Early-life history traits of two icefishes, spiny icefish Chaenodraco wilsoni and ocellated icefish Chionodraco rastrospinosus , in the Ross Sea revealed by otolith microstructure

S piny icefish ( Chaenodraco wilsoni ) and ocellated icefish ( Chionodraco rastrospinosus ) are two abundant channichthyids in the larval fish assemblages of the Ross Sea. However, little information is available about the early-life history traits of the two icefishes, which have limited the understanding of the biology and ecology of icefishes. The present study aims to investigate the early-life history traits of C. wilsoni and C. rastrospinosus in the Ross Sea. Through the analysis of sagittal otolith microstructure, the size and timing of hatching, onset of exogenous feeding, and growth rate were assessed in the two icefishes. In C. wilsoni , individuals with a standard length (SL) of 14–43 mm were estimated ages of 28–100 days. An exponential model was well fitted to the age–length dataset, indicating a mean growth rate of 0.34 mm day −1 . Larval hatching occurred at a size of 9.28 mm and was distributed over a relatively long period, lasting from October to December. The onset of exogenous feeding took place between 16 and 29 days after hatching. In C. rastrospinosus , individuals with SL of 14–48 mm were estimated ages of 29–126 days and mean growth rate of 0.38 mm day −1 . The larval size at hatching was estimated as 10.90 mm and hatching dates extended over a long period from September to December. The yolk-sac duration estimated from hatching to the onset of the exogenous feeding check was 21–41 days, which was longer than in other channichthyids. This study provides new information on the biological features and life history strategies of C. wilsoni and C. rastrospinosus .