In Science, Nielsen has revealed the average lifespan of the sharks was 272 years, and that they did not reach sexual maturity until 156 ± 22 years.
The oldest individual was estimated to be 392 years old, give or take 120 years. However, as this individual was 5 meters (17 feet) long, which is average for an adult female, some sharks almost certainly exceed four centuries.
Despite living on the other side of the world from most test sites, the younger sharks showed evidence of radioactive isotopes released during nuclear testing in the 1950s and '60s. However, the eyes of sharks longer than 2.2 meters (7.3 feet) showed no such signs. The isotopic ratios at the center of the eye are consistent with the diet of an adult shark, rather than a young one that would feed on smaller prey. Together, these findings confirmed the theory that the proteins contain atoms laid down before the shark was born, and that the age estimates are reliable.
Although the Greenland shark is widespread across the North Atlantic, and only classified as “near threatened”, long-lived animals usually have low birthrates and struggle to recover from population shocks, suggesting the sharks may be vulnerable.
The findings make the Greenland shark easily the current record-holder for the oldest vertebrate, almost doubling the previous record of 211 years for a Bowhead whale. Invertebrates such as a clam named Ming and deep sea corals, still have the advantage, however, living for more than 500 years.
Not bad for a species whose Latin name means tiny brain.
A Greenland Shark in Disko Bay, Greenland. Julius Nielson