Sleeper Shark Filmed in Antarctic Waters, Marking First Documented Sighting

First Shark Sighting Documented in Antarctic Waters, Challenging Previous Assumptions

A sleeper shark was filmed in Antarctic waters in January 2025, marking the first documented sighting of a shark in the region. The discovery was made by a baited video camera operated by the Minderoo-UWA Deep-Sea Research Centre, challenging previous assumptions about the presence of sharks in these frigid southern waters.

Discovery Details

The sighting occurred near the South Shetland Islands, off the Antarctic Peninsula. The location falls within the boundaries of the Antarctic Ocean, defined as below 60-degree south latitude. The camera recorded the shark at a depth of 490 meters (1,608 feet), where the water temperature was approximately 1.27 degrees Celsius (34.29 degrees Fahrenheit).

The filmed shark was estimated to be between 3 and 4 meters (10 and 13 feet) long. Oceanographer Jessica Kolbusz from the Minderoo-UWA Deep-Sea Research Centre identified the slow-moving creature as a member of the sleeper shark family (Somniosidae). This footage represents the first in-situ recording of a somniosidae or any elasmobranch (shark or ray) in the Southern Ocean.

Scientific Significance

While the exact species of the sleeper shark could not be definitively determined from the footage due to physical similarities within the family, conservation biologist Peter Kyne of Charles Darwin University described the footage as a significant record, suggesting it could be a Southern sleeper shark (Somniosus antarcticus). Southern sleeper sharks are known in sub-Antarctic areas, but this is considered the first record of any shark in Antarctica itself.

Alan Jamieson, founding director of the University of Western Australia-based research center, noted that "the presence of such a substantial shark was unexpected, with a general understanding that sharks were not found in Antarctica."

DNA tests from water samples collected during the expedition are awaiting examination, which may help identify the precise species.

Characteristics of Sleeper Sharks

Sleeper sharks are large, deep-dwelling sharks characterized by mottled skin and small fins. The Greenland shark, a related species, is known for its exceptional longevity, living for approximately 400 years. In the Southern Hemisphere, two similar-looking species are believed to exist: the Southern sleeper shark and the Pacific sleeper shark. The Southern sleeper shark was first identified from a sketch of a washed-up specimen on Macquarie Island in 1913.

Limited information is available on Southern sleeper sharks, with much of the current knowledge derived from rare collections as fisheries bycatch. Their stomachs have often been found to contain remains of colossal squid. A 2023 genetic study in the Pacific Ocean suggested that the Southern sleeper shark and Pacific sleeper shark might be the same species, though it is unclear if this applies to other regions. Research led by Erwan Saulnier is underway to address this knowledge gap, with genetic analyses including data from the South Atlantic and Indian Oceans scheduled to begin in mid-2026.

Environmental Context and Explanations

Sharks are uncommon in Antarctic waters due to extremely cold temperatures. Ocean temperatures in the region can drop to approximately -2 degrees Celsius, aided by high salt content which lowers the freezing point, making it too cold for most marine life. Greenland sharks are known to tolerate these temperatures, believed to be assisted by compounds like trimethylamine N-oxide and urea acting as natural antifreeze. The sleeper shark in the recent footage was observed in waters around 1.27 degrees Celsius.

Experts propose several factors that might contribute to this sighting:

The filmed shark maintained a depth of approximately 490-500 meters. This depth may represent a warmer layer within the heavily stratified Antarctic Ocean, which exhibits conflicting water properties. The Antarctic Ocean is layered to about 1,000 meters due to colder, denser water from below and freshwater from melting ice above. Other Antarctic sharks are anticipated to inhabit similar depths, potentially feeding on the remains of whales, giant squids, and other marine life that sink to the seabed.

Slow-moving sleeper sharks might have been present in Antarctica for an extended period without detection due to their sparse population and the challenges inherent in deep-sea observation.

Few research cameras are positioned at this specific depth in Antarctic waters, and they can typically only operate during the Southern Hemisphere summer (December to February). This restricted observation window may contribute to the infrequent detection of such marine life.

Future Outlook

It remains unclear whether this shark species may populate more Antarctic waters as the ocean warms due to climate change. Researchers suggest their distribution would most likely remain consistent, given the species' probable wide-ranging thermal tolerance, though their exact distribution is not fully known. While warming oceans might prompt some species to extend their ranges, data on such changes near Antarctica are limited due to the region's remoteness.