First Shark Filmed in Antarctic Deep Waters Marks Milestone for Polar Science

A sleeper shark gliding through the near-freezing depths off Antarctica has given researchers a rare new window into one of the planet’s least-understood marine predators. In January 2025, at a depth of 490 meters near the remote South Shetland Islands, a baited camera recorded a southern sleeper shark, Somniosus antarcticus, cruising slowly out of the darkness, inspecting the equipment and tied fish before fading back into the cold, blue-black water. The encounter, in water just 1.27 degrees Celsius, is the first filmed record of a sleeper shark in Antarctic deep waters and the southernmost sighting of its kind to date.

A Rare Encounter in the Antarctic Twilight

The shark, estimated to be between three and four meters long, approached cautiously from the edge of the camera’s field of view, its bulky body and broad head characteristic of sleeper sharks that inhabit some of the world’s coldest oceans. Moving with deliberate, unhurried strokes of its tail, it closed the distance to the bait pole, nudged and circled the fish briefly, and then disappeared into the gloom, leaving only suspended particles and a fading silhouette behind.

The footage was captured using a baited remote underwater video system deployed on the seabed. Such systems, which combine cameras, lights, and a standardized bait source, have become essential tools for monitoring elusive deep-sea species. In waters as hostile as those of the Southern Ocean, where sea ice, storms, and crushing pressure limit direct human observation, remote instruments are often the only way to document wildlife in its natural habitat.

For scientists, the brief appearance of the sleeper shark is more than a striking image. It confirms that large apex or near-apex predators are present and active in Antarctic deep waters that, until now, have been assumed to host relatively few large fish species compared with more temperate oceans. The shark’s measured approach and sudden departure underscore its reputation as a stealthy, low-energy hunter adapted to dim light and extreme cold.

Historical Context: A Long Quest to Understand Sleeper Sharks

Sleeper sharks have intrigued marine biologists for more than a century. Early records from the North Atlantic and Arctic described large, slow-moving sharks hauled up by longlines or trawls, often with partially digested fish and marine mammals in their stomachs. These animals, including the Greenland shark (Somniosus microcephalus), quickly gained a reputation as “ghosts” of the deep—common enough in polar regions, but rarely seen alive and almost never observed behaving in the wild.

In the Southern Hemisphere, the southern sleeper shark remained largely a taxonomic name on specimen tags and scientific papers. Most of what was known came from incidental catches by fisheries or research trawls in sub-Antarctic waters, where the sharks were encountered sporadically and often in poor condition. Without live observations, scientists could only infer behavior and ecological role from anatomy: a large liver for buoyancy and energy storage, small fins, and a body plan built for efficiency rather than speed.

The first filmed record of a southern sleeper shark off Antarctica therefore marks a significant transition—from a species known mainly from dead specimens to one that can now be studied in situ. It echoes other milestones in deep-sea exploration, such as the first images of giant squid or deep-living cephalopods, which transformed obscure names in field guides into tangible, observable animals. By placing a real, moving shark in its Antarctic setting, the footage begins to fill a long-standing gap in the historical record of polar marine predators.

Why This Antarctic Sighting Matters

The South Shetland Islands lie along the northern fringe of the Antarctic Peninsula, a region where cold, nutrient-rich waters support dense populations of krill, fish, penguins, seals, and whales. For decades, research here has focused on more accessible species—particularly penguins and krill—while the deeper waters remained comparatively unexplored.

Documenting a large shark at 490 meters provides several important insights:

• It confirms that southern sleeper sharks occupy high-latitude, deep habitats far into the Antarctic zone, not just in adjacent sub-Antarctic waters.
• It suggests that the deeper food web includes large scavengers and predators capable of consuming fish, squid, and potentially carrion from marine mammals.
• It demonstrates that deep, near-freezing environments around Antarctica are not biological deserts but host substantial top predators.

Such information matters because Antarctic marine ecosystems are often used as indicators of global ocean change. Shifts in predator distributions, especially large animals at or near the top of the food chain, can signal broader changes in currents, sea-ice cover, and prey availability. The new shark footage adds a crucial data point to this evolving picture.

Economic Implications for Fisheries and Conservation

Although sleeper sharks are not a primary commercial target in Antarctic waters, their presence has implications for fisheries and policy. Many Southern Ocean fisheries focus on species such as Patagonian toothfish and Antarctic toothfish, high-value catches that occupy deep habitats in some of the same regions where sleeper sharks are now confirmed to patrol.

The discovery raises several economic and management questions:

• Potential bycatch: Longline and deep-trawl fisheries may incidentally capture sleeper sharks, damaging gear and harming animals that are not intended targets. Understanding where and when these sharks occur can help reduce bycatch and its associated costs.
• Ecosystem-based management: International bodies tasked with managing Antarctic fisheries are moving toward ecosystem-based approaches that account for predator-prey relationships. Knowing that sleeper sharks are part of the deep-water predator community may influence assessments of sustainable catch limits.
• Market and reputation: Antarctic fisheries often promote themselves as among the most carefully regulated and environmentally responsible in the world. Demonstrating awareness of, and precautions for, rarely seen deep-sea predators like sleeper sharks can support that reputation and help maintain market confidence.

At a broader scale, the presence of large predatory sharks underscores the ecological value of the Southern Ocean. This can bolster arguments for marine protected areas and stricter controls on exploitation, which in turn shape economic opportunities, from fishing licenses to eco-tourism that markets the region’s unique biodiversity.

