The Greenland shark (Somniosus microcephalus) is the largest member of the sleeper shark family (Somniosidae), the largest fish in the Arctic, and the second-largest carnivorous shark in the world after the white shark[1]. It is also the longest-living vertebrate known to science, with some individuals estimated to exceed 272 years of age[2].

Its distribution extends from the Arctic Ocean and northern Europe southward to approximately the 32nd parallel north in the Atlantic Ocean. In Atlantic Canada and Québec, the Greenland shark is a year-round resident of the deep waters of the Gulf and Estuary of the St. Lawrence.

Despite its slow-moving and lethargic appearance, the Greenland shark is a powerful predator capable of sudden bursts of speed. Its diet includes fish, squid, seals, and occasionally larger marine mammals such as beluga whales, although scavenging also appears to play an important role in its feeding ecology.

Because of its deepwater bathybenthic habitat, the Greenland shark is only rarely observed alive in its natural environment. The first underwater images of a live specimen were taken in the Arctic in 1995, while the first footage of a Greenland shark swimming freely under natural conditions[3] was obtained in the St. Lawrence Estuary by ORS researcher Jeffrey Hay Gallant in 2003.

From 2003 to 2012, researchers from the St. Lawrence Shark Observatory (ORS) conducted long-term non-invasive diving observations with Greenland sharks near Baie-Comeau in the St. Lawrence Estuary. During the early years of the project, Greenland sharks were encountered on nearly every dive, allowing researchers to observe and film hundreds of individuals under natural conditions and to publish some of the first scientific studies based on repeated in situ observations of the species.

These dives represented the first documented case of predictable and repeated diver encounters with free-swimming Greenland sharks in the wild. To this day, no other location in the world has produced a comparable body of underwater observations and video documentation of Greenland sharks under natural conditions.

(1) Comparable in length to the white shark, but with approximately half the body girth.
(2) Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., Olsen, J., et al. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science, 353, 702–704.
(3) Non-invasive observation conducted without the use of bait, attractants, capture methods, or restraints. All encounters were initiated and terminated voluntarily by the sharks themselves.

The distribution of the Greenland shark extends from the Arctic Ocean and northern Europe southward to approximately the 32nd parallel north in the Atlantic Ocean, including the Gulf and Estuary of the St. Lawrence. Together with the Pacific sleeper shark (Somniosus pacificus), it is one of only two shark species known to tolerate Arctic conditions year-round.

In Québec, the Greenland shark has been documented throughout the St. Lawrence Gulf and Estuary, the Saguenay Fjord, and has also been observed in the lower reaches of Hudson Bay and James Bay (Gallant, unpublished data). Its presence in the St. Lawrence has been recorded for nearly two centuries and is therefore neither recent nor attributable to modern climate change.

The Greenland shark inhabits cold-water environments ranging from approximately −1.6°C to 16.1°C[1]. Seasonal temperature differences strongly influence its vertical movements within the water column. During the summer, individuals generally remain at greater depths where temperatures are coldest, while in winter they may rise toward the ice-covered surface layer, which can become colder than deep bottom waters.

Although commonly associated with Arctic environments, the Greenland shark is not restricted to polar regions and appears well adapted to the cold deepwater habitats of the Northwest Atlantic.

DNA analyses[2] contradict the reported capture of a Greenland shark in the Gulf of Mexico in 2013. The specimen captured by Florida State University was likely either a Pacific sleeper shark (Somniosus pacificus) or a Greenland–Pacific sleeper shark hybrid.

Because sleeper shark species are extremely difficult to distinguish visually and because their distributions overlap in some regions, many observations from submersibles and remotely operated vehicles (ROVs) cannot be confirmed to species level without genetic sampling.

The Greenland shark possesses highly specialised dentition that influences the way it feeds. The narrow pointed upper teeth, which lack serrations, are used primarily to grip and stabilise prey, while the broad lower teeth are strongly curved and overlap to form an effective cutting surface.

When feeding on large prey items, the shark is believed to anchor itself with the upper teeth and then twist its head in a circular motion, allowing the lower teeth to remove a rounded “plug” of flesh. This behaviour was documented on film by Dr. George Benz near Baffin Island. The upper jaw typically contains 48 to 52 teeth, while the lower jaw contains approximately 50 to 52 teeth.

