Great white sharks -- top predators in the world's oceans -- grow much slower and live significantly longer than previously thought, U.S. marine scientists say. Analyzing vertebrae from four females and four males from the northwestern Atlantic Ocean, researchers led by the Woods Hole Oceanographic Institution Age estimated the largest male was as much as 73 years old and the largest largest female was 40 years old. "Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies," lead study author Li Ling Hamady said. "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." Vertebrae grow throughout a fish's life, adding annual rings, similar to growth rings in trees, the researchers said. Previously, the oldest white shark individuals identified were from the southwestern Pacific Ocean and the western Indian Ocean and estimated at 22 or 23 years old. If the estimate of 70 years or more if correct, white sharks may be among the longest-lived cartilaginous fishes, the researchers said, and are therefore sensitive to fishing, environmental and other pressures because individual sharks are slow-growing and mature late. "These findings change the way we model white shark populations and must be taken into consideration when formulating future conservation strategies," co-author and Woods Hole scientist Greg Skomal said.