What are the technical points of "63 1" high-efficiency ecological culture mode in crab pond?

Jintan City, Jiangsu Province, discussed the reasonable collocation technology of various river crab culture ponds, and successfully put forward the "63 1" pond high-efficiency ecological culture mode, that is, the river crab is the main species, and other aquatic products such as freshwater shrimp, mandarin fish, crested erythroculter, allogynogenetic crucian carp, bighead carp and silver carp are scientifically collocated to achieve 60 kg per mu.

(1) culture conditions

① Site selection: The aquaculture pond is required to be close to the water source, with convenient water intake and drainage, sufficient water source, fresh and pollution-free, in line with the national fishery water standard, and no pollution source in the adjacent area. It also requires convenient transportation and guaranteed power supply.

(2) Pond reconstruction: The aquaculture pond is dominated by the beach surface, and the water in the pond is shallow. There should be crab ditches in the pond, hidden objects on the beach surface, covering an area of 20 ~ 30 mu, the depth of the pond is about 1.5m, the slope ratio is 1: 3, and 5cm silt is left at the bottom of the pond.

③ Drainage and irrigation facilities: It is required that the drainage and irrigation facilities in the crab pond are perfect and the water in the pond can be drained. If the water in the pond cannot be drained, it will bring inconvenience to crab fishing and pond drying in the later period. The entrance and exit shall be fastened with wire mesh and protected with arc escape net.

④ Anti-escape facilities: Anti-escape materials require smooth surface, which makes it difficult for river crabs to climb, and are durable, aging-resistant, widely available, simple in construction and convenient in maintenance. Usually, calcium plastic plates or escape prevention nets are used as escape prevention facilities.

(2) Preparation before stocking

① Cleaning and disinfection of pond: drain pond water in winter, freeze-dry for 1 month, and remove excess sludge. After cleaning the pond, inject 10 ~ 20cm of water, sprinkle 150 ~ 200kg of quicklime or 2kg of tea polyphenols per mu (soak in 40kg of 2.5% salt solution for 2 hours), turn over the bottom mud the next day, soak in the water for 2 ~ 3 days, then empty the pond water, rinse and rinse the pond twice.

(2) Planting aquatic plants: After 7 days of pond disinfection, apply 50 ~ 100 kg of bio-organic fertilizer per mu to improve water quality. Aquatic plants are planted with compound aquatic plants. The whole pond is dominated by Elodea, which is cut off and planted in sections. Other submerged plants such as black algae and Sophora alopecuroides are planted in the middle of Elodea, and the coverage rate of aquatic plants in the whole pond is maintained at about 50%.

(3) Setting up a temporary culture area: a circular or rectangular temporary culture area of river crabs is enclosed by a net, and an escape-preventing film is attached to the net, which accounts for about 20% of the water surface of the pool and is used for temporarily raising crab species.

④ Transplanting snails: Before and after Tomb-Sweeping Day, 200 ~ 250kg of high-quality live snails were put into each mu. In July and August, the snail increase per mu 150 ~ 200 kg.

(3) stocking mode

Rational allocation, scientific polyculture and interplanting of varieties with different niches are effective ways to realize ecologically efficient culture in crab ponds. The main requirements and practices are:

① Stocking self-bred crab species: Reasonable stocking of local self-bred crab species is the premise and guarantee to realize the synchronous growth of crab quality and yield. Crab species require a good system, sound limbs and disease-free local self-bred high-quality crab species in the Yangtze River system. The specification is 100 ~ 200 crabs/kg, and the dosage is 600 crabs/mu. First, put them into crab culture area for intensive cultivation. After May, shrimps were basically caught and then scattered throughout the pond.

(2) Rotation culture of freshwater shrimp: The crab pond was relatively idle before May, mainly for the growth of aquatic plants. The comprehensive benefit of the pond can be better improved by using this stage to rotate the cultivation of freshwater shrimp. The specific method is: after the pond is cleaned and disinfected (i.e.1~ February), release 1000 ~ 2000 shrimp species/kg per mu.

③ Intercropping between Siniperca chuatsi and Erythroculter ilishaeformis: In order to make rational use of the small miscellaneous fish at the bottom of the crab pond, from the end of May to the beginning of June, 30 5-7 cm intensive cultured Siniperca chuatsi were put into each mu; Erythroculter ilishaeformis is omnivorous, feeding on small fish and puffed pellet feed in the middle and upper layers. The fry size is too small, which is easy to be preyed by mandarin fish. From the end of April to the beginning of May, 20 large-scale culter ilishaeformis 10 ~ 15 cm were released per mu.

