A spectacular discovery is causing a stir in marine research: for the first time, a large sleeper shark has been filmed in the icy deep sea of Antarctica. The animal, estimated to be three to four meters long, was recorded at a depth of around 490 meters near the South Shetland Islands, in water temperatures close to freezing.
“As a rule of thumb, there are no sharks in Antarctica,” said marine researcher Alan Jamieson of the Minderoo-UWA Deep-Sea Research Center at the University of Western Australia. “And this isn’t even a small one. This is a huge shark. These animals are like tanks.”
The camera operated by the Minderoo-UWA Deep-Sea Research Center, which studies life in the deepest regions of the world’s oceans, was deployed off the South Shetland Islands near the Antarctic Peninsula. This location lies well within the boundaries of the Southern Ocean, which extends south of the 60th parallel.
According to Jamieson, he was unable to find any previous documented record of a shark this far south. Independent conservation biologist Peter Kyne of Charles Darwin University also confirmed that no shark had previously been recorded in this region.
The sleeper shark was moving slowly along the seafloor at a depth of about 500 meters. Beneath several layers of water, there is a comparatively warmer layer at this depth. The Southern Ocean is strongly stratified down to around 1,000 meters, which limits the exchange between water masses.
It remains unclear whether climate change and the warming of the oceans are driving sharks into more southern waters. Due to the remoteness of the region, there is very limited data available. It is also possible that sleeper sharks have lived at these depths for a long time but have simply gone undetected until now.
Because research cameras at this depth can only be deployed during the summer months of the Southern Hemisphere, large parts of the year remain unobserved. “During the other 75 percent of the year, nobody is looking at all,” Jamieson said. The discovery highlights how little is known about Antarctica’s deep sea and the potential for further surprises it holds.
Heiner Kubny, PolarJournal