1 Water and pond conditions
Wide water source, sufficient water, fresh water, no source of pollution, convenient drainage and irrigation, supporting power, and convenient transportation. The pond area is 30667-50667, the pool shape is rectangular, east-west, the length-to-width ratio is 4:1, long sunshine hours, large wind area, convenient operation and management; gentle slope, slope ratio of 1:3, soil quality that Clay loam is better. There is a "crab island" in the pool, which accounts for 30% of the area of ​​the pond. It is a quiet place where crabs can be found and eaten. The aquaculture pond is equipped with micropore aeration facilities and the power is 0.15kw/667.
2 Anti-escape facilities
Crabs climb very quickly and have a strong ability to escape. Therefore, anti-escape facilities should be built around crab ponds. The use of calcium-resistant plastic plates with strong anti-oxidation ability, embedded along the inside of the pool, the calcium-plastic composite plate is 60-70 high, buried in the soil 10-20 and compacted, higher than the ground 50-60, plate-to-plate reach The place should be tight, leaving no gaps. After the plate is punched, it is tightly fixed with a thin wire and slightly inclined into the pool. The corners are rounded. This kind of anti-escape facilities can resist large-scale storm attacks, and is currently a kind of anti-escape facilities widely used by crab farmers. In addition, on the outside of the Tanggu, 1.2-1.5m in height, buried in the ground at the bottom 10, surrounded by polyethylene nets fixed with wooden piles or bamboo piles, frogs, ducks and other predator organisms jump into the pool.
3 clear pond disinfection
After the winter dry ponds, the weeds in the ponds and silt in the bottom of the ponds were cleared and the ponds were reinforced. After 15-20 days of exposure, the whole pool was splashed with 150-200/667 quicklime and water. Lime clear pond can not only kill harmful organisms and various pathogens in the water, but also improve the bottom soil and increase the calcium content in the water and promote the growth and development of crabs.
4 Preparation before restocking
4.1 Planting aquatic plants
Planting aquatic plants is an important part of the crab breeding process and is an indispensable technical measure. In the crab breeding pond, compounded aquatic plants were planted. Elodea was planted on shallow slopes. Black algae and Vallisneria were planted in deep water, and some emergent plants, such as reeds and alfalfa, were planted on the beach. The water grass coverage rate was over 60%.
4.2 Water Injection and Fertilization
After fertilizing and cultivating bait organisms after planting, the general application of compound fertilizer is 50/667 and ammonium bicarbonate is 50/667; the best organic fertilizer with farmyard fertilizer is applied, and the application amount is about 1000/667, and the application is sufficient (farmer fertilizer effect is slow Long effect of fertilizer, no effect on the growth of crab).
4.3 Release screw
The snail has a low price and a wide range of sources. Live snail meat is delicious and is a natural feed for crabs. Putting snails in the crab culture ponds at the appropriate time to allow them to reproduce naturally will help reduce costs, increase production, and improve quality, so as to achieve the goal of ecologically efficient farming. Before and after Ching Ming Festival, put snails 200-250/667, let it grow and breed naturally, and provide animal foods for eating crabs. In August, it will make up one more investment and the amount will be around 100/667.
5 Crab species stocking
5.1 Crab quality
The quality requirements of crab species are: neat specifications, bright body surface, strong physique, complete appendages, crawling agility, no injuries, no disease, no attachments.
5.2 Sterilization of crab species
Before stocking, the crabs were placed in 3%-4% saline (without iodine) and sterilized for 3-5 minutes.
5.3 Specifications, Density, Time
Stocking specifications are 50-100/; stocking density is controlled at 500-600/667; stocking time is generally controlled at the end of February or early March, and it is also optional to stock in the winter of the previous year.
5.4 Stocking Methods
In aquaculture ponds, the pre-designated breeding area is one-fifth that of Datang, and the crab species are put into it for intensive cultivation. When the ponds in Datang grow to account for 50% of the entire pond surface, the snails have already been propagated in a certain amount. Then put it into the pond for feeding. When the crabs are stocked, the water level is controlled at 50, and when the weather is warm and sunny, the water temperature is high, and the water is used, the action is brisk, so as to ensure the survival rate.
6 Feeding
Crabs are omnivorous, common plant foods are plants, wheat, corn, bean cakes, bran, etc.; animal feeds are snails, oysters, clams, fish, shrimp, etc.; in addition to natural and artificial bait, there is full price cooperation Food. The feed should be scientific and reasonable. In the breeding process, scientific feeding should be carried out according to the nutrition and the requirements for the bait size at different stages of the crabs, and the main ingredients should be fed. Daily feeding amount is controlled at 2%-5%. From mid-March to mid-June, feeding time gradually transitioned from 7 o'clock in the morning to 6 o'clock in the morning. In the morning, the amount of bait was controlled at 30% of the whole day and 70% at night. In March-April, crabs lived in the breeding area, and the scope for feeding water grass and snails was small and their amount was small. The amount of feeding should be sufficient. From May to June, aquatic weeds generally cover the entire surface of the pond, and snails have also been propagated to a certain number. The crabs can be put into ponds for culture, and the feeding of ingredients is appropriately controlled. In the high-temperature season of July-August, some animal feeds will be added to the crabs. The specific amount of feeding should be within 1-2 hours after feeding.
