Rearing method and daily otolith ring of Japanese sardine larvae.

Abstract

Japanese sardine larvae Sardinops melanostictus hatched out from field-collected eggs, were successfully reared for 30 days with the survival rate of 13% of initial egg number. The relation between rearing days (D) and number of sagittal otolith rings (N) was expressed by the linear regression of N=0.99D-1.88 based on the 31 reared larvae, and the slope is not significantly different from 1(p>0.05). It is proved that ring on the otolith is formed daily. The first ring is formed mainly 3 (2-5) days after hatching which coincides with the first feeding.