The dark-shouldered Oriental Dolphin is a toxic migratory fish, but its delicious meat, high fat and protein content, rich in essential amino acids, vitamins and trace elements, therefore, quite popular with consumers. Since the success of the artificial breeding of the dark-skinned dolphins in 1991, this year the country has been able to produce nearly a million larvae, which will play an important role in promoting the breeding of dark-skinned Orientia. At present, China has carried out trials and trials on the breeding of dark-skinned eastern porpoises in individual provinces. Therefore, in some places, breeding of dark-skinned Oriental dolphins has also formed a certain scale. Hai'an, Jiangsu Province produces about 50 tons of dark-shouldered eastern dolphins annually, Changshu, Jiangsu Province produces about 10 tons of dark-skinned eastern dolphins annually, and Jiangsu Rudong produces about 10 tons of dark-shouldered eastern dolphins annually. It is estimated that 200-300 tons of dark-skinned eastern dolphins can be produced next year. In recent years, the author has learned a little about the process of breeding and artificial reproduction of Obsidian Oriental: I. Breeding of broodstock in marine pufferfish: Due to the influence of many factors such as the overfishing of broodstock and water pollution, the dark lines in the Yangtze River Oriental dolphins tend to be depleted. The price of broodstock caught in the Yangtze River estuary has soared to RMB 2,000-3,000/kg this year. Therefore, artificial breeding of brooded broodstock broodstock for artificial breeding is an urgent task. At present, individual units have used seawater to cultivate dark-lined eastern broodstock for artificial breeding. , And put into production. The exploration of artificial propagation using artificial seawater to cultivate broodstock is underway. On September 11, 1999, on September 20th, from Jiangsu Rudong, we purchased 52 batches of 3 yolks of obscure eastern guinea broodstock (3 in the air during transport) and 100 tails, with an average weight of 968 g and 784 g respectively. After three months of cultivation, its growth was good and the survival rate was 100%. On December 12, from Changshu, Jiangsu, another 100 instar broodstock was purchased. The average weight was 466 g, and the survival rate was 100%. The key technology for broodstock breeding is to control water quality, water temperature, and feed quality. Feed nutrition must meet the requirements of gonadal development of the dark-skinned Oriental dolphins; the water temperature for invertebrate rearing is controlled at 17°C to 20°C, due to the water temperature of the eastern Asian dolphins is 16 When the temperature was 18 °C, the food intake decreased obviously. The optimal growth temperature was 22 °C to 28 °C, and the optimum temperature was 25 °C to 26 °C. When the water temperature dropped to 11 °C, it began to stop eating. Water temperature should not be too high, otherwise it will cause premature sexual maturation in the spring. When the depth of pool water is 0.8 meters, the stocking density of broodstock is 1-2 fish per square meter, and the feed used for feeding is used for squid feed, which is suitable for mixed fish and mixed shrimp. Feeding once a day and in the afternoon, and setting up a feed station, the amount of feed is based on the amount of VE consumed in the evening. The broodstock breeding uses circulating filtration and vortex air pump oxygenation measures, requiring DO above 5mg/l, NH3-N≤2mg/l, NO2 to N≤0.2mg/l, and NH3-N exceeding 5mg/l. The poisonous effect of the river is obvious and it is worth noting. Second, artificial reproduction Artificial reproduction of the aphrodisiac used generally choose LRH-A2 or LRH-A3 better, due to the indirect role of the gland, therefore, can reduce the pro-fish mortality after oxytocin. After recultivation, broodstock will be used again in the following year. Through experiments, postpartum broodstock are reared in water bodies containing a certain degree of salinity, and the water temperature does not exceed 30%. In a dark environment, the survival rate is high and it is easy to die in an ordinary freshwater pond. Obsidian oriental dolphins are fish that grew up in seawater to gonadal development and maturation and then to rivers to spawn in freshwater. Therefore, in addition to spawning and hatching in freshwater, the juveniles are cultivated in low salinity, which is beneficial to solve the feed problems of fry and larvae, because the live baits such as phytoplankton, rotifers, and annual insects living in seawater are better than freshwater species. It is easy to cultivate and is conducive to the production of factory seedlings. After testing, newly hatched larvae can grow and develop at a salinity of 12 ,, which can also reduce the occurrence of larval diseases. 3. Fish Breeds The dark-lined larvae have been grown as young fish with a body length of 2-3 cm after more than 40 days of cultivation. In juvenile fish ponds, juveniles were raised in autumn until they reached a fish species weighing more than 50g in the fall. Fish breeding - generally using an area of ​​2000-3300 square meters (3-5 acres), the pool water depth of 1.5 meters or more is good, juvenile fish before the pond to do a thorough clearing pool and training cladocera type of work, so that Juveniles can get enough palatable natural feed after going down the pond and feed the cod feed on a fixed food table. The amount of fish fed every day is about 3% to 5% of the body weight of the fish, so it is advisable to eat it before the evening. Stocking density is 2-3 tails per square meter, so that in November, the large-sized fingerlings with a body weight of over 50g can be obtained. On the one hand, it can be used as a "fish" for sale. If the species is used for winter, it can reduce the occurrence of winter diseases, and can reach the commercial fish specifications of 0.4kg/over in the following year, shorten the breeding cycle and increase economic efficiency. 4. Overwintering of the dark-shouldered eastern dolphins. Because the dark-skinned eastern dolphins do not tolerate low temperatures, when the water temperature drops to 7°C, they will be frozen to death. At 16°C and 18°C, the food intake will drop significantly at the water temperature. Therefore, the dark-skinned eastern dolphins are generally Small overwintering in deeper waters of the ocean or lakes. Therefore, the artificial winter temperature of fish species is best controlled at 18 °C to 20 °C. In dense conditions, fish species are very susceptible to disease. In addition to the thorough decontamination of the water body in front of the fish species, the fish species must also be disinfected. The nets, tools and water supplies used for the operation must be disinfected so that the fish can grow in a good environment. In the same way, adding VE, Vc, etc. to the carp feed and properly mixing some fresh feeds can increase the fish's constitution and reduce the occurrence of diseases. Fifth, adult fish breeding ponds are moderate in size, about 4-5 acres, the best water depth is 2 meters, and the stocking density is 2-3 tails per square meter. Also, feed the catfish compound feed and a small amount of fresh live fish to avoid Fish kill each other. Oxygen generators should be used to prevent hypoxia. Appropriate amounts of VE and VC must be added to the feed. Furazolidone should be added to the feed regularly to prevent the occurrence of Enterobrachium enteritis disease. 6. Disease prevention and control The dark-backed Oriental dolphins have strong vitality, but they are also prone to disease during pond breeding and wintering in greenhouses. The common diseases are as follows: Bubble disease: hair growth occurs in juvenile rearing. The prevention and control method is to constantly change the water and increase the depth and fatness of the water when feeding. 2, small melon worms: juvenile fish and fingerlings often occur in the dense. Therapeutic method: In 5 ‰ original salt solution, and use a 0.1-0.3ppm, malachite green Quanchiposa. 3, bacterial enteritis: juvenile to adult fish feeding stage occurs. Treatment: In 5 phr of raw salt solution, sprinkle with 5 ppm furazolidone. Furazolidone is added regularly to the feed to prevent the occurrence of dark-lined Eastern enteritis. 4. Nutritional diseases: Due to incomplete nutrition of feeds. Therefore, in the feeding process, in addition to feeding compound feed, adding fresh fish, shrimp and VE and VC can prevent and control.
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