Daily growth increments in otoliths of milkfish, Chanos chanos (Forsskål), larvae

Abstract

The formation of daily growth increments of otoliths was studied in the reared larvae of milkfish. The first growth increment was formed during the yolk–sac reabsorption period c.2 days after hatching, and increment formation continued on a daily schedule regardless of growth rate. The initial incremental zone was of amorphous structure, and the subsequent incremental zone was of needle–shaped crystalline structure; the former structure was formed in the yolk–sac reabsorption period of the larva and the latter in the exogenous feeding period. Accordingly, ageing of milkfish larvae is possible by counting growth increments, and timings within the developmental stage of the larvae can be understood by examining the otolith microstructure.