Sea trout artificial propagation technology
First, the breeding site conditions
The breeding season of catfish is in winter in China, and the water temperature required for reproduction is above 20°C. The salinity requirement is above 18°C, preferably around 30°C. Therefore, the breeding site of larvae must be selected in order to have a higher salinity, better water quality, and a good freshwater source. Convenient transportation and sufficient power are also prerequisites. Because the entire breeding and breeding process needs to be carried out under warming and warming conditions, geothermal water or factory hot water is more ideal and can save energy. Off-season equipment for existing prawn seedlings on the coast can also be used for artificial breeding of squid.
The seedling factory shall have the following facilities: broodstock holding pond and wintering pond, with an area of ​​10 to 20 square meters, water depth of 1.2 to 1.5 meters, spawning pond of 10 to 30 square meters, round and Draining and digging equipment; hatching loops and hatching cylinders, can be inflated and running water to hatch fertilized eggs; nursery ponds, each pool area is not less than 5 square meters, water depth 1.2 to 1.5 meters; live bait cultivation pond, as Artemia The hatching of eggs and the collection of cocklepods for holding ponds in the field can also be used in common with nursery ponds; In addition, it must also be equipped with water supply, gas supply, heating equipment and emergency substation facilities.
Second, the collection and breeding of broodstock
From the wild caught in the sea or the carp cultivated in the pond, fish ages of 3 years old and over 4 years old can be used as broodstock. Choose healthy, full-fledged, disease-free, and disease-free individuals with an individual weight of 1 kg or more. Efforts are made in dedicated pools. The stocking rate is from 100 kg to 150 kg per mu, and the feed containing 30% or more of crude protein is added to feed. The daily feed is fish weight. 5% to 8%. During the rearing period, the transparency of the pool water is maintained at about 35 cm, and the dissolved oxygen level is not less than 3 mg/l. It is often flushed with fresh water, flushed once every half-month, flushed once a week after September, and flushed with water each time. Deepen about 30 cm. The salinity of the pool water can be appropriately reduced to less than 10 在 before August, and it should be gradually increased to about 20 ç› after that.
Third, indoor breeding
When the outdoor water temperature drops below 15°C in late November, the broodstock should be moved into the pool and the water temperature should be controlled at about 17°C to promote the development of the gonads of the carp. By the end of November, the ovaries of females generally develop to large growth stages, and the diameter of oocytes has reached 450 microns or more. Male sperm have been formed and can be activated in brackish water and can be stocked in temperature-controlled holding pools. A temperature-controlled holding pool holds 1 brood fish per cubic meter of water. In order to prevent fish from infection due to operation, nitrofurazone should be added in a concentration of 110-6 in the pool water. An inflatable filter stone is provided in the holding pool for continuous inflation to maintain dissolved oxygen saturation. Salinity above 18 ,, the surface of the pool to maintain the natural photoperiod, the surface illuminance of the water is not less than 200Lx. During the holding period, it is appropriate to feed pellet feeds that are not easily discretized, and timely absorb and replace new water. When changing the water, care must be taken to avoid excessive changes in water temperature.
Fourth, artificial induced spawning
Beginning in late November, artificially induced oviposition can be performed on broodstock with oocytes above 630 microns. Commonly used hormones are LRH-A and salmon pituitary, which can be used alone or in combination. When used alone, the dosage per kilogram of fish is: LRH-A300 micrograms to 400 micrograms, salmon pituitary 15 milligrams to 20 milligrams. The dosage used when mixing: LRH-A nbsp150 micrograms + 10 milligrams of salmon pituitary. The females were given two intramuscular injections at intervals of 24 hours. The two injection doses were 1/3 and 2/3 of the total dose, respectively. Males that are well matured can either be injected with hormones or given a single injection at the time of the second injection of the female. The dose is half of the total female dose.
Hormone-treated male and female brooders were placed in the spawning pool. The physical and chemical conditions of the spawning pond should be similar to those of the broodstock holding pool. Keep flushing and raise the water temperature to 20°C～23°C. Male to female ratio 1:1.5. When the water temperature is 20 °C ~ 23 °C, the hormone effect time is generally 15 hours to 20 hours, overdue omission should be checked when the oocyte development, such as normal development, but the slow progress, the third injection of hormones The dose is the same as the second time. When artificial insemination is used, the broodstock is stocked in a water container with a volume of about 1 cubic meter, and aeration equipment is added. Females can be observed before labor: the abdomen is obviously enlarged and falls; the anus is protruding outwards, and the congestion is purple; the respiratory rate is increased more than 140 times per minute; white calcium-containing stool is discharged from the anus. At this time, spawning and insemination are performed immediately, and dry insemination is generally used. Mature eggs have about 3,000 grains per milliliter.
Five, fertilized eggs hatch
The hatching water salinity is 20‰28‰, and about 1500 fertilized eggs per liter of water. During incubation, the temperature is controlled between 17°C and 23°C. Avoid sudden temperature changes. During the incubation period, continuous inflation should be maintained, with dissolved oxygen above 4.5 mg/l. Change fresh water in time according to changes in water quality. The incubation time is about 40 hours to 60 hours. The fry is kept in the hatching container for 4 days, and it can be transplanted to the nursery pond after the swim.
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