To raise crabs is to use the ecological environment of fresh water, abundant dissolved oxygen, and favorable growth in large water areas. Through engineering measures, a certain part of the water area is fenced up, and the basic principles and intensive culture techniques for pond cultivation are applied to the fence area. Inside, a new breed of crab technology is made available for high yields. Compared with crabs in ponds, this technology has superior breeding conditions, good water quality, high dissolved oxygen content, abundant live food such as aquatic weeds and snails, rapid growth of crabs, fewer diseases, low costs, high yields, and significant economic benefits. The characteristics are an important way to develop freshwater fisheries and increase the income of the people.
1 The choice of barrier water environment
Use large lakes, reservoirs, outcrops, rivers and other large water areas, choose a place where the water flow is gentle, sheltered from the wind, the water exploration is 1 to 2m, the bottom is flat, the yellow mud or mud bottom, the water quality is not polluted, and the water level is relatively stable.
2 Facilities for raising crabs
The shape of the water surface of the fence can be square, round or triangular. The area can range from several hundred square meters to tens of thousands of square meters. Generally small areas of 300 to 2000 m2 intensive cultivation is better. The lakes and the banks of the Kuwan River are blocked, and the river channels and the channels block the two sides, and the lake is open to the surrounding areas. In order to prevent the crabs from fleeing, two layers of blocks are required. The inner layer is made of polyethylene or nylon braided dense mesh, the mesh size is 0.8mm, and the iron bar at the lower end of the mesh is every 40 to 50cm and 30 to 40cm or Wooden sticks, embedded in the bottom mud 20 to 30cm deep, and then compacted to prevent crabs absconding. The upper edge of the net is 0.5 to 1m above the water surface. The net type is fixed by bamboo piles or stakes. Every 3 to 4m is drilled. The top of the pile is 1 to 1.5m above the water surface, and the upper end of the net is tied to the pile. on.
Outer blockers are usually made of 2 to 33 mesh polyethylene nets to form meshes with a mesh size of 0.5 to 2 cm. The mesh shrinkage factor is 0.75, the mesh height is 2 to 3 meters, and the upper and lower edges are tied to the rope. The next step is to sew the stone dragon and bury it in the mud for 30-40 cm to prevent escape. Shilong uses mesh mesh to form a cylinder with a diameter of 10 -15cm and a pebble or stone with a diameter of 3 to 4cm. The mesh is fixed and supported by bamboo piles. The pile height is 4m, buried in mud about 1m, and the pile spacing is 2-3m. The net is to be covered at the end of the block, and the width of the cover is 80 cm. The cover material and the size of the mesh are the same as those of the block. If you do not need to cover the net, you can also sew a 30cm wide Plastic Film on the inside of the bar to prevent escape. In order to make it easier for young crabs to inhabit holes and prevent mutual killings, piles of earth mounds or earthworms can be stacked inside the fences, and bamboo tubes, bricks, tiles and planted plants can be placed.
3 Stocking of crab seedlings
The crabs, frogs, crickets and all kinds of harmful aquatic insects in the enclosure should be fished before they are stocked. The stocking density of crab crab species is mainly related to the stocking specifications and the breeding cycle. Usually there are 160,000 crabs per kg, and the stocking capacity is 30,000-50,000 per 667m2; for example, the crab species with stocking specifications of 2-5g, each 667m2 It is more appropriate to stock 10,000 to 15,000. If the farming conditions are good, they can be put in more or less. Crabs are usually stocked for 4-5 months; crabs are stocked at the end of February and early March. Crabs are harvested in the fall season from October to November.
4 Feeding management
The feed used to fence crabs is mainly animal and plant feed. The animal feed consists of small trash fish, shrimp, silkworm cocoons, cockroaches, snail meat, carcasses, fish meal, blood meal, slaughterhouse waste, various animal carcasses, insects and their larvae, etc.; plant-based feeds mainly include aquatic grasses and floats. Ping, melons, cereals, cakes, bean dregs, bran, rice bran and so on. There is also artificial compound feed.
In the early period of feeding, crabs should be intensively fed. Generally, feeds such as fish gills, silkworm cocoons, pastes, bean pastes, and bran are fed once a day and in the afternoon, and they can be spilled directly in the enclosure. Each 10,000 crabs are fed with an average of 200-500 g per d According to the water temperature, water quality, weather conditions, and the feeding conditions of crabs, the increase and decrease will be flexible. With the growth of individual crabs, the amount of feeding will be gradually increased. When juvenile crabs are released, due to the lower water temperature, they do not eat basically, and they can be fed appropriately after the temperature of the water is gradually increased, and they are mainly fed with plant-based baits. Later, they are transferred to normal breeding baits. When crabs are reared for 1 to 3 months, when the shells are 1 to 3 cm in length, 100 to 500 fish of more than 10 cm in size can be reared per 667 m2 of the fence. After the crabs enter the young crab stage, they are usually fed with various aquatic plants, leaves, cooked wheat kernels, crushed animal ticks, snails, fish, etc. The bait is placed on the side of the soil piles, shallow water or aquatic plants, Feed once, and feed at 16 to 17 o'clock in the afternoon.
In addition to feeding, the focus of day-to-day management work is to prevent escape. Always check your crab facilities regularly for damage. If damage is found, repair and reinforce immediately. In particular, during the flood season, when the water level rises and windy weather, it is necessary to pay attention to timely inspections to prevent the nets from rushing to escape. The inner layer of crab seedlings is blocked due to small meshes, and the net cloth must be washed regularly to remove floating objects and weeds. If soft-shelled crabs are found, they should be kept in cages and kept in a cage. After the shells are hardened, they are put back into the circle.
Because the water inside the fence cannot be drained, crabs are usually caught using nets, nets, nets or crab trawls.
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