August 20, 2013
The menu says red snapper, but it’s actually tilapia. The white tuna, meanwhile, is really escolar, while the seabass is Antarctic toothfish.
Welcome to the wild world of modern seafood, where not everything is as it seems. New research is revealing that merchants and fish dealers often mislabel their product as an entirely different species to fetch a better price at market. A study realeased last week by UK researchers found that a number of species in the skate family are sold as “sting ray wings,” while a separate study produced in February by the group Oceana found that, of 1215 seafood samples from 674 restaurants and grocery stores in 21 U.S. states, a full third were mislabeled. In Chicago, New York, and Washington, DC, every single sushi bar that was tested was found to sell at least one mislabeled fish species.
How did the researchers figure all this out? Through the innovative use of DNA barcoding, in which a specific segment of genetic material (analogous to a product’s barcode) in a piece of fish is used to determine exactly which species it truly belongs to. For years, we had no real way of determining the true species of a piece of seafood—a filet of fish, after all, often looks like any other filet—but this new application of an existing scientific technique is rapidly becoming a crucial tool in combating seafood fraud.
Testing a piece of fish to determine its species is fairly straightforward—scientists perfected DNA barcoding years ago, albeit typically as part of other sorts of projects, like cataloging the complete assortment of species in a given ecosystem. Analyzing the DNA in a piece of fish is a relatively similar process.
To start, researchers acquire a piece of fish and freeze it, as fresher and better-preserved tissue samples generally yield more accurate results. Then, in the lab, they slice off a tiny piece of the sample for testing.
To extract and isolate the DNA from the tissue, scientists break open the cells—either physically, by grinding them or shaking them in a test tube filled with tiny beads, or chemically, by exposing them to enzymes that chew through the cell membrane. Next, they remove other components of the cell with various chemicals: proteases digest proteins, while RNAase digests RNA, an alternate form of genetic material that could cause errors in DNA testing if left in place.
Once these and other substances are removed, the remaining sample is put in a centrifuge, which spins it at high speed so that the densest component—in this case, DNA—is isolated at the bottom of the tube in a pellet. A variety of different approaches are currently used to sequence the DNA, but all of them achieve the same end—determining the sequence of base pairs (the building blocks of DNA that are unique to each organism), at one specific location in the fish’s genome. All fish of the same species share the same sequence at that location.
As part of broader DNA barcoding projects, other scientists have analyzed the sequence of base pairs at that same genetic location in thousands of pieces of fish tissue that can definitively linked to species. Thus, by comparing the genetic sequence in the mystery fish tissue to databases of other species’ known genetic sequences, such as FISH-BOL (which stands for Fish-Barcode Of Life and contains the barcodes of 9769 fish species so far), scientists can tell you if, say, the grouper you thought you were buying was actually Asian catfish.
Figuring out which species a piece of fish truly belongs to has significance that goes far beyond gastronomy. For one, cheaper fish species are most often substituted for more expensive ones: tilapia, which goes for around $2.09 per pound, is billed as red snapper, which can commonly fetch $4.49 per pound. (The fact that inexpensive fish is so commonly passed off as a pricier variety, while the reverse occurs much more rarely, indicates that intentional mislabeling by sellers is at play, rather than innocent misidentification.)
Additionally, species that are dangerously overfished and are on the verge of ecological collapse—such as orange roughy—are sometimes substituted for more environmentally-benign varieties. Customers that make the effort to choose sustainable types of seafood, in these cases, are thwarted by mislabeling.
Eating different species can also have vastly different effects on your own health. For one, different fish species can have different fat and calorie contents, so mislabeling can lead the nutrition-conscious astray. Moreover, certain species, like tilefish, are on the FDA’s “do not eat” list for sensitive groups of people (such as pregnant women) because of their high mercury content. The Oceana study, though, found several instances of tilefish being sold as red snapper. Perhaps even worse, 94 percent of the white tuna tested in the study was actually a fish called escolar, which has been found to contain a toxin that when ingested, even in small quantities, can cause severe diarrhea.
