Biological and ecological characteristics of Vannabin shrimp and key points of culture technology
1 Biological and ecological characteristics
Litopenaeus vannamei , commonly known as Penaeus vannamei , belongs to the crustacean , decapods , shrimp family , shrimp genus , shrimp genus , shrimp subgenus , native to the Pacific coast of the Americas , southern Peru to Santora , Mexico , the most concentrated in Ecuador. P. vannabin has a thin carapace , a transparent body color , bluish-white or pale bluish grey , and no markings all over the body , but covered with tiny spots. The body is fusiform, long and high on the sides; the cephalothorax is shorter, 1/3 of the length of the abdomen; and the cephalothorax has liver spines and gill horns, and the liver is more obvious. The frontal horn is shorter and slightly curved, and its tip length is shorter than the 1st antennal stalk, and the lateral sulcus and frontal horn ridge are short and stop below the upper spine of the stomach. The 1st antennae has 2 hairs of approximately equal length, which are about 1/3 of the length of the shank of the 1st antennae, the outer whip is thicker than the inner whip, and the 2nd antennal whip is pink. The upper limbs of the 1st to 3rd pairs of stepping feet are very developed, and the 4th to 5th pairs of stepping feet have no upper limbs. The 4th to 6th segments of the abdomen have a dorsal ridge, the caudal segment has a central groove, but no marginal spines, and the outermost edge of the tail fan is banded red. Females are open and have no seminal vesicles. Vannabin shrimp has the advantages of large individual, fast growth, strong adaptability, low demand for feed protein, strong disease resistance, long survival time from water and suitable for long-distance transportation and sales; its meat is tender and delicious, rich in nutrition, and the meat yield is as high as 65%, which is one of the world's three excellent shrimp breeding species.
Vannabin shrimp is highly adaptable, and its natural habitat is a sericine seafloor with a water depth of 0 to 72 m. Hatchlings and juvenile shrimp of Vannas are feeding, growing and developing in estuarine areas near seawater where plankton bait is abundant or in softer lagoon sediments off the coast with large salinity fluctuations. When the vannabin shrimp body length reaches about 12 cm, the migration time of the large number of vannabin shrimp mainly occurs during the lowest tide period of each month, which often overlaps with the time of the full moon and the new moon. Under the conditions of artificial seed rearing and pond culture, Vannabin shrimp usually dive into the bottom of the pond during the day and are active frequently at night. It can grow in waters with salinity of 0.5 to 35 and can live in seawater, brackish water and freshwater, and the suitable salinity range for 2 to 7 cm juvenile shrimp is 2 to 78. It can survive in waters with a water temperature of 6 to 40 °C, with a growth water temperature of 15 to 38 °C and an optimal growth water temperature of 22 to 35 °C. The high temperature tolerance limit is 43.5 °C, which is poorly tolerated to low temperatures, and below 18 °C, the feeding of Vannabin shrimp is significantly reduced, and the side lying below 9 °C is lying on the water. Dissolved oxygen is above 5 mg/l, and the minimum amount of dissolved oxygen that can be tolerated is 1.2 mg/l. The adaptable ph is 7.0~8.5, and the ammonia nitrogen content requirements are low, which is an excellent shrimp species with high-density intensive culture.
2 Water treatment requirements in the early stage of aquaculture
[Jishan Huayao Toutiao] In the early stage of Prawn farming, natural seawater, sea crystal blended seawater or artificially modulated seawater should be used, and in some places, if underground brackish water and other water resources are used, they must be extracted half a month in advance and treated by quicklime, aeration and other measures. At the beginning of the cultivation of Vannabin shrimp, the water can be purified with bacterial toxicity 150~200 ml/666.67 m2 the whole pond can be sprinkled with detoxification, and the oxygenation can be stopped within 1 week after sprinkling, and the salinity of the breeding pond can be adjusted. 1 week after sprinkling, you can use Green Weibao or pond water treasure to neutralize the toxicity of bacterial toxicity, and then sprinkle fertilizer water in the whole pond after soaking 3 kg + green algae source 0.5 kg/666.67m2 after soaking for 12 h. Due to the fragility of the water ecological balance system in the early stage of Vannabin shrimp farming, it can be appropriately topdressed within the first 1 month to stabilize the water quality. Do not use organic fertilizers such as chicken manure, peanut cake meal and soybean meal, if not well controlled in the process of temperature rise, it is easy to cause eutrophication to lead to "pond turning" or excessive plankton reproduction and destroy the water balance. Do not simply apply a chemical fertilizer to avoid the occurrence of red tides due to the multiplication of large numbers of harmful algae such as cyanobacteria. In order to maintain the ecological balance and water color stability of the pond, the live fungus king is often sprinkled to induce the pond to produce a balanced and stable bacterial phase and algae phase. Frequent opening of greenhouses helps to ventilate and oxygenate the aquaculture water body, while providing a sufficient carbon source for the algae of the aquaculture water body, helping the organic matter in the pond to provide nutrition for the algae, and promoting the absorption of toxic substances such as ammonia nitrogen, nitros nitros nitrogen and hydrogen sulfide in the aquaculture water. Shrimp pond phytoplankton grow and multiply gradually, and the water color reaches white turbidity. Frequent determination of various water quality indicators, the pH value is maintained at 7.5 ~ 8.5, the transparency is maintained at 30 ~ 40 cm, if the transparency is too low, it can be appropriately fertilizer water topdressing, such as the transparency is too high, some new water can be injected appropriately; at the same time, the dissolved oxygen is maintained above 5mg/l, the ammonia nitrogen is less than 0.1 mg/l, and the nitrite is less than 0.05mg/l.
