In order to develop China's deep-water cage aquaculture industry, the Marine Science Research Institute of Zhejiang Ocean University conducted a seawater acclimation test of the hybrid quail in July 2002 to August 2002.
First, materials and methods
1. The test site condition test was conducted in an indoor cement tank of a factory farm in Gong County. A total of 6 cement pools were used, including 4 test pools and 2 seawater deployment pools. The test pool area is 50m2, water depth 0.4m. The farm can provide freshwater and sand filter seawater. During the test, the water temperature was controlled at 21 °C to 25 °C, the dissolved oxygen was 6 mg/L to 7.5 mg/L, the ammonia nitrogen was less than 0.2 mg/L, the pH was 7.8 to 8.2, and the freshwater pH was 7.8 . The test cell was disinfected with bleaching powder and the freshwater for culture was treated with 0.3ppm chlorine dioxide and 0.5ppm EDTA.
2. Test seedlings and transportation On July 7th, 10,000 hybrid seedlings were purchased from Huaiyin Institute of Fisheries Science, Jiangsu Province. The average length of the seedlings was 11.7cm, and the average weight was 6.5g, of which, the smallest individual had 9. 0 cm, weight 5.0 g; maximum individual 14.4 cm in total length and weight 10.0 g. The parent of the hybrid brood broodstock was Daurian in Heilongjiang, and the father of the broodstock in Heilongjiang was Heilongjiang.
Before transportation, the hybrid seedlings must be intensively trained by pulling nets, and feeds should be stopped for more than 24 hours. Then they should be packed with nylon film bags and filled with oxygen. Each box should have a packing density of about 100 (20L nylon film bags). Ice bags cool down. Insulated car transport, transport time of 16 hours, the survival rate of transport is almost 100%.
3. The seedlings of the stockings are transported to the destination, and the seedling bags are put into the test tank. After half an hour, when the temperature of the water in the seedling bags is close to the water temperature in the test pool, the bags are opened again. 2640 fish were reared in each test pond, with an average of 132 tails/m3.
4. After entering the pond, marine acclimatization seedlings should first be allowed to adapt to the environmental conditions of the test pool and be stabilized on the 2nd to the 3rd for domestication of seawater. Increase the salinity of the water body by 3‰ every 2 to 3 days, that is, adjust the salinity of the test pool water from freshwater to 25‰ or more within one month. In the process of seawater acclimation, when the transition from low salinity to high salinity, the acclimation time will be slightly longer, which will help improve the survival rate of domestication.
5. Feeding management (1) Baits Feeding Powders made from hybrid larvae and pelleted feeds are fed on-site to produce wet pellets on the same day. The amount of bait that occupies 3% to 5% of the fish body weight is fed 6 times a day, feeding once every 4 hours. Feeding time, fixed point, quantitative, and then according to the daily fish feeding conditions, appropriate adjustment of the amount of daily feeding.
(2) Water quality management The physicochemical factors such as water temperature, salinity, dissolved oxygen, pH, ammonia nitrogen, and nitrate are measured daily at 6:00 and 14:00, and records are made. The siphon method is used to remove the residual baits and feces from the bottom of the tank once a day to keep the water fresh. Changing water by 1/2 per day, the daily flow rate accounts for 1/3 to 2/3 of the aquaculture water body. The test tank was continuously inflated for 24 hours.
(3) Disease prevention In order to prevent the occurrence of fish diseases, regular disinfectants such as dichlorohydantoin must be used to disinfect the body of water. The dosage is 0.25 ppm.
(4) Biological determination A biological assay is performed every 10 days to measure the length and weight of the hybrid quail, in order to timely adjust the amount of feed to be fed and the amount of exchanged water in the pool.
(5) End of acclimation On August 12th, the salinity of the domestication of hybrid seawater has reached more than 25 ,. We will move the hybrid quail into deep-water cages in the sea area. Since hybrid crickets are lower-lying benthic fish, care must be taken to prevent them from being scratched during fishing.
Second, the test results After 36 days of domestication of seawater, the length of the largest individuals of hybrid crickets reached 35cm, weight 150g; average length of individual hybrid crickets was 25cm, weight 97g; before the acclimation of seawater, the average individual individual growth of 14cm, weight Increase 90.5g. During the domestication of seawater, 198 hybrids died, and the survival rate was 98%. Freshwater fish species hybrids can fully live and grow in seawater.
Third, discuss
1. For long-distance transportation of seed, it is necessary to stop the food for more than 24 hours before transport, and to carry out intensive training of the net, after the fish body emptying waste, in order to improve the survival rate of seed transportation.
2. The degree of increase in the salinity of seawater acclimation should be small, and the hybrids should be adapted to the environment to improve the survival rate of seawater acclimation.
