For over two decades, Monterey Bay Aquarium and Stanford University have partnered to study some of the world’s most mysterious ocean predators at the Tuna Research and Conservation Center (TRCC). Some of the latest work to come from the TRCC include an innovative tuna tag design, and a paper recently published in the journal Sciencedetailing the discovery of a hydraulic mechanism in tuna dorsal fins, which helps them swim with speed and precision.
In his office at Stanford University’s Hopkins Marine Station in Pacific Grove, California, Dr. Vadim Pavlov holds a pale, sleeve-like device. Its smooth lines and soft edges make it seem more like a child’s toy than a high-tech scientific product. He slips the device over a model of a dolphin dorsal fin and “swims” it around his office, mimicking a dolphin’s movements as it leaps and twists out of the water.
The device is a prototype of a new tag design intended to track top ocean predators, such as sharks and tunas, without using pins and bolts that penetrate the fin.
“Even when the dolphin leaps, the tag stays on,” Vadim says. “But, how did we do it?”
Form and function
Vadim is one of the world’s top experts in biomimetics: the science of translating natural phenomena, such as the flow of water over a dolphin’s dorsal fin, into useful technology.
For years, he’s been tackling the challenge of tagging and tracking wildlife in the open ocean. He wanted to provide “animal-friendly” tags as an alternative to the invasive bolt tags anchored into the fins of apex marine predators such as sharks, dolphins and tunas. For Vadim, that’s not just a scientific goal; it’s personal, inspired by his experience as a free diver. “I don’t like swimming with lots of gear, so I don’t think [animals] do either,” he says. “They are very sensitive to anything on their bodies.”
Traditional bolt tags, a key tool in marine animal field studies for the last half century, are kind of like an ear piercing. Researchers punch through the cartilage and collagen in the dorsal fin and attach tags that can help track the animals, or collect environmental data such as salinity, temperature, and depth.
“But over time, these bolt tags do not move with the animals,” Vadim explains. “They can alter the flow of water around the animal’s bodies, and can even cause animals to turn more in one direction over time,” he says. “The faster the animal swims, the greater the energy needed to override the drag.”
Smaller animals, such as harbor porpoises and juvenile dolphins and sharks, are especially susceptible to the pitfalls of traditional bolt tags. “There’s a conflict between the animal’s biology and the technological requirements of the tag,” says Vadim. “So my job became how to reconcile that disconnect.” Continue reading Designing an animal-friendly fin tag
The ocean keeps scrupulous records of its past: The comings and goings of myriad creatures, the evolving conditions they lived in, even details of who ate what.
“The ocean has a memory. We just have to tap into it,” says Kyle Van Houtan, the Aquarium’s science director.
Consider the secrets we might glean from studying a single blade of algae – commonly known as seaweed. During the year or two it was alive, were the surrounding waters pleasantly cool, or unusually acidic? What plants were its neighbors? And what was the world around it like?
With the help of modern technology, historical specimens can now answer some of these questions. And in the world of ocean science, the details amount to hidden treasure.
Like antiques that startle and thrill their owners, proving to be worth small fortunes, pressed seaweeds can yield surprisingly valuable data. Museums and herbariums hold collections of these souvenirs from the ocean, often dating back decades – and too often left unnoticed in deep storage.
Kyle lucked into one such trove when he started work at the Aquarium last year.
John O’Sullivan, the Aquarium’s Director of Collections, was in Mexico on a mission. A young white shark equipped with an electronic tag had traveled over 650 nautical miles south from its release point in Monterey Bay, and the tag had popped off somewhere along the central coast of Baja California. The tag contained a complete data set documenting the shark’s movements and physiology since its release, and John aimed to recover it.
Instead his guide, a local fisherman, led John to a shark graveyard.
A grisly grimace
Sometimes, commercial and sport fishermen accidentally ensnare juvenile white sharks off the coasts of California and Mexico. But locals in some communities consider it bad luck to discard the unmarketable parts, such as the heads, back into the ocean. Instead, they deposit these shark parts at dump sites in the Mexican desert.
In central Baja, just north of Guerrero Negro, John and a team of local Mexicans encountered hundreds of shark heads, in various stages of decay. Some were fresh; others were rotting. Some had skin that was dry and well-preserved—in other words, mummified—in this arid location.
Many of us would turn away from that gruesome sight. But John and his colleagues looked into the mouths of the shark-head mummies and saw an opportunity.
Every living thing is constantly shedding fragments of itself into the environment. Police detectives take advantage of this at a crime scene when they search for hair, skin or saliva—all of which contain DNA, a full genome of information unique to their owner.
Fishes, sharks and other marine organisms shed their DNA, too. In every cup of seawater, there are sloughed-off cells and waste from the animals that have swum, drifted or floated there.
This DNA from the environment is called eDNA. Over the past few years, scientists at the Center for Ocean Solutions (COS)— a partnership among the Monterey Bay Aquarium, the Monterey Bay Aquarium Research Institute (MBARI) and Stanford University—have investigated how scientists, conservationists and resource managers can use eDNA to gain critical information about marine ecosystems, more quickly and more cheaply than ever before.
