Now showing items 1-13 of 13

    • Article

      A comparative study of various extenders of milkfish, Chanos chanos (Forsskal) sperm preservation 

      S Hara, JT Canto Jr. & JM Almendras - SEAFDEC Aquaculture Department Quarterly Research Report, 1980 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Four chemical extenders in 7 different concentrations (potassium chloride, sodium chloride, glucose, sodium citrate, Ringer s solution, cow serum and milkfish (Chanos chanos) serum) were compared in the preservation of milkfish sperm. Results showed milkfish serum to be the most suitable of the various extenders tested. This may be attributed to suitable osmotic potential and/or presence of proteins which may have directly or indirectly influenced sperm viability. The effects of milkfish serum on the motility and fertilizing capacity of sperm at different durations of storage however need to be investigated.
    • Article

      A comparative study of various extenders for milkfish, Chanos chanos (Forsskal), sperm preservation 

      S Hara, JT Canto Jr. & JME Almendras - Aquaculture, 1982 - Elsevier
      Various extenders, containing potassium chloride, sodium chloride, glucose, sodium citrate, Ringer's solution, cow serum and milkfish serum were used to preserve milkfish (Chanos chanos) sperm at near-zero temperatures (0-4°C) and in liquid nitrogen (?196°C). Milkfish serum was a superior extender in both cases. After 5 days, comparatively good motility (> 30%) and fertilizing capacity (6.7-18.9%) were observed in the near-zero liquid samples, while in other extenders, sperm ceased to show motility after 2 days. The fertilization success of 4-5 days cryopreserved sperm averaged 67.5% (n = 2) with milkfish serum, 60.5% (n = 2) with 400 mM glucose, 58.0% (n = 2) with 150 mM sodium chloride, 41.2% (n = 1) with Ringer's solution and 31.9% (n = 2) with cow serum.
    • Article

      Early development of fin-supports and fin-rays in the milkfish Chanos chanos 

      Y Taki, H Kohno & S Hara - Japanese Journal of Ichthyology, 1986 - The Ichthyological Society of Japan
      Development 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.
    • Article

      Early larval development of the seabass Lates calcarifer with emphasis on the transition of energy sources 

      H Kohno, S Hara & Y Taki - Nippon Suisan Gakkaishi, 1986 - Japanese Society of Fisheries Science
      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).
    • Article

      A fundamental study on the behavior of milkfish fry for improving the efficiency of traditional fry collecting gear in the Philippines 

      G Kawamura, S Hara & TU Bagarinao - Memoirs of the Kagoshima University Research Center for the South Pacific, 1980 - Kagoshima University Research Center for the South Pacific
      The reaction of milkfish fry to miving and stationary nets of different meshes and colors in an experimental tank was determined. The underwater visibility of the nets saw measured and the water filtration in a fry-sweeper was observed.

      Milkfish fry were both driven well by the moving nets and retained well by the stationary nets, with the fine-meshed black net most effective in both cases. The white and blue nets were found to be quite invisible to the fry in the blue-painted tank, particularly under contour lighting conditions; the black net was found to be very visible to the fry under both surface and contour light. The underwater visibility of the nets was found to vary with the sea conditions and the light direction. Water filteration in the fry-sweeper was found to be almost perfect.

      From the results, it was concluded that milkfish fry are caught by the moving fry collecting gear through driving and not by filtering. Since fry collection grounds are usually turbid, it was recommended that dark-colored materials be used for effective driving. It is also deemed much better to use larger mesh nets in the wings of the fry gear to minimize net resistance in the water and facilitate operation.
    • Article

      Fundamental study on the behavior of milkfish fry for the evaluation of the efficiency of traditional fry collecting gears in the Philippines 

      G Kawamura, S Hara & T Bagarinao - SEAFDEC Aquaculture Department Quarterly Research Report, 1980 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The response of Chanos chanos fry to moving and stationary nets of different mesh size and colour, underwater visibility of the nets and water filtration were studied. Results indicate that milkfish fry may be driven by nets of mesh size larger than that presently used; larger mesh size decreases the net resistance in the water so that collectors may move the equipment easily. The large mesh nets should be of a dark colour, preferably black for effective driving; bowever white mosquito net is best for the core end, since the fry are more easily visible on a white background.
    • Article

      Morphological aspects of the development of swimming and feeding functions in the milkfish Chanos chanos 

      Y Taki, H Kohno & S Hara - Japanese Journal of Ichthyology, 1987 - The Ichthyological Society of Japan
      Development of swimming and feeding abilities based on morphological development of larval and early juvenileChanos chanos was investigated. In larvae smaller than about 6.5 mm SL, mechanical supports of fins and branchial arches were in a primordial stage of development. Supports and rays of the vertical fins and branchial arches rapidly developed from 6.5 mm SL, and all components appeared by about 10.5 mm SL. Thereafter body depth proportion changed and the supports and rays of the paired fins and gill-rakers developed. These developmental events were nearly or totally completed by about 17 mm SL, and we concluded that the larvae transformed to juveniles at this size. By this time, the mode of swimming of the fish shifted from undulating locomotion to caudal propulsion and that of feeding from swallowing paniculate food to filtering and concentrating substrate food matters using gill-rakers and the epibranchial organ. One of the most characteristic, and well-known, phenomena in the life history ofChanos chanos is the mass occurrence in the surf zone of postlarvae of a limited size range. In view of the scheme of the development of mechanical supports of the body and fins, they may acquire a swimming ability strong enough to move against the current only upon reaching about 10.5 mm SL, and if active shoreward migration of the larvae occurs, it is only during the late period of their journey from the spawning grounds to the shore. The sudden disappearance from the surf zone of larvae larger than 15–16 mm SL is obviously related to a change in food habit.
    • Article

