Broodstock management and seed production of milkfish
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Milkfish (Chanos chanos Forsskal) remains one of the cheapest sources of protein for developing countries in Southeast Asia, particularly in the Philippines. The unpredictable supply of wild fry, the only source of seed for the milkfish farmer, contributed largely to the slow growth of the milkfish industry. Research on the artificial propagation of this fish was, therefore, given emphasis. Major research achievements in milkfish breeding of the SEAFDEC Aquaculture Department in the last decade include: (1) successful induced spawning of wild and captive breeders using gonadotropin preparations and gonadotropin-releasing hormone analogues (GnRHa); (2) spontaneous maturation and spawning of captive breeders; (3) completion of the life cycle of milkfish in captivity; (4) development of a simple egg-collecting method; and (5) development of techniques for mass production of milkfish fry. Information on fry ecology and behavior, larval morphology and physiology were also gathered. These published data constitute the bulk of current knowledge on milkfish biology and natural history. Milkfish breeding technology is currently being pilot-tested in several breeding sites of the Bureau of Fisheries and Aquatic Resources (BFAR). Spontaneous maturation and spawning of milkfish have been verified in four sites which differ in environmental characteristics. The economic feasibility of producing milkfish fry and the socio-economic impact of artificial propagation of milkfish are now being assessed.
Marte, C. L. (1988). Broodstock management and seed production of milkfish. In J. V. Juario & L. V. Benitez (Eds.), Perspectives in Aquaculture Development in Southeast Asia and Japan: Contributions of the SEAFDEC Aquaculture Department. Proceedings of the Seminar on Aquaculture Development in Southeast Asia, 8-12 September 1987, Iloilo City, Philippines. (pp. 169-194). Tigbauan, Iloilo, Philippines: SEAFDEC, Aquaculture Department. http://hdl.handle.net/10862/145
PublisherAquaculture Department, Southeast Asian Fisheries Development Center
Seed (aquaculture); Feed; Fish eggs; Morphogenesis; Fry; Husbandry diseases; Seed collection; Life cycle; Induced breeding; Seed production; Larval development; Environmental factors; Sex hormones; Feed composition; Gonadosomatic index; Wild spawning; Sexual maturity; Reproductive cycle; Cage culture; Feeding experiments; Parasitic diseases; Brood stocks; Aquaculture techniques; Fish culture; Chanos chanos; Milkfish; Philippines
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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 - Aquaculture Department, Southeast Asian Fisheries Development CenterMost 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.
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Conference paperB Sirikul, S Luanprida, K Chaiyakam & R Sriprasert - In JV Juario & LV Benitez (Eds.), Seminar on Aquaculture Development in Southeast Asia, 8-12 September 1987, Iloilo City, Philippines, 1988 - Aquaculture Department, Southeast Asian Fisheries Development CenterAquaculture practised in Thailand is in the form of pond culture and cage culture in freshwater, brackishwater and coastal areas. The main species cultured include freshwater prawns, brackishwater shrimp, cockles, mussels, and various freshwater and marine finfishes. There is good potential for increased production from freshwater, brackishwater and marine aquaculture. However, the 1983 production of 145 000 mt represents only about 6% of Thailand's total fish production and production in this subsector has fluctuated widely. It will be several years before aquaculture production will contribute substantially to total production. Nonetheless, the culture of high value species of shrimp and fish could contribute significantly to export earnings during the next 5 to 10 years. Conducted primarily by government agencies, research and development are along the lines of increasing seed supply, establishing new culture techniques or improving older ones. The Department of Fisheries (DOF) together with some private companies have ventured into the development and testing of artificial diets for the various cultured species using a variety of indigenous feed stuffs. It is estimated that with adequate investments and appropriate support, aquaculture production will increase from 145 000 mt in 1983 to 378 000 mt in 1991, showing an annual increase of about 13% over this period. Major increases would come from bivalve mariculture (131 000 mt), brackishwater ponds (36 000 mt) freshwater ponds (46 000 mt) and brackishwater cage culture (20 000 mt).