Determining the age of sea turtles is notoriously difficult. The size of the creatures cannot be used as a measure, and the lack of teeth rules out another potential marker. Estimates vary on the age the marine reptiles can reach, with many experts suspecting that they can probably get to around 100 years old. But researchers have now demonstrated that the age of sea turtles, and even the time at which they reach sexual maturity, can be calculated by looking at the carbon signatures found in their shells, the result of the nuclear bomb tests carried out at the height of the Cold War. Their results are published in the Proceedings of the Royal Society B.
By looking at the scutes – or bony external plates – of dead Hawaiian hawksbill sea turtles, the researchers were able to count the growth lines within them (a little like counting tree rings). They were then able to calculate that the hawksbill turtles formed on average eight lines per year, allowing them to figure out the turtles’ growth rates. In addition to this, they also worked out that the turtles reached sexual maturity at an astonishing 29 years of age, which goes some way to explain why the Hawaiian population of these reptiles has been so slow at recovery after being decimated for their desirable shell.[…]
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