Smaller prey items that fit entirely within the mouth are generally swallowed whole, often by suction feeding near the bottom.

The rounded bite wounds associated with Greenland shark feeding behaviour should not be confused with the so-called “corkscrew” wounds reported in the media and in a 2010 documentary film. Subsequent research suggests that these spiral wounds on seals are more likely caused by interactions with other seals rather than by Greenland sharks[1].

The skin of the Greenland shark is covered with dermal denticles, tooth-like structures more closely related to teeth than to the scales of bony fish. These microscopic denticles help reduce drag and turbulence as the shark moves through the water, contributing to quieter and more efficient swimming.

The denticles are extremely rough and abrasive, giving the skin a texture comparable to coarse sandpaper. Divers should therefore avoid intentional or accidental contact with Greenland sharks, as the skin can easily scratch exposed equipment and may even damage or puncture a drysuit under certain conditions.

Greenland sharks have been visually documented from the surface (0 m) to depths of approximately 2,200 metres[1]. One of the deepest confirmed observations was made near the wreck of the SS Central America, about 260 km east of Cape Hatteras, where an unmanned submersible filmed a Greenland shark in 1988[2].

At this depth, the surrounding pressure reaches approximately 3,200 psi (221 bar), exceeding the internal pressure of a standard scuba cylinder, which is typically filled to about 3,000 psi (207 bar). By comparison, the tires of a typical passenger vehicle are usually inflated to only 32–35 psi.

In 2012, a sleeper shark of uncertain species identity was also observed at a depth of 2,774 metres off the coast of Brazil, illustrating the remarkable deepwater tolerance of the Somniosidae family.

(1) The species of sleeper shark observed at a depth of 2,200 m in 1998 has never been confirmed. However, given the location of the observation, it is generally assumed to have been a Greenland shark.
(2) Herdendorf, C. E., and Berra, T. M. (1995). A Greenland shark from the wreck of the SS Central America at 2,200 meters. Trans. Am. Fish. Soc. 124, 950–953.

The Greenland shark is considered one of the slowest-swimming sharks in the world. During underwater observations in the St. Lawrence Estuary, ORS researchers have frequently documented individuals hovering just above the bottom with barely perceptible movements, sometimes appearing almost motionless in the water column.

Based on hundreds of visual observations of free-swimming Greenland sharks, combined with detailed video analysis and several months of telemetry data, ORS researchers estimated the species’ average swimming speed in the St. Lawrence Estuary at approximately 0.3 metres per second, or 1.08 km/h (0.67 mph)[1].

Despite this generally slow pace, Greenland sharks are capable of short bursts of acceleration. During tagging operations conducted by scuba divers on unrestrained individuals, ORS researchers observed burst swimming speeds approaching 1 metre per second, or 3.6 km/h (2.2 mph).

A previously published top swimming speed of 0.7 m/s (1.7 mph)[2] for the Greenland shark was measured under normal swimming conditions using sharks equipped with accelerometer tags. By contrast, the higher burst speeds documented by ORS researchers were observed during close-range tagging operations involving unrestrained sharks reacting to the brief contact of tagging equipment.

Although Greenland sharks are capable of extremely slow movements, with individual tail sweeps occasionally taking several seconds, such observations do not represent the species’ typical swimming speed under normal conditions, as demonstrated by repeated field observations and underwater video footage from the St. Lawrence Estuary.

The Greenland shark is certainly not a fast swimmer, but field observations suggest that its reputation as the “world’s slowest shark” may at times be exaggerated. During underwater encounters in the St. Lawrence Estuary, ORS researchers have repeatedly found that maintaining pace with free-swimming Greenland sharks while scuba diving can become physically demanding after only a few minutes, particularly in cold water and strong currents.

Although the species generally cruises slowly and efficiently, it is clearly capable of sustained movement over considerable distances. For example, one Greenland shark tagged by GEERG in 2005 travelled approximately 26 km (16 miles) in only 29 hours[1].

