Even as populations of sharks, bluefin tuna, and other large fish are being severely over-exploited, scientists still know surprisingly little about when and where the ocean’s biggest predators congregate to feed and spawn, making it difficult to protect biological hot spots. Stanford University marine biologist Barbara Block is seeking to narrow that knowledge gap by deploying an armada of satellite tags on the backs of ocean creatures.
Block envisions a wired ocean, a blue fount of data in which tags, smart buoys, and mobile robots reveal the secrets of marine life. She and her colleagues have been involved in the Tagging of Pacific Predators project, a long-running study that has affixed more than 4,000 tags to 23 different species and revealed that the eastern Pacific is a veritable “blue Serengeti,” rich with life and traversed by regular migration routes.
In an interview with Yale Environment 360 contributor Ben Goldfarb, Block — the architect of Shark Net, an app for iPads and iPhones that allows subscribers to track great white sharks off the coast of California — discusses the wealth of data gathered by the latest electronic tags and explains why it’s important to put the fruits of this research into the public’s hands. “What we need is environmental interest and awareness that connects humans to the world,” says Block, “or else we’re going to end up with the same problem that we had on the continents, where the large mammals are gone.”
Yale Environment 360: I gather you’ve done a lot of the tag design yourself? How do you create a tag that then stays in these creatures for five years?
Barbara Block: Well, you first have to dream big. And you have to say, “What is it I want to know?” Back in the mid-90s, we were at the table at big fisheries commission meetings, where we really didn’t know where big fish went. And so we asked the question, “How could we study something underneath the sea, that breathes through the gill?” You can’t use radio waves because sound has to travel through air primarily to get anywhere… So we used a technique that was first talked about many years ago, in which we took light from the sun and measure photons, so we can actually put together sunrise and sunset data. We have an accurate clock on the tags. It’s what mariners have done for all of time — we’re using light and time to calculate our position from Greenwich…
We try to use the same chips that are in your computer, the same devices that allow you to talk to satellites and cell phones, and we package them in small devices, put them on big animals like white sharks and tunas, and we follow them across the globe. What we’re trying to do is figure out how do big animals live in the ocean ecosystem, and where they are. And we’ve done this through huge tagging campaigns. One was in the Atlantic called “Tag a Giant” that focused on giant bluefin tuna, fish that are up to 1,500 pounds that carry these computer tags, sometimes up to four or five years. And we have a campaign in the Pacific we call “Tagging of Pacific Predators.” Over 5,000 animals have been tagged, 80 scientists working together, five nations, trying to figure out how the largest ocean on Earth works.
e360: I imagine that it’s incredibly hard to tag something like a blue whale or a white shark.
Block: For every animal it’s a different problem. For us, when we come face-to-face with a large shark, the goal is basically to get the tag on the animal with the least amount of challenges for the animal — great white sharks are sometimes as large as 5,000 to 7,000 pounds.
e360: How many of these tags do you have deployed at any given time?
Block: We have a data logger, or an archival tag. But with that archival tag, you have to get it back when humans intercept the fish. You can only put that into an animal that has a huge fishery, like a bluefin tuna. And we’ve put over 1,500 of those tags in tunas in the Atlantic and the Pacific Ocean. We get about 22 percent back in the Atlantic, 50 percent back in the Pacific, and when they come back, we download the information and find out where the animal’s been. But we got tired of waiting for people to turn tags back in. So we worked with engineers and packaged [the tags] into a tube. It’s got a little float on the top, and it rides on the tuna, takes the data, rides on the shark, takes the data, pops off a small piece of steel that corrodes away, comes to the surface, and then sends the data back to Earth-orbiting satellites. And then we get data back without any human interception.
Then finally, there are tags you can put on the dorsal fin of sharks, and they use radio waves and talk to Earth-orbiting satellites every day. I looked up this morning the location of a salmon shark that came from Alaska to Monterey Bay in the last six months.
e360: One of the cool things that you’ve done is you’ve put a lot of this data in the hands of the public. Can you talk a little bit about your efforts to make this stuff publicly available?
Block: We want to engage the public because we’ve got some of Earth’s greatest critters out there, the big sharks and the tunas, and most people look at the ocean and can’t even see anything. So it’s hard to imagine how we’re going to save animals, or build conservation strategies, when you can’t even see the animals. So lately what we’re trying to do is transmit the data in ways that become browser-friendly on your internet site or iPhone. “Shark Net” is our app. It’s free, and it allows you to keep track of great white sharks on the west coast of North America, and hopefully soon we’ll bring some other sharks into that.
Block and her colleagues use a so-called “wave glider” to track the comings and goings of sharks and other species in migration corridors in the Pacific Ocean. The surfboard-like instrument, which is propelled by wave power, is outfitted with various devices to detect tagged fish and transmit that information via satellite to Block’s laboratory. (image via Stanford University)
e360: You’ve also pioneered a lot of robotic technology, including something called a “wave glider.”
Block: The wave glider is built by Liquid Robotics. It’s a brand new technology, a green robot, and it’s a surfboard that is attached with a unique tether to a sub, or a glider. And it captures the motion of waves, and it is completely powered by the kinetic energy of waves. It then uses solar power to power the instruments on board. And right now we’re gliding off the coast of North Carolina and we’re seeing things like sand bar sharks, sturgeon, animals that are freely swimming in the sea that use acoustic tags that send sound waves to the underwater glider, which then is transmitted to us in real time through iridium uplinks from the glider.
e360: How many of these gliders do you have out there right now?
Block: Well, the company, Liquid Robotics, might have as many as 150 gliders that are plowing through the ocean looking for everything from natural gas, or oil, to helping us do our biological oceanography. We envision a day when our coastlines can be protected by devices that are telling us what ships are there, telling us in real time how the ocean is today. And then also finding out where these congregations of animals are — the hot spots — so that we might then put a marine protected area around them.