Great White Sharks Life-Expectancy is Much Higher Than Previously Thought

             Using a new technique to age the tissues of these impressive creatures, scientists have identified a male great white that lived into its 70's. This is good news (somewhat) because knowing that great white sharks live longer can allow scientists to take that into account when doing conservation efforts. Great white sharks are infamous, they are the poster-child for sharks, however we don't actually know too much about them. "Everyone thinks they know these animals so well, and the public perception is that they're either loved or hated. But in terms of the science, we're only just now beginning to understand what they eat, where they go and how long they live," said Li Ling Hamady, who is part of a joint program between MIT and the Woods Hole Oceanographic Institution in the US. The scientists have tried to age the sharks by using a method that is similar to the one used to age trees which is counting the annual growth rings in the shark's tissue, such as in their vertebrae. But the sharks' cartilage skeleton makes the division between these rings hard to discern even under the microscope. The scientists use a known radioactive marker in order to age the sharks, the marker is from the nuclear testing going on in the 1950's and 1960's. "Previous studies on Indian and Pacific Ocean animals - not using the A-bomb marker approach - had suggested great whites were certainly capable of living into their twenties. With the bomb markers, age estimates for the MIT-WHOI animals were up to 73 years old for the largest male in the study, and 40 years old for the largest female." All these animals came from the Atlantic, but the researchers do not think there are any significant differences between the lifespans of the sharks living in the three big ocean basins. Great white sharks need some conservation programs because they are considered "vulnerable" but, now seems likely, they are slower growing and later to mature than was previously recognised, it means also that great whites would find it harder to recover their numbers if populations are depressed because of fishing, environmental and other pressures. Ian Fergusson, a founding patron of the Shark Trust, commented: "White sharks have a fairly low fecundity in terms of litter size. Typically, females might have a handful of pups per litter, and we're not sure how often they even get pregnant in a lifetime.