カンパチの卵発生と仔稚魚の形態

抄録

Embryonic and morphological development of larvae and juveniles of the amberjack, Seriola dumerili Risso, are described using specimens raised at Yaeyama Station (Ishigaki Island, Okinawa Pref.), Japan Sea Farming Association. The specimens obtained from brood fish (3 females, 3 males) were treated with gonadotropin and spawned on 6th of April 1987. The eggs of amberjack are pelagic, spherical in shape and 1.01-1.17mm in diameter. The yolk is roughly segmented and has a single oil globule 0.22-0.24mm in diameter. The perivitelline space is narrow. During development, a few melanophores and no xanthophores were observed on yolk. Hatching took place 35hrs. 15min. after spawning out at temperatures 23.1-23.7°C. The newly hatched larvae were 2.84-3.04mm in TL with 27 (13+14) myomeres and an oil globule anteriorly situated beyond the head. 3 days after hatching 4.00mm TL, the mouth opened. 10 days after hatching 4.26mm TL, small denticles appeared on the margin of the upper jaw and there were 1 anterior and 2 posterior preopecular spines. At 5.96mm TL, notochord was slightly flexed. Caudal, dorsal and anal fins with rudiments of rays appeared at 8.00mm TL. The specific numbers of all fin rays and spines were obtained in a juvenile 9.60mm TL. In a juvenile 34.25mm TL, 54 days after hatching, the characteristic brown band of amberjack had appeared on head. Some notable changes in relative growth were observed at 5mm and 15mm in TL.