Bluefin tunas are among the ocean’s most fabulous fish. Sleek and strong, they cross oceans in mere weeks, warm their bodies by capturing their metabolic heat, and live for decades. They’re also prized commodities, especially as sushi in restaurants around the world. Given bluefin’s high cultural and economic value, overfishing has driven some populations of these prized ocean predators into steep decline.
How to rebuild bluefin populations remains a critical question — one science can help us answer.
Researchers and fisheries managers around the world are working to protect and recover bluefin tuna populations. But conservation efforts must be informed by basic science: When do bluefin mature? Where do they travel in the ocean? When do they stop to eat?
In 1993, Barbara was recruited to Stanford from the University of Chicago. During the visit, she and Chuck hatched a plan to join forces and build a tuna facility at Stanford: the Tuna Research and Conservation Center (TRCC). They hoped to jointly accomplish two missions: to help the Aquarium exhibit tunas, and to start a research facility specializing in the biology of these Olympic-caliber athletes.
The science of “fish and chips”
For more than 20 years, the TRCC team has focused on big-picture tuna challenges. First up was learning how to keep yellowfin and bluefin tunas in captivity — research that eventually enabled the Aquarium to display the sleek predators in the Open Sea exhibit.
In 1996, the TRCC team began asking where tunas go in the wild. Barbara had worked with the father of tuna biology, Dr. Frank Carey (to whom the TRCC lab is dedicated), to track tunas with telemetry. Using tracking technology, the team has explored questions of where tunas travel in the ocean and how their bodies handle the extreme conditions they face on their migrations — between continents, from subtropical to temperate waters, and to depths of more than 6,000 feet. Their findings are helping inform conservation practices that could help bluefin tuna populations recover in years to come.
The TRCC team’s research has been especially challenging and transformative for one reason: It’s difficult to understand where animals go, and what they do, when they’re underwater and far from shore.
“Most of us from [a] ship — even I — look out at the ocean and see a homogeneous sea,” Barbara explained during a 2010 TED talk. “We don’t know where the structure is. We can’t tell where the watering holes are, like we can on an African plain.”
Using the “fish and chips” strategy, TRCC scientists have uncovered critical information about where tunas travel. In the early 2000s, they documented tunas making transoceanic journeys. Some of the bluefin born in Japan travel to the California coast, and some born in the Gulf of Mexico travel to the European coast. The discovery of these fishes’ highly migratory behavior has greatly improved our understanding of all three bluefin species, and informs international negotiations on conserving bluefin tuna populations.
Warm-blooded but cold-hearted
Other studies have uncovered where bluefin tunas eat and where they spawn — two crucial bits of information when it comes to protecting them and essential tuna habitats. A recent paper in the journal Science Advances identified key bluefin tuna feeding locations in the Pacific, and determined they prefer searching for food in specific conditions.
“They tend to select a certain temperature range to live in,” Chuck explains. “They also have the ability to dive and explore in very warm or very cold water, for short periods of time.”
In collaboration with tuna researchers in Japan, Chuck and the TRCC have been working in the Sea of Japan to find out where Pacific bluefin spawn, and what habitat the young fish utilize as they develop. Their work should be published later this year.
The TRCC team is making important discoveries about bluefin physiology, too. Unlike most fishes, tuna are warm-blooded, or “endothermic,” meaning they can heat their bodies above the temperature of the surrounding ocean. But not every body part gets warmed equally. Bluefin maintain heat in their eyes, brain, swimming muscles and guts. But their hearts are cold, experiencing temperature drops of tens of degrees Celsius during deep dives. How do tuna manage to keep their hearts pumping at temperatures that would stop a human heart?
In 2015, Barbara and colleagues published a paper in the Proceedings of the Royal Society of London B that answered this question. They found that adrenaline was the secret. Cold temperatures trigger an adrenaline rush, which helps maintain the level of calcium in tuna hearts. Without calcium, the heart would not be able to beat normally at extremely cold temperatures.
In May, Barbara will receive the 2016 Peter Benchley Ocean Award for Excellence in Science. The award is just one of several she has earned over the past two decades — including a MacArthur Foundation “genius grant” — but her tireless work is far from finished. There are still hundreds of questions to be answered, more bluefin to track, and populations to preserve.
A chance to inspire change
By tagging bluefin tuna in the wild and learning more about their physiology in captivity, the TRCC team is producing data crucial to sustainable management. Barbara hopes that by bringing together global scientists, fishers, managers and policymakers, we can ensure that collaboration increases, transfer of knowledge improves, and the steep decline of bluefin populations in the Pacific and the western Atlantic reverses in her lifetime.
Chuck has high hopes the Bluefin Futures Symposium will bring the science to bear on management solutions. “Everyone at the Aquarium that’s involved in this has high expectations there will be positive outcomes,” he says.
No two days are the same in the life of Chuck Farwell, manager of the Aquarium’s Tuna Research and Conservation Program. Some days he’s helping the husbandry team maintain our stock of Pacific bluefin tuna. Other days he’s on a boat at sea, surgically implanting electronic tracking tags into the bellies of fish. And some days he’s in Japan, advocating for the conservation and preservation of the Pacific bluefin tuna.
