150-year-old Greenland shark found in Ireland offers rare clues to longevity and ageing

Highlights:

• Scientists examined a Greenland shark estimated to be over 150 years old.
• Researchers found signs of remarkable resilience against age-related decline.
• The rare stranding could help unlock longstanding mysteries about the species.

The rare stranding of a Greenland shark on Ireland's west coast has given scientists a unique opportunity to study one of the world's longest-living and least understood vertebrates, offering fresh insights into how the species survives for centuries while resisting many effects of ageing, reports the BBC. 

The shark, which washed ashore in County Sligo in April 2026, is the first Greenland shark ever recorded stranded in Ireland. Measuring about three metres long, researchers estimate it was more than 150 years old—already older than most human lifespans, but only just reaching sexual maturity.

"It's such a pity. This guy – it took him 150 years to get to the point where he could have reproduced, could have contributed to get the population on track, and may not have had the chance," said Emilie De Loose, a marine biologist at the Irish Whale and Dolphin Group.

Greenland sharks are regarded as the world's longest-living vertebrates, with some believed to survive for nearly 400 years. Scientists estimate that some individuals alive today may have been born during Shakespeare's lifetime.

"We were all just in awe," De Loose said. "It's so mind-boggling to think how long that animal lived, and what it might have seen."

Following the stranding, researchers transported the more than 200kg shark to a veterinary laboratory, where specialists carried out a full necropsy. They examined major organs, collected tissue samples and removed the eye lenses for radiocarbon dating to determine the shark's age more accurately.

"There is something very intimate about working with dead animals, because you really get to know the species," said Jasmine Stavenow Jerremalm, a marine ecology PhD researcher at University College Cork. "Dead animals can tell us a lot about the living ones."

Researchers also adopted strict biosecurity measures during the examination because the shark may have harboured unknown bacteria or viruses after surviving for more than a century.

Despite decades of research, Greenland sharks remain among the least understood large marine animals. Scientists still do not know where they mate or give birth, and only one pregnant female has ever been documented.

"For such a large shark with a broad distribution, that is not really a rare species throughout most of its range, it's amazing how little we know about these sharks," said Brynn Devine, an Arctic fisheries scientist at Oceans North.

"Even basic aspects of their biology and ecology are unknown," she said. "For example, we still do not know where their mating and pupping grounds are, and only one pregnant female has ever been observed so we don't even know for certain how many pups they have per pregnancy or how often they reproduce."

The knowledge gap complicates conservation efforts, particularly as accidental capture in fisheries continues to threaten the species.

"It's difficult to protect a species effectively if you aren't sure what areas or habitats are most important for them for key behaviours like mating and pupping, as well as not knowing how often they reproduce or how many pups they have," Devine said. "There are lots of big mysteries that still need to be solved beyond how they live so long."

According to BBC, the necropsy found no obvious injuries that could explain the shark's death. Its skin, organs and tissue samples have been preserved for future research, while the National Museum of Ireland hopes to display the specimen for educational purposes.

One of the study's most significant findings relates to the shark's eyesight. Contrary to the long-held belief that Greenland sharks are almost blind because of parasites attached to their eyes, recent research suggests their vision remains functional even after more than a century.

"For a long time, Greenland sharks have been described as having very poor vision, or even being blind," said Lily Fogg, a postdoctoral researcher in evolutionary biology at the University of Basel.

"Their eyes and retinas are actually intact and highly specialised for life in very dim light," Fogg explained. "Even in individuals over a century old, the cells and molecular machinery needed for vision are still there and still look healthy. Their visual system is essentially like a 'low-light camera', which makes perfect sense if you spend your life in the dark, cold depths of the Arctic Ocean."

"What's really remarkable is that this complex tissue appears to keep working for so long. It's a visual system that seems built to last for centuries."

Researchers also found that genes involved in DNA repair appear to be especially active in Greenland sharks, potentially helping explain their resistance to age-related decline.

"This is especially interesting because DNA damage and repair capacity are widely linked to ageing processes across animals," Fogg said.

Scientists were equally intrigued by the shark's 34kg heart. Although it showed some scarring associated with ageing, it appeared to function normally, supporting research that suggests Greenland sharks possess an unusual resilience to age-related cardiovascular deterioration.

Other organs, including the stomach, liver and digestive tract, have also been preserved for future analysis. While researchers observed abnormalities in one testicle and the spleen, they found no clear evidence of disease or trauma that could explain the shark's death.

"It makes you wonder, what happened?" De Loose said. "It's sad because it's old by our standards, but it really had much of its life ahead."