Research on marine fishes
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Research on marine fishes at SEAFDEC/AQD from 1995 to date was mostly on milkfish Chanos chanos. Studies focused on the refinement of broodstock and seed production techniques to improve egg and larval production as well as to eliminate morphological deformities in hatchery-bred fry. A verification study with former shrimp hatchery operators demonstrated the technical and economic viability of the AQD-generated milkfish hatchery technology. Production and efficiency of semi-intensive grow-out in ponds were enhanced by the use of formulated feeds and appropriate feeding scheme. Milkfish farming in the Philippines was critically reviewed and recommendations to sustain milkfish culture production were made. Tobacco dust and metaldehyde formulation were proposed as alternatives to organotin-based pesticides in controlling the population of pond snail. The growth hormone of milkfish has been isolated and purified. Addition of highly unsaturated fatty acid (HUFA)-rich oils in the diet did not improve the quality of spawned eggs of grouper Epinephelus coioides. A protocol for the intensive larval rearing of grouper was developed based on the results of several studies. A semi-intensive seed production method using copepod nauplii during the early feeding stages was also developed as an alternative to intensive method. Metamorphosis of larvae was significantly accelerated by exogenous thyroid hormones. Nutritional studies to reduce the amount of fish meal in grouper diets are in progress. Groupers grown in ponds or cages harbor a variety of parasites. Biochemical criteria to assess the quality of spawned Asian sea bass Lates calcarifer eggs was characterized. Diaphanosoma or other copepods may be an alternative or supplemental live prey to Artemia during sea bass larviculture. A practical diet for sea bass culture was developed. Studies to determine the essential amino acid requirements of sea bass are about to be completed. The effects of immuno-stimulants in sea bass are presented. Induced and natural spawning of mangrove red snapper Lutjanus argentimaculatus in concrete tanks or floating net cages has been documented. An improved larval rearing method has been developed using screened rotifers during the early feeding stage of the larvae. Exogenous thyroid hormones have advanced metamorphosis of larvae. A practical diet for snapper is under development. Research on rabbitfish Siganus guttatus were geared to developing tools for growth enhancement. Pituitary growth hormone (GH) has been cloned, allowing the production of recombinant rabbitfish GH. Rabbitfish prolactin, somatolactin have also been purified. Studies on marine ornamental fish focused on two species of seahorses, Hippocampus kuda and H. barbouri, and on blue tang Paracanthurus hepatus. Progress on the biology, breeding, and seed production of seahorses are presented. Successive natural spawnings of blue tang in concrete circular tank have been recorded.
Toledo, J. D. (2001). Research on marine fishes. In L. M. B. Garcia (Ed.), Responsible Aquaculture Development in Southeast Asia. Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia organized by the SEAFDEC Aquaculture Department, 12-14 October 1999, Iloilo City, Philippines (pp. 173–184). Tigbauan, Iloilo, Philippines: SEAFDEC Aquaculture Department.
PublisherSEAFDEC Aquaculture Department
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Conference paperK Fukusho - In TU Bagarinao & EEC Flores (Eds.), Towards sustainable aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994, 1995 - SEAFDEC Aquaculture DepartmentAquaculture production in Japan in 1993 was 1,351,000 tons, 15.6% of the total fisheries production. About 93.6% came from mariculture and 6.4% from freshwater aquaculture. The per cent contribution of aquaculture to total production has increased in recent years but partly because marine fisheries,especially of sardine and pollack, have decreased. Aquaculture has reached a plateau, and decreased slightly between 1992 and 1993. Diverse marine and freshwater species are cultured in Japan — various fishes, crustaceans, mollusks, seaweeds, sea squirt, sea urchin, and others. Research and development in mariculture focus on finding substitutes for animal protein in feeds, improvement of fish quality, protection of the culture environment, use of offshore floating culture systems, and protection from diseases. Research in freshwater aquaculture has expanded to include recreational fishing, the propagation and preservation of endangered species, and the construction of fish ladders for salmonids and other migratory species.
