Validation of otolith daily increment formation and growth analysis of yellow goosefish Lophius litulon

We validated the daily formation of increments in otoliths of yellow goosefish Lophius litulon using reared individuals to examine the growth in the field. Single, round-shaped core structures were observed in 41% of sagittae and in 73% of the lapilli. Therefore, lapillar otoliths were used for further observations of daily increment analysis. The lapillus radius of newly hatched larvae was 15.0 ± 1.4 μm (mean ± standard deviation) forming the hatch check (first check). At 6 days after hatching (DAH), the second check was observed, which may correspond to the energy transition from endogenous to exogenous nutrition, located at 28.1 ± 0.7 μm from the core structures. Thereafter, clear daily increments formed outside the check. To estimate larval growth in the field, we examined the relationship between the notochord length (NL) and lapillus radius by an allometric equation. The mean growth rate was estimated as ca. 0.18 mm in NL/day during 10–40 DAH. The results of this study provide insights into the previously unknown early life history and will enable further understanding of the population dynamics of the genus Lophius.