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!”
February 7, 2013
Scientists have long known that various marine animals use the earth’s magnetic forces to navigate waters during their life cycles. Such inherent navigational skills allow animals return to the same geographic area where they were born, with some migrating thousands of miles, to produce the next generation of their species.
As hatchlings, sea turtles scuttle from their sandy birthplace to the open sea as if following an invisible map, and, as adults, the females return to that spot to lay their own eggs. Bluefin tuna home in on their natal beaches after years at sea to spawn. Similarly, mature sockeye salmon leave open water after gorging on zooplankton and krill to swim back to the freshwater streams and rivers in which they were born.
But the mechanisms underlying this behavior are not well understood for most species, including the silver-bellied salmon. Previous studies suggest that tiny variations in earth’s magnetic field might have something to do with it, but research has been mostly limited to laboratory experiments—until now.
Using fisheries data spanning 56 years, researchers examined sockeye salmon’s mysterious sense of direction in their natural habitat. The findings, reported online today in Current Biology, show that sockeye salmon “remember” magnetic values of geographic locations. They imprint their birth location on this map when they leave their freshwater home for the sea, and use it as a compass during their journey back several years later, successfully returning home to spawn.
The salmon in this study originate in British Columbia’s Fraser River. They typically spend two to four years at sea, distributed widely throughout the Gulf of Alaska. As ruby-colored adult salmon, they begin their trek home. But on their way, they encounter a roadblock: Vancouver Island, the top of a submerged mountain range that stretches for 285 miles from the Juan de Fuca Strait in the south to Queen Charlotte Straight in the north. To get back to the Fraser River, the fish have to choose—the northern inlet or the southern inlet?
If the fish did possess some internal GPS that uses earth’s magnetic field as a map, researchers expected to see the salmon’s choice of inlet change in predictable ways over the years. This is because the planet’s magnetic field doesn’t remain constant; the field’s intensity and small-scale patterns change gradually over time through a process called geomagnetic field drift, caused mainly by movement in the Earth’s fluid core.
And that’s exactly what researchers observed: salmon showed a greater preference in a given year for the inlet that most closely resembled the magnetic signature of the Fraser River when they swam from it two years earlier. Their homeward route reflected how closely the field at each entryway, at the time of their return, resembled the field that the salmon experienced two years before, when they left the river to forage at sea.
Specifically, as the difference in the magnetic field’s strength between the Fraser River and Queen Charlotte Strait decreased, a higher proportion of salmon migrated through the northern inlet. Likewise, when the difference in magnetic intensity between the river and the Strait of Juan de Fuca decreased, a higher proportion of salmon migrated through the southern inlet.
For salmon, this ability is important, and in some cases, a matter of life and death. Efficiently navigating from foraging grounds to coastal breeding areas means more time spent feeding in open water, which translates into more energy for the journey home, researchers say. The imprinting capacity also ensures salmon reach their spawning sites at the right time.
Understanding this capacity may have implications for both wild and farmed salmon, a commercially important fish. For the last decade, salmon has been the third most consumed type of seafood in the United States, behind canned tuna and shrimp, with the average American citizen chowing down on two pounds of the fish per year.
“The Earth’s magnetic field is quite weak compared to the magnetic fields that humans can produce,” said study author Nathan Putman, a professor in the fisheries and wildlife department at Oregon State University, in a statement. “If, for instance, hatchery fish are incubated in conditions with lots of electrical wires and iron pipes around that distort the magnetic field, then it is conceivable that they might be worse at navigating than their wild counterparts.”
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