In this article, we explain what Greenland sharks look like, where they can be found, how long they live, and their current conservation status. Keep reading to learn more about these truly amazing creatures.
How Long Do Greenland Sharks Live?
Greenland sharks are bulky, rounded-snout creatures that live in the cold-water environments of the Arctic Ocean and North Atlantic, from Baffin Bay eastward to the Barents Sea, although they can also be found in the North Sea and in the waters adjacent to the Eastern Seaboard of the United States. According to the BBC, Julius Nielsen, a biologist at the University of Copenhagen, says that Greenland sharks can live from anywhere from 272 years to 500 years! “We had an expectation that they would be very long-lived animals, but I was surprised that they turned out to be as old as they did,” Nielsen told the BBC.
So, how did they come to this conclusion? Nielsen and his team of researchers used radiocarbon dating to determine the age of a female Greenland shark. According to the researchers, the shark was born between the years of 1501 and 1744, with her date of birth most likely in the 17th century. This means that she’d be likely around 400 years old or so, give or take a few hundred years since radiocarbon dating doesn’t produce exact dates. Still, “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 told the BBC.
-Prior to the discovery of the Greenland shark’s age, the oldest-living vertebrate was a bowhead whale estimated to be 211 years old.
–Invertebrates are known to live long lives, too. In fact, a 507-year-old clam named Ming holds the title of “most aged animal.”
How Researchers Determine Their Age
Because Greenland sharks are elusive and live in remote habitats, it’s hard to understand how long they actually live. Some studies show they grow extremely slow (less than a half inch per year), which suggests they have a long life span. But, determining the age of a shark isn’t as easy as determining the age of, say, a bony fish, which can be easily done by analyzing their ear stones. “The Greenland shark is a very, very soft shark – it has no hard body parts where growth layers are deposited. So it was believed that the age could not be investigated,” Nielsen told the BBC. That was until scientists found another way of figuring out just how long Greenland sharks live: they looked into their eyes. “The Greenland shark’s eye lens is composed of a specialized material – and it contains proteins that are metabolically inert, which means after the proteins have been synthesized in the body, they are not renewed any more. So we can isolate the tissue that formed when the shark was a pup, and do radiocarbon dating,” Nielsen said.
For their study, they analyzed 28 female Greenland sharks that had died accidentally during the Greenland Institute for Natural Resources’ commercial fish-monitoring program. Radiocarbon dating of the 28 sharks’ lens nuclei revealed a maximum life span of at least 272 years, with the largest shark in the study, at 16.5 feet long, estimated to be 392 years old. What’s interesting is that these sharks likely don’t start breeding until 156 years of age.
It’s still unknown why these creatures live so long, but some speculate that their cold environment keeps their body temperature low, which, in turn, slows their metabolism, resulting in less damage to their tissues.
Their Conservation Status
Although their exact population isn’t known, Greenland sharks are considered to be a Near Threatened (NT) species by the International Union for Conservation of Nature (IUCN). According to the IUCN, NT status means that a taxon, “has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.”
According to the BBC, because of their extreme longevity, Greenland sharks may still be recovering from being over-fished before World War II. And, even though Greenland sharks are rarely encountered by humans today, they are sometimes accidentally caught during fishing. This incidental capture is known as “bycatch” in the fishing industry. “Fisheries should do what they can to minimize bycatch. We need to have some respect for them,” Nielsen told National Geographic magazine.
Their habitat may be disturbed by climate change and many countries’ increased focus on the Arctic for fishing, oil, and other natural resources. “The longevity is remarkable, but I hope the public recognizes how important that is with regard to how we manage and conserve Arctic and deepwater ecosystems,” Aaron Fisk, an ecologist at the University of Windsor who was not involved in any of the research, told National Geographic.
-Greenland sharks were once widely hunted for their liver oil, which was used for machine oil until a synthetic alternative was found. They were fished (and over-fished before World War II) commercially from the 19th century until 1960, and in the early 1900s as many as 30,000 Greenland sharks were caught each year. Today, small-scale subsistence fisheries in the Arctic harvest fewer than 100 of them each year, and about 1,200 are caught accidentally in fishing trawls. Most fishermen today don’t even want them. In fact, a biologist told The New Yorker that netting a Greenland shark is about as fun as stepping in doggy doo.
-The flesh of Greenland sharks can be eaten, but beware: they are toxic if you don’t properly clean and dry them or don’t repeatedly boil them prior to eating them.
–Norway persecuted Greenland sharks during the 1970s. The country considered them to be a nuisance and a threat to other fisheries.
-Greenland sharks are not considered dangerous to humans, partly because they live in regions where most people don’t typically swim. But, there was a report of a possible attack by a Greenland shark on a person back in 1859 in Pond Inlet, Canada. According to the report, a Greenland shark was caught with a human leg in its stomach. However, this story was never substantiated.
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