Recommendation of Aging Fish with Transverse Sections of Otoliths

It is important to accumulate the information on age, growth, maturation, spawning, and survival to manage a fish stock properly. To know the age of fish, various hard structures such as scales, otoliths, vertebrae, opercular bones, fin rays have been used. Among these, scales have been frequently used for a long time, but it has gradually became apparent that scales apt to underestimate the actual age of fish, especially that of old one, as compared with the sections of otoliths. In this paper, we introduce our techniques to make sections of otoliths, and discuss the cause of the underestimation of age by scale or surface otolith readings, using the samples of a few fish species collected from the coastal waters of Kagoshima Prefecture, Japan