Comparisons with other slow-moving shark species further illustrate the difficulty of defining a single “slowest shark.” A study[3] on Pacific angel sharks (Squatina californica) showed that individuals sometimes moved only 30–75 km over a three-month period, with maximum nightly displacements of approximately 7.3 km (4.5 miles). Like the Greenland shark, angel sharks possess spiracles, specialised respiratory openings located behind the eyes, that assist with ventilation during slow swimming or while resting on the seafloor[4]. Other deepwater sharks, including sleeper sharks, gulper sharks, and lanternsharks, may also rival or exceed the Greenland shark in terms of low average swimming speeds under certain conditions.

Moreover, many of these species exhibit strong site fidelity (philopatry) and rely on highly energy-efficient lifestyles adapted to deepwater or benthic environments. Direct comparisons between species therefore remain difficult because swimming behaviour varies according to habitat, body size, ecology, and migratory patterns.

For these reasons, ORS researchers consider the title of “world’s slowest shark” to be more of a popular characterisation than a rigorously established scientific fact. While the Greenland shark is undeniably slow-moving compared with most large pelagic sharks, current evidence does not conclusively demonstrate that it is the slowest shark, or fish, in the world.

(1) Gallant, Jeffrey J., Marco A. Rodríguez, Michael J. W. Stokesbury, and Chris Harvey-Clark. (2016). Influence of environmental variables on the diel movements of the Greenland Shark (Somniosus microcephalus) in the St. Lawrence Estuary. Canadian Field-Naturalist 130(1): 1-14.
(2) Watanabe, Y. Y., Lydersen, C., Fisk, A. T., and Kovacs, K. M. (2012). The slowest fish: Swim speed and tail-beat frequency of Greenland sharks. Journal of Experimental Marine Biology and Ecology 426–427: 5-11.
(3) Fouts, W. R. & Nelson, D. R. (1999). “Prey Capture by the Pacific Angel Shark, Squatina californica: Visually Mediated Strikes and Ambush-Site Characteristics.” Copeia 1999(2): 304–312. American Society of Ichthyologists and Herpetologists.
(4) Unlike many shark species that must swim continuously to force oxygen-rich water across their gills, some sharks can remain nearly motionless while using spiracles, specialised respiratory openings located behind the eyes, to draw water into the gill chamber. The Greenland shark possesses unusually large spiracles that likely facilitate respiration while swimming slowly, conserving energy, or approaching prey stealthily in near-freezing environments.

The Greenland shark is an opportunistic feeder capable of consuming a remarkable variety of prey and carrion. Although it is fully capable of active predation, available evidence suggests that scavenging likely plays a major role in its feeding ecology, particularly in deepwater environments where food resources may be sporadic.

Fish: Arctic char, Atlantic halibut, Atlantic salmon, capelin, cod, eelpouts, eels, Greenland halibut (turbot), grenadiers, haddock, herring, lumpfish, Lycodes spp., pollock, sculpins, Sebastes spp., skates, wolffish, and other sharks.

Marine mammals and other vertebrates: Beluga whale, narwhal, harbour porpoise, seals, as well as remains of terrestrial mammals including dog, horse, reindeer/caribou, moose, and white bear*.

Invertebrates: Crustaceans, gastropods, jellyfish, octopus, sea stars (including sun stars and brittle stars), squid, sea urchins, whelks, and other marine snails.

Other material: Bird remains and kelp.

Caribou predation: Greenland sharks have reportedly been observed by scientists ambushing migrating caribou at Arctic river crossings in a manner somewhat reminiscent of crocodilian predation. Although this frequently repeated anecdote originates from credible observers, it has never been scientifically documented or verified. A more plausible explanation is that Greenland sharks scavenge the carcasses of drowned caribou that fall through unstable ice or perish during river crossings.

White bear predation: Media reports published in 2008 suggested that climate change might increase the likelihood of Greenland sharks attacking white bears*. However, there is currently no scientific evidence supporting active predation on healthy adult white bears.

*Throughout this website, we use the term white bear in preference to polar bear because the species (Ursus maritimus) was historically not restricted to polar environments. Before intensive hunting and regional extirpation, its range extended much farther south, including parts of the Gulf of St. Lawrence and surrounding regions. In this context, the expression polar bear reflects the species’ present-day distribution rather than its historical one. Referring to it as a white bear more accurately acknowledges its former ecological range and reminds us that its current Arctic confinement is, in part, the result of human impacts.

