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.

Related Links

Ten Threats: Mercury and Health Problems

  • Fish advisories warn about possible mercury contamination, but many people aren't aware of the risks. (Photo by Lester Graham)

There’s no disputing that fish is healthful food, but too much of certain
kinds of fish can be dangerous, especially if you’re a woman planning to
have children. That’s because some fish contain elevated levels of
mercury. Mercury is a toxic contaminant that can cause neurological
damage. Julie Halpert filed this report about the harms mercury can
cause:

Transcript

We’re continuing our series ‘Ten Threats to the Great Lakes.’ One of the
threats identified by experts was air pollution that in turn pollutes the
lakes. The Great Lakes Radio Consortium’s Lester Graham is our guide
in this series. He says the next report looks at one pollutant that
eventually affects people.


There’s no disputing that fish is healthful food, but too much of certain
kinds of fish can be dangerous, especially if you’re a woman planning to
have children. That’s because some fish contain elevated levels of
mercury. Mercury is a toxic contaminant that can cause neurological
damage. Julie Halpert filed this report about the harms mercury can
cause:


Three years ago, when she was 18, Ayla Brown was healthy, but
suddenly, she started getting sick all the time. She was always tired, she
became anemic and had sore throats. Her tonsils had deteriorated so
much that they had to be removed. Her doctor couldn’t figure out why,
so he decided to test her for heavy metals poisoning.


The result? Ayla’s mercury levels were off the charts. They were five
times higher than the normal level. Her entire family was tested and
their levels also were above normal.


“The only conclusion we could come to is that in the past year or so since
we had moved to Ann Arbor, we had started eating a lot of fish and a lot
of fish that we now know is very known to be high in mercury, such as
swordfish and tuna and stuff like that.”


The Browns ate several meals of fish every week. Some of it was
ocean fish. Some of it was Great Lakes fish. After the diagnosis, they
cut fish out of their diet altogether. Within a year, the mercury levels
returned to normal.


“You are trying so hard to eat healthy and my family always was very
health conscious and so it’s so frustrating when you’ve done something
that you thought was good for you and realize that it was completely the
wrong thing.”


Fish are generally considered part of a healthy diet, but not all fish are
entirely safe. That’s because of mercury. Mercury exists naturally in the
environment at low levels, but higher amounts are getting into the food
chain.


Coal-burning power plants emit mercury, which eventually settles into
the Great Lakes. Then, aquatic microorganisms convert the substance
into methyl mercury, which is more toxic.


Those microorganisms form the base of the food chain. Small fish eat
microorganisms. Then, larger fish eat the smaller ones. As that happens,
the mercury concentrations escalate, making big large mouth fish like
trout, salmon and some walleye especially contaminated.


When people eat the fish, the mercury is passed on to them. Women of
childbearing age and their fetuses are most at risk.


Michael Carvan is with the University of Wisconsin-Milwaukee’s Great
Lakes Water Institute. He says the exposure isn’t just from the fish that
women eat while they’re pregnant. A woman can pass her entire lifetime
load of mercury to her baby. He says that 15% of all women of
childbearing age have high enough levels so that their fetuses will
contain mercury of one part per million or higher.


“Even at really low levels, around one part per million, you’re talking
about some subtle coordination difficulties, you’re talking about
problems with memory and problems with neuro-processing and IQ
deficits.”


Because of these concerns, the Environmental Protection Agency and
the Food and Drug Administration issued an advisory for women of
childbearing age and children, suggesting they eat fish and shellfish only
twice a week.


But one expert is concerned by all this talk about how mercury harms
people. John Dellinger was on a task force, which provided guidance on
fish consumption advisories. Dellinger studied people who lived on
Lake Superior who he thought would eat a lot of fish, but he found
something else.


“We basically discovered that from an epidemiologic point of view, these
populations have other things that are adversely affecting their health,
that in fact will probably overshadow anything we’re going to see from
the contaminants in their fish.”


Dellinger said the people were so concerned about contaminants in
fish, that they started relying on store-bought, processed food instead.
Those foods were higher in fat and sugar and contained other, less
healthful, ingredients. So, obesity and diabetes caused health problems,
not mercury poisoning, and Dellinger says that ended up being a worse
situation.


He says the key is to choose wisely, avoiding fish such as swordfish,
tuna steaks and the larger predator Great Lakes fish that are high in
mercury. That’s the only measure you can take right now, but that doesn’t
solve the problem. The real challenge will be to get rid of the mercury
that ends up contaminating the fish.


For the GLRC, I’m Julie Halpert.

Related Links

Chefs Serve Up Fish Conservation

  • Rick Bayless, a co-founder of Chefs Collaborative, is working to persuade other chefs to think about the environment when they make their decisions about food.

Some restauranteurs are looking at the effect they’re having on the world’s ecology, and as a result their chefs are changing their menus and their recipes so that there’s less pressure on some kinds of fish species. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

Some restaurateurs are looking at the effect they’re having on the world’s ecology. And as a result their chefs are changing their menus and their recipes so that there’s less pressure on some kinds of fish species. The Great Lakes Radio Consortium’s Lester Graham reports:

It’s the middle of the week and there’s already more than an hour wait to get a table at this trendy Chicago restaurant. The Frontera Grill is the domain of executive chef and owner Rick Bayless. Bayless is known for several things: a television show on public TV, redefining Mexican cuisine, and co-founding a group that’s concerned about the impact chefs’ decisions have on the environment. The group Chefs Collaborative is especially concerned about what it calls “ecologically responsible seafood procurement.” It’s calling on chefs to learn about which fish species are over-fished, to ask questions of fish providers about the size and quantity of the catch, and to think about what they can do about taking pressure off of depleted fish supplies. The problem is that many of the world’s more popular fish species have been in such high demand; they’re being fished nearly out of existence.

