Hailing from the Memorial University of Newfoundland, the researchers were working with the Arctic Fishery Alliance to deploy underwater cameras into the open ocean. Maybe they would find some shrimp or sea snails during the survey. Or, maybe they would find some rarely seen Greenland sharks.
RARE GREENLAND SHARK FILMED BENEATH THE CANADIAN ARCTIC
Using squid as bait, they were able to capture footage of the latter. Their findings were published in late January in the journal Scientific Reports.
A deep-ocean drop camera is a digital camera enclosed in a protective, water-tight sphere. Attached to a weighted metal frame and baited, the rigs can film the mysterious world of what goes on below the ocean's surface for hours on end.
"We basically just set it and forget it, for eight to 10 hours," says Devine, a PhD candidate. "The camera allowed us to sample the bottom."
The researchers completed 31 drop cam deployments into Nunavut waters between July and September of 2015 and 2016. Eighty percent of those deployments captured footage of 142 different Greenland sharks, which the researchers identified based on their unique markings. In their 250-plus hours of footage, none of the sharks visited the cameras more than once.
The researchers were able to gather the sharks' sluggish swimming speeds from the footage. Some were about five feet long, and others were twice that size. The researchers write that nearly all the sharks were probably too young to reproduce.
The Memorial University team is not the first to capture the Greenland shark on camera, but spottings of the swimmers are rare. In 2014, National Geographic mechanical engineer Alan Turchik got quite a shock when one of the sleeper sharks glided through the feed of his underwater camera.
UNEXPECTED SHARK GIVES EXPLORER SHOCK OF HIS LIFE
A National Geographic researcher is startled to see a Greenland shark where none has ever been seen before: off Russia's Franz Josef Land. Video
"That was my first and last sighting of a Greenland shark," Turchik says. When he saw Devine's footage, "I didn't want to swear as much this time."
Greenland sharks aren't the only swimmers Turchik sees on assignment. In a January 2015 expedition to the Chagos Archipelago, he was with a team that captured footage of a gulper shark, a species that had not previously been seen in that area. During another expedition, he helped to capture images of a Pitcairn angelfish swimming around a reef system 40 miles away from the Pitcairn Islands.
"We actually get to see a lot of interesting stuff," Turchik says. "More often than not, we're seeing something in a location [where] you didn't expect it before."
Surveying Sleeper Sharks
Devine says the researchers weren't surprised to see Greenland sharks, since that species is known to frequent the cold, dark waters of the Arctic and North Atlantic oceans. But the poor accessibility of these deep-sea dwellers has made the elusive species hard to study.
A lot of the information we have on Greenland sharks comes from historical commercial fishing records. There are few records, but apparently their oily livers made the sharks attractive targets for fishers until 1960. In terms of size, Greenland sharks are similar to great whites. They can measure more than 20 feet long, but unlike their notorious relatives, don't swim very fast—a qualification that admits them into the "sleeper shark" family.
Past studies have shown that Greenland sharks only grow about a fraction of an inch each year, and they likely don't reach maturity until the females are nearly 15 feet long and the males are just under 10 feet long. Some records say they can live for upwards of 272 years, which could make them the longest living vertebrate on the planet. (Many sharks live longer than scientists thought.)
Because there's sparse information about these swimmers, overfishing and habitat loss could hurt their population. The baiting and photographing technique is less invasive than the past scientific methods of catching Greenland sharks on longlines, which can stress the fish out and lead to early deaths.
The exact geographic range of the Greenland shark is not well known, and research of the species is ongoing.
"This work is really just a first step," Devine says. "There's so many areas that are unexplored and unknown."