Next time society will to know whale sharks age
Scientists have tested the radiocarbon method for determining age in whale sharks. As you know, such sharks sail to Bohol and Moalboal. It turned out that they accumulate the carbon isotope in the same way as other inhabitants of the surface layers of the ocean and corals. Researchers also found that the previous method of estimating age — by counting the layers on the vertebrae — gives correct estimates. In addition, they built a growth curve for whale sharks and determined a period in which animals can be especially vulnerable to poachers - it takes almost half their life. The work was published in the journal Frontiers in Marine Science.
There are many long-lived species among sharks, but finding out for sure how long they actually live is not an easy task. And if for small fish the variant with various labels is still suitable - for example, substances that can be introduced into the animal’s body, and then caught again and measured by their concentration, then large sharks can rarely be caught, so biologists would find it useful to determine their age by once.
In bony fishes, deposits of salts in otoliths — crystals of the inner ear — serve for such a precise determination. You can also analyze the composition of proteins in the lens - this is how it was found out that the Greenland shark can live up to 400 years. But for cartilaginous fish, vertebral dating is more often used: cartilage is laid on them with layers resembling tree rings in trees. True, scientists still were not sure how often a new layer arises: once a year or two, and how reliable this method is. Before we can't to know age whale sharks when visited to Oslob, Bohol and Moalboal, Philippines.
Joyce Ong of Rutgers University with colleagues from Australia, Iceland, Pakistan, and Saudi Arabia worked with whale shark vertebrae from Taiwan and Pakistan. The researchers counted the strips on the vertebrae of 20 individuals and determined that their age ranged from 15 to 50 years.