As noted by ORS researcher Jeffrey Gallant:

More likely, the occasional white bear remains recovered from Greenland shark stomachs originated from scavenging events rather than active predation.

The only confirmed natural predator of the Greenland shark is the sperm whale (Physeter macrocephalus). During fieldwork in the St. Lawrence Estuary, ORS researchers documented two separate incidents involving a sperm whale displaying apparent predatory behaviour in the presence of Greenland sharks. Unfortunately, this same whale, an individual known as Tryphon, later died after becoming entangled in fishing gear in 2009.

Subsequent photo analysis conducted by ORS researcher Jeffrey Gallant revealed another possible indication that Tryphon may have fed on Greenland sharks over an extended period. The whale’s teeth showed unusually severe abrasion and wear, a condition strikingly similar to that observed in a pod of killer whales (Orcinus orca) documented feeding[1] on Pacific sleeper sharks (Somniosus pacificus) off British Columbia in 2008. The Pacific sleeper shark is very closely related to, and morphologically similar to, the Greenland shark.

Sperm whales and killer whales are believed to target sleeper sharks primarily for the large oil-rich liver, which represents a concentrated energy source. However, the sharks’ skin is covered with extremely abrasive dermal denticles capable of rapidly wearing down teeth during feeding. Repeated predation on sleeper sharks over a period of years may therefore transform normally sharp cetacean teeth into heavily rounded stubs through chronic abrasion.

(1) Ford, J.K.B., G.M. Ellis, C.O. Matkin, M.H. Wetklo, L.G. Barrett-Lennard, and R.E. Withler. 2011a. Shark predation and tooth wear in a population of northeastern Pacific killer whales. Aquat. Biol. 11: 213-224.

Relatively little is known about the reproduction of the Greenland shark. Based on growth studies and radiocarbon dating, females are believed to reach sexual maturity at approximately 156 ± 22 years of age[1], making the species one of the slowest-maturing vertebrates known.

The Greenland shark is generally considered ovoviviparous (aplacental viviparity), meaning that the eggs develop and hatch within the female without the presence of a placenta. Embryos are thought to rely primarily on yolk reserves during development, although many aspects of reproduction remain poorly understood because pregnant females and embryos are rarely encountered. Historical reports suggest litter sizes may exceed ten pups, and newborns are believed to measure approximately 35–45 cm in length.

Mating and birth have never been observed directly in the wild.

Female Greenland sharks observed by GEERG researchers in the St. Lawrence Estuary frequently displayed scars and abrasions around the caudal region consistent with mating bites. As in many shark species, males are believed to bite females during courtship and copulation in order to maintain position. The female’s skin is considerably thicker than that of the male, likely providing some protection during these interactions.

(1) Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., 2815 Olsen, J., et al. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science 353, 702–704.

A Finnish proverb states that “age does not bring wisdom, only slower movement,” a phrase that may aptly describe the Greenland shark. With an average cruising speed estimated at approximately 0.3 m/sec (1 ft/sec), the species is indeed an exceptionally slow and energy-efficient swimmer. This unusually reduced metabolism is thought to be linked in part to the shark’s cold deepwater environment and may help explain one of the most extraordinary discoveries ever made about a vertebrate animal: its extreme longevity[1].

For many years, determining the age of a Greenland shark was considered virtually impossible. Unlike many shark species, Greenland sharks do not possess calcified vertebral growth bands that can be counted in a manner similar to tree rings. Traditional age estimation methods were therefore ineffective.

In theory, accurately measuring growth would require repeated recaptures of known individuals over decades or even centuries, an unrealistic task for a deepwater shark inhabiting remote Arctic and North Atlantic environments. The challenge is compounded by the fact that Greenland sharks have never been maintained successfully in captivity for extended periods, and recapture data in the wild remain extremely limited.