      Optomotor reaction of milkfish larvae and juveniles 

      G Kawamura & S Hara - SEAFDEC Aquaculture Department Quarterly Research Report, 1979 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      The optomotor reaction of milkfish larvae and juveniles 

      G Kawamura & S Hara - Nippon Suisan Gakkaishi, 1980 - Japanese Society of Fisheries Science
      The development of the optomotor reaction (OMR) in milkfish (Chanos chanos), from the larval, through the metamorphic, to the juvenile stage was observed. The period from the appearance of the pelvic fins until the complete disappearance of the finfold was named "metamorphic stage". While the larvae showed strong rheotactic responses, their OMR was somewhat weak. It was clear that the OMR underwent a big change through the metamorphic stage, and became strong and almost perfect in the juveniles.
    • Article

      Preliminary studies on the rearing of the red-spotted grouper, Epinephelus coioides larvae using copepod nauplii as initial food. 

      JD Toledo, SN Golez, M Doi, RS Bravo & S Hara - UPV Journal of Natural Sciences, 1996 - University of the Philippines in the Visayas
      One day old red-spotted grouper (Epinephelus coioides) larvae from SEAFDEC, Iloilo, were packed at 3.300 ind/L and transported to Dagupan, Pangasinan for larval rearing. Transport time was about 10 hours. More than 90% of the larvae were active after transport. These were reared in two 7-on tanks (Tanks 1 and 2) using Acartia nauplii and rotifers as a initial food and in one 10-ton tank (Tank 3) provided with rotifers only. Feeding incidence at the onset of feeding (Day 3) was higher (90-95%) in Tanks 1 and 2 than in tank 3 (85%). All larvae sampled from days 4 – 10 in Tanks 1 and 2 had food in the gut while feeding incidence in Tank 3 was variable (75-100%). Larvae in Tanks 1 and 2 showed consistently higher food electivity for Acartia nauplii than rotifers. Higher survival rates were observed in Day 13 in tanks provided with copepod nauplii (16-18%) than with the rotifers only (2%). Average total length on Day 13 was higher in copepod-fed larvae (4.5 ± 0.5 mm) than larvae fed with rotifers only (3.0 ± 0.3mm). All larvae fed with rotifers alone died on Day 15. A total of 675 larvae were harvested on Day 45 from Tanks 1 and 2. These results indicate the feasibility of transporting one day old E. coioides larvae for at least 10 h and of using copepod nauplii as food for the first feeding E. coioides larvae.
    • Article

      Spawning behavior and early life history of the rabbitfish, Siganus guttatus, in the laboratory 

      S Hara, H Kohno & Y Taki - Aquaculture, 1986 - Elsevier
      The 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.
    • Article

      Transition from endogenous to exogenous nutrition sources in larval rabbitfish Siganus guttatus 

      H Kohno, S Hara, M Duray & A Gallego - Nippon Suisan Gakkaishi, 1988 - Japanese Society of Fisheries Science
      The early larval development of Siganus guttatus was studied with emphasis on the transition from endogenous to exogenous feeding. Three rearing trials were conducted as follows: 1) rearing in a 5 ton concrete tank at 27.9-29.3oC (T-85 trial); 2) rearing in a 0.5 ton fiberglass tank at 22.2-26.5oC (T-86A trial); 3) rearing in the same manner as in T-86A but without food (T-86B trial). On the basis of the developmental events and energy flow in T-86A trial, the early life history of the species could be divided into the following seven phases: 1) rapid larval growth due to rapid yolk resorption (from hatching to about 15 h after hatching (time after hatching: TAH)); 2) slow growth and organogenesis based mainly on yolk energy (to about 50 h TAH); 3) slow growth based on energy of yolk, oil globule and exogenous food (to about 50 h TAH); 4) slow growth based on two sources of energy, oil globule and exogenous food (to about 90 h TAH); 5) the same mode of development and energy flow as in the preceding phase, but with a certain level of feeding amount (to about 120 h TAH); 6) accelerated larval growth and effective feeding and swimming based only on exogenous food (to about 150 h TAH); and 7) the same mode as in the preceding phase with accelerated increase of feeding amount (beyond 150 h TAH). Differences in developmental mode were observed in T-85 and T-86A trials, but it could not be ascertained in this particular study which of the environment factors played the greatest influence. The results of T-86A and B showed that the larvae, in order to survive, have to get over two obstacles on feeding, that is, to start feeding and to change from endogenous to exogenous feeding suitably.
    • Article

      Year-round spawning and seed production of the rabbitfish, Siganus guttatus 

      S Hara, MN Duray, MM Parazo & Y Taki - Aquaculture, 1986 - Elsevier
      A series of experiments on the spawning and larval rearing of Siganus guttatus was conducted during a 14-month period in 1984–1985. Spawning occurred every month throughout the year, without hormonal treatment, between the first quarter and the full moon. Fertilization rates and hatching rates were high, with means of 84.2% (n=38) and 89.6% (n=34), respectively. Females that had been fed diets rich in cod liver oil or in a cod liver oil/soybean oil/soybean lecithin mixture spawned repeatedly for at least 4 consecutive months. Larvae reared in 20, 26, and 32‰ salinities showed no significant differences in survival rates at day 21. Survival was higher for larvae fed during days 2–4 with rotifers strained through an 80-μm-mesh plankton net than for those fed unstrained rotifers. Larvae readily accepted Artemia nauplii and artificial diets when these were first introduced on day 15 and day 23, respectively. Higher larval survival was obtained in large tanks (≥5 m3) than in small tanks (500 l). Survival rates of 3.5–16.6% (x=7.5%) at day 45 were obtained in six trials of mass larval rearing and 5500–50100 (x=27 700) juveniles per female were produced at day 45, ready for stocking in grow-out farms.