7 Water Quality Management
The crabs have high quality requirements for the water environment. Fresh water is good for the growth and shelling of crabs, and also increases the taste of crabs. If the pond is acidic, it is not conducive to the absorption of calcium by crabs and is not conducive to shelling. Therefore, water quality management is an important part of the entire crab breeding process and must be properly regulated.
7.1 Water Quality Regulation
In order to keep the water quality “new, live, tender, and coolâ€, the dissolved oxygen in the crab pond water quality reaches 5mg/l, the transparency is more than 40cm, and the PH value is 7.5 or so. The specific practice is to change the water for 5-7d once, and the water change amount is for the whole pool. About 1/4; high temperature season 2-3d water injection 1, especially in the crab shell phase, it is necessary to frequently inject water to promote normal crab shell growth; can also be used photosynthetic bacteria, Bacillus subtilis and other microorganisms to absorb water and toxic substances Hydrogen sulfide, ammonium salt, etc.; The use of bottom modifier, improve bottom sludge, decomposition of hydrogen sulfide, ammonia and other harmful substances in the sludge, in order to improve dissolved oxygen, stabilize PH value, increase the immunity of crab body.
7.2 Water Level Regulation
Water level regulation can be based on the determination of water temperature. In accordance with the principle of "super shallow, medium deep, and stable", water level regulation is carried out in three stages. From March to August, water depth is controlled from 50-60, and from June to August, it is controlled at 1.2-1.5m (appropriate deepening of water level in high temperature season), and it is stable at 1.0-1.2m from September to October.
7.3 Oxygenation measures
The main measures to increase dissolved oxygen in crab ponds are to use micropore oxygenation and sprinkling of particulate oxygen, especially from mid-July to mid-August. In hot weather, the amount of dissolved oxygen in crab ponds is relatively low. Special attention should be paid to oxygenation. The use of microporous oxygenation should be based on the situation of crab ponds and weather changes. From May to June, when the water quality and the weather are not suitable, it needs to increase oxygen in a timely manner. After June, it will increase oxygen at 12:00-15:00 on a sunny day. Oxygen in the morning depending on the actual situation, the rainy days should be turned on in advance of oxygen; 9 to 10 months, because the crab pond water quality is more fat, hot weather should be more boot oxygen. The length of time when the system is turned on and turned on should be flexibly controlled according to the weather, crab activities, and oxygen load. When oxygen-free equipment or oxygen-increasing equipment fails, the oxygen in the crab pond can be increased by using a method for removing the particulate oxygen.
8 Shell Management
Crab oyster shell is an inherent characteristic of its physiology and it is an important symbol of the growth, development and metamorphosis of crab. It can be said that in the life cycle of the crab, the more times its oyster shells grow, the faster the growth gains. The crab shell is a "reborn" process. The sturdy crabs can be completed within 5-10 minutes, while the weak ones require about 1 hour. When crabs in shells are the weakest, they are also the most dangerous period to attack by pathogens, enemies, and even the same kind. Therefore, we must pay attention to the rules of crab shells in the daily management work. It is better to take one week before the crab shells. Change the water disinfection measures to ensure that the crabs are shelled. It is worth noting that in the case of sufficient feed, the number of crab shells increases accordingly and the growth rate increases accordingly.
9 Disease Prevention and Control
The crabs have strong resistance to diseases in the natural environment. However, in the case of artificial breeding, due to the large stocking density, the limited range of activities, and the drawbacks of feeding and management methods, it is easy to cause diseases. Disease prevention and control of crabs is mainly controlled through drug prevention and treatment measures. Generally every 15-20d, with lime 10-15/667 add water to prepare a solution and then spilled once Quanchiposa, not only play a role in disinfection and disease prevention, but also to supplement the calcium required for crab growth. Regularly add Chinese herbal medicine, photosynthetic bacteria, immune polysaccharides, vitamins, and other drugs to the feed to make bait feeding, in order to enhance the crab body, improve crab body resistance, reduce the incidence of disease.
10 Crab fishing
10.1 Fishing time
When the proportion of mature crabs in the gonads accounts for 80% of crabs, it is generally better to start fishing in the middle or late October.
10.2 Fishing methods
One is to set cages, crab cages and other tools in the pond to capture. This is also a method commonly used by farmers to catch crabs; the second is to use nighttime water to drain at night and use the habit of migrating crabs to catch fish at the outlet. The third is to use the habit of crawling crabs to go ashore at night after discharging the pool water. When the river crab climbs to the side of escape prevention (net), it uses artificial freehand to capture.
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