One of the few reliable long-term recapture records comes from a study[2] involving a shark tagged off Greenland in 1936 and recaptured in 1952. Over a period of 16 years, the shark had grown only eight centimetres (3 in), corresponding to an estimated growth rate of approximately 0.5 cm per year. Additional, less reliable recapture records suggested growth rates of no more than about 1.1 cm annually. Such remarkably slow growth led some researchers to hypothesize decades ago that large Greenland sharks might live for several centuries.

This hypothesis received strong support in 2016 when a research team led by Julius Nielsen at the University of Copenhagen published a landmark study[3] in the journal Science. Using radiocarbon dating of eye lens tissue from 28 Greenland sharks, the researchers estimated that individuals born before atmospheric nuclear testing in the 1950s possessed extraordinary ages. The study suggested a minimum lifespan of at least 272 years, that females may not reach sexual maturity before approximately 156 ± 22 years of age, and that the largest shark examined (5.2 m / 17 ft) was approximately 392 ± 120 years old.

Although some scientific uncertainty remains because radiocarbon dating of deepwater marine organisms is inherently imprecise, the evidence strongly indicates that the Greenland shark is currently the longest-living vertebrate known to science.

Given that Greenland sharks may exceed seven metres (23 ft) in length, some living individuals could theoretically predate the arrival of Europeans in the western St. Lawrence.

(1) Hansen, P. M. (1963). Tagging experiments with the Greenland shark (Somniosus microcephalus (Bloch and Schneider)) in subarea 1. Int. Comm. Northwest Atl. Fish. Spec. Publ. 4, 172–175.
(2) Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., 2815 Olsen, J., et al. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science 353, 702–704.

The parasite most commonly associated with the Greenland shark is the copepod Ommatokoita elongata. This parasitic crustacean attaches itself to one or both eyes of the shark, where it can cause lesions to the cornea and potentially impair vision. Even if partially or completely blind, however, the Greenland shark is believed capable of surviving effectively by relying on its highly developed senses of smell, low-frequency vibration detection, and possibly electroreception to locate prey and carrion.

Because Greenland sharks inhabit deep, dark environments, often at depths where sunlight is absent and sometimes beneath sea ice, vision may play a relatively limited role in their ecology. Some researchers have proposed that Ommatokoita elongata may be bioluminescent and could potentially attract prey toward the shark, but this hypothesis has never been conclusively demonstrated.

Interestingly, the prevalence of this parasite appears to vary greatly between regions. While more than 90% of Greenland sharks examined in parts of the Arctic have reportedly hosted Ommatokoita elongata[1], fewer than 5% of the individuals observed by GEERG researchers in the St. Lawrence Estuary[2] carried the parasite.

In 2004[3], ORS researcher Jeffrey Gallant also documented a sea lamprey (Petromyzon marinus) attached to a Greenland shark near Baie-Comeau in the St. Lawrence Estuary, representing the first documented observation of this interaction.

(1) Koefoed E (1957) Notes of the Greenland shark Acanthorhinus carcharias (Gunn). 2. A uterine foetus and the uterus from a Greenland shark. Rep Nor Fish Mar Investig 11:8–12.
(2) Harvey-Clark, C. J., Gallant, J. J., and Batt, J. H. (2005). Vision and its relationship 2612 to novel behaviour in St. Lawrence River Greenland Sharks, Somniosus microcephalus. Can. Field Nat. 119, 355–358.
(3) Gallant, J., C. Harvey-Clark, R.A. Myers, and M.J.W. Stokesbury. 2005. Sea lamprey (Petromyzon marinus) attached to a Greenland shark (Somniosus microcephalus) in the St. Lawrence Estuary, Canada. Northeastern Naturalist. 2006 13(1):35–38.

Water and dissolved substances such as salts, calcium chloride, and sulphates move through the tissues and cells of fishes by a process known as osmosis. Smaller dissolved molecules pass relatively freely across biological membranes, while larger compounds, including proteins and trimethylamine oxide (TMAO*), contribute to osmotic balance without diffusing as easily through the tissues.

* Trimethylamine oxide (TMAO) is produced during the metabolism of proteins and amino acids.

In marine environments, the salt concentration outside most fishes is greater than that within their bodies. As a result, water tends to leave the body through osmosis while salts diffuse inward. To compensate, marine bony fishes must continuously drink seawater and actively excrete excess salts through specialised cells located primarily in the gills.