So, what to do? Testing the fish’s DNA at home is probably beyond most people’s capabilities. So to avoid being duped, Oceana recommends asking sellers lots of questions about a fish’s origin, scrutinizing the price—if a fish is being sold far below market value, it’s probably mislabeled as a different species—and buying whole fish at markets when possible.
August 12, 2013
Hawaiians knew the value of locally sourced foods decades before the term locavore became a buzzword at every Brooklyn, Portland and Northern California farmer’s market. Because of the 50th state’s isolation, Hawaii has always relied upon its easy access to bountiful local seafood to feed the islands. Seafood-heavy restaurant menus testify to this fact.
Many tourists, it turns out, view these colorful fish-filled menus as a great souvenir of their time in Hawaii. Over the years, thousands of pinched Hawaiian menus have found their way back to the mainland in suitcases and travel bags, only to wind up sitting on an attic shelf or stuffed into a drawer for the next 80-odd years. Kyle Van Houtan, an ecologist at Duke University and leader of NOAA’s Marine Turtle Assessment Program, realized the menus could serve a higher purpose than gathering dust. The stuff of breakfast, lunch and dinner plates, he realized, could potentially fill in gaps of historic records of fish populations by showing what species were around in a given year.
The basic premise is this–if a species of fish can be readily found in large enough numbers, then it’s likely to make it on restaurant menus. Van Houtan and colleagues tracked down 376 such menus from 154 different restaurants in Hawaii, most of which were supplied by private menu collectors.
The team compared the menus, printed between 1928 and 1974, to market surveys of fishermen’s catches in the early 20th century, and also to governmental data collected from around 1950 onward. This allowed the researchers to compare how well the menus reflected the kinds of fishes actually being pulled from the sea.
The menus, their comparative analyses revealed, did indeed closely reflect the varieties and amounts of fish that fishermen were catching during the years that data were available, indicating that the restaurants’ offerings could provide a rough idea of what Hawaii’s fisheries looked like between 1905 and 1950–a period that experienced no official data collection.
Prior to 1940, the researchers report in the journal Frontiers in Ecology and the Environment, reef fish, jacks and bottom fish commonly turned up on menus. These include pink snapper, green snapper and amberjack. But that quickly changed after Hawaii received its statehood in 1959. By then, those once popular fishes appeared on fewer than 10 percent of menus. Some, such as Hawaiian flounder, Hawaiian grouper and Hawaiian barracuda disappeared from menus completely after 1960. In their place, large-bodied pelagic species, or those that live in deep open water such as tuna and swordfish, began to turn up served with a wedge of lemon. By 1970, these large pelagic fishes were on nearly every menu the team examined.
Diners’ changing tastes and preferences may explain part of this shift away from the nearshore and out to the deep sea, but the researchers think there is more to the story than foodie trends alone. Instead, this sudden shift likely reflects a decline in nearshore fish populations. Because both the early and later menus corroborate well with known fisheries data, the 1930s and 40s menus likely represent a boom in nearshore fisheries, with the 1950s menus standing in as a canary in the coal mine signaling the decline of those increasingly gobbled-up populations. “This helps us to fill in a large gap–between 1902 and 1948–in the official fishery records,” Van Houtan said in an email. “But it also shows that by the time Hawaii became a U.S. state, its inshore fish populations and reefs were in steep decline.”
Those species that disappeared from menus more than a century ago are still present today, but their populations around Hawaii remain too low to support targeted commercial fishing. Some of them are considered ecologically extinct, meaning that their abundance is so low that they no longer play a significant role in the environment. While a few of those species have returned to Hawaiian menus recently, they are usually imported from Palau, the Marshall Islands or the Philippines, rather than being fished from Hawaiian waters.
The menu trick can’t work for every animal in the sea. Populations dynamics of some species, such as shrimp and mollusks, cannot be inferred from the menus since those animals mostly came from mainland imports. On the other hand, other species, the researchers know, were fished at that time but are not reflected in the menus. Sea turtles, for example, used to be harvested commercially, but they were butchered and sold at local markets rather than at tourist trap restaurants.
