This “pinkhouse” at Caliber Biotherapeutics in Bryan, Texas, grows 2.2 million plants under the glow of blue and red LEDs. Photo: Courtesy of Caliber Therapeutics

Post by Michaeleen Doucleff, The Salt at NPR Food (5/21/13)

The idea of vertical farming is all the rage right now. Architects and engineers have come up with spectacular concepts for lofty buildings that could function as urban food centers of the future.

An artist’s rendering of what a planned vertical farm in Linkoping, Sweden, will look like.
Photo: Courtesy of Plantagon

“The idea of taking a skyscraper and turning it into a vertical farming complex is absolutely ridiculous from an energy perspective,” says horticulturist Cary Mitchell of Purdue University, who’s been working on ways to grow plants in space for more than 20 years.

The future of vertical farming, Mitchell thinks, lies not in city skyscrapers, but rather in large warehouses located in the suburbs, where real estate and electricity are cheaper.

And oh, yeah, instead of being traditional greenhouses lit by fluorescent lamps, he says these plant factories will probably be “pinkhouses,” glowing magenta from the mix of blue and red LEDs.

Light is a major problem with vertical farming. When you stack plants on top of each other, the ones at the top shade the ones at the bottom. The only way to get around it is to add artificial light — which is expensive both financially and environmentally.

Vertical farmers can lower the energy bill, Mitchell says, by giving plants only the wavelengths of light they need the most: the blue and red.

“Twenty years ago, research showed that you could grow lettuce in just red light,” Mitchell says. “If you add a little bit of blue, it grows better.”

Plant’s photosynthesis machinery is tuned to absorb red and blue light most efficiently. They have a handful of other pigments in their leaves that catch other wavelengths, but the red and blue wavelengths are the big ones, supplying the majority of the light needed to grow.

Cary Mitchell and Celina Gomez, of Purdue University, harvest tomatoes grown next to a tower of blue and red LEDs. Photo: Courtesy of Purdue Agricultural Communication photo/Tom Campbell

And there’s another advantage to using LEDs in greenhouses and vertical farming, Mitchell says: Because these lights are cooler, you can place them close to the plants — even stacked plants — and lose even less energy.

Recently, Mitchell and his graduate student designed a 9-foot-tall tower of lights and grew tomato plants right up against it. “As the plants get taller, we turn on the [light] panels higher up,” he explains. “It takes about two months before all the panels are on.”

The towers cut energy consumption by about 75 percent, Mitchell and his team reported earlier this year.

Right now, experiments are using these specialized LEDs to supplement natural light, not replace it.

But as LEDs get more and more efficient, could growers forgo the natural light altogether and grow crops completely in enclosed rooms, where they’re protected from temperature changes or damaging pests?

That’s exactly what Barry Holtz, at Caliber Biotherapeutics, is already doing.

His farms have never seen the light of day.

Plants at Caliber Biotherapeutics grow under blue and red LEDs, with wavelengths of light that match those that get absorbed by the photosynthetic machinery. Photo: Courtesy of Caliber Biotherapeutics

“A photon is a terrible thing to waste,” Holtz tells The Salt. “So we developed these lights to correctly match the photosynthesis needs of our plants. We get almost 20 percent faster growth rate and save a lot energy.”

Holtz is growing a tobacco-like plant to make new drugs and vaccines. The indoor pinkhouse gives him tight control over the expensive crops, so his team can stop diseases and contamination.

Holtz says this type of indoor gardening isn’t going to replace traditional farms anytime soon. It’s still relatively expensive for growing food. “We couldn’t compete with iceberg lettuce farmers,” he says, “but for certain specialty crops, the economics wouldn’t be so bad.”

And, he says, the pinkhouse is actually quite efficient when it comes to water and electricity. “We’ve done some calculations, and we lose less water in one day than a KFC restaurant uses, because we recycle all of it.”

Copyright 2013 NPR.

Carbon isotope analysis: a scientific way to know just how much soda kids are drinking behind parents’ backs?
Photo: iStockphoto.com

The problem? We tend to underestimate, lie or forget what we’ve consumed.