Some fishes can tolerate only a narrow range of salinity and are therefore termed stenohaline. Others, such as salmon, are capable of adapting to both freshwater and seawater environments through physiological adjustments known as osmoregulation; these species are called euryhaline.

Sharks regulate osmotic balance differently from bony fishes. Although the concentration of salts in a shark’s tissues is lower than that of seawater, sharks retain large quantities of urea in their blood and body fluids. This elevated urea concentration increases internal osmotic pressure and helps prevent excessive water loss to the surrounding marine environment.

Because urea is toxic at high concentrations and can destabilise proteins, sharks also retain very high levels of trimethylamine oxide (TMAO), which counteracts the damaging effects of urea on cellular structures and enzymes. The combined effects of salts, urea, and TMAO make the body fluids of the Greenland shark slightly more concentrated than seawater itself.

In practical terms, the Greenland shark is effectively “saltier” than the surrounding ocean. Unlike many bony fishes, it therefore does not need to continually drink seawater to maintain hydration, allowing it to conserve energy in the cold, food-limited environments it inhabits.

In addition to contributing to osmotic balance, the unusually high concentrations of urea and trimethylamine oxide (TMAO) found in the Greenland shark’s tissues also help protect the animal from freezing in the near-freezing waters it inhabits. TMAO stabilises proteins and enzymes that would otherwise be damaged by the high levels of urea retained within the shark’s body.

This biochemical adaptation also assists the shark in tolerating the extreme cold and pressure associated with deepwater environments. By helping maintain cellular integrity at very low temperatures, these compounds reduce the likelihood of ice crystal formation within tissues, a process that can rupture cell membranes and lead to severe tissue damage or death.

When Greenland shark flesh is consumed, however, the digestive process converts trimethylamine oxide (TMAO) into trimethylamine (TMA), a compound associated with the strong odour of ammonia and decaying fish. In large quantities, TMA and residual metabolic compounds may produce symptoms resembling severe alcohol intoxication, including dizziness, impaired coordination, nausea, and neurological effects. In extreme cases, consumption of improperly prepared meat may be dangerous.

Despite this toxicity, Greenland shark meat has traditionally been consumed in parts of the North Atlantic, particularly in Iceland, where it is fermented and processed into a traditional food known as hákarl. See “Fisheries” section below.

According to the Canadian Shark Attack Registry, the Greenland shark has been implicated or suspected in four confirmed incidents involving humans in Canadian waters. As of 2023, most reported encounters have involved sharks approaching or following people near shorelines, small boats, or divers. None of these incidents resulted in injury or an actual attack.

Because the Greenland shark inhabits deep, cold, and generally inaccessible environments, direct encounters with humans remain exceptionally rare. For this reason, it would be scientifically imprudent to classify the species as entirely harmless based solely on the very limited number of documented interactions.

During long-term underwater observations conducted by ORS in the St. Lawrence Estuary, Greenland sharks were occasionally observed leaving the bottom to investigate diver activity near the surface. In one documented case, a shark followed a team of divers throughout their ascent to the surface at the conclusion of a dive. Such behaviour may represent exploratory or predatory investigation similar to that used by large marine predators when assessing potential prey.

Additional evidence of the Greenland shark’s ability to approach live prey stealthily was experienced firsthand by ORS researchers Harvey-Clark and Gallant during a close encounter in shallow water (approximately 5 m / 15 ft) and near-zero visibility conditions in June 2004.

Although no confirmed attacks have occurred, Greenland sharks have likely scavenged human remains associated with shipwrecks and maritime disasters throughout the North Atlantic and St. Lawrence over the centuries, including victims of the Empress of Ireland, which sank near Rimouski in 1914 and carried hundreds of victims to the bottom of the St. Lawrence. As deepwater scavengers, Greenland sharks routinely patrol the seafloor where they locate carrion and other organic remains by scent.

(1) Gallant, J. (2022. July 26). Canadian Shark Attack Registry (1st ed.). St. Lawrence Shark Observatory.

