For sharks, old age may be 70 or more: study

Great white sharks may live until their 70s, more than three times as long as previously thought, according to a new analysis of the marine predator's backbones out Wednesday, AFP reports. Using radiocarbon dating technology, researchers analyzed vertebrae from four male and four female adult white sharks from the northwestern Atlantic Ocean. The largest male was 73 years old and the largest female was 40, said the report by scientists at Woods Hole Oceanographic Institution (WHOI) in Cape Cod, Massachusetts. "Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies," said Li Ling Hamady, lead author of the study published in the journal PLOS ONE. Previous research on growth bands -- which are similar to rings in trees that signify age and growth -- in sharks' bones presumed that each band was equal to about a year. By those measures, the oldest white sharks ever found were a 22-year-old from the southwestern Pacific Ocean and a 23-year-old from the western Indian Ocean. However, the latest study measured their ages by looking at their bones for radiocarbon residue from nuclear tests done by the United States and Soviet Union during the 1950s and 1960s. Bomb carbon from these tests -- which were banned after 1963 -- got into the atmosphere and ocean. Sea creatures incorporated the radiocarbon into their tissues, offering a sort of time stamp to help determine the ages of those that lived during the thermonuclear tests. The bones studied came from sharks caught in the northwestern Atlantic Ocean from 1967 to 2010. White sharks are considered a vulnerable species worldwide, and researchers said that knowing more about how fast they grow and how long they live can aid conservation efforts.