3. When seawater is domesticated, care must be taken to avoid damage to the fish and cause fish disease.
First, materials and methods
1. The test site condition test was conducted in an indoor cement tank of a factory farm in Gong County. A total of 6 cement pools were used, including 4 test pools and 2 seawater deployment pools. The test pool area is 50m2, water depth 0.4m. The farm can provide freshwater and sand filter seawater. During the test, the water temperature was controlled at 21 °C to 25 °C, the dissolved oxygen was 6 mg/L to 7.5 mg/L, the ammonia nitrogen was less than 0.2 mg/L, the pH was 7.8 to 8.2, and the freshwater pH was 7.8 . The test cell was disinfected with bleaching powder and the freshwater for culture was treated with 0.3ppm chlorine dioxide and 0.5ppm EDTA.
2. Test seedlings and transportation On July 7th, 10,000 hybrid seedlings were purchased from Huaiyin Institute of Fisheries Science, Jiangsu Province. The average length of the seedlings was 11.7cm, and the average weight was 6.5g, of which, the smallest individual had 9. 0 cm, weight 5.0 g; maximum individual 14.4 cm in total length and weight 10.0 g. The parent of the hybrid brood broodstock was Daurian in Heilongjiang, and the father of the broodstock in Heilongjiang was Heilongjiang.
Before transportation, the hybrid seedlings must be intensively trained by pulling nets, and feeds should be stopped for more than 24 hours. Then they should be packed with nylon film bags and filled with oxygen. Each box should have a packing density of about 100 (20L nylon film bags). Ice bags cool down. Insulated car transport, transport time of 16 hours, the survival rate of transport is almost 100%.
3. The seedlings of the stockings are transported to the destination, and the seedling bags are put into the test tank. After half an hour, when the temperature of the water in the seedling bags is close to the water temperature in the test pool, the bags are opened again. 2640 fish were reared in each test pond, with an average of 132 tails/m3.
4. After entering the pond, marine acclimatization seedlings should first be allowed to adapt to the environmental conditions of the test pool and be stabilized on the 2nd to the 3rd for domestication of seawater. Increase the salinity of the water body by 3‰ every 2 to 3 days, that is, adjust the salinity of the test pool water from freshwater to 25‰ or more within one month. In the process of seawater acclimation, when the transition from low salinity to high salinity, the acclimation time will be slightly longer, which will help improve the survival rate of domestication.
5. Feeding management (1) Baits Feeding Powders made from hybrid larvae and pelleted feeds are fed on-site to produce wet pellets on the same day. The amount of bait that occupies 3% to 5% of the fish body weight is fed 6 times a day, feeding once every 4 hours. Feeding time, fixed point, quantitative, and then according to the daily fish feeding conditions, appropriate adjustment of the amount of daily feeding.
(2) Water quality management The physicochemical factors such as water temperature, salinity, dissolved oxygen, pH, ammonia nitrogen, and nitrate are measured daily at 6:00 and 14:00, and records are made. The siphon method is used to remove the residual baits and feces from the bottom of the tank once a day to keep the water fresh. Changing water by 1/2 per day, the daily flow rate accounts for 1/3 to 2/3 of the aquaculture water body. The test tank was continuously inflated for 24 hours.
(3) Disease prevention In order to prevent the occurrence of fish diseases, regular disinfectants such as dichlorohydantoin must be used to disinfect the body of water. The dosage is 0.25 ppm.
(4) Biological determination A biological assay is performed every 10 days to measure the length and weight of the hybrid quail, in order to timely adjust the amount of feed to be fed and the amount of exchanged water in the pool.
(5) End of acclimation On August 12th, the salinity of the domestication of hybrid seawater has reached more than 25 ,. We will move the hybrid quail into deep-water cages in the sea area. Since hybrid crickets are lower-lying benthic fish, care must be taken to prevent them from being scratched during fishing.
Second, the test results After 36 days of domestication of seawater, the length of the largest individuals of hybrid crickets reached 35cm, weight 150g; average length of individual hybrid crickets was 25cm, weight 97g; before the acclimation of seawater, the average individual individual growth of 14cm, weight Increase 90.5g. During the domestication of seawater, 198 hybrids died, and the survival rate was 98%. Freshwater fish species hybrids can fully live and grow in seawater.
Third, discuss
1. For long-distance transportation of seed, it is necessary to stop the food for more than 24 hours before transport, and to carry out intensive training of the net, after the fish body emptying waste, in order to improve the survival rate of seed transportation.
2. The degree of increase in the salinity of seawater acclimation should be small, and the hybrids should be adapted to the environment to improve the survival rate of seawater acclimation.
3. When seawater is domesticated, care must be taken to avoid damage to the fish and cause fish disease.
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