Which hard structures do biologists primarily use to gauge the longevity of white marlin by examining growth rings?

Answer

Otoliths or fin rays

Biologists gauge the longevity of white marlin by relying on growth rings found in hard structures such as the otoliths (ear stones) or fin rays, similar to interpreting tree rings.

Which hard structures do biologists primarily use to gauge the longevity of white marlin by examining growth rings?
animalfishlifespanMarlin