Morphological development of eggs, larvae, and juvenile of Sebastes koreanus (Scorpaeniformes: Scorpaenidae) from the Yellow Sea

Abstract

A total of 11 larvae [6.41–8.90 mm body length (BL)] and a juvenile (18.60 mm BL) of the genus Sebastes, collected from the Yellow Sea in 2012 and 2013, were identified as Sebastes koreanus on the basis of molecular mitochondrial DNA cytochrome oxidase subunit I (mtDNA COI) sequences (578 base pairs). Eggs and yolk-sac larvae of S. koreanus were also obtained from a gravid fish (168.60 mm standard length). The eggs of S. koreanus collected in this study were spherically shaped, and melanophores were completely absent on the head and body of embryos just prior to hatching. Melanophores were also absent in yolk-sac larvae, except on the upper margin of the abdominal region. However, melanophores were present on the head and abdominal region of pelagic larvae, and in a few larvae melanophores were present behind the nape (although these are considered to be individual variations). Three transverse stripes were present in juvenile, corresponding to the coloration observed in adults. The release season of S. koreanus larvae is known to be in winter, but in the present study larvae (6.41–8.90 mm BL) and a fully mature female were collected in May. In addition, a juvenile of S. koreanus (23.31 mm total length) was collected in July. On this basis, the release season of S. koreanus larvae is estimated to be in spring.