Between 2011 and 2018, American scientists caught hundreds of largemouth buffalo fish to study their age limits. These fish are considered the largest freshwater fish in North America and can gain up to 36 kg in weight in 20-30 years of life. But these data turned out to be outdated - after dating the prey, scientists found individuals both 80 and 90 years old. And the oldest was the fish, which was given the nickname "Grandmother" - she managed to live in the world for 112 years.
The age of freshwater fish is measured by the structure of otoliths - special formations of calcium carbonate in the ears of teleost fish that are used for balancing when swimming. In their structure, they are similar to a tree trunk with its annual rings, which makes it possible to calculate the age of the fish. The method is not very accurate, but even taking into account the errors, the age of under a hundred years is something extraordinary. How did Granny manage to live four times the normal for her species?
Grandma Fish Otolith
The person and his activities are to blame (exactly to blame) for this. Scientists applied carbon analysis and found that Grandmother, like many of her younger relatives, was born even before the First World War and before the first atomic bombs were tested. In the 1930s, when the US dam-building boom began, she was already an adult. And, probably, she was preparing to die in order to make way for the young. But that was not the case - the previous migration routes to the spawning areas were blocked.
This is a theory, but backed up by a lot of indirect evidence. When the fish, due to the blocking of rivers, lost the ability to spawn in the usual way, something in their behavior changed, a certain shift of instincts occurred. The fish did not stop reproducing, but the scale and nature of the process changed, which led to a decrease in the population and the emergence of such long-lived individuals as Grandmother. If this is the case, then scientists will have to reconsider the previous views on the life of freshwater fish and the impact of human activity on their existence.