Greenland shark

Greenland sharks eat fish and other sea animals.

They also eat food that has sunk to the bottom. They are not fussy eaters!

Greenland sharks eat a huge variety of food. Fish are the most common: herring, capelin, char, cod and their relatives, redfish, flounders, skates, eels and even small sharks. They also catch seals and porpoises, even though they are known as slow, sluggish sharks.

They are also scavengers that eat dead animals they find, and they often gather around fishing boats.

The Florida Museum lists small sharks, skates, eels, herring, capelin, char, gadoids, redfish, sculpins, lumpfish, wolffish and flounders as common prey. Seals and porpoises are often taken despite the shark's sluggish reputation. A few specimens have contained the remains of land mammals, including a whole reindeer.

Greenland sharks also scavenge carrion, are attracted to strong-smelling meat and often congregate in large numbers around fishing operations.

Greenland sharks move slowly through the cold water.

In summer they come closer to the coast. In winter they swim farther out to sea.

Greenland sharks are famous for moving slowly; even their scientific name, Somniosus, refers to sleep. They travel between the coast and deeper water with the seasons, moving inshore in summer and offshore in winter.

In some places, many young Greenland sharks gather in summer. Adults are much harder to find, and scientists still know little about where the biggest sharks spend their time.

The species moves inshore into coastal areas in summer and offshore in winter (IUCN). In unfished areas of the eastern Canadian Arctic Archipelago, summer densities of 0.4 to 15.5 sharks per square kilometer have been estimated, mainly juveniles averaging 2.48 meters, with a notable absence of adults.

Around West Greenland, trawl surveys caught only 106 sharks in 9,744 hauls from 1988 to 2011, yet swept-area estimates suggested about 100,000 individuals on the West Greenland shelf, a figure the IUCN calls highly uncertain. The Florida Museum notes that the International Shark Attack File holds only one report involving a Greenland shark, from about 1859, which was never investigated or proven; its cold, deep home is rarely visited by swimmers.

Greenland sharks grow up so slowly that they need extra care.

People are learning to let them go safely when they are caught by accident.

The IUCN lists the Greenland shark as Vulnerable. For hundreds of years people caught these sharks for the oil in their huge livers, which was burned in lamps. That fishing stopped in the middle of the 1900s.

Today about 3,500 are caught each year by accident in nets and on lines set for other fish. Because they take so long to grow up, even small losses matter. Special net gear and careful release help them escape alive, and melting sea ice is a new worry.

The IUCN assessed the species as Vulnerable A2bd (June 2019; published 2020; previously Near Threatened, 2006). Target fisheries for liver oil ran from the 13th century and peaked in the early 20th, with an estimated 58,000 sharks a year based on Norway's 1948 liver-oil production, then ended in the 1940s to 1960s with synthetic oils. Population reconstructions suggest a 30 to 49 percent decline over three generations (450 years with an assumed 150-year generation), within a wide range of 11.7 to 72.9 percent depending on generation length.

About 3,500 are now taken yearly as bycatch, a level the IUCN says may be enough to cause a decline, given a maximum population growth rate of 0.032 a year, nearly half the lowest previously calculated for any shark or ray. NAFO prohibits directed fishing, the EU has a zero catch limit for deep-sea sharks in parts of the northeast Atlantic, and the Nordmøre grate cut Canadian shrimp-trawl bycatch to under a tonne a year. Shrinking Arctic sea ice is opening new waters to fishing.