Can you tell the age of a swordfish by the size of its sword?

The size of the sword or bill of a swordfish is not a reliable indicator of its age. In fact, there is no definitive method for determining the age of a swordfish, as their growth is influenced by a number of factors including temperature, food availability, and genetic variation.

It was once believed that the size of a swordfish's sword could be used to estimate its age, with the theory that the sword grew at a relatively constant rate over the fish's lifetime. However, this idea has since been disproven, as studies have shown that the growth rate of the sword varies significantly between individual fish, and even within the same fish over time.

Today, researchers use a combination of methods to estimate the age of swordfish, including examining the growth rings on their vertebrae, analyzing their otoliths (ear bones), and using genetic techniques to estimate their age based on the rate of mutation in their DNA.

While the size of a swordfish's sword may not be a reliable indicator of its age, it is still an important characteristic that is used to distinguish swordfish from other species of billfish. The sword is used by the fish for hunting and defense, and can grow up to a third of the length of the fish's body, making it one of the most distinctive features of this remarkable species.