To do a good job of wintering shrimp is a very important part of the aquaculture production process. The overwintering of the shrimp is divided into two species: wintering of the young shrimp and wintering of the broodstock. The wintering of juvenile shrimp refers to shrimp breeding in August and September. By December, shrimps that have not yet grown to commercial specifications will need to pass through the winter to be reserved for stocking shrimp species in March and April of the following year. The overwintering of broodstock refers to the selection of broodstock to be used for breeding in the next year from commodity shrimp, allowing it to safely pass winter and intensify cultivation to meet the requirements for spawning and reproduction. The technical measures for the overwintering of shrimp ponds are described below.
First, the selection of wintering ponds
Overwintering ponds should be selected in a relatively regular shape, sheltered from the sun, have an area of ​​1000 to 1,500 square meters, and a water depth of 1.5 meters or more. It requires sufficient water for the pond, good water quality, convenient drainage and irrigation, and less silt at the bottom of the pond. There are many plants and no pollution.
Second, the winter time of shrimp
The overwintering time of the shrimp is generally late in the South and is early in the North. It starts in December in the Yangtze River and ends in April of the following year. It ends in most areas north of the Yangtze River from November to the end of April of the following year. During the winter, shrimp are generally lurking in the grass and rarely move. Therefore, in the overwintering pond, aquatic plants such as water peanuts and water lilies, or willows, can be set to provide a good warm wintering environment for the shrimps. After the winter, the plants sink by frost and can serve as overwintering and warming places for shrimps. Generally, 200 kg of aquatic plants or 30 kg of willow will be placed in each pond.
Third, the release of shrimp
1. The choice of overwintering shrimp
Overwinter broodstock should be physically strong, large individuals, complete limbs, specifications, health and disease-free. General choice of broodstock body length in more than 5 cm, females should reach 200 ~ 500 / kg, males should reach 140 ~ 240 / kg, male to female ratio of 2:1 or 3:1. Overwintering prawns should be selected from September to December in September to December and have not grown to commercial specifications.
2. Wintering shrimp stocking
Before wintering, the shrimps must be kept strictly clear ponds before they are stocked, and when the ponds are irrigated into the ponds after the clear ponds, screens should be set up at the water inlets for strict filtration to prevent the entry of predator organisms. Then put in the spent water plants and finally re-enter the overwintering shrimp. Green shrimp must be weighed, counted, and operated with water. During the operation, the shrimp cannot be piled up. The time of leaving the water must not exceed 5 minutes, nor should the wind blow or expose the sun. The size of the stocked shrimp in the same pond should be the same size. Give yourself enough time. The time of the lower pond is generally at the end of October. When the water temperature drops to 10-15°C, it is selected to be sunny. After transporting the shrimp, one day after the cultivation, the dead shrimp was removed and placed in the pond.
3. Stocking density of overwintering shrimp
The stocking density of overwintering green shrimp is generally 15-25 kg of broodstock per mu, and 20-40 kg of larvae (2 000-3 000 tails/kg).
Fourth, winter management
1. Sticking to feeding
There is a clear seasonal change in the feeding intensity of the shrimp, which is mainly affected by the water temperature. When the water temperature falls below 8°C, it stops feeding and sneaked into the deep water area for winter. When the water temperature rises above 8°C, feeding begins. For this reason, during the entire wintering period of the shrimp, as long as the water temperature is above 8°C, it is necessary to insist on feeding in order to maintain its life and activities. The diet of shrimp should be plant-based. For example, shrimp eats rice, bran, bean cake, distiller's grains, etc., but it should be used with animal feeds, such as snails, small fish, fish meal, cocoons, etc. These are all delicious shrimps. After the above-mentioned several feeds are mixed in a certain proportion, the mixture is ground into a mortar, and a granular material with good stability in water or made of a binder is added. This will not only increase feed utilization, but also reduce water pollution. The bait should be selected for feeding on a sunny morning. The daily feed amount is about 3% of the shrimp body weight. The bait should be small and fine, not too much.
2. Adhere to regular patrols
During the overwintering period of the shrimp, it is necessary to insist on regular inspections of the patrol ponds, mainly to check the overwintering conditions and changes in water quality of the shrimps, and to do a good job in prevention and control, escape prevention, and prevention of enemy damage. During the severe winter season, it is also necessary to prevent the water body from freezing. Once it is frozen, it must be broken or drilled in time to prevent it from suffocating.
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