How to increase the yield of crayfish in crayfish culture

In recent years, artificial culture of crayfish has been started in many areas of our country, but the yield is very different, with a yield of 400 to 500 kg per mu and only a few dozen kg per mu. In order to improve the survival rate of culture and obtain high quality and high yield, we must master the following main technical measures.

1 reasonable culture density

Keeping a reasonable culture density can not only give full play to the productivity of the pond, but also improve the yield, specification and economic benefit of shrimp. If the one-sided pursuit of production and increase the density of culture, it will increase the difficulty of culture management, crayfish will also compete for survival space and kill each other. A large amount of residual bait and excrement produced by high-density culture will also corrupt the water quality, further reducing the living space of crayfish. The pond environment has a great influence on crayfish digging holes. Under the conditions of fertile water quality, more bottom silt and rich organic matter, the number of caves will decrease, which will also lead to crayfish killing each other. Generally speaking, the reasonable culture density of crayfish in ponds is as follows: 30,000 to 40,000 young shrimps per mu of water surface in spring (February to March); in summer (July to August), there are generally no young shrimp, but high quality crayfish parent shrimp, 20,25kg per mu of water surface, with a male-to-female ratio of 3 ∶ 1. In autumn (September to October), 30,000 to 50,000 young shrimps (10-12mm in body length) just left the mother body on the water surface per mu.

2 the stocking specifications should be basically the same.

When stocking crayfish, it should be noted that the stocking specifications can not be too different, otherwise large, medium and small specifications must be used for separate ponds. In the process of cultivation, we should also pay attention to the specifications of crayfish, if the sizes are different, there will be the phenomenon of prawns eating crayfish, resulting in a great reduction in the survival rate, affecting the improvement of aquaculture production.

3 bait correctly

The feeding of cultured crayfish is the key. Attention should be paid to the following five aspects: the type of feed, the palatability of the feed, the determination of the amount of feed, the feeding method and the feeding time. Crayfish are omnivores, which can be eaten by both animal and plant baits. Some animal feeds such as cereals, grass plant baits and live snails are usually fed in aquaculture production. Crayfish is more gluttonous, insufficient feeding not only affects the normal growth of crayfish, but also cannibalism, so it is necessary to ensure that crayfish can eat enough bait, and the bait is fresh. Excessive feeding or improper feeding methods will result in waste of bait and deterioration of water quality. Generally, the feeding amount is calculated according to the body weight of prawns. In the peak growing season (April-September), the feeding amount is 7%-8% of the body weight of shrimp, and 1%-3% of the body weight of shrimp in other seasons. During the actual feeding, the feeding amount should be flexibly adjusted according to the specific conditions, such as weather conditions, water quality, the number of aquatic animals and plants in the pond, the amount of remaining bait, etc. Crayfish have the habit of sleeping during the day and going out at night. They often come out at night to move and feed, and generally live in the grass and water during the day. Therefore, generally, about 20% of the total amount of bait fed at 9 ∶ 00 is about 70% 80% at 17 ∶ 00.

4 improve water quality in time

Natural crayfish often live in smelly ditches, and many farmers mistakenly think that crayfish have strong pollution resistance and can survive in poor water quality. In fact, poor water quality will reduce the physique and vitality of crayfish. In the process of crayfish culture, the transparency of the pond water should be kept at 3040 cm, the pH value is 7.5 to 8.5, and the dissolved oxygen is more than 3 mg / L. To this end, it is necessary to strengthen water quality management, often add new water, and sprinkle raw lime slurry regularly (every 15 to 20 days), with a dosage of 3 grams per cubic meter of water, in order to regulate the water quality, increase the content of ionic calcium in the water, and provide calcium needed for shrimp molting growth. Once the pool water is aged, it should be changed in time to keep the pool water "fat, alive, tender and cool" to promote crayfish molting growth in time. In the case of suitable water temperature and adequate bait, the general 60-90-day young shrimp can reach the commercial specification of about 20 grams per tail.

5 increase concealment

Crayfish are ferocious in nature and have strong habits of occupying land. When there are not enough caves and aquatic plants for them to hide or hide, the phenomenon of self-harm is extremely serious. Making use of crayfish's habit of living in caves, the establishment of artificial caves can effectively prevent crayfish from killing each other. Artificial caves can be built on slopes below the water level, with a diameter of 6cm and a depth of 15cm. Crayfish also have the habit of climbing aquatic plants. Planting or putting aquatic plants such as water peanuts, verticillium verticillata, hyacinth, Eichhornia crassipes and water lilies in culture ponds can not only provide shelter for crayfish, but also increase their living space and reduce killing each other. At the same time, aquatic plants can also be used as food for crayfish to reduce the consumption of artificial feed and save breeding costs.