Conservation & Science

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.
Read more…

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…

Our best Conservation & Science stories of 2016

It’s been an exciting year for ocean conservation at the Monterey Bay Aquarium.

We’ve shared how our care for the animals in our living collections—including snowy ploverscomb jellies, ocean sunfish and Pacific seahorses—contibutes to the conservation of their wild kin.

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The Aquarium helps rehabilitate threatened Western snowy plovers.

We’ve visited the Canadian cousins of Monterey Bay’s sea otters, explored how sea otters use tools, and assisted scientists working to decode the sea otter genome.

We’ve collaborated with our colleagues in Baja, Mexico on a number of conservation missions—one of them involving ancient shark mummies. And we joined forces with U.S. aquariums and zoos to call for stronger protections for the endangered vaquita porpoises of the Gulf of California.

As 2016 comes to a close, let’s look back at the top 10 highlights from this blog:

White shark GIF_MBA
A white shark approaches schooling sardines.

10. Camera to Crack a White Shark MysteryOur senior reseach scientist teamed up with the Monterey Bay Aquarium Research Institute for a high-tech mission: to capture video footage of great white sharks in their most mysterious habitat.

“Some of the engineering team said it was an impossible job,” MBARI Engineer Thom Maughan recalled. “But I’m attracted to those opportunities.”

Read more…

Building bridges across an ocean to save a species

From a human perspective, the ocean is mind-bogglingly vast, deep and mysterious. Many of us live along the coast, or visit it on vacation, but few have experienced the high seas. We may not think much about marine life until it’s on our plates.

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Chef Ed Kenney

But this week Ed Kenney, a Hawaii-based celebrity chef and a member of the Seafood Watch Blue Ribbon Task Force, called on people to rethink our appetite for one particular fish: Pacific bluefin tuna. These huge, fast predators, which migrate thousands of miles across the Earth’s largest ocean, are now down to less than 3 percent of their historical abundance due to overfishing.

“We chefs must take Pacific bluefin off our menus now, and give these powerful fish a chance to rebound,” Kenney writes on the National Geographic Ocean Views blog.

The Aquarium shares his concerns. For years, our scientists have been working to unravel the mysteries of the fish itself, by studying live bluefin in the lab, keeping them in our Open Sea exhibit, and tracking them in the wild.

We’ve learned a lot about the movement of Pacific bluefin by tagging more than 1,400 fish off the coast of California. But, mysteriously, not one of these individuals has made it back across the Pacific to spawn in the Sea of Japan.

Read more…

Dispatch from the Sea of Japan: Bluefin karaoke

The Conservation & Science team at the Monterey Bay Aquarium has worked for more than two decades to understand and recover bluefin tuna—particularly Pacific bluefin, whose population has declined historically due to overfishing. A key piece of our efforts is tagging bluefin in the wild so we can document their migrations across ocean basins. Much of our work takes place in the Eastern Pacific, but this summer we’re partnering with Japanese colleagues to tag bluefin tuna in the Sea of Japan. Tuna Research and Conservation Center Research Technician Ethan Estess, working with Program Manager Chuck Farwell, is chronicling his experience in the field. This is the fourth and final dispatch in his series.


Last night got a little wild.  We haven’t seen a bluefin tuna in nine days, and we’re all starting to go a little stir-crazy. That night over dinner, we have beverages. Fine Japanese beverages. And after dinner? More beverages. Lo and behold, the restaurant owner pulled out the karaoke machine.

Estess_Karaoke_Japan
Student Kota Sebe lays down a high-energy karaoke performance.

I was first to the microphone with a reliable jam, “Under Pressure” by the late David Bowie and Queen. I didn’t realize the karaoke machines here have a complex vocal analysis system that scores your performance. Let’s just say I didn’t go platinum. (Definitely a problem with that karaoke software.)

It was Dr. Ko Fujioka who put on the winning performance of the night: a classic Japanese pop song from the ’80s. Fujioka-san rocked it, getting a high score of 91.7 points, the third-highest in the restaurant’s history.  People were dancing and cheering—karaoke is a big deal here.

Then researcher Mitsuake Sato got up and sang a powerful love ballad, replacing the female subject’s name with maguro (Japanese for “bluefin”). In tears from laughing, we went to bed, glad to have vented our Bluefin Blues in some way.

Read more…

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