Investigating past populations of turtles was in fact the motivation for this project. “Green turtles here nearly went extinct in the early 1970s, and lots of blame was put on increasing tourism and restaurant demand,” Van Houtan explains. He decided to examine just how much restaurants contributed to that near-miss for the green turtles, so he started collecting menus. However, he says, “we were in for a surprise.”
He and his colleagues first got ahold of 22 menus from the early 1960s, only to find that not a single listed turtle soup, turtle pie, turtle stir-fry or any other turtle-themed recipe. He found another 30, then 25 and then 40 menus. By this time, he was 100 menus deep, and had found only a single mentioning of turtle anything. “By doing much background research on the fishery, we discovered turtles were sold over-the-counter at fishmongers and meat markets in Chinatown and other open air markets in Honolulu,” he says. The restaurants, in other words, were not to blame–at least not for the turtles.
Left with all of these menus, however, the team decided to take a closer look into the marine life listed there. “When I assembled those data, it became a story of its own, helping to fill a significant gap in our official government records,” he says.
Collecting all of those menus, he adds, was no small task. He hustled between appointments with Hawaiiana experts, archivists, publishers, Hawaiian cooking historians, tourism historians, museums and libraries. But some of the more pedestrian venues proved most useful, including eBay collectors who would occasionally invited Van Houtan over to dig through boxes of hoarded menus. “I met a lot of interesting people along the way,” he says.
Scientists often turn to historic documents, media stories, artwork, photographs or footage to infer past events or trends. And while researchers have used menus to track a seafood item’s popularity over time, not many think to use dining data as a proxy for fish population abundance. The most interesting thing about the study, Van Houtan thinks, is “not that we used menus as much as that no one previously thought to.”
That, he says, and a few of the more odd-ball items that turned up on some of the old menus, like magnesium nitrogen health broth. “I have no idea what that was,” he says. “And pineapple fritters with mint sauce doesn’t sound very yummy to me either!”
August 6, 2013
Media reports have called them the “tigers of the sea” and “white death,” striking potential prey with the “power of a horse
.” Such descriptions are fearsome enough, but it’s the great white shark’s purported appetite for human flesh that sends chills skittering up spines. A 1916 article in the Richmond Times-Dispatch, printed just after the still-famous string of shark-related deaths that year, came to a truly creepy conclusion: Those who believe that the great white’s propensity to dine on humans is real and steadily increasing “have the weight of evidence on their side.”
Thanks to the movie Jaws, the great white’s reputation as a ruthless man-eater pervades to this day. So you can’t be blamed for being slightly concerned if you took
a quiz claiming to match your personality with a shark’s, put together by the Discovery Channel, and found out that you are a great white. Sure, you may indeed be “curious yet cautious” and “aggressive but also recessive;” people may be “dangerously intrigued” by you. But does your personality really match that of such a loathed creature? Can an entire species of sharks be generalized in that way?
Jean Sebastien Finger, a biologist at the Bimini Biological Field Station in the Bahamas may have answers. For a little over a year, Finger has been trying to find out whether sharks have personalit
ies. Personality, by its very name, seems to apply only to a person, e.g., a human. But can a shark actually be shy? Social? A risk-taker? Fierce or mellow?
Though Finger is the first, to his knowledge, to study sharks in this way, he is not alone among animal behaviorists. His work fits with a growing field of research investigating what scientists call “behavioral syndromes,” or ways of acting that differ from one individual to another but are consistent across time and situation. It turns out scientists are finding personality in a whole range of species, sharks now included.
The basic idea that nonhuman animals have personality isn’t all that new. In the 1920s in Conditioned Reflexes, Ivan Pavlov describes his observations of different behavioral responses in dogs “depending on the type of nervous system of the animal.” And in 1938, an American psychologist named Meredith P. Crawford developed a behavior rating scale for young chimpanzees, publishing the work in the Journal of Comparative Psychology. Jane Goodall was a bit more personal, noting in the memoir Through a Window, that the personality of one chimp named Passion was as different from another chimp’s “as chalk from cheese.”
Yet only recently has scientific opinion shifted beyond viewing this variation as meaningless noise. Researchers now want to quantify individual variation and figure out why it exists. For example, scientific observers are increasingly coming to the realization that animals don’t always behave in the best way in a given situation, says Alexander Weiss, a psychologist at the University of Edinburgh who studies evolution of personality. An animal may not go off on its own to look for food, even though that seems like the best choice. “They are behaving suboptimally,” Weiss says, “what is underlying that?”
