1 Graduate School of Agricultural and Biosciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, 2The University Museum, The University of Tokyo, Bunkyo, Tokyo 113-0033, 3Kanagawa Prefectural Fisheries Research Institute, Misaki, Kanagawa 238-0237, Japan
Otolith microstructure was used to determine extrusion date, planktonic larval duration and settlement size of the juvenile black rockfish Sebastes inermis collected at two sites, Sajima and Kaneda Bay located along the coast of Miura Peninsula, central Japan. Early life histories of juveniles from the two locations were different. Juveniles from Sajima and Kaneda Bay were mainly extruded in February and in January, respectively. The duration of the planktonic period for Sajima (28-68 d) was significantly shorter than for Kaneda Bay (51-109 d). The back-calculated settlement size for Sajima (9.1-19.5 mm) was significantly smaller than for Kaneda Bay (12.0-26.1 mm). Sajima juveniles exhibited larval growth rates higher both during the planktonic period and after settlement than did Kaneda Bay juveniles. The growth rate during the planktonic period had an inverse correlation with planktonic larval duration within and between locations, indicating that individuals with faster growth had shorter planktonic durations than those with slower growth. These results suggested that respective groups might be distributed in the two study sites.