Study

Eye lens radiocarbon reveals centuries of longevity in the Greenland shark

Nielsen, Julius; Hedeholm, Rasmus B.; Heinemeier, Jan; Bushnell, Peter G.; Christiansen, Jørgen S.; Steffensen, John F.

Science, 2016

Peer-reviewedcomparative studywild

What they did

Sharks have no bony structures that lay down annual rings, so conventional ageing fails. The eye lens nucleus, by contrast, forms before birth and is metabolically inert thereafter — so its carbon dates from the animal’s conception. Radiocarbon in lens nuclei from 28 females was measured and calibrated against the atmospheric bomb-testing spike of the 1950s and 60s.

Studied in: Somniosus microcephalus
Sample size: 28 female Greenland sharks aged by eye lens nucleus radiocarbon

What they found

The largest individuals were estimated at several hundred years old, with a central estimate around 392 years for a 5-metre female and a wide confidence interval. Sexual maturity appears not to be reached until around 150 years.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The Greenland shark is the longest-lived vertebrate known, with an age at maturity far exceeding that of any other.

How NatureHQ reads it

The method is the story. Sharks cannot be aged the way a fish or a tree can, and the trick here is finding the one tissue in the body that never turns over — so its atoms are as old as the animal. The conservation implication is severe and worth stating plainly: a species that does not reproduce until it is 150 cannot recover from fishing pressure on any timescale that means anything to us.

Limitations

Confidence intervals are very wide; the headline figure is a central estimate, not a measurement.
Calibration depends on assumptions about ocean carbon and on the bomb-spike marker.
Twenty-eight females; males and juveniles are under-represented.