they’re getting a much higher dose.

For The Environment Report, I’m Rebecca Williams.

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Farm Chemicals Mixing Up Toads’ Sex

  • A study finds farm fields may not be the best environment for toads (Photo courtesy of the US Fish and Wildlife Service)

A new study connects chemicals from
farm fields to mutant toads. Rebecca Williams
has more:

Transcript

A new study connects chemicals from
farm fields to mutant toads. Rebecca Williams
has more:

This study looked at toads that live near farm fields and toads that live
near other kinds of not-so-pristine areas like parking lots.

The researchers found in areas with more agriculture – and more farm
chemicals – there were more mutant toads. They found male toads with
both male and female parts. Not ideal when it comes to mating.

Louis Guillette is an author of the study, in the journal Environmental
Health Perspectives.

“It may in fact be a mixture of chemicals along with who knows what
other variables, nutrition, other stressors, that may be leading to these
problems.”

He says next they’ll try to figure out what chemicals are at play, and
exactly how the toads are being turned into hermaphrodites.

For The Environment Report, I’m Rebecca Williams.

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Study: Dead Zones Cause Sex Changes in Fish

New research indicates that polluted run-off might be causing reproduction problems for ocean fish by making more males than females. The GLRC’s Lester Graham reports:

Transcript

New research indicates that polluted run-off might be causing
reproduction problems for ocean fish by making more males than
females. The GLRC’s Lester Graham reports:


Rivers dump much of the pollution and agricultural runoff they carry into
the oceans. That often causes a dead zone… an area where the oxygen is
depleted. New research being published in the journal, Environmental
Science & Technology, indicates low levels of oxygen can cause sex
changes in embryonic fish. That’s leading to an overabundance of
males.


The lead researcher, Rudolf Wu at the City University of Hong Kong
finds since there are a lot more males… it’s less likely the males fish will
find females to reproduce. That means there might not be enough new
fish to maintain sustainable populations.


Some dead zones develop naturally, but scientific evidence suggests that
often dead zones are caused by fertilizers used on farmland crops
running off into rivers and finally into the oceans.


For the GLRC, this is Lester Graham.

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