Question: How do you age validate sharks?
Unlike trees or even mammals sharks are cartilaginous, they do not have bones or tree rings to look over after they die.
Bones and tree rings can give you the age of your target research specimen pretty quickly. With most shark species that's a much harder proposition.
Enter some smart folks at the Pacific Shark Research Center in California who are doing age validation of sharks and rays using radiocarbon isotopes.
As it turns out above ground testing of nukes in the 50's and 60's dropped these isotopes (14C) all over the planet and for a time every living thing on the planet had higher levels in their bodies. By tracking these higher levels in cartilage researchers can get a pretty accurate look at the age of long lived sharks like the white shark.
For more information go here.