Cold War atomic bomb tests help determine the age of a whale shark. The usual way to establish the duration of her life was not possible – the fact is that sharks and stingrays have almost no bone structures, otoliths. A study by scientists from the Australian Institute of Marine Sciences, a study published in Frontiers in Marine Science.
To assess the age and longevity of fish, scientists use the analysis of otoliths – solid bone formations that are stored for a long time in water and in soil. Sharks and stingrays have almost no such structures.
In a new work, researchers tried to estimate the life expectancy of whale sharks, which, as scientists suggest, are on the verge of extinction. Until now, biologists have tried to estimate age by the dorsal vertebrae of whale sharks, which have distinct stripes that appear like rings on trees. However, some studies have shown that a new ring is formed every year, while others have come to the conclusion that this happens every six months.
In search of a more accurate method for determining the age, researchers turned to the analysis of radioactive elements in shark tissues. In particular, they tracked the half-life of carbon-14, a radioactive element that was formed as a result of nuclear bomb tests by the United States, the Soviet Union, Britain, France and China in the 1950s and 1960s.
Carbon-14 is a naturally occurring radioactive element that is often used by archaeologists and historians to date ancient bones and artifacts. Its decay rate is constant and easy to measure, making it ideal for estimating ages over 300 years.
After analyzing the content of this element in the tissues of sharks, scientists came to the conclusion that one strip on the dorsal vertebrae of the fish appears once a year. This allowed us to determine the age of whale sharks – they live from 50 to 100 years.