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 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?”
April 3, 2013
For decades, a total of 124 swords, tridents and spears taken from the Pacific Ocean’s Gilbert Islands in the mid-1800s sat untouched in vaults in Chicago’s Field Museum. The weapons—each made up of dozens of individual shark teeth that islanders lashed to a wooden core with coconut fibers—were primarily considered artifacts of anthropological value.
Then, Joshua Drew, a marine conservation biologist at the museum, had an unusual idea: that the shark teeth lining the serrated blades could also serve as an ecological snapshot of the reefs that lined the islands more than a century ago. Sharks can be clearly identified solely by their teeth, so the teeth that islanders had harvested and used for their weapons might reflect historical biodiversity in the reefs that’s since been lost due to environmental degradation.
When Drew and others closely examined the hundreds of teeth on the weapons, they found that they came from eight different shark species, six of which were known to commonly swim in the Gilbert Islands’ waters. Two species, though—the dusky shark (Carcharhinus obscurus) and the spottail shark (Carcharhinus sorrah)—were something of a surprise. When the researchers looked at the scientific literature and various museum holdings of fish collected in the area, they found that these two species had never been documented within thousands of miles of the islands.
Drew calls this “shadow biodiversity”—a reflection of the life that lived in an ecosystem before we even started studying what was there. “[These are] hints and whispers of what these reefs used to be like,” he said in a press statement accompanying the paper documenting his team’s find, published today in PLOS ONE. “It’s our hope that by understanding how reefs used to look we’ll be able to come up with conservation strategies to return them to their former vivid splendor.”
Working with Mark Westneat, the museum’s curator of fishes, and Christopher Philipp, who manages the anthropology collections, Drew classified each tooth on every weapon by shark species, primarily using field guides and photos. In cases where the tooth’s identity was ambiguous, he made use of the Museum’s own ichthyological holdings, comparing it to preserved specimens from each shark species.
Because dusky and spottail shark teeth were found on the weapons—crafted sometime between the 1840s and 1860s, shortly before they were collected—the researchers believe these two species were once part of the ecosystem and have since been eradicated. There is the possibility that the teeth were harvested elsewhere and came to the Gilbert Islands via trade, but the team says it’s unlikely.
For one, sharks figure largely in the islanders’ traditional culture, and it’s well-known that they had effective shark-fishing techniques, making it unlikely that they’d go to the trouble of exporting teeth from afar. The two species’ teeth were among the most common found on the weapons, so it also stands to reason that they were fairly abundant nearby. Secondly, there is no historical or archaeological evidence that trade occurred between the extremely remote Gilbert Islands and either the Solomon Islands (the closest known location of spottail sharks) or Fiji (for dusky sharks).
It’s impossible to know for sure, but given the environmental degradation that’s occurred over the past century in the Pacific’s coral reefs, the researchers suspect that humans played a role in these sharks’ local eradication. Because sharks mature slowly and have a small number of offspring per individual, they can be wiped out quickly by moderate levels of fishing, and the commercial shark fishing industry started up in the area as early as 1910.
Rigorous fish surveys of the Pacific didn’t begin for a few more decades, so these weapons—and perhaps other human artifacts that incorporate biological specimens—serve as a valuable time capsule of the ecosystems that predated scientific study. Drew thinks that the “shadow diversity” we’ve since lost should inspire people in the marine conservation field to recreate the biodiversity that predates the Industrial Age.
“When we set up modern conservation plans, we shouldn’t sell ourselves short,” he told Nature last year, when he revealed his preliminary results at a conference. “We might not recapture the vivid splendor of those super-rich levels, but this information argues for setting up management plans to protect what sharks are there.”
December 18, 2012
Despite covering 70 percent of the earth’s surface, the ocean doesn’t often make it into the news. But when it does, it makes quite a splash (so to speak). Here are the top ten ocean stories we couldn’t stop talking about this year, in no particular order. Add your own in the comments!
2012: The Year of the Squid From the giant squid’s giant eyes (the better to see predatory sperm whales, my dear), to the vampire squid’s eerie diet of remains and feces, the strange adaptations and behavior of these cephalopods amazed us all year. Scientists found a deep-sea squid that dismembers its own glowing arm to distract predators and make a daring escape. But fascinating findings weren’t relegated to the deep: at the surface, some squids will rocket themselves above the waves to fly long distances at top speeds.
