It can live for several centuries and, measuring at least 5.5 meters from snout to tail tip, is one of the world's largest carnivorous sharks. The Greenland shark is usually associated with the cold deep waters of the Arctic, where it lives a slow life shrouded in mystery, with a white worm-like parasite dangling from each eye.
A new study led by researchers from the Greenland Institute of Natural Resources and the Natural History Museum of Denmark presents important new pieces of the puzzle surrounding the mysterious life of the Greenland shark. Among other things, the study shows that the Greenland shark is found much closer to Denmark than most people imagine.
The researchers have examined catch data from over 1,600 Greenland sharks across the North Atlantic, and here the Skagerrak—between Denmark, Norway, and Sweden—stands out as the area with the highest proportion of young sharks between 90 and 200 centimeters.
“We consider the deepest areas of the Skagerrak to be a potentially important feeding ground for ‘teenage Greenland sharks’, and in fact, the study is the first to systematically examine the occurrence of Greenland sharks in the Skagerrak,” says Associate Professor and marine biologist Peter Rask Møller from the Natural History Museum of Denmark.
The mystery of shark birth
One of the biggest mysteries surrounding the Greenland shark's way of life has been where it gives birth to its (presumably) hundreds of pups per pregnancy. Newborn Greenland sharks measure approximately 40 centimeters at birth, and the new study concludes that this is unlikely to take place in fjords or on the continental shelf in the waters around Canada, Greenland, Iceland, Norway, or Russia. This is because neither pregnant females nor newborn pups have ever been recorded in any of these areas.
However, through a thorough review of Danish, Norwegian, and German museum collections, as well as unpublished scientific databases from Iceland, Norway, and Russia, the researchers have managed to find observations of newborn Greenland sharks—all recorded near the Mid-Atlantic Ridge and the Irminger Sea south of Iceland.
“Future targeted studies will most likely confirm that the Greenland shark gives birth to its many pups in undisturbed parts of the deep sea near the Mid-Atlantic Ridge in deep waters , where there is little activity from commercial fisheries,” says the study's lead author Julius Nielsen, a visiting researcher at the Natural History Museum of Denmark and former employee of the Greenland Institute of Natural Resources.