And this is a challenge for researchers who study the links between sugar-sweetened beverages and obesity.

A new study published in the Journal of Nutrition explains a technique that could help researchers get a good measurement of sugary beverage consumption — by analyzing a piece of hair or a blood sample.

Researcher Diane O’Brien of the University of Alaska and her colleagues have used carbon isotope analysis to develop their measuring tool. “We’re isolating the [carbon] isotope ratio in a specific molecule,” explains O’Brien. The molecule is an amino acid called alanine, which captures carbon from sugars.

It turns out that when you consume sweetened soda, slightly more of a particular kind of carbon called C-13 gets trapped in alanine and incorporated into proteins. And proteins hang around in the body much longer than sugar does. So the scientists say they can sample proteins to look for extra amounts of C-13 in alanine. People with a lot of C-13 are likely to be people who have consumed a lot of corn syrup and cane sugar.

Using this technique, O’Brien says, you can capture a longer-term picture of sugar consumption compared with urine samples — which only reveal how much sugar a person has consumed in the past day or so.

Carbon isotope analysis has helped scientists piece together ancient dietary patterns, explains Dale Schoeller of the University of Wisconsin, Madison, in a commentary about the study: “The use of stable isotope signatures has even provided information about the diet of Otzi [aka The Iceman],the 5,000-year-old natural mummy found in the Alps in 1991.”

And he writes that he thinks the technique will be helpful for researchers studying the obesity epidemic.

“This should be a major step toward resolving the controversy over the role of
caloric sweetener intake in the development of obesity,” writes Schoeller.

Not everyone is convinced.

“This is an interesting, but preliminary, finding,” says Dr. David Ludwig of Boston Children’s Hospital and director of the New Balance Foundation Obesity Prevention Center, in an email to The Salt.

Barry Popkin of UNC-Chapel Hill, another obesity researcher, sounds the same note: “This might be useful,” Popkin writes in an email. But the big drawback, he says, is that such testing is expensive to carry out.

Still, as the mom of a teenage son who has been spotted more than once sneaking off on his bike to the corner store for a big old soft drink in the afternoon, it would be nifty to perform the r-u-drinking-soda? test.

So can O’Brien help?

“Sure, in theory we could run your son’s hair and find out if he’s quaffing on the sly,” O’Brien says.

Or maybe I should just check the bottles in the recycle bin. (‘Fess up, Luke, I’m on to you!)

Copyright 2013 NPR.

William von Schneidau, who owns the BB Ranch butcher shop at Pike Place Market in Seattle, has made prosciutto from pigs fed marijuana. Photo: Courtesy of BB Ranch

William von Schneidau, an intrepid butcher in Seattle, is giving a whole new meaning to “potbelly pig.” Lately, he’s been feeding marijuana refuse to the pigs he turns into prosciutto for BB Ranch, his butcher shop in the city’s famous Pike Place Market.

Pot-scented bacon? Well, not quite.

The stems, leaves and root bulbs von Schneidau recoups from Top Shelf Organic, a medical marijuana dispensary, don’t season the meat, he says. But the meat from the first few “pot pigs” he’s butchered has been “redder and more savory” than what he usually works with, he says.

It’s not clear whether the pigs feel anything from the weed in their feed, or how much, if any, THC — the psychoactive substance that gets humans high — ends up in the meat. Rather than an attempt to develop a new meaty treat for stoners, the “pot pig” experiment seems mostly to be an (effective) publicity stunt. Von Schneidau’s first Pot Pig Gig event — where he promoted the product, as well as other local foods — sold out quickly. And he says all the media attention he has gotten is generating lots of interest in the next event he’s planning.

Still, von Schneidau’s creative reuse of a local waste product is part of a larger trend of small farmers looking for new, free sources of livestock feed, especially since prices for corn and soy have been on the rise. In addition to the pot refuse, von Schneidau has linked up ranchers and farmers in the region with a vodka distillery and with vegetable vendors at Pike Place Market who have waste that would otherwise end up as compost or in the landfill.