How Antarctic Deep Waters Compare with Other Polar Seas

Sleeper sharks are already known from the Arctic and North Atlantic, where studies of the Greenland shark have revealed remarkable traits, including extremely slow growth and potential lifespans reaching several centuries. These sharks inhabit cold, deep waters and often appear in fjords, continental slopes, and near the edge of the ice, where they scavenge and occasionally prey on fish and marine mammals.

The new Antarctic footage aligns the Southern Ocean with these northern counterparts in several ways:

• Temperature: With a recorded water temperature of 1.27 degrees Celsius, the South Shetland site mirrors the frigid conditions where Greenland sharks thrive in the Arctic. Both environments test the limits of vertebrate life, favoring slow metabolism and energy-efficient movement.
• Depth range: A depth of 490 meters places the Antarctic shark in the upper part of the deep-sea zone commonly occupied by sleeper sharks elsewhere, suggesting comparable vertical distributions between hemispheres.
• Ecological role: In both polar regions, sleeper sharks likely serve as important scavengers, cleaning up carcasses that sink from the surface, and as opportunistic predators on fish and other deep-living animals.

There are also key differences. The Southern Ocean is encircled by the Antarctic Circumpolar Current, a powerful flow that isolates Antarctic waters and shapes distinct temperature and nutrient patterns. Ice dynamics, seasonal daylight extremes, and the dominance of krill in the food web give the Antarctic a different character from Arctic shelf seas. Documenting sleeper sharks in this context suggests that the genus Somniosus has found parallel ways to exploit cold, deep habitats in two very different polar systems.

Climate Change and Shifting Polar Ecosystems

The Antarctic Peninsula and its surrounding waters are among the fastest-warming regions on Earth, with documented changes in sea-ice duration, glacier retreat, and shifts in the distribution of species such as krill and penguins. The presence of a large shark in the deep waters off the South Shetland Islands adds another piece to the puzzle of how climate change may reshape polar ecosystems.

As temperatures rise and sea ice retreats, several scenarios become possible:

• Prey redistribution: Changes in krill, fish, and squid abundance may alter the food supply for deep predators, potentially affecting where and how often sleeper sharks appear.
• Range shifts: If conditions become more favorable at different latitudes or depths, sleeper sharks might expand or contract their range, influencing interactions with other species and fisheries.
• New stressors: Increased human activity, from research vessels to tourism and fishing, could bring additional noise, pollution, and bycatch risks into areas where sleeper sharks were previously rarely disturbed.

While one recorded shark cannot answer these questions, it provides a baseline for future comparisons. Repeated sightings or systematic surveys over time could reveal whether sleeper sharks become more common, rare, or simply more frequently documented as technology improves.

The Role of Technology in Revealing the Deep

The 2025 sighting illustrates how advances in underwater technology are transforming polar research. Baited cameras, autonomous underwater vehicles, and long-term observatories now operate in conditions that, until recently, were almost inaccessible to science.

The key advantages of these systems include:

• Non-lethal observation: Sharks and other species can be documented without being captured or harmed, providing more natural behavior records.
• Standardized sampling: Using consistent bait and camera setups allows comparisons between sites and over time, revealing patterns in species presence and abundance.
• Cost-effective coverage: Remote systems can stay in the water for extended periods and operate in harsh weather, extending the reach of research vessels.

In the case of the southern sleeper shark, the technology did more than simply record a rare animal. It captured behavior, environmental conditions, and precise location, creating a dataset that can be integrated with broader oceanographic information. As similar deployments expand around Antarctica, they may uncover additional deep-sea predators, unknown species, or new behaviors that refine current models of the Southern Ocean food web.

Public Fascination and Scientific Responsibility

News of a large, mysterious shark in Antarctic deep waters is likely to capture public imagination. Sleeper sharks, with their slow movement, deep-set eyes, and association with the world’s coldest oceans, evoke a sense of otherworldliness that few marine animals match. The first Antarctic deep-water footage adds a new chapter to that story, blending scientific discovery with a powerful visual.

This interest brings responsibility. Scientists and policymakers must communicate findings clearly, avoiding exaggeration while highlighting why such discoveries matter. A single shark does not mark a new “invasion” or sudden shift in the ecosystem, but it does underscore how much remains unknown below the ice and waves. Accurate, measured reporting can help the public appreciate these nuances while supporting informed debate about conservation and sustainable use of Antarctic resources.

A New Reference Point in Deep Antarctic Research

The southernmost filmed record of a southern sleeper shark is, in one sense, a simple observation: a large shark, cold water, a brief visit to a baited camera, and a slow retreat into the dark. Yet within that moment lies a convergence of decades of polar research, technological progress, and growing concern about the future of the world’s coldest oceans.

By capturing the shark in its natural Antarctic setting, scientists have added a crucial reference point for understanding how deep-sea predators fit into the Southern Ocean ecosystem. The sighting connects the Antarctic to other polar seas, highlights potential implications for fisheries and marine management, and underscores the importance of continued monitoring as climate and human activity reshape remote marine environments.

As more instruments descend into the depths around Antarctica, the 2025 sleeper shark may come to be seen as an early sign that a once-hidden layer of the polar world is starting to emerge into view—slowly, like the shark itself, but with profound implications for how humanity understands and manages the planet’s final frontiers.