It has lengthy been suspected that whale sharks, the most important fish within the sea, are long-lived, and now this has been confirmed utilizing a carbon courting approach. It seems these animals live for at least 50 years, and probably far longer.
Knowing how lengthy animals live is necessary for conservation, says Steven Campana of the University of Iceland in Reykjavík. “It makes a big difference whether they are fast-growing and short-lived, or slow-growing and long-lived.”
But figuring out how lengthy sharks and rays live is troublesome. They would not have the bony buildings known as otoliths of their ears which might be used to work out the age of most fish. Instead, sharks are aged based mostly on progress rings of their cartilaginous vertebrae – however these progress rings type at completely different charges in several species, and might cease forming after sexual maturity.
Two many years in the past, Campana’s crew confirmed that growth-ring-based age estimates for some long-lived animals could possibly be checked by taking a look at ranges of the carbon-14 isotope within the rings. The nuclear bomb assessments carried out from the 1950s onwards created distinctive peaks in carbon-14.
This approach has proven that the age estimates for many sharks had been wildly off. For occasion, it was thought nice white sharks lived solely 12 to 15 years however latest research have revealed people as outdated as 73.
Now the carbon-14 approach has been utilized to the preserved stays of two grownup whale sharks, one washed up lifeless in Pakistan and the opposite caught in Taiwan earlier than a ban was launched in 2007. It reveals that one in every of these whales was at least 50 years outdated. Other people might live even longer.
In 2016, a examine utilizing the identical technique reported that Greenland sharks are the longest dwelling vertebrates, probably dwelling so long as 500 years. Campana is sceptical about such excessive lifespans, however says it’s clear they can live greater than a century.
Journal reference: Frontiers in Marine Science, DOI: 10.3389/fmars.2020.00188
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