Verification of Daily Ring Deposition in the Otoliths of Age-0 Spotted Bass

Abstract

Deposition of daily rings in the otoliths of spotted bass Micropterus punctulatus and the time of first ring formation were determined with larvae that were taken from two nests, hatched in the laboratory, and raised for up to 40 d. The relationship between daily ring counts and known age in days for larvae from the first nest indicated rings formed prior to swim-up. However, larvae from the second nest deposited only one ring daily, beginning at swim-up. Disparate results between the two nests was attributed to individual differences in the number of days between hatching and swim-up and the inability to distinguish prolarval rings from daily rings in fish less than 15 d old. Sequential sampling of spotted bass from a third nest revealed that rings were deposited daily for about 94 d after swim-up. Compressed rings, resulting from decreased growth rates, caused ages to be underestimated after d 94.