Australia scientists have finally found a way to determine the real age of the elusive whale sharks and it involves cold -war era atomic bombs.
Marine science has grown leaps and bounds over the last century and so has our understanding of aquatic animals. However, one of the biggest unanswered question for marine biologists is the age of a Whale Shark. Up until now, scientists have been left befuddled by their lack of knowledge about these magnificent creatures known for being the largest animal on earth. Besides the fact that they are huge, move very slowly, docile, and are generally seen in tropical waters, there's very little we know about them, apart from the fact their impromptu leaps out of the water are nothing short of a breath-taking spectacle. Thankfully, a few researchers writing for the journal Frontiers in Marine Science beg to differ. According to this latest study, they have found a way to calculate the true age of whale sharks - data from atomic bomb tests conducted during the cold war. Apart from its detrimental effect on humans, the lethal atomic bomb testings have officially come of good use in a real-world situation.
Unlike usual fish, the anatomy of whale sharks shows that they don’t possess the bony structures called otoliths that are usually used to age fishes, so the researchers instead used the relics of Cold War-era nuclear fallout. Dr Mark Meekan, from Australian Institute of Marine Science in Perth, Western Australia, who's also one of the study authors, said: "Earlier modelling studies have suggested that the largest whale sharks may live as long as 100 years. However, although our understanding of the movements, behaviour, connectivity and distribution of whale sharks have improved dramatically over the last 10 years, basic life-history traits such as age, longevity and mortality remain largely unknown."Our study shows that adult sharks can indeed attain great age and that long lifespans are probably a feature of the species. Now we have another piece of the jigsaw added," Meekan said.
Scientists have found that whale sharks have vertebrae that look like distinct rings or bands, which are thought to increase in number as they age, in a way similar to that of tree trunks. Despite knowing this piece of critical information wasn't enough for the study. That's when the cold-war atomic bomb idea came in. Between the years 1955 and 1963, the continued use of atomic bombs increased the amount of an isotope called carbon-14 in the atmosphere. Carbon-14, for the uninitiated, is a naturally occurring radio element archaeologists use to determine the age of ancient bones and other artefacts.
As the use of atomic bombs increased twofold, every living thing on the planet ingested a minuscule amount of this isotope. The researchers measured the presence of this element on two dead Whale sharks stored in Taiwan and Pakistan and began to understand the frequency of the ring's growth. Further analysis showed that one of the sharks was at least 50 years old at the time of death. “We found that one growth ring was definitely deposited every year," Meekan said. "This is very important, because if you over or under-estimate growth rates you will inevitably end up with a management strategy that doesn’t work, and you’ll see the population crash.”