Chef Bayless says restaurants and their chefs play a major role in fish consumption. By making a particular type of fish popular to eat, chefs also help decide what people eat at home or demand from other restaurants. So a chef can make a difference. Bayless says instead of using a popular fish that’s seen its numbers decline due to over-fishing, the chef can substitute another kind of fish, or if necessary take it off the menu.

“I would say that we have taken off – we used to do Chilean sea bass; we no longer do it. We used to do a lot of blue fin tuna; we don’t do hardly any of that anymore. We rarely serve snapper because that’s become a pretty heavily fished species. There’s a lot of things we don’t do that we used to because we realize that diversity is going to be the answer to not over-fishing.”

But the effort to get chefs to think about the ecological consequences of their decisions isn’t embraced by everyone. Many chefs take pride in serving only the very best regardless of the financial or environmental cost. So, some chefs are not willing to take a popular fish off the menu. Bayless says they’ll keep using an over-fished species even though they know the fish’s population is being depleted.

“There’s some great chefs in this country that have more or less made their reputations on dishes that involve Chilean sea bass. And they’re going to be the last ones to change because they think of these dishes as their signatures, so a lot of those guys will shy away from these kinds of discussions.”

And if the chefs demand a fish at any price, there will always be some commercial fishers who will provide it if they can.

Peter Jarvis operates Triar Seafood in Hollywood, Florida. He supplies fish to chefs across the nation. Jarvis says some of his chefs are concerned about over-fishing. They know that certain ocean fish have dropped in numbers and have dropped in size in the past. But sometimes their information is out-dated. Back in the 1980s the Reagan administration pushed the international boundary waters out to 200 miles off the coast.
Then federal agencies closed or restricted fishing for certain species. Some of those populations have rebounded. So, Jarvis says it’s important that chefs talk to their providers rather than make decisions on old information. But Jarvis says it’s a different story farther out in international waters, and along the coasts of other nations. There, he says, little is done to check over-harvesting.

“We don’t seem to have a very good handle on the over-fishing situation outside of our own borders. You know, you go two-hundred miles off into international waters and it’s all renegades out there with very large vessels that are just pillaging the waters.”

And some chefs resort to buying fish from those sources or from countries with weak conservation laws. Even more bothersome to Jarvis are huge trawlers taking tons of fish for fish sticks and fast food fish sandwiches. But Jarvis says the more sophisticated consumer, the kind who frequents upscale restaurants, seems to be willing to put up with some changes on the menu. Chefs tell him that many of their patrons are willing to be flexible.

At the Frontera Grill, the patrons we talked to seemed to agree. We asked Lyn Schroth how she would feel if her favorite restaurant dropped a dish from the menu because that fish was being over-harvested.

“I’d be very happy with them because I wouldn’t want to eat anything that – you know, I’m a big animal lover, okay? And, most the time I don’t know what’s endangered and what’s not. And, the restaurant takes it off the menu, I’m proud of them.”

While restaurant patrons might be willing to make changes for the sake of the environment, getting the message to chefs is harder. Chef Rick Bayless says the culinary schools aren’t talking about the source of foods or the pressure on stocks in the ocean or on the ground with their student chefs.

“I think that’s the biggest disservice this country is making to the next generation of chefs. They’re teaching young chefs mostly to say ‘I’m demanding the best quality,’ but they should be demanding the products that are going to ensure that we have a future. And, they’re not doing that. They’re not teaching them that kind of stuff, about how to be responsible.”

But, Bayless says that some of the young chefs are learning that responsibility on their own through professional organizations such as the Chefs Collaborative and talking with fellow-chefs who are concerned about the environment. And Bayless adds they’re also learning from consumers who put pressure on the restaurants to think about the ecological impact of what they put on the menu.

For the Great Lakes Radio Consortium, this is Lester Graham.

Related Links

CHEFS SERVE UP FISH CONSERVATION (Short Version)

  • Rick Bayless, a co-founder of Chefs Collaborative, is working to persuade other chefs to think about the environment when they make their decisions about food.

Some chefs are working on campaigns to raise awareness about ocean fish conservation. Their efforts could mean some changes on your favorite restaurant’s menu. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

Some chefs are working on campaigns to raise awareness about ocean fish conservation. Their efforts could mean some changes on your favorite restaurant’s menu. The Great Lakes Radio Consortium’s Lester Graham reports:

Some celebrity chefs from across the nation are working together to stress the importance of conserving fish species. Several fish have been over-harvested and the chefs are calling on their colleagues and consumers to be more ecologically responsible. Rick Bayless is a chef in Chicago and has a television show on public TV. He says his restaurants and chefs have tried to keep informed about the fish they use.

“And then as we hear that certain things are stressed populations or if, for instance, tuna is not coming in as big as it used to be or marlin from Florida is getting smaller and smaller. And we can see that. And then we’ll all sort of get together and go ‘I think we should really not do this anymore because this doesn’t look very good.”

Bayless and other chefs involved in conservation programs are urging people to use fish in a way that doesn’t continue to cause pressure on the fish populations that are disappearing due to over-harvesting.

For the Great Lakes Radio Consortium, this is Lester Graham.

Related Links