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Could underwater gadgets tell us why baby sharks hang out at LA beaches?

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Camera tags and autonomous underwater drones give scientists a window into white sharks’ secret lives

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A white shark caught on an underwater camera.
Video: Cal State Long Beach Shark Lab

It was about 2AM on a Friday morning, and Connor White couldn’t find the baby great white shark he was supposed to be tracking off the Southern California coast. He wasn’t worried about the shark, really — these Pacific waters are its home. But he was starting to panic about losing the $9,000 accessory called a SmartTag that the shark was wearing around its dorsal fin, like a giant, bright orange Fitbit.

Equipped with a handful of sensors and a camera, the SmartTag is part of a growing suite of gadgets that gives scientists a window into a day in the life of a shark. That is, as long as the scientists can find it once it releases from the shark’s fin. Lose the shark, and you lose the pricey tag — along with all its data. To keep costs down, White hadn’t outfitted the tag with a satellite transmitter.

So all he had to go by was the high-frequency radio signal the tag was supposed to emit when it floated to the surface, and outside of a 15-mile radius, he wouldn’t be able to hear it. “You know the shark can’t be that far away,” White says. “But each minute that you can’t find it, the area that the shark could be in gets bigger, and bigger.”

Chris Lowe releases a young white shark after attaching a smart tag to its fin in Spring, 2017 off Belmont Shore, California.
Photo: Cal State Long Beach Shark Lab

White helped develop the SmartTag when he was a graduate student in Chris Lowe’s Shark Lab at California State University, Long Beach, which was part of a collaboration with Harvey Mudd robotics professor Chris Clark. There are other, similar tags out in the world helping scientists study animals that spend their lives underwater. But the SmartTag was designed specifically to fit around the fins of smaller sharks. Like, for example, baby great whites.

The team wants to use these tags to figure out what’s drawing baby great white sharks to popular Southern California beaches, packed with the biggest threat to sharks in the world: lots and lots of people. “Why are these little sharks here? How much time are they going to spend here, and do we have to worry about them?” Lowe says. “We needed the right tools to answer those questions.”

Other than a video camera, the SmartTag sports a thermometer and a depth sensor. And at its heart is an inertial measurement unit, or IMU — the same technology that helps your phone or Wiimote detect movement in three dimensions. On your phone, the IMU tells your screen when to flip from vertical to horizontal. On a shark, it logs when the shark dives, swerves, or surfaces. With this information, White says, “You can really reveal its secret life, and remove the water through your computer screen.”

The SmartTags can be used for more than just white sharks. Here, a leopard shark is earing one.
The SmartTags can be used for more than just white sharks. Here, a leopard shark has just been tagged with one.
Video: Cal State Long Beach Shark Lab

That’s key, because for all the Hollywood mythology and hysteria built up around great white sharks — which are really just called white sharks in science textbooks — their lives are still a mystery. We know, for example, that white sharks live throughout the world’s oceans and eat marine mammals, keeping the food web in balance from their position at its apex. We know that the babies are about four to five feet long when they pop out of their mothers with a full set of teeth, and that they can live for around 70 years.

But we don’t know how many of them are swimming through the oceans, where they mate, and where exactly they give birth to their young. And we have no idea why baby white sharks are congregating in the warm, shallow waters between Santa Barbara and Baja, California. The team suspects that these baby white shark hot spots in places like Santa Monica Bay and Huntington Beach are nurseries that the babies swim between for their first five or so years, munching on stingrays and avoiding being eaten by larger sharks. White doesn’t know for certain, however, which is where the SmartTags come in.

The day before White found himself hunting for the baby white shark in the middle of the night, tagging it had gone smoothly. He and two boatloads of researchers had journeyed from the CSU Shark Lab to just off Belmont Shore in Southern California. Every piece of trash or bird on the water’s surface looked like a fin to White. But it only took about 10 minutes for the real thing to appear — a tell-tale little triangle, cutting through the water. Ten minutes later, he saw another.

With the help of an aerial drone, he and the crew used boats to stretch out a net and snare a baby white shark. They dragged it to the bigger of the two boats, where the shark was hoisted out of the water and dunked into a saltwater tub on the deck. Baby white sharks look like the short, stubby versions of the adults, White says. But they’re remarkably lazy and relaxed. “Put them in a little bathtub, and they kind of just lay there, chilled out,” he says.

