Gulf of Mexico
Researchers Dean Grubbs, left, and Gavin Naylor on a recent shark-tagging trip with university students in the Gulf of Mexico. (Kristen Grace/Florida Museum)

Scientists finally tag an elusive shark deep underwater

Deep-sea sharks are elusive creatures. Many of the seafloor-skimming creatures predate dinosaurs. But the shady lives of the rare sharks are poorly understood because of the depths in which they swim.

So how can scientists study them?

Easy: Just head into the ocean depths with the help of a submersible, a satellite tag and a spear gun. That’s the tactic used by scientists from the Florida Museum of Natural History and OceanX. They were the first people to successfully tag a shark from a submersible.

The bluntnose sixgill shark thrive far from the ocean surface, making them almost impossible to tag and track without stressing out the animal and even causing it to change its behavior.

“The changes in pressure stress it physiologically,” explains Gavin Naylor, who directs the Florida Program for Shark Research at the Florida Museum of Natural History at the University of Florida. He fired a custom-built spear gun to tag the shark about 1,700 feet below sea level in the Bahamas. “The animal is stressed and has to swim back down to where it belongs.”

Nobody had ever tagged a shark underwater before, but the concept made sense to Naylor and colleagues. “If we do it where it lives, it will be no different than if it got bitten by another shark,” Naylor says. The expedition was spearheaded by Florida State University Coastal and Marine Laboratory’s Dean Grubbs, who has tagged more than 10,000 sharks.

With the help of the OceanX Nadir submersible and a spear gun designed especially for underwater tagging, the team lured the shark with hundreds of pounds of bait.

It took months of planning and multiple failed attempts. At first, scientists were stymied by swift sharks, misfires and a spear that just bounced off a shark’s skin. But after finally succeeding, they have a three-month-long satellite connection to a male sixgill and its mysterious undersea habits.

Meanwhile, there’s a stunning up-close video of the shark taken during the scientists’ effort.

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