Chuck has been working with tuna since the 1960s, when he first surveyed albacore tuna ranges for the California Department of Fish and Wildlife. He joined the Aquarium before it opened in 1984, with a long-term vision of developing husbandry techniques to allow us to keep and maintain tuna. At the time, no aquarium outside Japan had ever kept tuna on permanent exhibit. In 1996, Monterey became the first, with displays of yellowfin and bluefin tuna.
Now, Chuck focuses on Pacific bluefin tuna, large predators that can migrate across ocean basins in a matter of weeks. They’re beautiful, lightning-fast and as majestic as they are delicious. The species is prized among seafood enthusiasts – primarily for the high-end sushi trade.
This summer, Monterey Bay Aquarium and Monterey Bay National Marine Sanctuary hosted Big Blue Live – an unprecedented series of live natural history broadcasts from PBS and the BBC. Big Blue Live highlighted the remarkable marine life that gathers in Monterey Bay, and celebrated the recovery of the bay as an ocean conservation success story of global significance. Many conservation efforts contribute to the health of the bay and our ocean planet, and we’eve highlighted several in a series of guest commentaries. This comes from Lindley Mease, a senior research analyst , and Kristen Weiss, an early career fellow – both at the Center for Ocean Solutions. The Center is a collaboration among the Stanford Woods Institute for the Environment and Hopkins Marine Station of Stanford University, the Aquarium and the Monterey Bay Aquarium Research Institute.
MPAs often aim to protect ocean habitats from local pressures, from fishing to offshore oil drilling. Research now suggests that they’re also an ideal way to address some local impacts of climate change. While resource managers might not be able to directly manage fossil fuel emissions, they can implement local mitigation and adaptation measures that help protect coastal ecosystems from impacts such as hypoxia (oxygen-deficient water) and ocean acidification.
It’s summer beachgoing season and with the recent spate of shark bite reports in the Carolinas, sharks are more top of mind than ever. But are shark attacks really on the rise?
Research published today by Stanford University’s Hopkins Marine Station and the Monterey Bay Aquarium shows that, indeed, the overall number of shark bites on the California coast is climbing gradually every year. But there’s a catch. Since 1950, the annual rate of shark attacks has actually decreased – and fairly dramatically.
Using data from the Global Shark Attack File, Aquarium shark biologist Sal Jorgensen and his Stanford colleagues discovered a surprising story. The research team noticed that even though the number of attacks was rising, they weren’t keeping pace with the tripling of California’s coastal population – from 7 million people in 1950 to 21 million coastal residents by 2013.
The numbers of surfers, scuba divers and swimmers rose at much faster rates than the overall population. So when the team weighted their data to reflect the number of ocean users, they found that the likelihood or rate of an individual being bit by a white shark dropped substantially – by 91 percent between 1959 and 2013.
“This shows that the goals of public safety and conserving the ocean wilderness, intact with top predators, are actually compatible.” Sal says. “Our results also suggest that attacks could be further reduced by modifying when and where we get in the ocean.”
Using a statistical model, the team was able to determine the most and least risky times and locations for shark attacks. According to their data, October through November – when sharks are feeding on seals along the coast – are the most likely times for attacks to occur. March through May are relatively safer times to be in the water – when most white sharks are far offshore at the mysterious White Shark Café.
The authors noted that beachgoers and water enthusiasts face many greater perils than a shark attack. Hospitalizations from drowning and scuba-related decompression sickness occur at much higher rates than those from shark bites.
“Our disproportionate fear of shark attacks is amplified by a lack of having control when we enter the ocean wilderness,” notes Sal, an avid surfer himself. “This type of data can give people the ability to have more control and minimize their risk.”
For instance, the results showed it’s 1,566 times safer to surf between San Diego and Los Angeles in March, compared with surfing between October and November in Mendocino County.
Making these types of informed choices would be far more effective at increasing public safety than culling, the research finds. In Australia, officials have tried to reduce public risk by killing white sharks in a large culling program – a tragic and uninformed approach. In fact, culling sharks is ineffective.
“These programs often serve more to reassure people rather than effectively increase beach safety,” says Francesco Ferretti, a postdoctoral research fellow at Hopkins Marine Station and the study’s lead author.
Though culls are meant to target white sharks, other shark species are often killed as well. Because of the importance of all shark species to maintaining the balance of the food web, culls can dramatically disrupt the ecosystem. And they’re extremely costly. The cull in western Australia is slated to cost $22 million.
Francesco says the money could be more wisely used to promote research and awareness of sharks, and to come up with more effective solutions to keep people from encountering sharks.
In California, white shark attack rates have declined so much that the researchers wonder if perhaps the numbers reflect a decrease in the shark population over the last half decade. An alternative possibility is that as populations of marine mammals – adult white sharks’ favorite prey – have bounced back, the sharks have relocated closer to their rookeries.
Marine mammals, especially elephant seals, tend to congregate on island beaches far away from those used by people. The Aquarium’s ongoing research with Hopkins colleagues may provide some answers in the near future.