Greenland Sharks' Surprising Presence in Skagerrak Reveals a Massive Secret About These Species

For some time, researchers have been noticing a unique pattern followed by certain Greenland sharks. These creatures were all gathering between Denmark, Sweden, and Norway for no apparent reason, according to Discover Wildlife. Researchers now have some answers regarding this uncanny phenomenon. They believe that the deep-sea sharks are collecting here due to the facilities provided by a passage of water in the North Sea called Skagerrak, situated between the three countries. The results of the analysis challenge a long-held assumption about this mysterious creature's place of birth. Findings regarding this investigation have been published in the journal Ecology and Evolution. 

Skagerrak: A Surprising Deep Shark Territory

The study claims that Skagerrak (a strait between Denmark, Norway, and Sweden) boasts around 1,610 Greenland sharks. Not only is the number surprising, but the fact that it is the place with the highest proportion of young sharks makes the whole phenomenon more uncanny. Greenland sharks have always intrigued experts due to their unique features. They are not only enormous, reaching a length of around 20 feet on average, but they also supposedly live for multiple centuries. Hence, such unique patterns in their living cycle become crucial developments for researchers to analyze.

Peter Rask Møller, associate professor and marine biologist from the Natural History Museum of Denmark, believes that the high proportion of teenage Greenland Sharks in Skagerrak indicates that it is an important feeding ground for these young sharks. The study further claims that the immense biodiversity of this strait also makes it an appealing place for Greenland sharks. The deep-sea shark feeds on a variety of prey, including several fish and marine animals. The high population of these beings in Skagerrak aligns with the needs of Greenland sharks, as per researchers. 

Challenging Greenland Shark's Arctic Origin

The presence of so many young Greenland sharks in Skagerrak led researchers to suggest that these creatures were possibly not born in Arctic waters. As the name suggests, experts have long assumed that Greenland sharks were born in Greenland or Arctic waters, according to Mirage News. However, the finding challenges the assertion, as the presence of so many young ones in the Skagerrak in the Atlantic Ocean implies that they are not giving birth in the faraway Arctic Ocean. They are known to move slowly and can't supposedly cover the massive distance, even if they begin migration just after being born.

To date, researchers have not spotted any pregnant or newborn Greenland sharks in the Arctic or around it, such as those of Canada, Greenland, Iceland, Norway, or Russia. On the contrary, analysis of specimens from Danish, Norwegian, and German museums and unpublished scientific databases from Iceland, Russia, and Norway suggests a high density of newborn Greenland sharks near the Mid-Atlantic Ridge and the Irminger Sea south of Iceland. Study's lead author Julius Nielsen, a visiting researcher at the Natural History Museum of Denmark, believes that future studies will most likely verify that pregnant Greenland sharks give birth to their pups in undisturbed portions of the deep sea near the Mid-Atlantic Ridge. 

Experts suggest, based on their findings, Greenland sharks born in the Mid-Atlantic Ridge spend their teenage years in the Skagerrak and then live out their adult lives in South Greenland or Iceland. Researchers want to conduct further tagging investigations to verify how the different areas are used by Greenland sharks. 

Insights from the Findings

The study sheds new light on the life cycle of Greenland sharks and how they spend a large amount of their life swimming through the North Atlantic. "The study breathes new life into the story of the Greenland shark throughout the North Atlantic—and, among other things, provides an understanding of how Denmark's deepest sea area also plays a role in the species' life history," Møller said. This information is key to preparing protection strategies for these creatures, listed as 'vulnerable' on the International Red List of Threatened Species, and in constant danger from several commercial fishing activities.