As we’ve reported, high feed prices have led some farmers elsewhere to seek out food scraps and even bakery byproduct — bread, dough, pastries and cereal — for their pigs and cattle.

Pigs have stomachs pretty similar to humans and can eat just about anything we eat. But we couldn’t find any research on what happens when you feed them marijuana.

Scientists at the European Union Food Safety Authority looked into the safety of using hemp, a plant that’s a close relative of marijuana, in feed for dairy cows. When the cows were fed hemp plants, enough THC made its way into their milk that the scientists recommended prohibiting its use. (However, feeding the cows hemp seeds was just fine, they found.)

Von Schneidau says he’s all for finding out what his dietary supplement is doing for his pigs.

“If we had a vet that stepped up to the plate and wanted to check out their joints and mood, and what drugs make pigs happy, that would be great,” he says. “But me, I just get out there, and cut them up, and put them on a BBQ, and eat them.”

Copyright 2013 NPR.

Does ADHD affect eating and weight?
Photo: iStockphoto.com

The men who had ADHD weighed 19 pounds more at age 41 than otherwise similar men who hadn’t had ADHD as boys, the researchers found.

“It makes sense, because they’re self-medicating with carbohydrates,” says Dr. Edward Hallowell, a psychiatrist in Sudbury, Mass., who has ADHD and treats adults with ADHD. “Carbs do the same thing that stimulant medications do — promote dopamine,” says Hallowell, who wasn’t involved in the latest study. “So you get the gallon of ice cream at midnight.”

Attention deficit-hyperactivity disorder may affect up to 11 percent of American children, the majority of them boys.

Earlier studies had suggested that adults with ADHD may be more likely to gain weight.

That research doesn’t prove that the ADHD is causing the weight gain. And this new study doesn’t prove that, either. But it does provide better evidence for a potential link because it followed the same group of people over time. It looked at a group of 111 boys with ADHD at age 8. Then their weight was assessed at age 41. The men with ADHD were then compared to similar men who didn’t have ADHD as children.

The men who had had ADHD weighed an average of 213 pounds, and 41 percent of them were obese. By contrast, the men who hadn’t had ADHD weighed 194 pounds on average, and 22 percent were obese.

The study leaders realized that weight was becoming an an issue for their participants when some who came in for MRI scans were too fat to fit in the machine.

“In most studies you eliminate those people,” says F. Xavier Castellanos, a psychiatrist at the Child Study Center at NYU Langone Medical Center in New York and a co-author of the study, which was published in the journal Pediatrics. Instead, the researchers started collecting information on the participants’ weight and body mass, or BMI.

This study doesn’t figure out why boyhood ADHD might be causing weight problems in adulthood. The weight gain could be caused by psychological factors or neurobiology, Castellanos speculates. Differences in the pathways for dopamine, a neurotransmitter in the brain, have been found in both people who are obese and people with ADHD, he says.

Or it could be that the impulsiveness typical of ADHD makes it harder for people to say no to food. Children who take stimulant medications like Ritalin typically don’t have problems with weight gain because the medications suppress appetite. But eating issues may emerge later.

Hallowell says he often sees adult patients with ADHD who struggle with overeating. “Nutrition should be part of the treatment plan,” he says.

Parents of children with ADHD should take particular care to make sure their children develop lifelong good eating habits, Castellanos says. “The reality is that ADHD people can be at risk for being swayed by temptation.”

Copyright 2013 NPR.

Heifers at Timber Ridge Cattle Co., an operation in Osceola, Iowa, that feeds some of its cattle flax seed.
Photo: Courtesy of Timber Ridge Cattle Co.

Post by Eliza Barclay, The Salt at NPR Food (5/17/13)

Flax is the oily seed usually spotted in the nutritional supplement or cereal aisle. It’s marketed as a superfood because of its high levels of omega-3 fatty acids and fiber.

Omega-3s may do all kinds of good things for humans – like protect against Alzheimer’s, heart disease and even cancer — so it seems reasonable to think they could also protect the health of animals.