Fallen Empress (oil on canvas) © Jean-Louis Courteau. Courteau’s painting depicts how the Empress of Ireland may have appeared in the weeks following its sinking. In reality, such a panoramic view of the wreck would require exceptionally clear conditions, as visibility at the site rarely exceeds six metres. Drawn by the scent of carrion and decomposing organic matter, opportunistic Greenland sharks were likely frequent visitors to the wreck in the aftermath of the disaster.

Sable Island (Nova Scotia), and later parts of the North Sea around England and Scotland, became the focus of considerable controversy surrounding the Greenland shark because of the repeated discovery of seals bearing unusual spiral or “corkscrew” wounds. For many years, these injuries were widely attributed to Greenland shark attacks, particularly because the wounds appeared twisted along the length of the carcass and because Greenland sharks are known scavengers and occasional predators of marine mammals.

Following extensive analysis and debate, however, we do not believe that Greenland sharks are responsible for these so-called “corkscrew” kills. The environmental conditions and behavioural evidence associated with the cases do not correspond with our own observations of Greenland sharks in the St. Lawrence, including repeated underwater encounters and telemetry data. In several of the affected regions, the environmental conditions normally associated with Greenland shark distribution are also absent or poorly represented.

Under certain conditions, Greenland sharks may still scavenge or occasionally prey upon seals at locations such as Sable Island. However, the only confirmed bite pattern associated with the species is circular. Greenland sharks feed by biting into tissue and twisting repeatedly to remove a circular plug of flesh, a feeding behaviour that has been directly observed and filmed underwater. The elongated spiral wounds seen on so-called “corkscrew” carcasses do not match this pattern.

Current evidence suggests that many corkscrew injuries are instead caused by grey seals attacking other seals, a behaviour documented in Nova Scotia (1993)[1], Scotland (2016)[2], and during ORS observations in the Magdalen Islands in 2023. By contrast, white shark predation, which also occurs at Sable Island, typically produces large ragged wounds and extensive tissue trauma rather than spiral lesions.

For more information: Who is the Corkscrew Killer?

(1) Bédard, C., Kovacs, K. and Hammill, M. (1993). Cannibalism by grey seals, Halichoerus grypus, on Amet Island, Nova Scotia. Marine Mammal Science, 9: 421-424.
(2) Brownlow A, Onoufriou J, Bishop A, Davison N, Thompson D. (2016). Corkscrew Seals: Grey Seal (Halichoerus grypus) Infanticide and Cannibalism May Indicate the Cause of Spiral Lacerations in Seals. PLoS ONE 11(6): e0156464. doi:10.1371/journal.pone.0156464

Unlike the deep cultural reverence for sharks found in certain Pacific societies, sharks in Western culture have long been viewed with fear and suspicion. Often portrayed as indiscriminate killing machines, they are rarely appreciated for their ecological importance. Curiously, the Greenland shark has sometimes escaped this reputation among coastal fishers, some of whom mockingly refer to it as the “bottom shark” and consider it slow, passive, and harmless.

Historically, Inuit communities made practical use of the Greenland shark. The skin was dried to produce durable boots and other materials, while the teeth were reportedly used as cutting tools. Sailors also used the shark’s rough denticle-covered skin beneath their boots to improve traction on wet wooden decks.

To this day, some fishers continue to regard the Greenland shark as a nuisance because it damages fishing gear and scavenges catches. In some cases, sharks caught incidentally are mutilated and discarded alive, practices that inevitably lead to the animal’s death despite the absence of any commercial value.

Public perception of sharks in general remains heavily influenced by sensationalist media coverage and films such as Jaws, which for decades shaped the public imagination far more strongly than science. Although many people fear sharks, they are simultaneously fascinated by them, and few marine animals generate as much curiosity, controversy, or media attention.

Through research, education, and public outreach, the St. Lawrence Shark Observatory seeks to promote a more accurate and scientifically grounded understanding of sharks and their role in marine ecosystems.

As of 2026, there are currently no locations in the world where divers can reliably encounter free-swimming Greenland sharks under entirely natural conditions, that is, without the use of bait, attractants, capture methods, or restraints.

Between 2003 and 2012, researchers from the St. Lawrence Shark Observatory documented hundreds of such encounters near Baie-Comeau in the St. Lawrence Estuary during long-term non-invasive research dives. To this day, no other location in the world has produced a comparable frequency of repeated underwater observations of Greenland sharks under natural conditions. Additional natural encounters have also been reported from locations such as the Saguenay Fjord and Qaanaaq, Greenland.

