Now showing items 1-20 of 31

    • Conference paper

      Artificial incubation for intensive fry production of Nile tilapia Oreochromis niloticus (L.) 

      GC Mair, CC Estabillo & LR Dahilig - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Two experiments were conducted to evaluate and compare the production, quality, and survival of eggs and the subsequent growth and survival of fry in two small scale production systems: (i) natural incubation (NI), and (ii) egg collection followed by artificial incubation in upwelling glass funnels (AI). Cost benefits analysis was applied to the production figures to compare the economic viability of the two methods. The results were used to design a fry production system for the intensive production of Genetically Male Tilapia (GMT) from limited numbers of novel YY-male broodstock.
    • Conference paper

      A brief account of the experience of Sabah Fisheries Department in fish larval rearing 

      CF Komilus & FD Parado-Estepa - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Venturing into the aquaculture sector especially in pond and cage culture is a step that has been taken up by entrepreneurs and traditional fishermen of Sabah. However, shortage in the supply of fish fry is a stumbling block to the progress of the industry.

      The Sabah Fisheries Department has taken steps to overcome this problem by setting up a hatchery with the objectives to transfer know-how on hatchery technologies to the private sector besides producing fry for distribution.

      The Tanjong Badak multi-species hatchery is a newly established hatchery, completed in mid-1990. The species reared for production purposes are tiger shrimp and finfish which include red snapper, grouper, sea bass and polkadot grouper. The Department has not close to producing sea bass fry. Shrimp fry at juvenile stages (PL 40) are distributed as subsidies to local fish farmers while some are reared at the Department's various cage and pond culture projects. Limited success in producing grouper and red snapper fry have been achieved to date. The incidence of very low fertilization rates of eggs coupled with low survival rates are major problems facing the hatchery.

      In conclusion, the Sabah Fisheries Department's experience in fish larval rearing is still limited. Greater scientific research and studies need to be carried out to improve further the performance of the hatchery to achieve the target of fry sufficiency for the aquaculture industry.
    • Conference paper

      Changes in lipid and fatty acid content during early larval development of milkfish (Chanos chanos): influence of broodstock diet 

      CL Marte, IG Borlongan & AC Emata - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The influence of amount and type of lipid given to milkfish broodstock by developing larvae was investigated by feeding broodstock commercial diets that differed in lipid content and composition. The two commercial feeds used had the following proximate composition: RFP - 28.16% crude protein, 2.40% crude fat, 7.58% crude fiber, 53.94% N-free extract; RCP - 43.28% crude protein, 4.58% crude fat, 6.18% crude fiber, 37.0% N-free extract.

      The lipid content and fatty acid composition of spawned milkfish eggs reflected that of the broodstock feed. Percent lipid in egg from broodstock fed RFP and RCP dropped by 22.5% and 26.9% in newly-hatched larvae and by 53.0% and 65.0% in day 2 larvae (>90% yolk resorbed), respectively. Decreases in total PUFA and increase in monoenoic fatty acids during yolk resorption indicate that milkfish as in other marine fishes utilize PUFA during early larval development. While differences in rate of utilization of individual n-3 and n-6 FA in two groups of larvae seem to be influenced by levels of the fatty acids in eggs, the influence of other nutrients on fatty acid utilization need to be investigated.
    • Conference paper

      The commercial production of green grouper fingerlings, Epinephelus suillus, from wild caught fry - an industry experience 

      JV Juario, JR Silapan & LL Silapan Jr. - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Wild-caught fry of the green groupers, Epinephelus malabaricus and E. suillus ranging in standard lengths (SL) from 1.5 to 3.0 cm were bought from different fry dealers all over the Philippines. These were reared from 1.0 to 2.5 months in 10 to 40 m3 (small) concrete tanks, in 240 m3 (large) concrete nursery tanks with sandy bottom, in 10 m3 hapa nets installed either in large nursery concrete tanks with sandy bottom or in 0.8 to 1.0 ha earthen ponds. The initial stocking density was 33-150/m3. When the fingerlings reached 5 to 7 cm SL, these were harvested and stocked in cages. The wild fry were fed adult brine shrimps for the first few days and later, trash fish. Rearing water in small concrete tanks was changed daily while that in large nursery tanks and hapas was changed only when dissolved oxygen level was about 4 ppt or lower. Survival rates ranged from 3% to 64%. Although survival rates varied, rearing grouper fry in hapa nets installed in earthen ponds were found to be the most suitable for the commercial production of grouper fingerlings to a size suitable for stocking in cages. The large variation in survival rates is attributed mainly to the quality of wild fry bought from different fry dealers all over the country and the occurrence of diseases during the culture period. The problems encountered in the commercial production of fingerlings are discussed.
    • Conference paper

