One female shark in their study was found to have lived between that minimum age and 512 years, giving an average of 400 years to put her birth in the early 1600s.
Also read: What’s a Greenland shark doing in the Caribbean?
It was a Danish biologist who first showed that the species, which lives in the cold, deep waters of the Arctic and North Atlantic oceans and can reach 5m in length, grows only a few centimetres over several years.
However, its lifespan had remained a mystery until the international team of researchers led by Julius Nielsen decided to adapt an ageing method usually associated with archaeology, and used carbon-14 dating of the sharks’ eye-lenses.
“As with other vertebrates, the lenses consist of a unique type of metabolically inactive tissue,” said Nielsen. “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.” The method is imprecise in terms of year of birth, but gives a reliable range.
The sharks were found to reach sexual maturity around the age of 150, when they are around 4m long.
“Greenland sharks are among the largest carnivorous sharks on the planet, and their role as an apex predator in the Arctic eco-system is totally overlooked,” said Nielson. “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.”
Working with the Greenland Institute of Natural Resources, Arctic University of Norway and Aarhus University for its carbon-dating expertise, the three-year PhD project studied 28 shark specimens that came mainly from accidental by-catch. The team’s paper has been published in Science.
* The shark-longevity announcement coincided with that of a discovery from the same distant era – remains of an early colonial ship or ships, probably French, off Florida’s Cape Canaveral.
Marine-survey company Global Marine Exploration found three ornate bronze cannon and what is believed to be a hand-carved marble monument bearing France’s fleur-de-lys emblem, along with ballast, munitions and many large encrusted objects.
“The historical and archaeological significance of these artefacts cannot be overstated,” said GME’s Chief Archaeologist Jim Sinclair. Further in-situ analysis as well as recovery and conservation was planned as soon as possible, because harsh conditions in the shallow waters near Cape Canaveral’s rocket-launching sites were said to be causing rapid deterioration of the remains.
