A team of researchers exploring an active underwater volcano have captured footage of shark species (including a significantly rare species) living within the deep-sea crater. The researchers from the University of Rhode Island were dropping video cameras, bait, and lights – an instrument package called a drop-cam – into the deep ocean off the Solomon Islands as part of their volcano work where they observed various shark species, including an elusive Pacific Sleeper Shark, swimming past.
Sleeper sharks are a group of deep-dwelling, slow-moving fish that includes the Greenland shark and can normally be found in the Northern Pacific and Northern Atlantic oceans, as well as the waters around Antarctica and Tasmania. The fact that the species was observed inhabiting the waters off of the Solomon Islands – east of Papua New Guinea – and within an underwater volcano no less, proved a very exciting find for the researchers. It is the third ever video recording of the species.
“We were freaking out,” says Brennan Phillips, a Ph.D. student studying underwater volcanoes at the University of Rhode Island.
The footage also revealed hammerheads and silky sharks living inside, seemingly unaffected by the hostile temperatures and acidity.
“You never know what you’re going to find. Especially when you are working deep underwater. The deeper you go, the stranger it gets.” says Phillips.
“No one has ever looked in the deep sea there, period. No one’s been out to anywhere in the Solomon Islands and gone deeper than a few hundred meters or deeper than a scuba diver has gone, really. So we were very excited. We thought there was a lot of potential.”
The volcano in question, Kavachi, is one of the most active submarine volcanoes in the south-west Pacific Ocean and is named after a sea god of the New Georgia Group islanders. The researchers had lowered their equipment, including the video camera, to 3,074 feet (937 meters) down. When the team retrieved it and downloaded the 7 hours and 45 minutes of footage the Pacific Sleeper was spotted .
Phillips and his team had a limited knowledge of sharks and so they consulted shark biologists to try and identify the species. The animal seems to be a Pacific sleeper shark, says Marcelo Carvalho, a shark researcher at the University of São Paulo in Brazil.
Usually, experts identify a sleeper shark’s species based in part on its location. The three species—the Pacific sleeper, Southern sleeper, and Greenland shark have distinct ranges, Carvalho explains. Since the Solomon Islands are fairly close to Australia, the shark could potentially be the Southern sleeper shark, however Southern sleepers tend to be lighter in colour than the one in the video. The mystery shark’s colour matches that of the Pacific sleeper, as does its gill slits, which are longer than the slits on a Southern sleeper.