Greenland sharks live for centuries

The mystery of the lifespan of Greenland sharks has finally been unveiled thanks to new research. 

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Greenland shark
Greenland sharks can grow to 5m in length © Julius Nielsen

 

The Greenland shark is one of the world’s largest sharks, but it grows slowly, at only a few centimetres over several years, hinting at a long lifespan.

But until now biologists could only guess at the life expectancy of these little-understood creatures.

Marine biologists from the University of Copenhagen used radiocarbon dating on the sharks’ eye lenses to gather information, which helped them to estimate the life expectancy of the sharks.

The technique of carbon-14 dating has previously been used to discover the age of whales, but had never before been used to estimate the age of fish.

Findings from the data revealed that the shark’s life expectancy is at least 272 years, making it the oldest living of all vertebrate animals known to science.

The research team looked at the eye lenses of 28 female Greenland sharks, which ranged from 81 to 502cm in length.

The data revealed that the sharks reach sexual maturity at around 150-years-old, with the largest animal estimated to be around 400-years-old.

The results of the research have been published in American scientific journal, Science.

The paper’s lead author, Julius Nielsen, explains why the eye was crucial in determining the age of the sharks: “As with other vertebrates, the lenses consist of a unique type of metabolically inactive tissue. 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.”

Nielsen hopes that findings from the research will help to inform sustainable management plans for the sharks.

“Greenland sharks are among the largest carnivorous sharks on the planet, and their role as an apex predator in the Arctic ecosystem is totally overlooked,” he said.

“By the thousands, they accidentally end up as by-catch across the North Atlantic and I hope that our studies can help to bring a greater focus on the Greenland shark in the future."

Read the full Science report

Read more wildlife news stories in BBC Wildlife Magazine

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