By contrast, encounters involving sharks that have been hooked, restrained, or lassoed by the tail cannot be considered natural observations and may result in significant stress, injury, or even mortality to the animals. This controversial and overlooked practice is discussed in greater detail in our editorial, Hooked on Conservation.

Because the flesh of the Greenland shark contains high concentrations of urea, the species has long been associated with a strong pungent odour. This characteristic gave rise to an Inuit legend explaining the shark’s origin: an old woman washed her hair in urine and dried it with a cloth. The cloth was carried away by the wind into the sea, where it transformed into Skalugsuak, the first Greenland shark.

In Inuit tradition, Sedna is the great goddess and ruler of the sea and its animals. According to one version of the legend, a young Inuk woman wished to marry a bird against her father’s will. Her father later killed the bird husband and attempted to bring his daughter home by kayak. During the journey, a violent storm arose and, fearing for his life, the father threw his daughter into the sea. As she clung to the side of the kayak, he cut off her fingers one by one until she disappeared beneath the water.

Sedna descended into the depths and became the Mother of the Sea. Her severed fingers transformed into marine mammals such as seals, walruses, and whales. Although not created directly from Sedna’s fingers, the Greenland shark remained closely associated with her. Because of the shark’s pungent smell, Inuit tradition sometimes describes it as living in Sedna’s urine pot. The shark was also regarded as one of Sedna’s agents of vengeance. In one account, it ultimately capsized the kayak of the father who betrayed her and devoured him.

In Pangnirtung and other Inuit communities, the Greenland shark is also associated with the raven because it scavenges scraps left behind by more powerful predators such as the killer whale.

Arnakuagsak (“Old Woman of the Sea”) is the Greenlandic equivalent of the Canadian Inuit sea goddess Sedna. In Greenlandic tradition, the Greenland shark is sometimes regarded as a helping spirit associated with shamans and the spiritual world of the sea.

We have identified numerous documented references to Greenland sharks in the St. Lawrence and Saguenay Fjord dating back to the early nineteenth century, demonstrating that the species has long been part of the region’s marine ecosystem and coastal history.

In 1922, the crew of a Newfoundland sealing vessel trapped in the ice reportedly captured more than 30 Greenland sharks after attracting them to the surface by discharging bilge waste containing seal fat and blood. The sharks, hauled aboard with gaffs, measured approximately 3.7 to 4.9 metres (12 to 16 ft) in length. Many similar accounts from fishers and sealers describe Greenland sharks gathering in large numbers around marine mammal carcasses and processing sites.

During the period when beluga whales were commercially hunted in the St. Lawrence, Greenland sharks were frequently attracted at high tide to locations where whales were butchered and bled in coastal communities such as Bergeronnes. As the tide receded, some sharks became stranded on shallow shoals, where fishers cut them open to remove their livers for oil. Contemporary accounts describe how certain sharks, despite severe injuries, were still capable of swimming away when the tide returned.

The Greenland shark (Somniosus microcephalus) is currently listed as Special Concern by COSEWIC (Committee on the Status of Endangered Wildlife in Canada). The species is considered particularly vulnerable because of its extraordinary longevity, extremely slow growth, very late age at sexual maturity, and low reproductive rate. These biological characteristics mean that Greenland shark populations are likely incapable of recovering quickly from overexploitation or elevated mortality.

Globally, the Greenland shark is classified as Vulnerable by the International Union for Conservation of Nature (IUCN). Historical fisheries targeting the species for its liver oil caused substantial declines in some regions of the North Atlantic, and the species continues to face threats from by-catch in commercial fisheries, marine pollution, and climate-related ecosystem changes.

Although no directed commercial fishery currently exists for the Greenland shark in Atlantic Canada, individuals are still occasionally captured accidentally in deepwater fisheries targeting species such as Greenland halibut (turbot), cod, and northern shrimp. Because the species matures so slowly, possibly not before 150 years of age, even relatively low levels of human-caused mortality may have long-term impacts on population recovery.