That’s what got Jim Drouillard, a professor of animal sciences and industry at Kansas State University, wondering whether flax might be good for beef cattle. In a series of experiments over the last 10 years, he found that feeding flax seed to cattle in the five months before slaughter reduced inflammation and the need for antibiotics, and offset some of the negative effects of a corn-based diet. It also had an unexpected benefit for consumers.

“We were interested in improving the health of the animals, but we also saw that we could get large increase in omega-3s in the [meat],” Drouillard tells The Salt.

Drouillard had stumbled upon omega-3 enriched beef, and some people who sell beef took notice. Their hunch was that consumers might prefer to get their omega-3s from beef rather than salmon, tuna or walnuts. The U.S. Department of Agriculture got on board, too.

“Assuming a lot of people are not going to eat flax or be able to afford salmon, one of our arguments [for flax-fed beef] is that there are a lot of people who like to eat beef,” says Scott Kronberg, a research animal scientist with USDA’s Agricultural Research Service who has done his own research on the benefits of flax-fed beef.

NBO3 launched its enriched ground beef at the Tops grocery chain in New York in March. Photo: Courtesy of NBO3

And in Osceola, Iowa, Peter Woltz is giving his cattle flax for the omega-3 enriched beef sticks, summer sausage and jerky products he sells online and at farmers markets under the brand name Timber Ridge.

Before he got into the flax-fed beef business, Woltz used to raise cattle on a conventional feedlot. But he says he decided to sell it because it required too much crisis management.

“There’s always the risk of disease,” he says, “so you have a very active antibiotic program, and sometimes you give it to them whether they need it or not. That turned me off.”

When Woltz heard that there were opportunities to produce “all natural” beef without hormones, additives or antibiotics, he was intrigued. “It sounded like a more sane, responsible way of producing beef,” he says. Drouillard’s flax feed also appealed to him as a way to make a niche product.

About one-fifth of Woltz’s cattle now eat flax in the last 100 days before slaughter, when it makes up about 8 of their feed. And he says those cows are healthier than the ones that don’t get flax.

“It was a real surprise to us how big the health benefits to the [flax-fed] herd were,” he says. “Pinkeye outbreaks are very common in raising cattle, but in six years of doing this, I have never seen a flax-fed cow with pinkeye.”

Woltz says he believes his herd of flax-fed cattle will continue to grow. “It’s just a question of how fast do we want to expand the herd.”

But Kronberg of the USDA cautions that the economics of flax-fed beef aren’t yet well understood. “Flax is pretty expensive nowadays, and the profitability of beef production is not always so good,” he says. “So it will be interesting to see how these companies do.”

Across the pond in Europe, animal science researchers are enthusiastic about flax, too. They’re feeding it to dairy cattle to improve their digestive health and reduce methane emissions from their belching.

Copyright 2013 NPR.

The U.S. Capitol building. Photo: Jewel Samad/AFP/Getty Images

Post by Dan Charles, The Salt at NPR Food (5/16/13)

Two seemingly common-sense, bipartisan food reforms have gotten mugged on Capitol Hill in recent days. If you’re a loyal reader of The Salt, you’ve heard of them.

First, there’s the proposal — backed by an odd-couple alliance of egg producers and animal-welfare activists — to set minimum standards for the housing of egg-laying chickens. Second, the Obama administration wants to change the way the United States provides food aid to people in foreign countries, buying more of that food close to where it’s needed.

Neither proposal seems, at first glance, controversial. Changing the rules for food aid should save money, according to most independent analyses, allowing the program to feed more hungry people. Similar reforms, in fact, were proposed by President George W. Bush. The “egg bill,” meanwhile, is a remarkable instance of pragmatic compromise between bitter adversaries.

Any change, however, threatens somebody, and both of these proposals have run afoul of politically well-connected people.

