Techniques of artificial propagation of cultured herring

Black carp is an excellent breed of freshwater culture in China. It uses benthos as bait, grows fast, has large body, tender meat, beautiful taste, high fat, protein and vitamin content, and is valued by the masses and professional farmers. The demand for fry is increasing day by day, and the prospect of artificial propagation of green fish is broad.

Breeding of green fingerling

The green fingerling bred by the author comes from the original seed of the Yangtze River waters. Select over 6 years old weight more than 15 kg, healthy physique, no damage, male and female according to the ratio of 1:1 for breeding. The cultivation pond covers an area of 3 mu to 7 mu, the water depth is more than 2 meters, the bottom of the pond is flat, the soil is loam, the herring seeds are cultivated in the grass herring pond, one to two herrings are cultivated in each mu, and the herrings are concentrated in a special pond for cultivation one month before spawning. Feeding fresh snails and clam meat mainly, and auxiliary feeding a small amount of cake and bean cake bait. To flush regularly, generally flush once a month in winter, flush once every 5 - 7 days after spring, flush once every 3 - 5 days for a month before labor, in order to promote the gonad development of green fish.

oxytocin

1. The spawning time is in the middle and late May, the water temperature is 22℃-30℃, and the best water temperature is 25℃.

2. The maturity of herring directly affects the effect of spawning. Herring should be selected strictly when spawning. Male fish selection criteria are light squeeze abdominal genital pores have semen outflow, warm water can spread out; female abdominal expansion, soft and elastic, abdominal scales are sparse for the better.

3. Type, dosage and injection of oxytocin. Common oxytocin drugs for herring include PG, pituitary gland, LRH-A, HCG, GTH, DOM and other oxytocin. Usually, a mixture of 3 - 4 drugs has a good effect on oxytocin. The dose of LRH-A 2 mg-5 mg/kg was given to female fish in the first injection, 8 h-12 h after the injection interval, and the second injection was given at the dose of LRH-A 10 mg-20 mg +PG2 mg-4 mg +HCG500 IU-1200 IU or DOM5 mg. Blended into a mixture and injected intraperitoneally. The dosage of male fish was 1/3-1/2 of female fish dosage. The effect time is 8 - 10 hours.

Estrus and artificial insemination

After the second injection of oxytocin, return the herring seed to the spawning pond. When the effect time is reached, artificial egg collection and fertilization are carried out in time when black carp is in estrus. The length of the benefit time varies with the temperature of the water. The water temperature is 25℃-28℃, and the benefit time is 8 hours-10 hours. At this time, we should carefully observe the estrus of herring: when the estrus time of herring arrives, catch herring and check herring with fish clips. At this time, if the female fish gently presses the abdomen, the eggs can flow out from the reproductive hole by themselves; if the male fish can squeeze out the semen and disperse quickly in warm water, artificial egg collection, sperm collection and artificial fertilization in dry water can be started; if the natural sperm eggs cannot be collected, the herring species can be put back into the spawning pool; waiting for the herring to come into estrus. The collected eggs and sperm should be mixed thoroughly to fertilize them. Avoid direct sunlight when doing artificial insemination.

After insemination, the fertilized eggs should be diluted quickly with water and placed into the loop for incubation. Before artificial insemination, personnel, tools, washbasins, nets, fish beds, brushes, etc. should be prepared. The personnel coordinate and cooperate well to make the movement light and agile, so as to avoid injury to the herring species.

loop incubation

Artificial collection of fertilized eggs, should be timely placed in the loop prepared in advance of the water incubation, honey per square meter does not exceed 1.2 million. The flow velocity in the loop should be appropriate. The flow rate of water in the early stage is about 17 cm/s, and the fertilized energy after expansion can be washed up and rolled to the surface. When the fry just out of the film, should strengthen management, prevent the eggs attached to the loop filter cloth, prevent water flow, so to increase the flow rate of water (30 cm/s), at the same time to prevent the fish sink or stick on the filter cloth suffocation death. After fry see waist point, should reduce water flow rate, avoid consuming fry physical strength. 8 hours after the waist point, fry can be sold on the box, fry can eat, feed four times a day, each time every 100,000 fry feed egg yolk, in order to enhance the fry physique.

disease Control

Before artificial reproduction, tools and drugs for spawning incubation should be prepared. Before artificial reproduction work is carried out, tools and drugs for spawning incubation should be prepared. At the same time, we should adhere to the principle of "prevention first, prevention is more important than cure", that is, microscopic examination. Such as the incidence of black carp fry, it can prescribe the right medicine, the disease, pests timely and thoroughly killed, thereby improving the survival rate of green fish fry.

In a word, the main experience is: first, cultivate the black carp well, promote the black carp gonad to reach good maturity; second, strictly select the black carp with qualified standard maturity; third, use efficient mixed oxytocin agent to induce labor; fourth, use artificial insemination method to collect eggs for fertilization; fifth, strengthen incubation management to improve hatching emergence rate and fry survival rate.