      Control of gonad growth, maturation and spawning in teleost fish: A review 

      AD Munro & TJ Lam - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Despite their great variety of reproductive strategies, a general characteristic of most teleosts is that (where known) natural reproduction shows a long-term periodicity, even in tropical habitats (e.g. see contributions in Munro et al. 1990a). Typically, gonad development from puberty leads to fully-grown gonads by the advent of the spawning season; if conditions are appropriate, then final gonad maturation leads to the production of viable gametes during one or more breeding bouts. Subsequently, in those larger species which spawn over more than one season, the gonads regress and the individual returns to a phase where any growth is somatic. However, there is wide interspecific variability in the pattern of gonad development (Wallace and Selman 1981, de Vlaming 1983, Billard 1986, Selman and Wallace 1989).
    • Conference paper

      Correlations of oocyte diameter with some morphometric characters in the nile tilapia, Oreochromis niloticus L. 

      MAR Garcia-Abiado, HJS Paras & GC Mair - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      A study was conducted to determine the correlation of oocyte diameter with some morphometric characters in a Philippine strain of Oreochromis niloticus L. One hundred and thirty-five 7- to 9-month old sexually mature female broodstock (body weight: 71±35 g; standard length: 13.1±2.1 cm) were randomly sampled from a pool of broodstock maintained in 4 m2 net enclosures suspended in an earthen pond. The following morphometric characters were determined for each fish: body weight, standard length, genital pore dimension, and genital papilla dimension. Intra-ovarian oocyte samples were obtained by inserting a soft silicon rubber tubing into the ovipore of the fish and aspirating the oocytes by mouth. There were no significant correlations between the average oocyte diameter and any of the morphological characters studied. Results justify the adoption of an ovarian biopsy technique for assessing the stage of gonadal maturity in sexually mature tilapia.
    • Conference paper

      Effects of different fat sources on the egg quality of grouper, Epinephelus suillus 

      GF Quinitio, RM Coloso, A Duller & D Reyes - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effect of different fat sources on the egg quality of grouper, Epinephelus suillus eggs was evaluated. Fish in three tanks, each containing 3 females and 1 male, were fed various types of feeds namely: trash fish (control), trash fish + cod liver oil (treatment 1) and trash fish + SELCO, a lipid emulsion containing high levels of highly unsaturated fatty acid (HUFA) (treatment 2).

      Approximately 77.9 million eggs spawned from January to October 1992 by the control group, 40.0 million by fish in treatment 1, and 36.4 million by the treatment 2 group. Egg production (0.45 million eggs/kg BW) among the control group was significantly higher than treatment 2. Egg production of treatment 1 (0.06-0.36 million eggs/kg BW) was not significantly different (P<0.01) from the control group nor treatment 2 (0.02-0.30 million eggs/kg BW). Fertilization and hatching rates showed significant differences among the three groups with control > treatment 1 > treatment 2. There were no differences detected in the egg and oil globule diameters among the treatments. Crude protein and lipid levels of floating (good) and sinking (bad) eggs collected in February to March 1992, and August to September 1992 were similar in all treatments. Unfed larvae from treatment 1 survived until the fifth day after hatching while those in the control and treatment 2 groups lasted only until the third day. These results suggest that supplementation of cod liver oil and SELCO in the trash fish diet of E. suillus broodstock does not influence egg production, fertilization and hatching rates, and egg quality.
    • Conference paper

      Effects of single injection of carp pituitary extract and human chorionic gonadotropin on germinal vesicle migration and ovulation in lampan sungai, Puntius schwanenfeldii (Bleeker): A preliminary study 

      SA Harmin, R Joannes & SH Cheah - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effects of crude pituitary extract (CPE) and human chorionic gonadotropin (hCG) on germinal vesicle migration and ovulation in lampan sungai Puntius schwanenfeldii (Bleeker) were investigated. Sexually mature female lampan sungai were divided into four groups (n=3 per group). In both experiments, fish were injected intramuscularly (im) once and were checked for germinal vesicle migration and sign of ovulation 8 h following injection. In experiment 1, females were treated with CPE at doses of 2, 4, or 6 mg/kg body weight (BW) while controls were administered an equivalent volume of saline. Ovulation occurred in one fish given 2 mg/kg and in another fish that received 6 mg/kg CPE. In a second experiment, female fish were administered hCG at doses of 1000, 2000, or 4000 IU/kg body weight. Similarly, controls received only saline. One female injected with 4000 IU/kg hCG responded positively to the hormone treatment. Clearly, in our study, a single intramuscular injection of CPE and hCG induced spawning in lampan sungai as well as accelerated oocyte development as evidenced by the increasing percentage of oocytes showing germinal vesicle migration.
    • Conference paper

      Endocrine changes associated with overripening of ovulated eggs in goldfish, Carassius auratus L. 

