Browsing by Author "Kohno, Hiroshi"
ArticleY Taki, H Kohno & S Hara -
Japanese Journal of Ichthyology, 1986 - The Ichthyological Society of JapanDevelopment of fin-supports and fin-rays was observed in larval and juvenileChanos chanos, Chondrification of the caudal complex started at 4.70 mm SL. Ossification of the caudal elements started at 7.80 mm SL and was nearly completed at about 30 mm SL. Cartilaginous fusion of caudal elements, which occurs in hypurals of higher teleostean fishes but is not seen in lower teleosts, was observed between the neural arch of the preural centrum 1 and that of the ural centrum 1 via a small cartilage bridging the distal tips of the two arches. Caudal finrays began to develop at 6.60 mm SL, and an adult complement of principal rays was attained at 7.35 mm SL. Dorsal and anal pterygiophore elements were first evident at 6.70 mm and 6.65 mm SL, respectively. All proximal radiais were formed at 8.15 mm SL in both fins. Formation of dorsal and anal fin-rays started simultaneously at 8.60 mm SL, and adult fin-ray complements were attained at 10,00 mm and 10.70 mm SL, respectively. In the pectoral fin, the cleithrum, coraco-scapular cartilage and blade-like cartilage (fin plate) had already been formed at 4.65 mm SL. The mesocoracoid was observed to originate from the coraco-scapular cartilage and become detached from it in the course of ossification. Pectoral fin-ray formation started at 13.80 mm SL and was completed in number of rays at 20.00 mm SL. In the pelvic fin, the basipterygium was first evident at 13.00 mm SL. Pelvic fin-rays appeared at 13.80 mm SL and attained their adult count at 17.15 mm SL.
Early larval development of the seabass Lates calcarifer with emphasis on the transition of energy sources The early growth, yolk and oil globule resorption, early morphological and behavioral de-velopment, and initial feeding of hatchery-raised Lates calcarifer were studied. Based on the developmental events and the energy the reby utilized, the early life history of this species can be broken down into the following five phases: 1) rapid early growth due to rapid yolk resorption (from hatching to about 15 hr after hatching (TAH); 2) morphological differentiation and slowgrowth based on energy from yolk (to about 50 h TAH when the yolk is exhausted); 3) slow growth with initiation of feeding and swimming activities, based on energy from oil globule and from exogenous food (to about 110 h TAH); 4) accelerated growth and effective feeding and swimming based on the same two sources of energy as in the preceding stage (up to about 120-140 h TAH when the oil globule is exhausted); and 5) accelerated growth, effective feeding and swimming and further development based solely on exogenous energy (beyond 140 h TAIT).
ArticleH Kohno -
Japanese Journal of Ichthyology, 1986 - The Ichthyological Society of JapanLarval developments of Pempheris xanthoptera and P. japonica were described on 31 (6.45–22.40 mm SL) and 5 (10.35–35.70 mm SL) specimens, respectively, with particular attention to cartilaginous development. Comparison between the two species indicated that P. xanthoptera was discriminated from P. japonica by the following key characters: two supracleithral spines (one in P. japonica); longer pectoral fin; shorter ventral fin; and absence of melanophore on mid-ventral part of lower jaw and anterolateral region of trunk, and web of ventral fin.
ArticleThe spawning behavior and embryonic and larval development of Siganus guttatus are described from laboratory observations. Characteristic prespawning behavior began 4 h before actual spawning: the female touched the anal region of the abdomen on the bottom of the tank; the male displayed short, jerky, rushing movements towards the female, often with rapid circling around her. The male and the female separately released small amounts of milt and eggs several times during the pre-spawning ritual. The color of both sexes changed, the male becoming lighter and the female darker in ground color. Spawning took place at 02.30 h on the third day after the first quarter of the moon. During actual spawning, the pair swam side by side, with the female slightly ahead of the male. Fertilized eggs were small (0.56±0.008 mm), demersal and adhesive, with many oil globules. Larvae measured 1.74±0.043 mm total length at hatching, and possessed eight pairs of free neuromasts with long cupulae (60–180 μm) from 6 h to 39 h after hatching. The adult complement of fin ray counts was attained on day 16 when larvae (=juveniles) measured 8.34 mm total length on the average.
Survival of larval milkfish, Chanos chanos, during changeover from endogenous to exogenous energy sources H Kohno, M Duray, A Gallego & Y Taki - In R Hirano & I Hanyu (Eds.), The Second Asian Fisheries Forum. Proceedings of the Second Asian Fisheries Forum, 17-22 April 1989, Tokyo, Japan, 1990 - Asian Fisheries SocietySurvival of laboratory-reared larvae of milkfish, Chanos chanos , during transition from the prelarval to postlarval stages was examined in relation to the changeover of energy sources. The prelarval and early postlarval stages of the fish can be divided into 5 phases; 1) rapid growth corresponding to rapid yolk less rapid yolk resorption; 3) stagnant growth with rapid yolk resorption, yolk being still the only nutrient for the larvae; 4) stagnant growth based on both yolk and exogenous food, from the onset of feeding to the complete exhaustion of yolk; and 5) rapid growth based solely on exogenous food. The survival rate decreased when the larvae depended solely on yolk, then leveled off when they had both endogenous and exogenous energy sources, and again declined when they came to depend totally on exogenous food. Feeding during the period from the onset of feeding to complete yolk resorption seems important for the successful survival of milk-fish larvae thereafter.