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.
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.”
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.” Continue reading Designing an animal-friendly fin tag
The Conservation & Science team at the Monterey Bay Aquarium has worked for more than two decades to understand and recover bluefin tuna populations – particularly Pacific bluefin tuna, whose population has declined historically due to overfishing. A key piece of our efforts is tagging bluefin tuna in the wild so we can document their migrations across ocean basins. Much of our work takes place in the Eastern Pacific, but this month 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 the first dispatch in his series.
Tags are laid out on a tatami mat, prepped and ready for use when the tagging team heads out to sea.
The alarm buzzes beside my head and, opening my eyes, I have no idea where I am.
I’m lying on the floor of a room covered wall-to-wall in woven straw mats, with rice paper windows and a table rising a foot off the ground. Right. Japan. Sado Island in the Sea of Japan, where I’m sleeping on a traditional tatami mat. Yesterday’s cannery whistle is blowing back home at the Monterey Bay Aquarium at noon, but my 4 a.m. alarm tells me it’s time to get up and find some Pacific bluefin tuna.
One year ago, I sat in a third-floor office at the aquarium with my colleague Chuck Farwell and Dr. Ko Fujioka from Japan’s National Research Institute of Far Seas Fisheries as we went through the steps necessary to deploy a satellite tag on a bluefin tuna. We discussed the tag attachment system that anchors the small electronic device to the animal for up to a year at a time, as well as the process for programming the tag’s onboard computer to record the whereabouts and behaviors of these wide-ranging fish. Continue reading Dispatch from the Sea of Japan: Tagging takes teamwork
Conservation & Science 