      MJ Formacion & TJ Lam - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Changes in steroid hormone levels in the serum and ovarian fluid were studied during overripening in goldfish. Ovulated eggs retained in the ovarian cavity become overripe at around 12 h after ovulation and completely overripe 24 h after. Blood and ovarian fluid were taken at 0, 3, 6, 12, 18, and 24 h after ovulation. Estradiol-17ß (E 2) , testosterone (T), progesterone (P) and 17α,20ß-dihydroxy-4-pregnen-3-one (17α,20ß-P) in the serum were extracted directly with a solvent while those in the ovarian fluid were separated by HPLC before radioimmunoassay. Both serum and ovarian fluid P showed a highly significant decline at 18 h with a further decline at 24 h; P levels were higher in the ovarian fluid. Serum 17α,20ß-P showed a progressive and more rapid decline, decreasing significantly at 12 h with further decreases at 18 h and 24 h; the level was five-fold lower at 24 h compared to the 0 h level. Serum T increased significantly at 3 h which was maintained until 18 h, when it declined to 0 h level. No significant changes in E2 were observed in the serum, except for a significant difference between 6 and 24 h. There were no significant changes in E2, T and 17α,20ß-P in the ovarian fluid. Of the four steroids measured, only 17α,20ß-P and P showed changes which bear some correlation with the time course of overripening. The declines in the mean ratios of 17α,20ß-P/E2 in the serum and P/E2 in the ovarian fluid also appeared to have a good correlation with the time course of overripening. The postovulatory follicles (POFs) showed degenerative features which likewise correspond to the decline in P and 17α,20ß-P.
    • Conference paper

      Feeding habits of hatchery-reared grouper, Epinephelus suillus larvae 

      MN Duray - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The feeding habits of hatchery-reared Epinephelus suillus larvae were determined by examining their gut contents. The larvae (2.6 mm TL) were initially fed rotifers on day 2 and newly-hatched Artemia nauplii on day 21 (9.1 mm TL). The amount of rotifers initially ingested averaged 1.3 individuals/larva. The ingestion rate increased as larvae grew. Larvae immediately showed strong preference for Artemia to rotifers on the first day of introduction. E. suillus larvae showed diurnal feeding pattern at day 7 (3.6 mm TL), day 14 (4.9 mm TL), day 21 (9.1 mm TL) and day 28 (11.1 mm TL). Feeding incidence decreased in the evening and was nil at 2100-2200 h. Active feeding started earlier in older larvae and satiation was between 0900-1000 h. The results of this study will be used as a basis in developing a good feeding scheme for E. suillus larvae.
    • Conference paper

      Flounder metamorphosis: its regulation by various hormones 

      EG de Jesus, T Hirano & Y Inui - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The elongation and shortening of the flounder fin rays during its metamorphosis may be parallel to the appearance and resorption of the tadpole tail during amphibian metamorphosis. The dorsal fin rays of the Japanese flounder (Paralichthys olivaceus) elongate during the time when thyroid hormone levels are low and are resorbed during climax of metamorphosis when thyroid levels are elevated. Using an in vitro system for culture of isolated flounder fin rays, we examined how various hormones affect the process of resorption. Both T4 and T3 directly stimulated fin ray shortening, T3 being more potent than T4. Other hormones did not directly affect the resorption process but modified the tissue's response to thyroid hormones. Cortisol enhanced the stimulatory effects of both T4 and T3. On the other hand, estradiol and testosterone were inhibitory. Ovine prolactin (oPRL) also diminished the effect of T3 while ovine growth hormone (oGH) was without effect. Similar observations were observed from the in vivo studies.

      Thyroid hormone levels, especially T4, were low during premetamorphosis, increased during prometamorphosis, to peak levels during metamorphic climax, and declined in the juveniles. The changes in whole body concentrations of Cortisol paralleled the changes in thyroid hormone concentrations. On the other hand, whole body estradiol and testosterone concentrations did not show significant change and remained low throughout the larval period. The expression of GH and PRLmRNA, as assessed by in situ hybridization using cDNA for flounder PRL and GH also increased during the metamorphosis. However, the increase in the expression of GH and PRL genes was observed later than the increases in tissue levels of thyroid hormones and Cortisol. At late climax, the flounder larvae have undergone considerable transformation, presumably triggered by both hormones, hence the increase in PRL could hardly be antimetamorphic but may have other physiological implications.
    • Conference paper

      Growth and survival of milkfish (Chanos chanos) larvae reared on artificial diets 

      IG Borlongan, CL Marte & J Nocillado - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      A preliminary feeding experiment was conducted to determine growth and survival of milkfish larvae reared on various feeding regimes involving the use of artificial diets. Two larval diets (Feed A and Feed B) containing 45% protein and 10% lipid were fed either alone or in combination with Brachionus from day 8 to day 21. The feed in the control treatment were Brachionus (10 ind/ml) from day 8 to day 14 and Artemia (2-3 ind/ml) from day 15 to day 21. Larvae in all treatments were fed Brachionus (10 ind/ml) from day 2 to day 7.

