Greenland shark | Oceana Canada

Canadian Marine Life Encyclopedia

Greenland shark

Somniosus microcephalus

Also known as

Gurry Shark, Grey Shark, Sleeper Shark, Eqalussuaq

Distribution

Polar latitudes from Baffin Island down to the Carolinas in deep water canyons

Écosystèmes/habitats

Cold, deep waters of the Arctic and Atlantic Ocean

Feeding Habits

Opportunistic feeders

Conservation Status

Threatened

Taxonomie

Order Squaliformes (sharks with two dorsal fins), Family Somniosus (sleeper sharks)

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Greenland sharks are one of the world’s largest sharks and the largest fish found in the eastern Arctic Ocean! The largest one ever recorded was 6.4 metres long and weighed a whopping 1,023 kilograms! They’re usually found in cold, deep waters, sometimes at depths greater than 1,500 metres and are known to live an incredibly long time. The oldest Greenland shark studied had lived for nearly 400 years, making it the longest known living vertebrate! These sharks belong to the family Somniodae, known as the sleeper sharks, due to their slow swimming and low activity level. Despite the large size and long lifespan of Greenland sharks, they are still poorly studied. There is a lot for us to learn about this species and how they’re impacted by threats such as climate change and fishing.

Greenland sharks have variable colouring, predominantly grey ranging into brown and black with reports of white spots or scarring on their bodies. Some sharks have a spooky dark violet glow when viewed out of the water, due to a mucous layer on their skin. Greenland sharks have a short, rounded snout and a plump body with two dorsal fins. 

There are very few measurement records for Greenland sharks, but most reported lengths are within three to five metres. Contrasting their large bodies, they have tiny eyes. Their eyes, or rather the species that dine on them, are particularly interesting. Almost every single Greenland shark has the common parasitic copepod, Ommatokoita elongata, attached to their cornea! This three-centimetre long pinkish-white copepod permanently attaches itself to the sharks and can severely impact their vision.

Despite their poor vision, Greenland sharks prey on a variety of marine species such as capelin, Arctic char, halibut, herring and marine mammals such a seals and sea lions. They have even been known to feed on smaller sharks, whale carcasses and unsuspecting caribou near the water’s edge.

Greenland sharks reproduce through internal fertilization and give birth to live young. It is suspected they they’re ovoviviparous, meaning babies hatch from eggs located inside the body of the mother. Typically, Greenland sharks will have litters of up to 10 pups with the babies born at a length of approximately 38 centimetres (15 inches). 

Much about their reproductive cycle is unknown, such as the length of the gestation period and the age at which they become sexually mature. Greenland sharks are extremely slow-growing animals, with some estimates suggesting they grow only one centimetre per year. Based on this, it is thought that they reach sexual maturity at around 150 years of age!

Historically, Greenland sharks were fished in Norway, Iceland and Greenland to support the liver oil industry. Today, Greenland sharks don’t have their own targeted fishery, but bycatch has posed a large problem for their populations. Bycatch is the capture of non-target of species. Greenland sharks are often caught in the Greenland halibut fisheries using long-line, gillnets and bottom trawls. 

By implementing more sustainable and selective fishing practices in the waters where Greenland sharks live, we can reduce the negative impacts that bycatch is having on this species.

Greenland sharks can be found in Canada’s Arctic, a place that is warming twice as fast as the rest of the world due to climate change. The long-term impacts of this are largely unknown but melting ice is allowing for more activity in the Arctic, including an increased fishing pressure.

Greenland sharks are a long-lived species with slow growth, late maturity and low fecundity. This makes them particularly vulnerable to human and climate impacts. In addition, there is very little research on their populations, and it is unknown how much fishing pressure the population can withstand. 

Greenland sharks are listed as near-threatened under the IUCN, although it should be noted that the last assessment was done in 2006. The IUCN highlights the need for more information in their assessment, indicating that research is needed to know the population size, distribution, life history and threats, which would help us better understand and protect these historic creatures.