Hatchery technology of milkfish

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in this presentation you can see and learn some steps on how milkfish undergo Artificial Propagation .

Transcript of Hatchery technology of milkfish

  • 1. Hatchery Technology of Milkfish (Chanos chanos)

2. Milkfish (Chanos chanos) is an important food fish in the Philippines, Taiwan and Indonesia. It is a popular fish for culture because it tolerates a wide variety of salinity, temperature and water quality, adapts well to high density, and reaches marketable size in 4-7 months. Introduction 3. They are hardy and fast growing, and can be raised in fresh and brackish water ponds and pens. Being one of the cheapest sources of protein, milkfish are acceptable to all socioeconomic strata in the country. 4. Taxonomic Classification Kingdom : Animalia Phylum : Chordata Subphylum : Vertebrata Class: Osteicthyes Order : Gonorhynchiformes Family : Chanidae Genus: Chanos Lacepede 1803 Species: Chanos chanos Forskal 1775 English name: Milkfish Scientific Name: (Chanos chanos) 5. Biological Features Body fusiform, elongated, moderately compressed, smooth and streamlined. Body colour silvery on belly and sides grading to olive-green or blue on back. Dorsal, anal and caudal fins pale or yellowish with dark margins. Single dorsal fin with 2 spines and 13-17 soft rays. Short anal fin with 2 spines and 8-10 soft rays, close to caudal fin. Caudal fin large and deeply forked with large scale flaps at base in adults. Pectoral fins low on body with axillary (inner basal) scales. Pelvic fins abdominal with axillary scales and 11 or 12 rays. 6. Scales cycloid, small and smooth, 75-91 on lateral line. No scutes (modified pointed scales) along belly. Transparent 'adipose' tissue covers eye. Mouth small and terminal without teeth. Lower jaw with small tubercle at tip, fitting into notch in upper jaw. No bony gular plate between arms of lower jaw. Mouth small and terminal without teeth. Lower jaw with small tubercle at tip, fitting into notch in upper jaw. No bony gular plate between arms of lower jaw. Attains typical length of 1 m but may reach maximum length of 1.8 m (male). 7. The behavior of milkfish is still one of the areas that has yet to be extensively studied. Large schools of milkfish have been seen in near shore waters with well-developed reefs and in coastal lagoons, suggesting that they are social. Behavior of Milkfish 8. Distribution Milkfish occurs near coasts and islands in the tropical Indo-Pacific area and is largely centered around the Philippines and Indonesia. Their distribution coincides with coral reef areas where the water is warm (more than 20C), clear and shallow. Milkfish do not inhabit areas of the Pacific Ocean influenced by cold currents but they do occur in seas affected by warm ocean currents. 9. Growth The milkfish fry grow at a rate of 0.5 mm per day. 10. Using a line equation to estimate the age and growth of milkfish fry, it is estimated that shore-caught fry with a mean total length of 13.5 mm are about three weeks old from spawning while small ones of a mean total length of 10 mm are two weeks old. Growth rates of wild and pond-reared juvenile milkfish vary from 7.0 to 8.7 mm weekly. However, growth rates in ponds and in pens vary considerably depending on initial fish size, food, stocking density, climate, season, locality, water turnover rate, pond area and depth, pests and predators . 11. Reproduction There are no distinct morphological variations between milkfish of opposite sex, especially among sexually immature adults and juveniles. Sexually mature males possess only two openings. Virgin females maturing for the first time may also have two distinct pores in the anal region. milkfish reared in sea cages in the Philippines attain their first reproductive event at the age of five years. Tank and/or pond-reared milkfish attain their first maturational event at a later age (69 years). 12. Milkfish is a highly fecund species. Mature ovaries usually comprise around 1015% of the body weight of the spawner. Fecundity estimates of 0.3 to 1 million eggs per kg body weight have been reported. As in other fish species, the spawning cycle of milkfish is seasonal and varies in different localities. The length of the spawning season in various localities may be a consequence of elevated seawater surface temperatures. 13. Tolerance to Environmental ConditionThe success of milkfish as a cultured food fish species may be attributed to its ability to tolerate extremes of environmental conditions. These conditions include extremes of temperature, salinity, dissolved oxygen, ammonia, nitrite, crowding and starvation. Low temperature (23C) decreases survival, activity, food intake, and growth and development of milkfish fry and juveniles; high temperatures (up to 33C) have the opposite effect. Lethal temperatures for juveniles are 42.7C and 8.5C. 14. Tolerance of milkfish juveniles to low dissolved oxygen levels also varies with the size of the animal. Symptoms of asphyxiation are discernible at 1.4 ppm oxygen among 200 to 300 g fish; 50% mortality occurs at around 0.1 to 0.4 ppm at 31 to 34C. Seven day old larvae are most sensitive to salinity changes and handling stress, tolerating only levels within the range of 16 to 20 ppt. 21 day old milkfish fry can tolerate salinities within the range of 0 to 70 ppt. 15. Milkfish can tolerate high amount of ammonia level from 2o-21 ppm.