Then they got to work outfitting the shark with both an acoustic tag, and the SmartTag. First, the team made a little cut in the shark’s abdomen, and slipped the acoustic tracker inside. The acoustic tag lasts about 10 years, so it’s a longer-term, lower-resolution way to keep track of the sharks once the SmartTag falls off. It acts kind of like an E-ZPass on a toll road, Lowe says. By setting up stations that listen for the acoustic tracker’s little pings, scientists can monitor when and how many times a shark passes.

Then, the crew cinched the SmartTag in place around the shark’s dorsal fin. (The tag has a lock that corrodes after 24 hours, sending the tag floating back up to the surface.) Finally, they released the shark back into the ocean. “After all that excitement, you feel like it’s victorious,” White says.

But then comes the hard part: following the shark with a microphone that picks up the pings from its new acoustic tracker. White and a rotating crew of Shark Lab members chased the shark overnight, losing it once for a stress-filled two hours before finding it again around 3AM. By around noon the next day, the shark had reached Dana Point — about 35 miles south of where it had started.

The crew desperately needed to refuel the boat, but by the time they returned to the place they’d last seen the shark, it was gone again. And with it, the tag — which was due to release from the shark’s fin at any moment. For about an hour, they drove around in a grid pattern, listening for the high frequency radio signal the tag is designed to emit when it reaches the surface. When they finally spotted it, White breathed a big sigh of relief. “Finding the tag is one of the most stressful parts,” he says. “Because if you don’t find it, you’ve not only lost all the effort of tracking the shark, but you lose the $9,000 of technology on the tag.”

The first thing he did when he got back to shore was download all of its data and graph the sharks’ movements. The second thing he did was sleep for the next 12 hours. “Adrenaline rushes by far the most when you have the shark in the boat,” he says. “But I think the most exciting part is definitely when you download the tag and see what the shark actually did.”

So far, the Shark Lab has only monitored three white sharks with these new SmartTags. So they haven’t collected enough information to glimpse more than the tip of the iceberg, White says. “It’s like trying to infer what all humans do by looking at three peoples’ Fitbit data.” But they’re hoping that tagging more sharks, and changing up how they track them, could help paint a more complete picture about what’s drawing these young sharks to Southern California’s beaches.

Video by Chris Clark, Harvey Mud College and Chris Lowe, Cal State Long Beach Shark Lab

To that end, the Shark Lab is working with Harvey Mudd’s Chris Clark to develop a fleet of autonomous robots that track the sharks by themselves. There are other autonomous underwater vehicles that can do this, too, like the REMUS AUV developed by the Woods Hole Oceanographic Institute. In 2013, Massachusetts marine fisheries biologist Greg Skomal used a custom-built REMUS-100 AUV to track and observe four white sharks off the coast of Mexico. (Several sharks tried to bite the AUV, possibly because it looked like food.)

But, Lowe says, the REMUS is a little pricey for his team. So he and Clark are developing smaller, cheaper underwater drones that can track any creature bearing an off-the-shelf acoustic transmitter. Shaped like torpedoes sporting underwater microphones, the robots have successfully followed a leopard shark by listening for the pings of its acoustic tag. They’re designed to circle the shark at a fixed distance. “We don’t want to get too close,” Clark explains. “If there’s a robot butting up against it all the time, it’ll affect the shark behavior and ruin the experiment.”

The advantage of using autonomous robots is that they can film the shark and learn about its environment in a way that’s impossible from a boat. The robots can measure oxygen levels, water temperature, acidity, salinity — and can even map the seafloor using sonar. “The robot can swim and chew gum at the same time,” Lowe says. The problem is that right now, the robots aren’t fast enough to catch up with a white shark if it slips out of range for their microphones. But his team is working on it, Clark says.

“The cool thing about combining all that technology is for the first time, it’s giving us the opportunity to understand how some of these sharks may be making decisions,” Lowe says. And that could go a long ways to restoring great whites’ reputations. The more we know about these sharks, he says, “the less likely the public is to demonize them or fear them. And the more likely they are to want to protect them.”