Conservation & Science

‘Historic moment’: Nations act to save Pacific bluefin tuna

Today in Busan, South Korea, Pacific nations came together and agreed, for the first time, to recover the population of Pacific bluefin tuna to a sustainable level.

Bluefin tuna at auction in Tokyo’s Tsukiji Market. Japan consumes 90 percent of the world;s catch of bluefin tuna. Photo courtesy Associated Press.

“This is a historic moment for this remarkable species, which is so important to the ocean ecosystem and to coastal communities around the Pacific Rim,” said Margaret Spring, Chief Conservation Officer for the Monterey Bay Aquarium.

At the annual meeting of the Northern Committee of the Western and Central Pacific Fisheries Commission—the body responsible for managing tunas and other highly migratory species across the western Pacific Ocean—international delegates discussed ways to recover the population of Pacific bluefin tuna after years of decline. Ultimately, they took a major step forward by agreeing to recover the population to a sustainable level and establishing a long-term management plan.

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John Kerry: It’s time to act for Pacific bluefin tuna

For John Kerry, saving the ocean is a “life or death” issue. As an ocean champion in Congress, and as Secretary of State, securing a healthy future for the ocean was central to his public service. Now he has joined with conservation leaders and with some of the world’s top chefs in a call for immediate action to recover one of the most valuable—and depleted—fish in the ocean, Pacific bluefin tuna:

John Kerry has been an ocean advocate, in Congress and as Secretary of State.

“Of all the environmental progress achieved in recent years, it is particularly important that the one direct line that so many, from a wide variety of different backgrounds and ideologies, have drawn is between the fate of our oceans and our existence, our economic well-being, and the diversity of human cultures around the world. Whether it’s through the U.N. Sustainable Development Goals or the Our Ocean Conferences, which I founded as Secretary of State, or through groundbreaking work in corporations and philanthropies, together the international community has elevated the centrality of the oceans to our global responsibilities.

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Chefs worldwide speak out to save Pacific bluefin tuna

Leading chefs on five continents have pledged to keep Pacific bluefin tuna off their menus until there’s effective international action to manage the fishery and reverse a precipitous decline in the population.

Chef Alex Atala of Brazil: “We are not living within our means when it comes to Pacific bluefin tuna.”

Nearly 200 prominent chefs and culinary leaders from around the world—including Alex Atala of Brazil, James Beard Award nominee Michael Cimarusti of the United States and Annabel Langbein of New Zealand—say Pacific Rim nations must act immediately to recover Pacific bluefin tuna.

Bluefin tunas are among the planet’s most iconic and prized fish. In recent decades, global demand for Pacific bluefin tuna has driven the population down to a critical level—just 2.6 percent of its historic abundance, significantly lower than those of the two other bluefin tuna species, Atlantic and Southern bluefin tunas, and lower than all other assessed tuna species.

The chef pledge comes as fishing nations charged with securing the future of Pacific bluefin tuna prepare to meet in Busan, South Korea from August 28 to September 1, to craft a new recovery plan in the face of growing international criticism that the current plan falls far short of what’s needed.

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Science shows a path to recover Pacific bluefin tuna

The ruby-red slice of maguro presented on a piece of nigiri sushi does nothing to convey the sheer power of Pacific bluefin tuna. These top ocean predators can grow to be twice the size of lions; at top swimming speed, they’re faster than gazelles. But it’s been a huge challenge to halt the decline of these incredible fish.

Pacific bluefin tuna at the Monterey Bay Aquarium. Photo by Monterey Bay Aquarium/Randy Wilder

The Pacific bluefin population is down to just 2.6 percent of its unfished level—yet it continues to face intense fishing pressure. The fish are prized commercially, command staggering market prices, and are difficult to manage because they cross through national and international waters on trans-Pacific migrations.

Monterey Bay Aquarium has long advocated for use of the best available science to inform management decisions that can bring the Pacific bluefin population back to a healthy level. Now researchers at the Aquarium, together with colleagues from Harvard University and the National Museum of National History, have identified new evidence of migration trends that underscore the need for comprehensive fishing restrictions and enforcement across the Pacific—especially in the Western Pacific, where all Pacific bluefin spawn, and where most of the fish are caught.

The source of spawning-age fish

The analysis, published in Science magazine, concludes that—in many years—the majority of spawning-age bluefin tuna in the Western Pacific are migrants who left the waters off Japan when they were just one to two years old, and spent the next four to six years on rich feeding grounds off the coasts of California and Mexico, before returning to the Western Pacific.