(pond reared). Juvenile milkfish can also tolerate high levels of nitrite (freshwater: 12 ppm; brackish water: 675 ppm.. Milkfish fry and juveniles can tolerate crowded conditions. With just enough food for body maintenance, milkfish juveniles can be kept crowded and stunted in nursery ponds for several months. 16. The age and time of sexual maturity. The season of propagation. The place of propagation. The extent of parental care. 17. Breeders more than five years of age are preferred. They are expected to spawn readily one or two months after transport. Season bound spawner. Sexual Maturity Season of propagation Place of propagation Marine water system Passive Parental Care Parental Care 18. Artificial Propagation of Milkfish Artificial Propagation of Milkfish 19. Site Selection There must be ample supply of clean seawater and freshwater. Electricity must be available to run the life support systems in the hatchery such as air blowers and water pumps. The hatchery must be located within the convenient access to fry buyers. 20. a. Complete Hatchery is a milkfish hatchery complete with spawning tanks and breeders. Egg production is an integral part of the business operation. Land area requirement may exceed one hectare. Capital outlay and operational costs are higher than satellite hatcheries. Technical and management requirement is comprehensive. b. Satellite hatchery is a milkfish hatchery that procures eggs from a complete hatchery, do the hatching and larval rearing until the market fry stage of 18 to 21 days. They maybe newly built facilities or old prawn hatcheries converted into milkfish hatcheries. Types of Milkfish Hatcheries 21. Spawning Tanks A milkfish hatchery needs larval rearing tanks.A Larval Rearing Tank is Circular (2-3-meter diameter) canvas or concrete tanks (3-5-ton ca-pacity) with an airstone at the center may be used. Tanks of smaller volumes are preferred for easy management. Larval rearing tanks should be placed under a shade to protect the larvae from the glare and heat of direct sunlight and to deter growth of diatoms that contribute to poor water quality. The tank is provided with a sturdy net cover to keep the breeders from jumping out 22. Selection of Breeders Males are determined by the presence of milt oozing out of the urogenital pore. Females are determined by inserting a polyethylene cannula (0.85 mm) to the urogenital pore. Females are determined by the presence of spherical yolky oocytes. 23. Induced Spawning Milkfish egg maturation and ovulation do not occur under captive condition hormonal injection is necessary. To induce spawning, use the following hormones: SPH acetone dried pituitary gland homogenate of coho salmon prepared by the British Columbia Research Council at Vancouver, Canada; one gram of the powder contains 17.6 mg gonadotropin. HCG human chorionic gonadotropin, manufactured by Ayerst Laboratories, New York. 24. DF Durandron Forte "250", a long-acting androgen manufactured by N.V. Organon, Holland. This is an oily solution containing 30 mg testosterone propionate, 60 mg testosterone phenylpropionate, 60 mg testosterone isocaproate and 100 mg testosterone decanoate. Preparation of the injection Dissolved HCG using its accompanying diluent. The volume of the diluent to be used is determined by the desired concentration of HCG in the 3 ml injection. To avoid possible damage to the muscle tissue, it is recommended that not more than 3 ml of solution is used for injection. 25. The necessary amount of acetone dried pituitary gland is homogenized in this solution before it is finally administered. Intramuscular injection of gonadotropins. Injection is administered a few centimeters below the dorsal fin. 26. Induced Spawning of Female MilkfishOnly fish with eggs having an average diameter of at least 0.65 mm should be induced to spawn. Usually, 2 injections are needed to induce both captive and wild adult milkfish to spawn. For the first injection, give the fish a combination of 10 mg SPH/kg body weight + 1,000 IU HCG/kg body weight. For the second, 10 mg SPH/kg body weight + 2,000 IU HCG/kg body weight. The time enterval between injections is 9-12 hours both for wild and captive milkfish. 27. Male Milkfish One of the problems in the artificial fertilization of eggs has been viscous, non-dispersing milt of milkfish caught during the natural breeding season. This problem can be solved by injecting newly caught males that have viscous milt with 1 ml DF. A day after the injection, the viscous milt will become more fluid and copious and will disperse easily when mixed with seawater; moreover, the percentag