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Robo-sharks: Robots used to track movement, behavior of sharks

Dr. Chris Lowe is seen with two of his shark-tracking robots off Catalina Island in July 2012. Dr. Lowe is a marine biologist and has been running the CSULB Shark Lab since 1998. (Courtesy of Dr. Gwen Goodmanlowe)
September 24, 2012 12:00:00 AM PDT
Sharks are among the most mysterious and elusive creatures on earth. No one really knows how great white sharks mate, where they give birth or even why they sometimes attack humans.

But two Southern California scientists and their young students are making breakthroughs in their respective fields, and their research is revealing new insight into the behavior of sharks.

"It is a game-changer, it's game-changing already," said Dr. Chris Lowe, a marine biologist and professor at California State University, Long Beach (CSULB). "We're tracking a shark... with robots -- this is so cool."

Autonomous underwater vehicles (AUV), or robots, are revolutionizing the science of sharks. Lowe is collaborating Dr. Chris Clark, a computer scientist at Harvey Mudd College, on a three-year shark tracking project.

"Our ultimate objective is to be able to use this to kind of peer into the secret life of sharks," said Lowe.

Back in July, Lowe and Clark, along with a team, tracked leopard sharks in Fisherman's Cove off Catalina Island for the very first time. During the warmer months, leopard sharks gather in large numbers in the cove.

"You can swim out there in the middle of the day and look down and see at least 40 sharks right below you," said Clark.

Finding a shark is easy, but tagging it can be challenging. The scientists must get close enough to the animal to fit it with an acoustic tag.

"We go down and just dart it into its back," said Lowe. "The animal feels a little pinch and then it's still swimming around right here. So we know we haven't altered the shark's behavior very much."

Once the shark is tagged, that tiny acoustic tag begins to ping, sending sound waves straight to the robots. The AUVs are listening through two hydrophones, one on each end of the device.

The AUV has a propeller with a motor just like you'd see on most boats, as well as a compass, depth sensor, GPS in the antenna, and Wi-Fi.

"So, they're able to take all these different measurements of water temperature, light levels and chlorophyll," said Lowe. "Some of them have video cameras, so we can actually view what the sharks might be seeing as they're swimming through the water."

But the robots keep their distance, never disturbing the shark.

"We're designing them to be stealth-like, so that the sharks don't even really know they're there," said Lowe.

The robot uses comparable shark behavior to locate the tagged shark. It moves in a sinusoidal pattern in order to detect changes in acoustic signal gradients and then uses this information to predict where the shark is heading, according to Lowe. The AUV doesn't need to be directly behind the tagged shark to localize it -- the robot can be to the side, in front or even moving away from the animal.

"We can tell the robot to come home, we can say stop your mission, start your mission," said Clark.

Next summer, the team plans to tag and track a baby great white shark in the Santa Monica Bay.

"Southern California is a well known nursery ground for the white sharks," said Lowe.

From their previous tagging data, Lowe and Clark have found several hot spots along the coast where newborn white sharks tend to hang out, including northern Santa Monica Bay, San Onofre and San Diego.

"Our goal is to use the robots to try to understand what makes those areas so special," said Lowe.

And why are we seeing more white sharks off our coast?

It is illegal to catch or kill a white shark in California waters. However, every year worldwide, it's estimated that approximately 100 million sharks are killed, according to Lowe, mostly from the practice of shark finning. But as protections increase for sharks, so do their numbers.

"The reality of it is many shark populations are doing better because we've taken better care of our oceans," said Lowe.

Marine mammals like sea lions are also protected. There are now more than 300,000 sea lions in California and Baja, and that means good eating for sharks.

"So their populations have recovered wonderfully since this protection, which means there's a lot of good things for white sharks to eat," said Lowe.

And more sharks mean more work for the robots.


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