Imagining primates and even pets with their own personalities isn’t so hard. But some of the most fascinating work stars less predictable animals–birds, fish, hermit crabs and spiders, among others. Unlike the shark quiz offered by the Discovery Channel, the studies distinguish not one species from the next, but individuals within a species.
Finger’s species of choice is the lemon shark, and with good reason. These sharks are the lab mice of the sea. Scientists know a ton about the biology of lemon sharks–they are easy to capture and handle, and they are amenable to captivity. What’s more, Finger works with juveniles, which measure a meter or less in length.
After catching and tagging these sharks in the shallow waters of Bimini, about 60 miles east of Miami, Finger and his colleagues run a battery of tests in experimental pools. In a test looking for sociability, they allow the sharks to swim around together for about 20 minutes, documenting every 30 seconds whether a shark is interacting with its peers. “If you see two sharks following each other, that is typical social behavior,” says Finger. “It’s very similar to humans in the sense that some people will be in groups more often than other people.” In another test looking for an interest in novelty, Finger and his team put sharks, one at a time, in a 40-by-20 foot pen that the sharks have never experienced. The team documented how much each shark explored the pen.
In both cases, sharks are tested again after a week and after six months (returning to their natural habitat during the longer interim, only to be caught once again). The repetition allows the researchers to test for consistency. Preliminary results presented in July in Albuquerque, New Mexico, at the Joint Meeting of Ichthyologists and Herpetologists show that individual lemon sharks do have different degrees of sociability and novelty-seeking. “They are not machines, they have personality,” Finger says.
What’s more, initial data hint at a trade-off: Sharks more interested in novelty tend to be less social, and vice versa. Finger suspects that animals that have the safety of a group take fewer risks. Novelty-seekers venture off on their own and, though more prone to danger, they also don’t have to share the food they find with others. It’s sort of how the risk-takers and game-changers in human societies aren’t always so good at playing well with others.
In time, scientists hope to compare personality data from a range of species to try to understand why animals, including people, have personality and how it evolved. Personality, and even a mix of personalities within a group, may turn out to have huge consequences for survival. “We find in the human literature that personality is massively important for things like work satisfaction, marital stability, how long we live, whether we get heart attacks,” Weiss says.
Until then, Finger’s big message is that “you can’t generalize behavior of one individual to a species.” Even if a species as a whole tends to be more aggressive than another, some individuals within that species could still be pretty mellow.
So although your concept of self isn’t likely to be wrapped up in an online quiz, you may find comfort in Finger’s words. Maybe
you are a great white, but not every great white is the same.
August 5, 2013
People have been fascinated and terrified by sharks for thousands of years, so you would think that we know a fair bit about the roughly 400 named species that roam the ocean. But we have little sense of how many sharks are out there, how many species there are, and where they swim, let alone how many existed before the advent of shark fishing for shark fin soup, fish and chips, and other foods.
But we are making progress. In honor of Shark Week, here’s an overview of what we have learned about these majestic citizens of the sea in the past year:
1. Sharks mostly come in shades of gray, and it’s likely that they only see that way as well. Now, that knowledge is being put to use to protect surfers and swimmers offshore. In 2011, researchers from the University of Western Australia found that, out of 17 shark species tested, ten had no color-sensing cells in their eyes, while seven only had one type. This likely means that sharks hunt by looking for patterns of black, white and grey rather than noticing any brilliant colors. To protect swimmers, whose bodies often look like a tasty seal from below, the researchers are working with a company to design wetsuits that are striped in colorblocked disruptive patterns. One suits will alert sharks that they aren’t looking at their next meal, and a second suit that will help camouflage swimmers and surfers in the water.
2. The thresher shark has a long, scythe-shaped tail fin that scientists long-suspected was used for hunting, but they didn’t know how. This year, they finally filmed how the thresher shark uses it to “tail slap” fish, killing them on impact. It herds and traps schooling fish by swimming in increasingly smaller circles before striking the group with its tail. This strike usually comes from above instead of sideways, an unusual technique that allows the shark to stun multiple fish at once—up to seven, the study found. Most carnivorous sharks only kill one fish at a time and so are comparatively less efficient.
