During the height of the Cold War in the late 1950s to early ‘70s, the United States, Russia, and other countries exploded so many nuclear warheads that it significantly raised the amount of C-14 (also known as bomb carbon) in the atmosphere and in the surface layers of the ocean. Because C-14 has a half-life of 5,730 years, its presence remains in earth’s air and oceans for millenniums and serves as a timestamp in fish otoliths.
When using bomb carbon to age fish, we match the increase in C-14 radioactivity found in otoliths with recognized amounts in the atmosphere or in biological structures of known age.
How the Age Validation Method Works
If we know the year a fish was collected and have determined the fish’s age in the laboratory (that’s fish ageing), then we know when the otolith core was laid down. We then know how much C-14 activity there should be in that core. Species for which this method has been applied include: Pacific ocean perch, Dover sole, yellowfin sole, and northern rockfish.