The whale shark is the biggest known fish in the ocean, but until recently, scientists weren’t quite sure how long these spotted giants lived for. A new study used carbon-14 from atomic bomb tests during the 1950s and 60s to finally determine the age of these ocean dwellers.
Carbon-14 is a radioactive material that decays at a steady rate. It occurs naturally and is present in all living things on Earth, but atomic bomb testing caused a surge in its prevalence all over the world in the mid 20th century.
Shark vertebrae grow in rings, much like tree trunks, and by analyzing levels of carbon-14 in whale shark vertebrae, the researchers from the Australian Institute of Marine Science were able to determine that they grow by one ring each year, rather than every six months as previously thought by some scientists.
Using this method, the team was able to successfully date one whale shark to 50 years old. Some scientists have estimated that the sharks could live to be 100 years old. Only time and analysis of more deceased fish will tell how long these animals can truly live.
Having a clear picture of population age and growth is critical for species conservation. Without a complete understanding of population demographics, it is difficult to design an effective species management strategy. This newer and more accurate technique for whale shark dating will help scientists all over the world preserve these fish for generations to come.