Graphical Abstract

Daily changes in otolith increment widths from the core to the edge in 0+ Pacific saury, Cololabis saira , were examined. There appeared a first peak of increment width at 22.9 ± 9.6 (73) [mean ± SD (sample number)] days old, followed by the bottom of the first trough [88.6 ± 25.3 days old (73)] and a second peak [143.8 ± 24.6 days old (62)]. The ages at the second peak formation were strongly related to the estimated hatch da...