3 Purchase and stocking of shrimp fry
Vannabin shrimp can be stocked in whole ponds or half a month after the pond angle is marked. The method of thick angle marker is to enclose a small pond with an area of 333.34~1 333.34 m2 in the corner of the pond through the purse seine, with a water depth of 1 m, and through salinity and water quality control, the breeding conditions in the small pond are closer to the conditions of the large pond, and the environmental stimulation when the whole pond is released is reduced. Select shrimp fry with a size of about 1 cm, transparent body color, smooth body surface and strong vitality, and adjust the salinity and temperature of nursery seedlings so that they are similar to the salinity and temperature of the breeding pond. After the pond detoxification is about 10 days after testing the water for 24 h, the survival rate of shrimp fry should be more than 90%. 2 to 24 h before seed stocking, in order to reduce the impact of stress, enhance the adaptability of shrimp fry, and improve the survival rate of shrimp fry, it is possible to use high stability vitamin C, stress nin, suan and glucose and other whole pond spills. Turn off most of the aerators when releasing seedlings, and keep the aquaculture water body with a slow flow of water, which helps to reduce the stimulation of shrimp fry and promote the spread of shrimp fry. 50,000 to 70,000 shrimp seeds can be stocked at one time/ 666.67 m2, and then the oxygenation equipment can be turned on and the dissolved oxygen is maintained at more than 5 mg/l. Before releasing seedlings, it is best to pay close attention to weather changes, and it is best to carry out seedlings during the day when the water temperature is above 22 °C, to avoid releasing seedlings during the transition period of weather changes such as cold tide, rainy rain, and just warming, and also to avoid releasing seedlings at the peak of shrimp molting.
4 Factory breeding and feeding management
Water temperature, salinity, temperature, bait and density vary considerably as shrimp fry are transported from the nursery to the culture pond; Therefore, the early purse seine seeding and feeding of high-quality bait are the keys to ensuring the survival rate and success of shrimp farming. You can choose high-quality shrimp slices for seedling strengthening, and then add various nutrients and immune substances, such as growth promoters, immunogly polysaccharides and shrimp multidimensional, etc., add once a day, and add 20 to 30 days continuously. Feed high-quality shrimp compound feed, after the release of seedlings at a rate of 0.1 kg / 10,000 tails, adjust the amount of feeding every 5 d, the daily amount of bait does not exceed 3.5% of the weight of Vannabin shrimp, "rather less than more", "a small number of times", often check the bait table, to avoid excessive bait caused by the water quality becomes smelly, fattened and bad. Each pond is divided into 2 to 3 bait feeding stations, and the amount of bait is most suitable for 1.5 h of Vannabin shrimp to basically eat and 80% of shrimp to be full of stomach. Weather changes drastically, water changes, shrimp molting and hot days to feed less, do not feed, on the contrary, you can feed appropriately, regularly stop feeding 1 to 2 meals. The middle and late stages of farming are the rapid growth period of shrimp, because nutrition can not meet the needs of rapid growth, coupled with the deterioration of water quality, the peak period of shrimp incidence gradually comes, so the disease prevention and control of shrimp in the middle and late stages of breeding is very important. Various nutrients can be supplemented, such as shrimp multidimensional, Chinese herbal medicine, 1 to 2 times a day, for 5 days.
5 Common disease control in factory farming
Although the factory farming of Vannabin shrimp is efficient and environmentally friendly, there are still many problems that need to be solved. Especially in China, the factory culture of Vannabin shrimp is still in the exploration and primary stage, and there is still a certain gap between the level of biosecurity and developed countries, and disease prevention and treatment is still the top priority of vannabin shrimp factory culture. At present, viral diseases brought in by seedlings or water bodies include leukoplakia syndrome virus, infectious subcutaneous and hematopoietic tissue necrosis virus, etc. Such diseases are mainly prevented and prevent complications. Therefore, the disease detection of shrimp fry in the early stage and the early treatment of water for shrimp farming are particularly important. Vannabin shrimp factory breeding process often occurs in the diseases and enteritis, white stool, stealing death, etc., its infection and transmission routes are diverse, the current commonly used disease prevention methods include thorough disinfection of aquaculture water, supplementation of probiotic feed, feeding fermentation feed, the use of immune enhancers and safe antibacterial preparations.