Researchers have discovered the average life span of a great white shark is much longer than previously estimated, according to a new study by Woods Hole Oceanographic Institution (WHOI).
"Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies," Li Ling Hamady, MIT/WHOI Joint Program student and lead author of the study, said in a press release. "Understanding longevity of the species, growth rate, age at sexual maturity, and differences in growth between males and females are especially important for sustainable management and conservation efforts."
The findings published in PLOS ONE calculated the radiocarobon age of four female and four male great white sharks. Using the vertebrae from each shark, researchers were able to analyze and validate their ages.
"Traditionally, ageing sharks has relied on the assumption that band pairs are annual. In many cases this has been proven correct for part or all of a species life, however in more and more cases this is being disproven," said coauthor Lisa Natanson, a fisheries biologist at NOAA's Northeast Fisheries Science Center (NEFSC) lab in Narragansett, R.I.
The oldest shark was estimated to be up to 73-years-old while the oldest female is believed to have lived to be 40-years-old. Previous studies analyzed shark's growth bands to determine age, which lead researchers to believe the animals lived an upwards of 30 years on average. Radiocarbon age analysis provided the scientists with a "time stamp" that helped pinpoint their age.
"This research demonstrates the power of applying cutting-edge techniques in isotope geochemistry to answer fundamental questions in ocean ecology," said co-author Simon Thorrold, a biologist at WHOI and Hamady's Ph.D. advisor. "The radiocarbon time stamp in white shark vertebrae provides irrefutable evidence of white shark longevity that had proved to be impossible to verify using traditional age estimation methods."
To read more about radiocarbon age analysis and the study, click here.
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