In recent years, Nantong City, Jiangsu Province, in the process of the development of artificial breeding of squid, the development of all seedlings subject to introduction from outside has not developed quickly. To this end, in 2001, based on a small scale artificial breeding trial of squid, in 2002 the State Aquaculture Farm in Haimen City, Jiangsu Province undertook the implementation of the “Study on Artificial Breeding Technology of Squid†issued by the Science and Technology Bureau of Nantong City. The broodstock 15 groups produced 617,000 seedlings and bred about 72,200 seedlings of 2 cm in diameter. The relevant technology is introduced as follows:
First, broodstock fish breeding broodstock cultivation pool, an area of ​​2 acres, stocking broodstock 16 groups, of which 12 groups for the 1999 and 2000 introduced seedlings from Guangdong to cultivate, 4 groups are captured from the wild outside the wild trout. The broodstock is fed with bonito, salmon, and white bream as bait fish. Starting from May 18, we will start flushing and flush water once a day for 1 hour each time.
Second, brooding fish production
1. The time of oxytocin production began from May 28th in three batches of broiler production, the first batch of oxytocin on the 28th, and oxytocin 4 groups; the second batch of oxytocin production on the 30th, and oxytocin production in 5 groups; The temperature of the first batch of urine production was about 25.1°C, the temperature of the second batch was 23.3°C, and the third batch of water was 22°C. The first batch of female hens had an average body weight of 2.28 kg, males had an average body weight of 2.3 kg, the second batch of female hens had an average body weight of 2.26 kg, males had an average body weight of 2.06 kg, and the third batch of hens had an average body weight of 2.12 kg. The average weight of fish is 2.11kg.
2. Identification of male and female broodstock First look at the reproductive process, the female has two openings in the reproductive process, the genital hole in the middle of the reproductive process, urine opening in the top of the reproductive process, the male is the puerperal and urine holes coincide Venthole, opening at the top of the reproductive process. In the case of unclear identification of the above-mentioned appearance characteristics, the jaws of the broodstock are rounded at the front end, and are not more than the upper jaw. The male jaw has a pointed shape at the front end of the mandible, which is much larger than the upper jaw.
3. Injecting the oxytocicides we used lrh-a2, hcg oxytocin, the dose of female lrh-a213.3ug/lg+hccl333iu/kg, the male fish halved. The first batch of oxytocin production time is from 18:00 to 18:45, the second batch of oxytocin production time is from 15:00 to 15:40, and the third batch of oxytocin production time is from 15:00 to 15:50, using one injection method.
Third, after the spawning of the broodstock a group of a cylinder, direct water stimulation in the incubation tank, at 22 °C ~ 26 °C water temperature, after 26 hours ~ 30 hours squid began to heat. Each group of batches stays in its own production, and the rest uses dry artificial insemination. Considering that the water stimulating in the hatching tank, the chasing situation of the broodstock when the estrus is not easy to be found, so after 25 hours of injecting oxytocic agents, the broodstock was removed every half hour to observe the development of gonadal. After broaching the broodstock, place the female abdomen upwards and gently press the abdomen with the granules out. Then, grab the genital hole, clean the water on the body surface of the fish, then turn the belly down and squeeze the egg into the pre-cleaned. In the porcelain basin, male semen is added at the same time and stirred with feathers for 1 minute to 2 minutes so that the eggs are fully mixed, then a small amount of fresh water is added, and the mixture is stirred again. After standing for 1 minute, it is incubated in an incubation tank.
Oxygen production condition Batch date Water temperature Oxygen production group Spawning group Number of cohorts Egg production (10 thousand grains) Effect time (hours)
1 4.28 25.3 4 4 100 32 26
2 4.30 22 5 5 100 24.6 30
3 5.01 24 6 6 100 28 28
IV. Incubation of Fertilized Eggs After spawning, the fertilized eggs are placed in an incubation tank for incubation. The volume of each cylinder is 0.14 m3, and the fertilized eggs range from 60,000 to 140,000 grains. The water temperature is 22°C～26. When the flow rate was 11.9 l/min at °C, the fertilized eggs passed through the membrane for 39 to 48 hours.
