Sharks, rays live twice as long, Qld study


Sharks and rays live a lot longer than thought, some twice as long as previously estimated, according to a Queensland study.

The university study, published on Friday, has found a number of errors in the way the ages of Elasmobranchii have been measured and that they have been underestimated by an average of 18 years.

James Cook University researcher Dr Alastair Harry conducted research on 53 different populations of sharks and rays.

Dr Harry discovered a grey nurse shark can live up to 40 years, twice as long as had been estimated earlier.

“And the age of New Zealand porbeagle sharks had been underestimated by an average of 22 years,” he said.

“Across the cases I studied, age was underestimated by an average of 18 years and up to 34 years in one instance.”

A majority of the scientists usually measure sharks’ age by counting the rings in their vertebrae.

Dr Harry explained errors in calculations appeared to have occurred owing to growth rings ceasing to form or becoming unreliable beyond a certain size or age.

Age calculation for these animals, which often end up trapped in fishermen’s nets, is important for the management of marine resources.



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