In the case of food aid, the skeptics include American shippers and dock workers, who will get slightly less work if the U.S. sends cash to buy food abroad. They, in turn, have a powerful friend in Congress: Sen. Barbara Mikulski, proud native of the port city of Baltimore and chairwoman of the Senate Appropriations Committee. In an e-mail to NPR, Mikulski wrote that “we need to find a sensible center that will allow us to implement smart reforms without jeopardizing U.S. jobs, particularly those in the maritime industry.”

In part because of Mikulski’s resistance, advocates of reform are now trying a different route entirely — a free-standing bill that’s been introduced by Edward Royce, the Republican chairman of the House Foreign Affairs Committee. Its prospects are uncertain.

The “egg bill,” meanwhile, has some influential supporters. Secretary of Agriculture Tom Vilsack brings it up frequently as an exemplary compromise between large-scale agriculture and its critics. Debbie Stabenow, D-Mich., chairwoman of the Senate Agriculture Committee, actually tried to include it in her draft of the farm bill, which is up for renewal (again) this year.

Pork and beef producers, however, object in principle to the notion of federal regulation of farm animal housing — even though, in this case, the egg producers themselves are asking for federal regulations as a way to pre-empt state rules that are more troublesome.

When the agriculture committees of both House and Senate finished their versions of the farm bill this week, all mention of guaranteed living space for egg-laying hens had vanished.

In fact, the House committee adopted a provision that could make it more difficult for states to set such standards. This amendment, offered by Rep. Steve King, R-Iowa, would prohibit any effort by state governments to control the way that their food is produced by out-of-state farmers. The measure is aimed specifically at California’s Proposition 2, which is set to ban farmers in Iowa or Idaho from selling their eggs in California if those eggs come from chickens housed in traditional cages.

Copyright 2013 NPR.

Even Sophia Loren felt compelled to smuggle mortadella, despite a U.S. ban — well, her character did, anyway, in the 1971 film Lady Liberty. Photo: Warner Bros/The Kobal Collection

Post by Sylvia Poggioli, The Salt at NPR Food (5/16/13)

American gourmets and lovers of Italian food products, your days as food smugglers are over.

No more stuffing your suitcases with delicacies bought in Italy, hoping the sniffer dogs at JFK or other American airports won’t detect the banned-in-the-USA foodstuffs inside your luggage.

In the U.S., they’re called cured meats, the French say charcuterie and in Italy, the word for cured-pork products is salumi.

Starting May 28, a four-decades-old ban on the import of many Italian salumi will be lifted.

The U.S. Department of Agriculture has announced that the Italian regions of Lombardy, Emilia-Romagna, Veneto and Piedmont, and the provinces of Trento and Bolzano, are free of swine vesicular disease. Imports of pork products from those areas, says the USDA, present a low risk of introducing the disease into the U.S. The disease was first detected in the 1960s and can survive cooking and even long curing.

Up to now, only a few Italian pork products were approved for import to the U.S.: prosciutto di Parma and prosciutto di San Daniele, as well as mortadella — which was also banned until 2000.

Starting soon, as long as they receive USDA approval, hundreds of artisanal products will arrive on American tables. It’s not yet clear, however, what standards the producers will have to meet and what the costs will be. But even without a ban, Italian cured meat producers must pay hefty fees as part of the process of getting certified for importation.

For centuries, Italians have been making some of the highest-quality cured meats in Europe. It’s time to start learning some of their names: sopressata, a slow-cured dried pork, similar in appearance to salami; pancetta, bacon made from the pork belly, but unlike the American variety, which is smoked, Italian pancetta is cured in salt and spices; coppa or capocollo, made from pork shoulder or neck and seasoned with wine, salt and spice.

What’s the secret behind the high quality of Italian salumi?

Many say it’s the quality of the pigs, the climate where they’re raised and what they’re fed.

Every Italian region and province, and even many towns have their own distinctive salumi, many of them celebrated in weeklong folk festivals. There are fans of Coppa Piacentina or those who swear by Coppa di Parma; there’s an infinite variety of salamis — from Brianza, Vicenza, Cremona and many more, spiced with garlic, juniper and myrtle berries, fennel and red wine.

One of the delicacies that may soon reach U.S. shores is salame di Felino, named after the small town of the same name near Parma.