New research supports the need to limit fishing for Pacific bluefin tuna — and to enforce the limits — in order to recover the species. Photo courtesy NOAA

If too many of the young fish are caught in the Western Pacific before they can make the migration east, there won’t be enough returning fish years later to maintain or recover the already-depleted population.

And if fishing pressure is too great in the Eastern Pacific, the fish won’t survive to make the migration back to their spawning grounds near Japan.

“These fish were passing through two gauntlets, in the west and in the east, before they had a chance to spawn,” said Dr. Andre Boustany, the Nereus Principal Fisheries Investigator for the Aquarium. “Many fish have to pass through both the Western and Eastern Pacific Ocean. So by taking too many of them out in both locations, we end up with a severely depleted population.

“We need much better management of the fishery in the west, and to continue to at least maintain current management in the east,” he added.
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Designing an animal-friendly fin tag

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 Science detailing 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.”

Fin flow
A traditional tag can cause drag on an animal as it swims through the water.

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.” Read more…

Playing your part through citizen science

On Earth Day,  Monterey Bay Aquarium staff and volunteers joined in March for Science events along with tens of thousands of people in more than 600 cities around the world. With representatives at marches in seven cities across the U.S. and Europe, the Aquarium stood up for one of our founding principles: that evidence-based science should drive conservation action.

From recording and sharing wildlife observations to reporting stranded sea otters, there are many ways to contribute as a citizen scientist.

It’s clear that the March for Science isn’t just about scientists, and it’s more than a one-day phenomenon. People of all ages and backgrounds participated, because you don’t have to be a trained scientist to appreciate the benefits science offers—or to contribute to the scientific process.

Much of the science taking place at the Aquarium, from saving sea otters to tracking white sharks, relies on dedicated citizens quite literally taking science into their own hands. Thanks to our increasingly connected society, opportunities abound for everyone from middle school students to retired teachers to participate in citizen science at the Aquarium—and beyond. Here are a few of the many ways you can become a citizen scientist. Read more…

Using science to save ocean wildlife

The Monterey Bay Aquarium is a science-driven organization, and rigorous science underpins all of our public policy, research and education programs. Much of our research centers on marine life that visitors can also see in our exhibits – from sea otters to sharks and tunas, even our giant kelp forest. Here’s some of what we’ve learned over the past 30-plus years that is contributing to conservation of key ocean species and ecosystems.

A sea otter works to crack a mussel shell open on a rock off the coast of Moss Landing, California. Photo by Jessica Fujii

Sea otters crack open tool-use secrets

Revolutionary female scientist Jane Goodall was the first person to discover that chimps use tools and live within complex social systems. Our team of female researchers are walking in Jane’s footsteps with their recent studies on use of tools by another mammal: the sea otter. When observing sea otters along the Monterey Peninsula, sometimes we can hear a “crack, crack, crack!” above the roar of the tide. That sound comes from sea otters using rocks and other tools to open prey items, such as crabs or bivalves, as they float on their backs. Sea otters are avid tool users, but until recently not much was known about how sea otters choose their tools, what aspects of their environments influence tool use, or whether they teach tool use to other otters. The Aquarium’s decades of research into sea otter behavior provided years of observations of sea otter foraging and tool-use behavior, including sea otter pups pounding empty fists against their chests. Could such activity be instinctual? Research Biologist Jessica Fujii has devoted much of her young career to studying the frequency and types of tools used and whether tool use can be coded in sea otter genes. Jessica is looking ahead to see how sea otters learn, teach, and eventually master tool use in the wild.

A sea otter rests in an eelgrass bed in Elkhorn Slough National
Estuarine Research Reserve. Sea otters contribute to the recovery of eelgrass and ecosystem health in this vital wetland on Monterey Bay. Photo by Ron Eby.

Sea otter surrogacy helps restore Elkhorn Slough

With 15 years of experience rescuing, rehabilitating, and then releasing surrogate-reared sea otters into Elkhorn Slough, an estuary near Moss Landing, California, the sea otter research team at the Aquarium began to wonder how and if their work was affecting the otter population there. Does releasing a few animals into the slough each year really make any difference? After crunching some serious numbers from the surrogacy program and the U.S. Geological Survey’s (USGS) annual sea otter census, the researchers discovered that it did. Nearly 60 percent of the 140 or so sea otters living in Elkhorn Slough today are there as a result of the Aquarium’s surrogacy program. While we’d known that sea otters served as ecosystem engineers for the giant kelp forests in Monterey Bay, we have now documented that sea otters in Elkhorn Slough are restoring the health and biodiversity of the estuary. This gives us further insights into how sea otters may contribute to coastal ecosystem resilience. Read more…

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