He added that the shark most likely died at around 390 years old, but due to the noted age range, he and his team stuck with the lower and more conservative figure for the paper.
It has long been suspected that Greenland sharks live ultra-long lives, but figuring out just how long has stumped marine biologists for decades. Usually the age of sharks and rays can be determined by counting seasonally deposited growth layers in hard calcified structures, such as fin spines. Greenland sharks, however, lack these hard structures.
To get around the problem, Nielsen and his team analyzed the eye lens nucleus of 28 female sharks sampled as accidental by-catch during the Greenland Institute of Natural Resources' annual fish and shrimp surveys. The research project is nicknamed Old and Cold, referring to the sharks' chilly environment and advanced ages.
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Co-author Christopher Bronk Ramsey, a professor of archaeological science at the University of Oxford, told Discovery News, "The eye lens in all large animals forms during the initial development of the animal, and so dating this gives the age of the animal. Other body parts typically grow, or at least the carbon overturns over time. This is not possible for the lens because it has no internal blood supply."
The scientists measured the radiocarbon content of the Greenland shark eye lenses. Then, they estimated the age of the individuals by matching and calibrating the data using data representing radiocarbon changes in the northern North Atlantic marine food web the past 500 years.
The study marks the first time that scientists have applied a radiocarbon approach on eye lenses to date the longevity of a fish, which sharks are. Ramsey indicated that even he is in awe of the fact that the Bayesian statistics behind some of his and his colleagues' work were formulated in the 18th century, when the oldest of the sharks in the study were alive.
"This perhaps puts quite nicely into perspective how long the lives of these animals are, and conversely, how much humans have achieved within the lifetime of one of these sharks," he said.
WATCH VIDEO: NOAA Expedition's 2013 Encounter with a Greenland Shark