Incubation condition Batch number of eggs laid (10,000 grains) Fertility rate Fertilized eggs Emergence (10, 000) Hatching rate
1 32 87 27.84 22 79.1
2 24.6 94.6 23.2 19 81.9
3 28 91 25.48 20.7 81.3
V. Supply of bait fish and cultivation of summer flowers From the third day after the first batch of squid was produced, we used 10 batches of squid per day as the bait fish after opening the squid fry, and a total of 8 batches of squid were elicited. Due to the absence of broodstock, three groups of white oysters were used to feed bait fish. At a water temperature of 23.1°C to 26.2°C, the yolk sac was completely absorbed from the trout seedlings from 92 to 106 hours after they were released from the film and began to turn into an exogenous nutrition phase. When the eel seedlings are filmed for hours, we put the eel fry about 24 hours into the fish tank as a bait. Then we regularly observe the density of the bait fish and timely feed the fish so that the density of the bait fish stays at the eel. 4 to 8 times of fry. After the opening of the carp fry, the flow rate of the hatching tank is gradually reduced, the physical energy consumption of the fry is reduced, and the density of the fry is gradually diluted and cultivated.
VI. Disease Prevention
1. After progeny treatment of broodstock, the broodstock disinfects the wound with potassium permanganate after spawning. A streak of streptomycin is given to each broodstock at a dose of 1500 iu/kg. The post-partum broodstock continue to rest in the hatching tank for 2 days, and then put back. The pond is then disinfected with potassium permanganate before putting it back into the pond to prevent infection. 2. Treatment of Fertilized Eggs Incubate the disinfectant in the incubator to prevent watery mildew.
3. Disease prevention and control measures for fry The first batch of fry began to eat from 92 to 106 hours after the film was released. On the second day after the start of eating, we found that there were worms on the carp fry. We used copper sulphate and ferrous sulfate mixture (5:2) ) 1.2ppm all-cylinder spilled, and stop the water for 50 minutes to prevent and cure, once a day, once in a row 5 times, then use 0.7ppm dose once a day, pest control effect is better. Before the second and third batch of carp seedlings found worms, the use of copper sulfate, copper sulfate mixture 0.7ppm Quanchiposa, 45 minutes to stop the water prevention method, every other day, the effect is very good.
VII. Discussion
1. After 20 days of cultivation, the carp seedlings grow to about 2cm. From June 20th onwards, the carp seedlings were cultured in batches of ponds. After counting, a total of 72,200 carp seedlings were cultivated for about 2cm. The survival rate of seedlings was 11.76%. . In addition to the death of one of the brooded broodstock fishes due to injury, the rest of the broodstock recovered well.
2. The priming time should be advanced. This year, our artificial breeding of eels began only after the artificial reproduction of the four major species of fish began. Therefore, there was a case where the bait fish could not keep up in the late stage of the breeding. Therefore, in the future, artificial breeding of squid should take measures in the breeding of broodstock so that it can be artificially propagated 15 to 20 days in advance, alternating with the artificial breeding of the four major species.
3. No special measures have been taken to filter the hatching water of this year's carp fertilized eggs, resulting in a large density of large blisters in the hatching tank, which has a certain impact on hatching. In the future, artificial breeding of catfish should be carried out using 60-mesh sieve in the original facilities. Filtration facilities.
4. The use of disulfide compounds. During the treatment of trichoderma in the first batch of carp fry, we used disulfide cocktail too frequently, resulting in impaired function of the first carp fry and hypoxia symptoms. The survival rate of the seed was low, only 3.2%. . Therefore, the use of disulfide should be controlled within 2 days to 3 days. (Yang Jie, Zhang Libing, Yang Zhengbing, Zhang Jie, Jiang Zuofang)
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