3. How many sharks do people kill each year? A new study published in July 2013 used available shark catch information to estimate the global number—a staggering 100 million sharks killed every year. Although the data are incomplete and often do not include those sharks whose fins are removed and bodies are thrown back to sea, this is the most accurate estimate to date. Slow growth and low birth rates of sharks mean that they are not able to repopulate fast enough to catch up with the loss.
4. The 50-foot giant megalodon shark is a staple of shark week, reigning as the great white’s larger and even more terrifying ancestor. But a new fossil discovered in November turns that supposition on its head: it looks like the megalodon isn’t a great white shark ancestor after all, but is more closely related to the fish-munching mako sharks. The teeth of the new fossil look more like great white and ancient mako shark teeth than megalodon teeth, which also suggests that great whites are more closely related to mako sharks than previously thought.
5. Sharks are worth more alive in the water than dead on the plate (or bowl). In May, researchers found that shark ecotourism ventures—such as swimming with whale sharks and coral reef snorkeling—bring in 314 million U.S. dollars globally every year. What’s more, projections show that this number will double in the next 20 years. In contrast, the value of fished sharks is estimated at 630 million U.S. dollars and has been declining for the past decade. While dead sharks’ value terminates after they are killed and consumed, live sharks provide value year after year: in Palau, an individual shark can bring up to 2 million dollars in benefits over its lifetime from the tourist dollars that pour in just so that people can view the shark up close. One citizen science endeavor even has snorkeling travelers snapping photos of whale sharks in an effort to help researchers. Protecting sharks for future ecotourism endeavors just makes the most financial sense.
6. Bioluminescence isn’t just for jellyfish and anglers: even some sharks are able to light up to confuse predators and prey alike. Lanternsharks are named for this ability. It’s been long known that their bellies light up to blend in with sunlight shining down from above, an adaptation known as countershading. But in February, researchers reported that lanternsharks also have “lightsabers” on their backs. Their sharp, quill-like spines are lined with thin lights that look like Star Wars weaponry and send a message to predators that, “if you take a bite of me, you might get hurt!”
7. What can an old sword tell us about sharks? Far more than you might expect—especially when those swords are made of shark teeth. The swords, along with tridents and spears collected by Field Museum anthropologists in the mid-1800s from people living in the Pacific’s Gilbert Islands, are lined with hundreds of shark teeth. The teeth, it turns out, come from a total of eight shark species—and, shockingly, two of these species had never been recorded around the islands before. The swords give a glimpse into how many more species once lived on the reef, and how easy it is for human memory to lose track of history, a phenomenon known as “shifting baselines.”
8. Sharks know some pretty neat tricks even before they’re born. Bamboo shark embryos develop in egg cases that float on the high seas, where they are vulnerable to being eaten by all manner of predators. Even as developing embryos, they can sense electric fields in the water given off by a predator—just like adults. If they sense this danger nearby they can hold still, even stopping their breathing, so they won’t be noticed in their egg cases. But for sand tiger shark embryos, which develop inside the mother, their siblings can pose the biggest threat—the first embryos to hatch from eggs, at just roughly 100 millimeters long, will attack and devour their younger siblings.
9. Shark fin soup has been a delicacy in China for hundreds of years, and its popularity has only increased in the last several decades with the country’s growing population. This increasing demand has heightened the number of sharks killed every year, but the expensive dish may be losing some fans.
Even before last year’s Shark Week, the Chinese government banned the serving of shark fin soup at official state banquets—and the conversation hasn’t died down since. Countries and states banning the trade of shark fins and regulating the practice of shark finning have made headlines this year. And just a few weeks ago, New York Governor Andrew Cuomo signed a ban of the possession and sale of shark fins in the state that will go into effect in 2014.