      No significant differences were observed in survival rates, total length, wet weight and dry weight among fish fed combination of Brachionus and Feed B and the control feed (Brachionus and Artemia). These promising results indicate the possibility of using Feed B as partial replacement or supplement to live food. However, lowest survival rates, total length, and weight were obtained in fish fed either Feed A or Feed B alone, indicating that the test artificial diets given solely to milkfish larvae starting from day 8 can not support good growth and survival. Further studies on the development of improved artificial diets for larval milkfish need to be done.
    • Conference paper

      Impact of nickel poisoning on the histology of the ovaries of Oreochromis mossambicus 

      C Sioson & A Herrera - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Ovaries of Oreochromis mossambicus exposed to sublethal concentrations of nickel sulphate (0.5 mg/1 and 1.0 mg/1) were histologically analyzed. Changes following exposure to 0.5 mg/1 nickel sulphate include irregularities in the shape of egg follicles, subcellular oocyte damage, lifting off of the theca layer and proliferation of connective tissues. In the ovaries exposed to 1.0 mg/1 nickel sulphate, degenerative changes are worse. Invasion by connective tissues is extensive, oocytes have bizarre shapes, yolk granules are scattered in the interfollicular spaces, abnormal growths are evident and previttelogenic oocytes abound.

      Nickel is a toxicant in Oreochromis mossambicus ovaries.
    • Conference paper

      Induced spawning of the mangrove red snapper, Lutjanus argentimaculatus 

      AC Emata, B Eullaran & M de los Santos - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Wild-caught mangrove red snapper, Lutjanus argentimaculatus, reared for a year in 4.0 m diameter by 1.5 m deep circular concrete tank spontaneously matured and were used for induced spawning trials. On 19 August 1992, a sexually mature female (4.6 kg BW) and male (3.2 kg BW) fish were given a single intramuscular injection of 1500 IU human chorionic gonadotropin (hCG)/kg BW. Spawning occurred 27 h after injection with total egg collection of 1.3 M. Hatching occurred 16 h after spawning at 28 °C and 32 ppt. On 18 March 1993, the same male and female together with a newly-caught spermiating male (6.3 kg BW) were injected intramuscularly with 100 µg luteinizing hormone-releasing hormone analogue (LHRHa)/kg BW. Spawning occurred 44 hours after injection with the total egg collection of 0.7 M. Hatching occurred 16 hours after spawning at the same temperature and salinity as the first trial. The successful spawning trials encourage further research to determine the effective minimum dose of hCG and LHRHa.
    • Conference paper

      Influence of LHRHa and methyltestosterone on milt production of sea bass Lates calcarifer (Bloch) 

      GV Hilomen-Garcia, RB Baldevarona & FJ Lacanilao - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Milt volume, sperm density, and number of spermatozoa were determined to quantify milt production of mature sea bass after a single injection of LHRHa [(D-Ala6,Pro9-N-ethylamiide)LHRH] in saline solution and 17α-methyltestosterone in corn oil (MT). Two measures of sperm density, sperm count and spermatocrit, were highly correlated (r=0.85). Compared with control, milt volume and the number of spermatozoa collected increased but sperm count decreased (24% at 24 h) after a LHRHa (20 µg/kg body weight treatment, suggesting a stimulation of spermatozoa production and not merely milt dilution. Further milt dilution (44%) was induced by 80 µg/kg LHRHa (LHRHa80) at 12 h post-treatment but not by 200 µg/kg MT (MT200) alone. A milt dilution of only 27% at 12 h after simultaneous injections of LHRHa80 and MT200 may indicate some inhibitory effect of MT on the efficiency of LHRHa. These results demonstrate that the stimulation of milt production by LHRHa involves testicular hydration resulting in milt dilution.
    • Conference paper

      Larviculture of milkfish (Chanos chanos) in outdoor tanks 

      MN Duray - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In the past, larviculture of milkfish depended entirely on the use of rotifers and brine shrimp nauplii and rearing trials were done under roofed facilities. Since the dietary value of live food varies according to culture and feeding conditions, rotifers were enriched with SELCO, a lipid emulsion containing high levels of highly unsaturated fatty acids (HUFA) prior to feeding the larvae. Alternatively, a microbound larval feed (Nosan R-1) was given as a supplement to rotifers during the first two weeks of culture. Larval growth was enhanced and survival was significantly improved when rotifers were enriched or supplemented with these diets. All rearing trials were conducted in 5-10 tons concrete circular/rectangular outdoor tanks.

