A North Atlantic shark species, the Greenland shark, is believed to be the longest-living vertebrate animal with a life span of at least 272 years - perhaps even over 500 years, according to a study.

A team of international researchers, including marine biologists at Copenhagen University in Denmark, used radiocarbon dating of the sharks' eye lenses as part of research into the life span of the animal.

They traced a pulse of carbon-14 produced by nuclear bomb tests in the 1950s to help establish the age of the 28 female sharks they studied. Most were accidentally caught in fish nets.

The estimated age of the oldest shark was 392 years. The researchers said the probability for the estimate was 95 per cent but gave a margin of error of 120 years, suggesting the female Greenland shark could have been 272 years old or 512 years old.

This makes it the longest-living vertebrate known. A bowhead whale has previously been estimated to be 211 years old.

"Because the centre of the lens does not change from the time of a shark's birth, it allows the tissue's chemical composition to reveal a shark's age," said marine biologist Julius Nielsen, lead author of the article published Friday in the scientific journal Science.

The Greenland shark can grow to around 5 metres, but according to earlier research grows only a few centimetres over several years.

The sharks studied were between 0.81 to 5.02 metres long.

The researchers estimated that Greenland sharks mature at about 150 years of age, highlighting the need for viable conservation methods.