The early life history of kurosoi, Sebastes schlegeli , in the Sea of Japan
Nagasawa, T.; Domon, K.
Ichthyological Research 44(3): 237-248
ISSN/ISBN: 1341-8998 Accession: 033762394
Larval and juvenile stages of kurosoi, Sebastes schlegeli, are described and illustrated from wild specimens. Some ecological aspects of larvae and juveniles are also described. Notochord flexion occurred between 5.67.5 mm SL. Transformation occurred between 13-20 mm SL. Preflexion and flexion larvae of S. schlegeli can be distinguished from similar larvae by the pigmentation of the dorsal and ventral midlines of the tail and absence of pigmentation on the ventral portion of the rectum. After notochord flexion, the dorsal and lateral regions in both larvae and pelagic juveniles were heavily pigmented suggesting adaptation for neustonic life style. Larvae and juveniles were caught at many coastal stations, but did not occur in cooler offshore waters. Larvae smaller than 20 mm SL inhabited surface waters. Until ca. 40 mm SL, juveniles inhabited mainly surface waters (without drifting seaweed), but also used other habitats, such as the drifting seaweed, and near the sea bed. Small larvae ( lt 7 mm SL) fed mainly on copepod nauplii. Larger larvae fed on calanoid copepodites and Evadne nordmanni. Pelagic juveniles fed mainly on fish eggs, with fish larvae also being important food items for some individuals. Most food items taken by juveniles that were associated with drifting seaweed were eggs with attaching filaments (Cololabis saira and Hyporhamphus sajori), suggesting that the high density of such food items both attracts and keeps juveniles around drifting seaweed.