According to the website prosciuttopedia, salame di Felino traces its origins to the Middle Ages. The oldest pictorial representation is found in the Parma Baptistery, where one can see two salamis draped over a saucepan. And in 1905, the wording “Salame di Felino” was officially included in the dictionary of the Italian language.

Various types of pancetta, bacon made from pork belly, on display in Turin, Italy. Unlike the American variety, which is smoked, Italian pancetta is cured in salt and spices. Photo: Giuseppe Cacace/AFP/Getty Images

But what cured meat aficionados are most eagerly waiting for is the king of Italian salumi, culatello, a product of the flatlands of Zibello and neighboring towns near Parma — a product whose secret ingredient is the dense winter fog that hovers at a particular bend in the Po River.

Culatello dates back at least to the 15th century. It’s made with the muscular part of the hind leg of pigs born, raised and slaughtered in the Emilia-Romagna and Lombardy regions.

The Italian poet Gabriele D’Annunzio, a culatello enthusiast, wrote in 1891, “It is aged only in the square of land surrounding Zibello, where the air of the Po is often humid and good for the mold that preserves this fatless cut of meat.”

I first experienced culatello at the Trattoria La Buca di Zibello, a long-established restaurant run for four generations solely by women. A huge room is dedicated to curing the zibelli — hundreds hang from the ceiling. The women told me one of the key steps is a loving massage that helps salt penetrate the meat.

Culatello is an expensive delicacy even in Italy, and of the two culatelli produced by the same animal, one is always better than the other: It’s said that pigs are animals of habit and always sleep on the same side, which ends up being the less tender of the two thighs.

But there are some cured pork products that won’t soon be imported to the U.S. The region of Tuscany is still on the USDA-restricted list. So, you’ll still have to travel there to savor wild boar sausages (my favorite) and finocchiona of Siena, a fennel-flavored salami.

And then there’s that most sinful of products (sinful for those who have to watch their cholesterol intake), lardo di Colonnata, the small town perched above the marble quarries of Carrara. That velvety white lard — pork fat from the back of the pig — is cured in marble vats. Locals claim it’s the porous quality of the stone that’s responsible for its unique, refined taste.

Buon appetito.

Copyright 2013 NPR.

Roxarsone, a drug linked to elevated levels of inorganic arsenic in chicken meat, is no longer used in chicken farming, producers say. But another arsenic-based drug is still used to raise turkeys. Photo: iStockphoto

Post by by Allison Aubrey, The Salt at NPR Food (5/16/13)

A study published online recently in the journal Environmental Health Perspectives documented slightly elevated levels of arsenic in samples of chicken purchased at grocery stores in 10 cities in the U.S.

So how did trace amounts of this toxin end up in supermarket poultry?

Well, arsenic-based drugs are approved for use in chicken and turkey production. And at the time of the grocery-store testing, back in late 2010 and early 2011, a drug called Roxarsone was still being used in chicken feed to stave off infections with parasites. (The drug was voluntarily pulled from the market in June 2011 by its manufacturer.)

“We did the study to learn whether using arsenic-based drugs leads to increases in the toxic form of arsenic in meat,” explains researcher Keeve Nachman of Johns Hopkins. And it turns out, it does. A little.

The researchers documented 2.3 ppb — that’s parts per BILLION – of inorganic arsenic (the more toxic type of arsenic) in the meat of chicken that had measurable levels of Roxarsone.

By comparison, the meat from chicken that had no detectable levels of Roxarsone had .8 ppb of inorganic arsenic. That’s three times less.

But it’s important to point out that these low levels are far below the 500 ppb tolerance levels set by the FDA.

The researchers found no measurable trace of the arsenic-based drug in the 25 organic samples they tested (Roxarsone is not allow in organic chicken). By comparison, 20 of the 40 samples of meat from chickens raised conventionally did contain the drug.

The National Chicken Council released a statement calling the study’s conclusions misleading. Chicken producers, the council says, are no longer using any arsenic-based drugs.

