greenland-shark
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greenland shark

Around the same time pilgrims were trying to make it on the colony of Jamestown, a young shark was swimming around the Arctic seas. This special female shark—born approximately 400 years ago—might be the world's oldest vertebrate, according to a new study published in the journal Science.

The ancient and mysterious Greenland shark is likely the world's oldest animal with a backbone. Flickr

As it turns out, the Greenland shark species can live longer than any animal with a backbone, marine biologist Julius Nielsen of Copenhagen University and his team discovered.

"We had our expectations that we were dealing with an unusual animal, but I think everyone doing this research was very surprised to learn the sharks were as old as they were," Nielsen told the BBC.

The previous longest-living vertebrate was the bowhead whale which can live more than 200 years. This shark's age is even within striking distance with the world's oldest animal. An ancient ocean quahog clam (an invertebrate) was 507 years old when it was found.

Unfortunately, as The Independent pointed out, the four-century-old shark was accidentally killed not long ago by fishermen. In fact, the only way the researchers were able to pull off this study was because they had obtained 28 female Greenland sharks that were unintended bycatch from 2010 to 2013.

Greenland sharks grow at an incredibly slow growth rate of less than a centimeter per year on average, Gizmodo noted. The sharks that were studied ranged in sizes between 2.6 feet to 16.4 feet.

There has not been a lot of prior study on the Greenland shark. To determine the age of these mysterious sharks, researchers used radiocarbon dating on the sharks's eye lens. The study said that this large yet slow-growing species do not even reach sexual maturity until they are about 150 years old, when they are about 13 feet long. The largest shark was born about 392 years ago, but could have been aged between 272 and 512 years old.

"Even with the lowest part of this uncertainty, 272 years, even if that is the maximum age, it should still be considered the longest-living vertebrate," Nielsen said.

The Greenland shark lives in the icy, deep waters of the North Atlantic and are a near threatened species, according to the International Union for Conservation of Nature. Once hunted for its liver oil, the current population is now threatened due to it being accidentally hauled by fishing operations.

The authors of the study have raised concerns about species conservation due to the commercial fishing industry.

"Our estimates strongly suggest a precautionary approach to the conservation of the Greenland shark, because they are common bycatch in arctic and subarctic groundfish fisheries and have been subjected to several recent commercial exploitation initiatives," the study states.

Additionally, as the The Independent described from the study, these sharks have had to bear the brunt of a lot of human activity:

Some of the sharks bore signs of humans' impact on the planet—such as the radiocarbon signature left by open-air nuclear bomb tests in the mid-20th century and possibly a chemical time marker caused by emissions of fossil fuels, which has been detected in the marine food chain since the early 20th century.

The story of the Greenland Shark also highlights the importance of conservation. Nielsen described how it might be difficult for its population to rebound.

"When you evaluate the size distribution all over the North Atlantic, it is quite rare that you see sexually mature females, and quite rare that you find newborn pups or juveniles," he told the BBC.

"It seems most are sub-adults. That makes sense: if you have had this very high fishing pressure, all the old animals—they are not there any more. And there are not that many to give birth to new ones.

"There is, though, still a very large amount of 'teenagers,' but it will take another 100 years for them to become sexually active."

Nielsen told Gizmodo that he does not consider the sharks threatened, "but I do consider them vulnerable."

"This definitely advocates for a precautionary approach in terms of exploitation, and for minimizing bycatch," he said.

Sonja Fordham, president of Shark Advocates International, seconded the opinion. "While scientists may continue to debate absolute longevity, it is clear that the Greenland shark is exceptionally slow growing, late to mature, and long-lived, even by shark standards," she told Gizmodo. "As is the case for most sharks, these life history characteristics make Greenland sharks particularly susceptible to overexploitation and slow to recover once depleted."

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