Fish are a major part of human cultures around the world. They are commonly exploited for food, sport, and pets. Without informed conservation and knowledge of species’ life histories, fish populations are easily over-exploited, extirpated, or driven to extinction. In fisheries, it has become crucial to understand natural longevity, growth, and replacement (recruitment) rates so that populations can be sustained in the context of increasing anthropogenic pressures. In order to understand these biological rates of natural fish populations, accurate age analysis is necessary.
Understanding an organism’s age also matters so that we can more fully appreciate the natural life history and strategy of a given life form – to understand their true nature. Several fish species can outlive the maximum human lifespan while others may only live a few months. Studying the basis for such a range in longevity is valuable in understanding why and how organisms (including humans) are senescent and mortal.
Finally, fish are rather unique vertebrates because most fishes secrete metabolically-inert calcium carbonate stones, called “otoliths”, that grow throughout their entire lives. In short, these structures make fish a group of vertebrates in which precise and accurate age analysis is more readily possible.