How can crab farmers strengthen the nutrition of young crabs when the temperature drops suddenly?

Hello, this is Hua Fu talking about cars. Today, we will talk about river crab culture, hoping to help you.

With the gradual decline of temperature, the sales market of river crabs is becoming increasingly hot, and crab farmers are faced with two choices. One is to catch dry crabs as soon as possible, prepare ponds, and buy crabs and put them in ponds years ago; The second is to raise crabs, postpone sales time and wait for higher prices. Some farmers even raise crabs around the Spring Festival. No matter what marketing model or breeding plan, it is necessary to face the problems of crab damage and safe wintering in winter, especially the severe winter caused by El Ni? o phenomenon in recent years.

The core of overwintering management is diet nutrition, sediment and water quality management, disease control and so on. According to research and statistical observation, when the temperature is lower than 10℃, the crab basically does not eat and its activity is weakened. Eat a little when the water temperature is higher than 10℃, and you can basically eat normally when the water temperature rises above 16℃. However, the overwintering management of young crabs is still quite different from that of adult crabs. The following management suggestions are put forward for young crabs and adult crabs to overwinter.

First, overwintering management of young crabs

1.？ Disinfect the pond and prepare the water body before releasing the seedlings. After crabs are caught and put on the market, it is necessary to clean up the pond, remove miscellaneous fish and old crabs in the pond, and kill pathogenic organisms. Quicklime 150kg/ mu and tea seed cake 20k g/(μm water depth) can be used to disinfect and kill wild miscellaneous fish. If conditions permit, the whole pond can be turned over and sunned, so as to fully improve the bottom environment and lay a good foundation for aquaculture in the coming year. Before releasing the seedlings, appropriate operations such as cultivating algae and planting grass should be carried out when the temperature is appropriate, so as to create a good environment for stocking and wintering crab seedlings. Anti-stress products can be sprinkled in the pond two hours before the seedlings are released, so as to reduce the stress of river crabs entering the pond.

2.？ Choose high-quality crab seedlings. Priority is given to local high-quality crab seedlings or crab seedlings from reliable sources, because local crab seedlings are more suitable for local water quality and climate environment. Eliminate precocious crabs. It is required that the crab seedlings have ten complete limbs, clean shells, good color of hepatopancreas and clear food lines. If possible, crab seedlings can be fortified in autumn to accumulate enough nutrition for overwintering. Before or one week after seedling release, the crab body or crab pond can be disinfected with iodine preparation with appropriate concentration to avoid the introduction and breeding of germs. For crab seedlings purchased from Hunan and Hubei, it is more important to conduct a comprehensive investigation and identification of germplasm and quality.

3.？ Strengthen nutrition when the weather is suitable. The degree of nutrient accumulation and physique of crab seedlings after wintering is one of the key factors for the success of molting for the first time. Therefore, in early winter or early spring, when the water temperature is higher than 10℃, high-quality compound feed should be properly fed according to the activity of river crabs, and crab seedlings should be continuously enriched in low temperature seasons (such as feeding Australian crabs). Ensure that the river crab overwinters safely and shed its first shell smoothly.

4.？ Strictly prevent and control diseases. According to practical experience, the parasitism and algae attachment of crab ciliates are heavier in autumn and winter. Before overwintering, ciliates should be controlled at noon on sunny days 1 ~ 2 times, and attention should be paid to avoiding the peak period of molting of young crabs, and at the same time, the pond water should be disinfected regularly to improve the water quality.

5.？ Strengthen overwintering management. Keep the water level in the crab pond stable in winter and replenish fresh water in time. Measures such as artificial ice-breaking and water injection should be taken in time after snow or water surface freezes to prevent crab species from anoxia or freezing.

Second,? Overwintering management of adult crabs

1.？ Nutritional strengthening before overwintering. According to the development degree of Eriocheir sinensis, choose appropriate feed, strengthen nutrition before wintering, and ensure nutrition during wintering. For well-developed river crabs, coarse feed can be used to avoid excessive nutrient accumulation and paste explosion death; The immature Eriocheir sinensis should be fed with high-quality concentrate to ensure its gonadal development and hepatopancreatic nutrient accumulation.

2.？ Pay attention to the regulation of water quality and sediment. Eriocheir sinensis likes fresh water environment, and the water quality should be kept fresh. If possible, aquatic plants can be planted in the wintering pool of Eriocheir sinensis in advance. If you overwinter in the original pond, you should pay attention to improving the environment at the bottom of the pond, because after one year of cultivation, more organic matter and harmful substances will be deposited at the bottom of the pond, so you can strengthen the oxygenation at the bottom of the pond and use bottom-increasing products to improve the bottom of the pond.

3.？ Disease prevention and control. The parasitism and algae attachment of ciliates are serious in autumn and winter. Before overwintering, we should control ciliates 1 ~ 2 times at noon on sunny days to avoid the death of river crabs or affecting the market.

4.？ Daily management. Autumn and winter are the periods of breeding and migration of river crabs. Therefore, it is necessary to strengthen inspections during the wintering, pay attention to escape, and at the same time guard against theft and enemy injury.

5.？ Fishing and listing. According to the market price and the overwintering situation of river crabs, they are caught and listed in time. When the water temperature is low, the activity of river crabs can be enhanced by flushing, which is convenient for fishing.