Greenland shark and the secret of long life



by LORENZO CIOTTI

Greenland shark and the secret of long life

Since 2001, the Greenland Shark and Other Elasmobranch Research and Education Group (GEERG), led by Canadian researchers, has been studying the Greenland shark in the waters of the Saguenay Fjord and the San Lorenzo Estuary.

The presence of this species in the area has been repeatedly documented as early as 1888. The research undertaken by GEERG involves the study of shark behavior thanks to the use of divers equipped with cameras and of acoustic and satellite signaling equipment positioned on the sharks themselves; despite all the studies carried out, however, this giant of the sea still remains almost unknown.

The Greenland shark

Also known as the arctic shark or gray shark, the Greenland shark is a large shark belonging to the Somniosidae family. The distribution of this species is restricted to the Atlantic and Arctic oceans.

Very closely related to the Pacific lemargo, it goes further north than any other shark species and also lives much longer than other sharks. It is one of the largest shark species and its size is comparable to that of the white shark: the largest specimens measure 6.4 meters in length and weigh 1,000 kg and some of them can reach 7.3 meters.

Together with the Pacific lemargo it is the largest species of the Somniosidae family. It is the longest-lived vertebrate in the world: the oldest specimen has been estimated to be 512 years old. The Greenland shark reaches sexual maturity around 150 years of age.

The flesh of the Greenland shark is poisonous, due to the presence in it of a toxin, trimethylamine oxide, which, when digested, breaks down into trimethylamine, a substance that causes effects equal to those of a strong intoxication.

Due to this neurotoxin, sled dogs that have fed on the meat of this shark can no longer stand up. However, if it is boiled by changing the water often or if it is dried and fermented for a few months to produce the so-called Kæstur Hákarl, also called simply Hákarl, it can be consumed.

Myths and legends about the Greenland shark

The Greenland shark is not thought to be dangerous to humans, but some Inuit legends speak of sharks attacking kayaks.
Its poisonous meats, with a high urea content, are the basis of the legend of Skalugsuak, the first shark in Greenland.

According to this legend, an old woman washed her hair with her own urine and dried it with a rag; from this rag, thrown into the ocean, Skalugsuak originated.
Another legend is that of Sedna, a girl whose fingers her father cut off while he was drowning. It is said that each severed finger gave rise to a creature of the sea, including the Greenland shark.