The management of Penaeus sinensis aquaculture is divided into three stages: early stage, middle stage, and late stage. In the early days, 30-40 days after the stocking of the shrimp seedlings, the body length of the young shrimp is within 6 cm. At this stage, the shrimp seedlings enter the breeding pond from the nursery pond. Due to great changes in growth and ecological environment, the shrimp body is young, the range of activities is narrow, and the swimming feeding capacity is weak, and the ability to resist predators and diseases is poor. Therefore, it is not only necessary to have a good ecological condition, but also to formulate appropriate production technology measures to improve the survival rate of shrimp seedlings, accelerate growth, and lay a good foundation for future breeding.
First, develop a good basic food
By means of artificial fertilization, phytoplankton in water is propagated, and zooplankton and small benthic animals are also bred to meet the needs of shrimp for feeding. This is an important technical measure in the early stage of shrimp farming. Within 4 cm of juveniles, due to their limited ability to swim and feed, benthic diatoms, zooplankton and small benthic animals are essential feeds.
Second, control the water level
After the shrimp ponds have been exposed to sunlight, dredging, and disinfection, they can be poured into seawater. The water level varies depending on the season and climate. In early spring (2-3 months), the light is poor, and the water level can be controlled at 0.6-1.0 meters. In summer, especially during the summer season, the light is strong and the pool water should be deepened accordingly.
Third, rational fertilization
Fertilizer can be divided into organic fertilizer (animal husbandry fertilizer) and inorganic fertilizer (fertilizer). Lean-drained shrimp ponds have to be treated with organic fertilizers for a long period of time. In general, the shrimp ponds can be treated with more fertilizers, which saves time and effort. For example, the first application amount of livestock and poultry fertilizer is 200-300 kg (dry product) per mu; the amount of chemical fertilizer is 1.5-2 kg of urea and 0.5-0.6 kg of phosphate fertilizer, evenly thrown. Since then, depending on the changes in water color, fertilizer is applied once every 3-6 days, urea 1-2 kg each time, and phosphate 0.3-0.6 kg. The entire fertilization stage starts from about 10 days before the planting and ends about 25 days after the planting.
Fourth, physical and chemical factor control
During the cultivation of the basic bait, the pH of the pool water is maintained at 8.4-9.2, the transparency is 25-45 cm, and the water color is controlled in tea-brown or yellow-green. According to the basic bait culture situation, grasp the time for seedlings laying. After the first fertilization, the plankton began to multiply in the pool, and if the water was gradually yellow-green or dark brown, it could be planted. However, due to the influence of light and weather, the early spring time should be longer, generally 10-15 days. After the rain, light is relatively long and the water temperature is relatively high. Generally, the seedlings are released 7-10 days. For example, if the basic bait is too long (more than 30 days) to cause water quality deterioration, and the five-shrimp should be bred, the trichlorfon and tea gluten poisonous ponds should be re-used to continue the fertilization and cultivation basis until the drug disappears and then the seedlings are released. it is good.
Five, bait delivery
In the early 20 days after the shrimp was put into use, feeding was very important. Practice has shown that cultivating basic bait can increase the amount of biological feed in the pond, but its quantity is limited, and it cannot fully meet the needs of pond feeding. Therefore, in the early stage, you must feed bait, put the appropriate amount of fish, crustaceans and shellfish pulp or use these pulp to add steamed eggs into cakes, or fish meal, shrimp and other foods and other high-quality bait. At the time of delivery, it is necessary to pay attention to the freshness of the meat or cake to be placed, and use a 20-mesh sieve to filter the whole pool evenly. When the shrimp grows to more than 3 cm, it can be fed directly. The daily dosage should be increased or decreased according to the shade of water (which can reflect the plankton density). The general feeding amount is 2 times body weight. The number of servings per day depends on the size of the shrimp body, 1-2 times within 3 cm, and 3-4 times within 3-6 cm.
Six, pool water regulation
Doing a good job of regulating and managing pool water is a central part of the overall aquaculture management, especially in the early stages, it should be more meticulous and intensified. Within 25 days after release, the regulation of pool water should be based on the principle of “low water level, thicker color and less water changeâ€, and it is not suitable for large-scale irrigation. Put the water level of the pool water at 50-80 cm before putting the seedlings. Add 10 centimeters of fresh seawater when laying seedlings, and add water once every 3-5 days. Add water 10-20 centimeters at a time and the maximum water level is controlled at about 1 meter. After 25 days, a small amount of water was changed, and the amount of water changed every time was about 20%. About 30 days of breeding, juvenile shrimp 4-6 cm, should be replaced 8-10 mesh filter water, and gradually increase the amount of water. The water color is tea-brown or yellow-green, and the fertilizer is suitably top-dressed according to the change of water color. When the seedlings are released, the salinity of the shrimp and nursery ponds should be close to each other, and the salinity should be gradually controlled within the range of 12-16 ‰ (specific gravity 1.010-1.012) after the seedlings are released to prevent drastic changes in salinity.
Seven, check seedlings make up
In order to maintain a reasonable stocking density and scientific feeding, we must always check the number of shrimp seedlings and make timely replanting. The inspection may use a flashlight to illuminate the edge of the pool at night to observe the density of the shrimp seedlings, or to place 2-4 small larvae (one square metre each) on each representative area of ​​the prawn pond. In the net, the bait was used to attract the shrimp seedlings to feed. After 2-3 hours, the number of shrimp seedlings was counted. After repeated inspections, if no or very few shrimps are found, they must be replanted or replanted. The shrimp to be added should be selected to be robust and substantially the same as individuals in ponds and shrimps to facilitate uniform growth. In addition, it is necessary to regularly check the growth rate of juveniles, the body color of juveniles, the fullness of their stomachs, and the length of their bodies. Analyze whether the growth of juveniles is normal, so that effective measures can be taken to improve shrimps’ water temperature, water quality, and feeding. Normal growth.
Eight, pool shrimp shelling
Tea bran has fertilizer ponds, changes in water color, kills the shrimp surface, appendages, gills and shells, and promotes growth. In ponds with a salinity of 15 ‰ or more, the effect is even more pronounced. The tea bran can be used for the first time after 25 days of stocking, and then used once every 15 days with a concentration of 20-30 ppm. The application of tea bran should be selected in the morning during the tide, the pool water should be discharged to the lowest safe depth, then the crushing soaked tea bran Quanchiposa, sprinkled into the sea water after about 3 hours of application, the shrimp will be a lot of shelling the next day .
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