400-year-old sharks ‘living time-capsules’

archive – Diving News

400-year-old sharks ‘living time-capsules'

The Greenland shark's extreme lifespan means that it should be given special conservation status, says a geneticist who has been sequencing the DNA of the world's longest-living vertebrate.

Professor Praebel of UIT the Arctic University of Norway has told an audience of marine scientists at the University of Exeter that he believes the genes of the sharks, known to live for 400 years or more, could hold the secret to long life for other vertebrates – including humans.

Prof Praebel’s team has been studying DNA taken from shark-fins during tagging operations as part of the “Old and Cold” project, which also involves researchers from Denmark, Greenland, the USA and China.

The scientists have now sequenced the full mitochondrial DNA data of almost 100 Greenland sharks, but need to isolate the “long-life” genes that could explain what dictates the life-expectancy of different species.

The Greenland shark is found in deep North-Atlantic waters, including those off northern Britain, and is part of the 110-million-year-old sleeper shark family.

The oldest shark studied so far has been a 5m female reckoned to be 392 years old (plus or minus 120 years, or between 512 and 272 years old).

“Since the Greenland shark lives for hundreds of years, they also have enough time to migrate over long distances, and our genetic results showed exactly that,” said Prof Praebel.

“Most of the individuals in our study were genetically similar to individuals caught thousands of kilometres away.”

It was thought possible that mating occurred in deep Arctic fjords, he said.

With sharks alive today that predate the Industrial Revolution, Professor Praebel described them as “living time-capsules”, and said that their tissues, bones and genetic data could help to measure the impact of climate change, industrial pollution and commercial fishing on their populations and on the oceans.

Meanwhile another set of scientists have noted that Greenland sharks have an unusually slow heart-rate – with just a single beat every 10 seconds. The observation came during a recent tagging expedition to Greenland led by Prof Steffensen of the University of Copenhagen aboard the Sanna research vessel.

Divernet first reported on the current collaborative Greenland shark research programme last August.

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