Key technical points for overwintering storage of river crabs: these methods you need to master

River crabs are generally caught and brought to market in a concentrated period from early October to the end of November each year, so the volume is large and the price is low, and farming profits are not high. Overwintering storage of river crabs helps stagger the peak marketing season, raise the market price of river crabs, and thereby achieve the best economic benefits.

1. Pond requirements: area of 5-10 mu, pond water level maintained above 1.5 m, good water source, convenient water intake and drainage, pond dikes that do not leak, dike surface width of 2-3 m, and bottom mud below 15 cm. Ten days before the river crabs are put into the pond, clear the pond with quicklime, and after 7 days add water and stock. Before adult crabs are put into the pond, divide them into ponds for storage.

2. Quality and quantity requirements: river crabs for storage need to be disease-free and injury-free, with complete appendages and strong vitality, individual size around 120 g, stored at 500-600 kg per mu, and aquatic plants such as alligator weed and Hydrilla verticillata as well as an appropriate amount of river snails need to be placed in the pond to keep the river crabs from losing condition during storage.

3. Feed feeding: choose bait according to local conditions, such as melons and fruits, vegetables, soybean cake, aquatic plants, cooked sweet potato strips, wheat grains, and chopped small fish and shrimp, silkworm pupae, and scraps from livestock and poultry processing plants, etc. Feed animal and plant baits in combination, mainly animal feed and supplemented by plant feed, of which animal feed accounts for 60%-70% of the total feed. When the water temperature is above 10°C, the daily feeding amount is about 10% of the river crab's weight, fed in two portions: in the morning feed 30%-40% of the total daily amount, and in the afternoon feed 60%-70%. When the water temperature is below 10°C, reduce the feeding amount by 3%-5%, until feeding stops during hibernation.

4. Water quality management: river crabs like a fresh water environment, with transparency of about 40 cm, pH between 7.5-8.5, and dissolved oxygen maintained at 5 mg/L. During storage, a certain water level should be maintained, and the pond water depth should gradually increase as the air temperature decreases. In order to ensure that the pond bottom maintains a relatively high water temperature in severe cold weather, the water depth should not be less than 1.5 m. Water should be changed frequently. When the water temperature exceeds 10°C, one third of the pond water should be changed every 7-10 days (large ponds) or 3-5 days (small ponds). When a large area of the water surface freezes, break the ice to increase oxygen. Small ponds should be aerated frequently.

5. Pond patrol inspection: first, check water color and water level. Maintain good water quality and sufficient dissolved oxygen; second, check activity conditions. Feed an appropriate amount to ensure they eat well and are full, and promptly remove spoiled leftover bait to keep the water fresh.