In lieu of Roxarsone, which had been used to prevent intestinal parasites, chicken producers have switched to drugs known as ionophores.

“Today, folks (chicken producers) are just doing the best they can without” Roxarsone, says Tom Super of the National Chicken Council. He says the ionophores are not as effective against the parasites.

The FDA, in this Q & A, says another arsenic-based drug known as Nitarsone is still being marketed. It’s approved for use in chickens and turkeys. Though FDA does not disclose animal drug sales data, the drug is used to prevent outbreaks of Blackhead, an infection caused by parasites, in turkeys.

The National Turkey Federation says Nitarsone is used primarily in the turkeys’ first few weeks of life, and used more heavily during the summer months, when Blackhead is more likely to occur. The industry depends on the drug as a preventive, since there’s no effective treatment once an outbreak occurs.

The authors of the new study say they hope the FDA considers their conclusions in making decisions about the approvals for these drugs.

“Roxarsone still continues to be sold by (drug company) Zoetis in Latin America” and is still approved for use here, despite the fact that it was voluntarily pulled from the market in 2011,” Johns Hopkins’ Nachman says.

The FDA says it continues to investigate all uses of arsenic-based drugs in food-producing animals, and agency spokesperson Jalil Isa says the agency “will take the appropriate action to protect public health.”

Copyright 2013 NPR.

Crew members unload a catch of sockeye salmon at Craig, Alaska, in 2005. Researchers say fish are being found in new areas because of changing ocean temperatures. Photo: Melissa Farlow/National Geographic/Getty Images

Listen to the Story on All Things Considered

Post by Richard Harris, The Salt at NPR Food (5/15/13)

Climate change is gradually altering the fish that end up on ice in seafood counters around the world, according to a new study.

“The composition of the [global] fish catch includes more and more fish from the warmer areas, and cold-water fish are getting more rare, because the temperatures are increasing,” says Daniel Pauly at the University of British Columbia, a co-author of the study.

As oceans warm — a result of climate change — fish maintain their preferred water temperature by moving away from the equator and toward the poles.

So, for example, people in Denmark are now encountering swordfish, which you’d normally find in the Mediterranean and off the coast of Africa.

“In British Columbia, where I live, we have Humboldt squid, giant squid from Mexico,” Pauly says. “They eat all the herrings and stuff, and people don’t know them. They are stranded on the beach, and people think they are sea monsters.”

And fishermen have scuffled over Atlantic mackerel quotas, as the fish moves north to new grounds around Iceland.

The new study in Nature shows these anecdotes aren’t simply a fluke. Data from fish catches from around the world show it’s happening everywhere the ocean is warming — which is just about everywhere.

This trend isn’t obvious at American fish counters. That’s because 80 percent of our seafood is imported, and we don’t know whether fishermen are catching our swordfish in the tropics or the North Atlantic. Also, half of all seafood is now produced in enclosures — not caught in the wild.

But if it’s invisible to us, that’s not the case for many people who rely on their local fisherman for protein.

“In the tropics, there are lots of developing countries’ fisheries where their ability to adapt to changes in the resources is much lower,” says William Cheung, the report’s lead author. Like Pauly, he’s at the University of British Columbia’s Fisheries Center in Vancouver.

The paper documents a migration of some species out of the tropics, as they seek cooler waters. But there are no fish to replace the ones that are leaving. As a result, “these fisheries in the tropics will be most vulnerable to climate change impacts,” Cheung says.

The United States will gradually feel the effects as well.

“Imagine a reef fish that is driven by temperature into North Carolina or the Delaware coast,” Pauly says. “That reef fish will not find reefs. It’s like you having to move, but you cannot take your furniture with you, or your house. That is the problem.”

Many fish will have a hard time adapting to this very rapid change, he says.

Mark Payne at the National Institute for Aquatic Resources in Denmark was not involved in the research, but he’s impressed by the result.

“This is suddenly a wake-up call,” he says. “It’s a strong suggestion that climate change is here. It’s real, and it’s really starting to affect what we catch and, therefore, what we eat.”

Copyright 2013 NPR.