Eriocheir sinensis, the scientific name of Eriocheir sinensis, is a precious freshwater product with delicious taste, rich nutrition and high economic value. Eriocheir sinensis is a large crustacean belonging to the genus Eriocheir, which is divided into 2 1 node. Because the head and chest segments are mutually healed, the whole body is divided into two parts: head, chest and abdomen. Adult crabs have a dark green back and a gray belly. The average length of the head breastplate is 6-7 cm and the width is 7.5 cm.
Culture technology of river crab
(1) Breeding of Eriocheir sinensis
In order to improve the survival rate of young crabs and increase economic benefits, crabs should be raised first. At present, in order to make the big-eyed larvae reach the commercial crab, most of them adopt temporary rearing technology in plastic greenhouse. Choose one with good water quality and sufficient water resources; Note: ponds with convenient drainage, no water leakage, no water seepage and less silt should not be too large and the water depth should not exceed.
1.2m, with good east-west direction and abundant sunshine. The construction of greenhouse can refer to the construction method of agricultural vegetable greenhouse.
(2) Adult crab culture
Adult crabs like the clear and transparent water environment, rich in aquatic plants and rich in bait, which is most suitable for the growth of river crabs. At present, it is mostly cultivated in ponds, lakes, rivers and rice fields. Now give priority to with the pond for a brief introduction:
1, pond conditions
Clay, sandy soil or sub-sandy soil with sufficient water, convenient water intake and drainage, good water pollution and good ventilation are beneficial to the growth and reproduction of aquatic plants, benthic insects, snails and water worms. The old pond should be thoroughly dredged, the silt should not exceed 20cm, and the pond area should not be too small.
2. Transplant aquatic plants
The natural yield of Eriocheir sinensis mainly depends on the number of aquatic plants and benthic organisms (bait organisms) in the waters. In the process of aquaculture, it is an indispensable technical measure to plant aquatic plants well. Planting aquatic plants can not only feed crabs and supplement vitamins for ten days, but also support fighting and concealment, which is a powerful measure to improve the survival rate of river crabs in various periods. In addition, it can absorb harmful ammonia nitrogen, carbon dioxide and organic matter in the pool, release oxygen and stabilize water quality. 3. Escape prevention facilities
Escape prevention facilities mostly use plastic film, but also useful cement board, depending on their own situation. 4, pond cleaning and disinfection
Generally, the pond is disinfected with quicklime half a month before the seedlings are released, and the dosage is 75 kg per mu. On the one hand, it can kill pests, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in the water and promote the molting growth of Eriocheir sinensis. Fertilize in time after receiving water to cultivate algae and basic bait, and the transparency is generally maintained at 40-50 cm. If tadpoles or frog eggs are found, they should be taken out in time to avoid competing for food and hurting young crabs.
5, put the seedlings
Crab seedlings produced in the Yangtze River system are the best seed selection, requiring neat specifications, complete steps, strong physique, active crawling and no injuries.
Pay attention to the temperature difference density when releasing seedlings: at present, most of them are polyculture, especially fish, shrimp and crab polyculture, and the economic benefit will be higher. The density can be controlled within 1500 crabs/mu, and the specification is120-150 crabs/kg.
6. Daily management
(1) Feeding: The whole process of intensive culture in ponds mainly depends on artificial feeding, so the type and quality of feed have a great influence on the growth and development of river crabs. When feeding, we should adhere to the principle of reasonable combination of fine, green and coarse, with animal concentrate accounting for 40%, aquatic plants accounting for 35% and other plant feed accounting for 25%.
Like pond culture, the feeding method of river crabs is "four observations and four determinations", that is, watching seasons, weather, water quality and crab activities, timing, fixed point, qualitative and quantitative.
Look at the season: in spring, young crabs should be fed some live animal feed, and the amount of animal feed should be appropriately increased, but mainly plant feed. In the later stage, the river crab needs a lot of nutrition to meet the gonad development, so it should be fed with more animal feed to make it gain weight, with delicious meat, less activity and less food intake. It can be fed every other day, and it can be fed without water at 3-5 degrees Celsius.
Look at the weather: feed more in sunny days, less in rainy days, stop feeding when it is sultry and windy before showers, and feed in foggy days.
Look at the water quality: the water quality is clear, it can be fed normally, and the water quality is strong. Reduce the feeding appropriately and change the water in time.
Look at the activity of crabs: generally, they are eaten up the next morning after feeding, and the feeding amount is appropriate, indicating that crabs have a bad appetite or an excessive number. Therefore, it is necessary to analyze the reasons in time, reduce the feeding amount, and appropriately increase the feeding amount during molting.
Timing: Eriocheir sinensis has the habit of staying up late at night and going out for food at night. Feeding is carried out at 8: 00 and 9: 00 in the morning and in the afternoon and evening, and the feeding amount in the evening is 60-70% of the feeding amount in the whole day.
Fixed point: The feed to be fed should have fixed food, and the feed should be scattered on the feed table or on the slope near the shallow water level, so as to observe the feeding and activities of the river crab and increase or decrease the feed at any time.
Qualitative judgment: Eriocheir sinensis is sensitive to the taste of fragrance, sweetness, bitterness, saltiness and odor, and its feed must be fresh and palatable, and rich in protein.
Quantification: "If you don't eat fish for one day, it won't be bad for three days", so does the river crab. This requires that the feeding amount should be determined according to the size, density, different seasons, weather and activities of river crabs. Generally, the daily feeding amount is 8- 10% of the crab weight in the pond. If the feeding amount is small, it can only maintain life, and if it exceeds the timely range, it will also affect growth and increase feed coefficient.