The Greenland shark, known for being the world’s longest-living vertebrate, can live for centuries and grow up to 5.5 meters. It is often associated with the Arctic, but this study highlights its presence closer to Denmark than previously thought.

The research, published in Ecology and Evolution, is based on catch data from over 1,600 Greenland sharks across the North Atlantic. It shows that Skagerrak has the highest concentration of juvenile sharks, measuring between 90 and 200cm. 

Peter Rask Møller, a marine biologist at the Natural History Museum of Denmark, said, “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.” 

Birthing grounds and newborns

This discovery challenges the longstanding mystery of where Greenland sharks give birth. While newborn sharks are typically around 40cm long, they have never been found in traditional Arctic breeding grounds, like Greenland or Iceland. Instead, the study reveals sightings of newborns near the Mid-Atlantic Ridge and Irminger Sea south of Iceland, based on museum records and scientific databases from multiple countries.

Threats, distribution and protection

Greenland sharks face significant threats, particularly from bycatch in deep-sea fisheries targeting halibut and cod. The shark is listed as “vulnerable” on the International Red List of Threatened Species. Understanding the geographical distribution of the shark’s life stages is critical for conservation efforts, especially as individual sharks may travel across large parts of the North Atlantic during their lifetimes.

Although the Mid-Atlantic Ridge is likely the birth area, young sharks may spend their early years in Skagerrak before moving on to areas like South Greenland or Iceland as they mature. The study also underscores the importance of recreational fishers in Sweden, who have provided valuable catch data on juvenile sharks in Skagerrak. This new information is vital for improving the protection of Greenland sharks across international waters. However, more research, such as tagging studies, is needed to fully understand their migration patterns.

“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,” said Julius Nielsen, the study’s lead author, visiting researcher at the Natural History Museum of Denmark, who previously worked for the Greenland Institute of Natural Resources.