10. Shark fin bans aren’t the only method of protecting sharks. The island nations of French Polynesia and the Cook Islands created the largest shark sanctuary in December of 2012—protecting sharks from being fished in an area of over 2.5 million square miles in the south Pacific Ocean. And member countries of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) voted to place export restrictions on five species of sharks in March 2013. Does this mean that the general perception of sharks is changing for the better and that the public image of sharks is veering away from its “Jaws” persona? That, in essence, is up to you!
–Emily Frost, Hannah Waters and Caty Fairclough co-wrote this post
June 21, 2013
Sharks have it tougher than most when it comes to public relations. Unlike a number of disgraced celebrities, politicians and athletes who’ve somewhat managed to come out on the other side of a scandal, the marine creatures haven’t been able to shake their bad reputation for 38 years. What’s more, they probably didn’t even deserve it in the first place.
Stephen Spielberg’s Jaws, which premiered this week in 1975, was adapted from a 1974 novel of the same name. The book was inspired by real-life events, a series of shark attacks along the Jersey Shore in July 1916 that killed four people. The type of shark behind the attacks was never confirmed, but Spielberg picked the prime suspect to be his villain: the great white shark. However, the movie has allowed viewers to paint all kinds of sharks as massive, bloodthirsty killers with a taste for revenge.
That’s about 440 species of sharks. Talk about one fish (unknowingly) ruining it for the rest of them
Here’s the thing: most of these sharks don’t have a taste for human blood—they don’t express special interest in mammal blood as opposed to fish blood. Diets vary across the many species around the globe, but they usually include other fish, crustaceans and marine mammals such as seals. The biggest species, the whale shark (which can reach up to 60 feet in length) only feeds on plankton.
And those supposed voracious appetites that in movies give them unnatural speed?
Most of the time, sharks are just not hungry. While they can reach up to 30 miles per hour or more in sudden bursts, they tend to cruise at a lackadaisical pace of about five miles per hour. And sharks that swim with their mouths open aren’t always in attack mode—they open wide to ventilate their gills.
Not all sharks are big enough to ram into and capsize unsuspecting boats, either. About 80 percent of all shark species grow to be less than five feet long. Only 32 species have been documented in attacks with humans, the repeat players being the great white, tiger and bull sharks. Your lifetime risk of suffering an attack from one of these predators is pretty small: 1 in about 3,700,000. Compare that to your odds of dying in a car accident (1 in 84), a fall (1 in 218), a lightning strike (1 in 79,746) or fireworks (1 in 340,733). Yet many people have an irrational fear of sharks, born from movies like Jaws.
Today, an emerging public relations campaign is underway to show that sharks aren’t the bad guys anymore—they’re the victims. According to the International Union for Conservation of Nature, 30 percent of open-ocean sharks and stingrays, their fellow sea dwellers, face extinction. True, 12 people are killed by sharks each year worldwide. However, 11,417 sharks are killed every hour by humans, adding up to roughly 100 million a year. Some of these deaths are intentional: sharks are often hunted for their fins to make soup or caught for sport, their toothy jaws kept as trophies. Others fall prey to recreational fishing or nets meant to protect humans. Still others die because their habitats are slowly disappearing due to human activity, which reduces their food supply and pollutes the water pumping through their gills.
The numbers are stark: In some parts of the world, the scalloped hammerhead shark population has shrunk by 99 percent in the last 30 years. In tropical Atlantic waters, the population of silky sharks is now half of what it was in he early 1970s. The Pacific’s whitetip shark population fell by 93 percent between 1995 and 2010.
This spring, an international organization implemented a ban on international trade in the whitetip, the porbeagle and three species of hammerhead sharks. The Shark Conservation Act, signed into law by President Barack Obama in 2011, closed loopholes in existing shark conservation legislation and promoted U.S.-led protection efforts worldwide. Even Discovery Channel’s Shark Week, which for a quarter of a century has hooked viewers with the promise of a fear-filled thrill ride, is partnering with conservationists to help boost sharks’ public image.
But perhaps the biggest shift in the Jaws-dominated shark culture is this: some survivors of shark attacks are actually teaming up to save the creatures that once nearly killed them. As shark attack survivor Debbie Salamone explains on their PEW Charitable Trust website, “If a group like us can see the value in saving sharks, shouldn’t everyone?”