      Verification runs on the use of HUFA-enriched rotifers to milkfish larvae were tried in two nearby private hatcheries. Results from mis collaborative work are presented.
    • Conference paper

      LHRHa and pimozide-induced breeding in the catfish, Clarias macrocephalus (Gunther) 

      JD Tan-Fermin, RSJ Gapasin, AM Tan, MA Garcia & AC Emata - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Clarias macrocephalus is endemic yet dwindling freshwater foodfish in the Philippines. Induced breeding protocol was developed by monitoring the size and maturation of eggs at 0-48 h after a simultaneous injection of luteinizing hormone-releasing hormone analogue (LHRHa; 0.0005 - 0.10 µg/g BW) and pimozide (PIM; 1 µg/g BW). Based on its similar osmotic pressure with catfish plasma, eggs were fixed in 1% phosphate-buffered formalin. Mean egg diameter of fish that were induced to mature increased during ovulation. Oocyte maturation, indicated by oocytes with germinal vesicle breakdown (GVBD), was observed at least 12 h post-injection in fish given 0.01 - 0.10 µg LHRHa + 1 µg PIM/g BW, followed by ovulation 4 h thereafter. Results showed that a simultaneous injection of C. macrocephalus with 0.05 µg LHRHa + 1 µg PIM/g BW at 1800-1900 h followed by stripping at 16-20 h post-injection resulted in high ovulation, fertilization and hatching rates.
    • Conference paper

      Mass larval rearing technology of marine finfish in Japan 

      K Fukusho - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      With economic development and increased demand for high price fish, industrial scale marine finfish culture in Japan was started in 1960-1965 for yellowtail Seriola quinqueradiata. Sustainable supply of wild juvenile and development of floating cage with synthetic fiber net have spurred the culture of nearly 30 species and total production in 1991 is 265 x 103 metric tons (nearly 25% of total aquaculture production). Although salmon ranching had been started in 1888, a national project of ocean ranching was only initiated in 1963 with the present target of 26 species of marine finfish. Ocean ranching aims to increase fisheries resources in coastal sea by stocking hatchery-reared juveniles and preservation of environmental capacity and habitat. Therefore, mass production of marine finfish juveniles is being done for the intensive culture in net cage and for stocking coastal sea in Japan.

      Nearly 200 million juveniles are produced by ocean ranching centers (14 national, 49 prefectural, 21 city and town, 53 fishermen's association). The number of target fish is about 60 species (excluding salmon and trout). The main species produced are red sea bream, Pagrus major, flounder, Paralichthys olivaceus, puffer, Takifugu rubrapes, rockfish, Sebastes shlegeli, and mud dab, Limanda yokohamae. More than one million juveniles of these species are produced at one hatchery or ocean ranching center per one fry production season. About 70% of total production of juveniles consist of red sea bream and flounder. Red sea bream could be used to introduce mass larval rearing technology in Japan since its mass production is well developed. The focus of the present paper is the present status and short history of the development in larval rearing technology for red sea bream.
    • Conference paper

      Maturation of Oreochromis niloticus gonads 

      AA Casauay & VS Carino - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      At hatching when fry were 5 to 6 mm, primordial germ cells (PGCs) were found to concentrate along the dorsomedian region of the peritoneal wall at the root of the developing mesentery and in places far from the appearance of testocoel and ovocoel. At 56 days posthatching, oogenic cells in the ovary had enlarged approximately 2 to 3 times their former size. The testis remained quiescent although the stromal tissues with developing efferent ducts increased distinctly in amount. Spermatogenesis occurred at three months posthatching.
    • Conference paper

      Natural spawning of four Epinephelus species in the laboratory 

      MNR Alava, MLL Dolar & JA Luchavez - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Natural spawnings of four Epinephelus species reared in the laboratory were observed from 1987 to 1992. These species are: E. summana, E. caeruleopunctatus, E. macrospilus and E. fuscoguttatus. Spawning was serial, usually occurring at night, on or 1-6 days after the new moon. Egg characteristics of these four species were compared. Fertilized egg and early larval development of E. summana and E. fuscoguttatus are discussed.