James Cameron Explores the Deep Sea Filmmaker James Cameron has never shied away from marine movie plots (See: Titanic, The Abyss), but this year he showed he was truly fearless, becoming the first person to hit the deepest point on the seafloor (35,804 feet) in a solo submarine. While he only managed to bring up a single mud sample from the deepest region, he found thriving biodiversity in the other deep-sea areas his expedition explored, including giant versions of organisms found in shallow water.
Small Fish Make a Big Impact Forage fish—small, schooling fish that are gulped down by predators—should be left in the ocean for larger fish, marine mammals and birds to eat, according to an April report from the Lenfest Forage Fish Task Force. These tiny fish, including anchovies, menhaden, herring and sardines, make up 37% of the world’s catch, but only 10% are consumed by people, with the rest processed into food for farmed fish and livestock. With the evidence mounting that forage fish are worth more as wild fish food, state governments and regional fishery management councils are making moves to protect them from overfishing.
Marine Debris and Plastic Get Around In June, a dock encrusted with barnacles, sea stars, crabs and other sea life washed ashore on the coast of Oregon. It had floated across the Pacific from a Japanese port more than 5,000 miles away—a small piece of the estimated 1.5 million tons of marine debris set afloat by the 2011 Tohoku tsunami. But that’s not the only trash in the sea. Researchers found ten times as much plastic in the “pristine” Antarctic oceans than they expected. Some species are even learning to adapt to the ubiquitous ocean plastic.
Taking Measure of Coral Reef Health Australia’s iconic Great Barrier Reef, so large it can be seen from space, is not doing well. An October study found that since 1986, half of the living coral has died because of warming water, predation and storm damage. And it’s not just Australia: the December Healthy Reefs report gave most Mesoamerican reefs a “poor” rating. It’s hard to escape that gloom, but there were glimmers of hope. Some coral species proved able to adapt to warmer water, and changing circulation caused by the warming ocean may create refuges for coral reef habitat.
Shark Finning Slowing Down? The fishing practice of shark finning—slicing off a shark’s fins before tossing it back in the ocean to slowly sink and suffocate—began its own slow death in 2012. A steady stream of U.S. states have banned the sale of shark fins
ning; the European Union will now require fisherman to land sharks with their fins on; four shark sanctuaries were created in American Samoa, the Cook Islands, Kosrae and French Polynesia; and, in July, China announced that official banquets would be prohibited from serving shark fin soup (although the ban may take up to three years to go into effect).
Arctic Sea Ice Hits All-Time Low On September 16, sea ice extent reached a record low in the Arctic, stretching 3.41 million square kilometers—that’s 49% lower than the 1979-2000 average minimum of 6.7 million square kilometers. What’s more, its melt rate is increasing: 2012 had the largest summer ice loss by more than one million square kilometers. This change is expected to affect ecosystems—from polar bears to phytoplankton—and accelerate warming in the area, eventually melting Greenland’s ice sheet and raising sea level dramatically.
Hurricane Sandy Elevates Awareness of Sea-Level Rise This year certainly opened our eyes to the severity of climate change and sea-level rise. The east coast of the U.S., where scientists project sea-level will rise three to four times faster than the global average, got a glimpse of its effects when Hurricane Sandy caused $65 billion in damage, took at least 253 lives, and flooded Manhattan’s subways in October. The disaster inspired The Economist, Bloomberg Businessweek and other major news sources to take a closer look at climate change and what it means for us all.
Counting Ocean Animals from Space Scientists took advantage of satellite technology this year to learn more about ocean wildlife. The first satellite-driven census of an animal population discovered that there are twice as many emperor penguins in Antarctica as previously thought, including seven new colonies of the large flightless birds. A second study tracked the travels of sea turtles by satellite, which could help researchers get a better idea of where they might interact with fisheries and accidentally end up caught in a net.
The Ocean Gets a Grade The first tool to comprehensively assess ocean health was announced in August 2012—and the ocean as a whole received a score of 60 out of a possible 100. This tool, the Ocean Health Index, is novel in that it considered ten ways the ocean supports people, including economies, biodiversity, and recreation. The U.S. scored a 63, ranking 26th globally, while the uninhabited Jarvis Island took home an 86, the top grade of the 171 rated countries.
–Hannah Waters, Emily Frost and Amanda Feuerstein co-wrote this post