There is no place like a submarine to get a closer look at what lurks beneath. With just a few thin inches of glass separating the operators from the creatures, it’s an up-close-and-personal look at some very interesting stuff. Case in point: the bluntnose six-gill sharks researchers from Ocean X interacted with.
It was a history-making trip. “After a week in the Bahamas with our wonderful partners at the CAPE ELEUTHERA INSTITUTE,” the researchers wrote, “this weekend we managed to achieve history—tagging an animal from a submersible (submarine) for the first time—EVER.”
While it wasn’t the first time a six-gill has been tagged, it was the first time one was tagged down deep. Generally, they’re caught, pulled to the surface, tagged, and released, but there’s a problem with doing it that way. “Those sharks can’t get that high up in the water column that fast and they can’t get back down that fast,” said an Ocean X researcher. “The information you’re recording on that shark is not natural behavior because it’s freaked out. It’s totally whacked out from being on the surface.”
Bluntnose six-gills, also called cow sharks, are an incredibly old species. In fact, they predate most dinosaurs. They’ve proven difficult to study. “In their typical life cycle they won’t experience daylight, and very rarely will they feel the low pressure, warmer temperatures of surface waters,” scientists wrote. “Typically, the data obtained after surface tagging of a six gill is believed to be skewed, as the shark does not return to its natural behaviors for some time after the tagging.”
The solution? Go to where those sharks spend most of their time, which in this case was hundreds of feet down and in the middle of the night. So, using a submarine off Oceanx’s research vessel, Alucia, they dropped into the clear depths of the Bahamas.
Attached to the sub was a speargun to shoot the tag into the shark, but as one might expect, shooting a shark from a submarine isn’t exactly easy. The area suitable for tagging is about the size of an iPad, and on a shark as big as a six-gill, that’s a small target.
“The first night there were bluntnose sixgills everywhere,” OceanX explained. “We lined up the shot, fired the tag, and it bounced off the female sixgill’s skin. On night two, we made the relevant adjustments… but no sharks showed up. Night three: The sharks were back, and we were very excited to deploy the tag, but unfortunately a large grouper came and tagged itself (exactly in the correct tagging position. So we may have grouper tag info in a couple of months, unless a sixgill eats it).”
Finally, though, on the fourth and final night, they found success. They’d used about 300 pounds of bait and spent many hours in the cramped submarine. At just before 10 p.m., those manning the radios at the surface received a crackling transmission. “Wait, —can you repeat that?” topside operators asked. “Roger, Nadir. Tag went into a large male.”
So, with a tag successfully in the side of a bluntnose six-gill, OceanX researchers sat back and went through the footage. And, as you can see, it is absolutely stunning.