Conference paperAC Emata - In TU Bagarinao & EEC Flores (Eds.), Towards sustainable aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994, 1995 - SEAFDEC Aquaculture DepartmentMost of the fish research at SEAFDEC AQD in 1992-1994 was on milkfish. Studies were conducted on year-round spawning through hormonal or environmental manipulation; optimum lipid and protein levels and ration size for captive broodstock; and the influence of spawner age on reproductive performance. The economics of hatchery operations, alone or integrated with broodstock as a commercial enterprise, was assessed. Mass production of larvae was refined with the use of commercial or SEAFDEC-formulated larval diets. Alternative rearing schemes in large tanks and ponds were tried. Hatcheryproduced and wild-caught larvae were compared in terms of growth and production in experimental nursery and grow-out ponds. Supplemental diets for brackishwater grow-out culture were formulated. Studies on broodstock management of grouper Epinephelus spp. included lipid enrichment of the diet and hormonal induction of sex inversion. Seed production techniques were developed but survival rates were low. Grouper culture was found economically feasible in experimental ponds with 'trash' fish as feed. The mangrove red snapper Lutjanus argentimaculatus was successfully induced to spawn with injection of human chorionic gonadotropin. Initial larval rearing trials were successful but survival rates must be improved. Hormonal manipulation of spawning of the Asian sea bass Lates calcarifer allows seed production during most of the year. Photoperiod manipulation leads to maturation of females, but not males, beyond the natural breeding season (April-November). Nursery rearing of 9 mm juveniles is feasible in floating net cages with night lights that attract food zooplankton. The requirements of sea bass for lipid, protein, carbohydrates, and essential amino acids were determined. In the rabbitfish Siganus guttatus, weekly injections of luteinizing hormone releasing hormone analogue (LHRHa) sustains milt production for three weeks. Thyroid hormones injected into broodstocks improved the growth of larvae to day 7. Induced spawning techniques for the Asian catfish Clarias macrocephalus were refined by determining the seasonal responsiveness to LHRHa and pimozide injections and testing for pheromonal induction of spontaneous spawning. The optimum insemination rate was determined and egg hatchability was enhanced by removal of the adhesive coat before incubation. Several practical diets for catfish during grow-out culture were tested against 'trash' fish. The broodstock management for bighead carp Aristichthys nobilis was studied. Cage-reared juveniles from cage-reared broodstock showed the best growth. To improve the reproductive performance, the broodstock diets were supplemented with vitamins A, C, and E. Research on tilapias focused on genetics and strain selection. Several strain testing procedures for Nile tilapia were evaluated in their efficiency to detect economically important strain differences. Reference lines were developed from two existing red tilapia strains to measure and reduce the effects of uncontrolled nongenetic variables in strain evaluation experiments with Nile tilapia. The tolerance of two Nile tilapia strains to heavy metals was similar when gauged by the 24-hour and 96-hour lethal concentration and by fish growth, survival, and reproductive performance. In a separate study, four strains of red tilapia showed generally higher seed production when reared in tanks than in cages. Improvements in the feed and feeding management for Nile tilapia were also studied. Intensive tilapia farming and feeding have led to oxygen depletion and fish kills in Sampaloc Lake. To rehabilitate the lake, it is imperative to reduce the farming area from 30 to 6 hectares; stop the use of commercial feeds; and remove the water hyacinths and other debris. Fish kills in Laguna de Bay have also become serious in recent years, and a review of the occurrences, losses, and possible causes is currently being conducted. Studies on the epizootic ulcerative syndrome of snakeheads in Laguna de Bay have yet to pinpoint the pathogen. Skin lesions in tilapias in several ponds and lakes in the country were found to be due to bacteria.
Growth and survival of grouper Epinephelus coioides (Hamilton) larvae fed free-living nematode Panagrellus redivivus at first feeding OS Reyes, MN Duray, CB Santiago & M Ricci -
Aquaculture International, 2011 - European Aquaculture SocietyThe free-living nematode, Panagrellus redivivus, was tested as live food for grouper Epinephelus coioides larvae during the first feeding stage. A series of experiments were conducted to determine the acceptability of the free-living nematodes in grouper larvae at first feeding, the optimum nematode density and the response of the larvae to nutritionally enriched nematode. All experiments were conducted in 200-L conical tanks filled with 150-L filtered seawater and stocked at 15 larvae L−1. Duration of feeding experiments was up to day 21 (experiment 1) and 14 days (experiment 2 and 3). Brachionus plicatilis and Artemia (experiment 1) and Brachionus plicatilis alone (experiment 2 & 3) was used as the control treatment. Observations indicated that the grouper larvae readily fed on free-living nematodes as early as 3 days posthatching, the start of exogenous feeding. Optimum feeding density for the larvae was 75 nematodes ml−1. The enrichment of cod liver oil or sunflower oil influenced the total lipids and n-3 highly unsaturated fatty acids of P. redivivus, which in turn influenced those of the grouper larvae, however, growth and survival of the larvae were not affected (P > 0.05). The results from this investigation showed that the nematode, P. redivivus, can be used as first live food for grouper larvae from the onset of exogenous feeding until they could feed on Artemia nauplii.