④ Reasonable collocation of silver carp, bighead carp and allogynogenetic crucian carp: put 10 silver carp and silver carp per mu in February and March, and put 5-7kg allogynogenetic crucian carp with specifications of 15-20 /kg per mu. At the same time, allogynogenetic crucian carp can spawn and reproduce, providing adequate palatable bait fish for Siniperca chuatsi.

(4) Feeding management

① Bait feeding: Because there are many kinds of pond culture and the biological load is large, it is the key to feed different kinds of culture scientifically and reasonably. The specific requirement is "overall consideration, each with its own emphasis".

First, during the winter rotation period, shrimps are stocked outside the temporary breeding area. When the water temperature rises to 10℃, apply organic fertilizer 100 ~ 150kg/ mu in the whole pond to cultivate plankton and benthos, and provide natural active bait for the freshwater shrimp. At the same time, we insist on feeding the special granular feed for freshwater shrimp, and the feeding amount is calculated by 5% of the weight of shrimp in the pond.

Second, in the temporary breeding area, in order to strengthen the breeding, the crab species are fed with chopped fresh small miscellaneous fish and other animal bait every day, and the feeding amount per mu is 1 kg. In the case of insufficient bait for small miscellaneous fish and other animals, crab pellet feed should be supplemented appropriately.

Third, in May, after the shrimps were basically caught, the temporary crab breeding area was dismantled and the whole pond was kept free-range. Because allogynogenetic crucian carp was released, in order to prevent allogynogenetic crucian carp from competing with river crabs for food, feed allogynogenetic crucian carp feed before feeding river crabs, and then feed river crabs feed two hours later to ensure the normal feeding of river crabs. There are three kinds of feeds for river crabs: plant feed, animal feed, compound feed and pellet feed. In mid-June, the feed ratio of animals to plants was 60 ∶ 40; From late June to mid-August, the feed ratio of animals to plants was 45 ∶ 55; From the end of August to the middle of 10, the feed ratio of animals and plants was 65∶35. The daily feeding amount is about 1% of crab body from March to April, 5% ~ 8% from May to July, and 8 ~ 10% or more. And according to the weather and water color, feed more on sunny days and throw less on rainy days. In high temperature season, two changes are implemented, namely, the feeding place is changed from shallow water to deep water, and the high-protein feed is changed to low-protein feed to ensure the safety of river crabs in summer. When crabs are sexually mature, they eat less in the afternoon, so feed them in the afternoon, not in the morning, to prevent their physique from weakening.

Fourthly, Erythroculter ilishaeformis mainly feeds on small wild miscellaneous fish in the upper and middle waters. In order to supplement the shortage of wild miscellaneous fish and ensure the normal growth of erythroculter ilishaeformis, it is necessary to supplement puffed feed. At first, it was mainly domestication, feeding minced fish and puffed feed at fixed points for several times, and then gradually reducing the amount of minced fish until the puffed feed was used. The daily feeding amount should be eaten within 2 hours and fed at the same time as the crab pellet feed.

Fifth, the allogynogenetic crucian carp is stocked in the pond, and other small wild fish spawn and breed, which can basically meet the growth needs of mandarin fish. If the bait is insufficient, it is necessary to supplement allogynogenetic crucian carp or silver carp and silver carp summer flowers for feeding.

② Water quality and water level adjustment: In terms of water quality adjustment, the water quality should be "fresh, lively, tender and cool". Specifically, the dissolved oxygen should be kept above 5 mg/L, the transparency should be above 40 cm, the pH value should be around 7.5, and the ammonia nitrogen should be below 0. 1 mg/L. Water should be injected 1 time every 5-7 days, and10-20 cm every day in high temperature season, especially in the molting period of river crabs, to promote river crabs. Under the condition of good water quality in the whole pond, the self-purification function of aquatic plants, snails and other organisms is used to implement zero emission, and the use of oxygen aerator in crab pond is emphasized. In the high temperature period, the aerator is frequently turned on at noon, after midnight and before dawn on sunny days, and it is turned on all day on rainy days to ensure the normal growth of river crabs, fish and shrimp, and the crab pond is not deprived of oxygen.

In terms of water level regulation, according to the principle of "shallow in front, deep in the middle and stable in the back", the water level regulation is carried out in three stages. From March to May, the water depth is 0.5 ~ 0.6m, from June to August, the water depth 1.2 ~ 1.5m, 9 ~1October1~1.2m, and the water temperature for crab growth. In the middle and high temperature season, deepening the water level is conducive to lowering the water temperature, allowing the river crabs to eat and molt normally, and stabilizing at a moderate water level in the later period is conducive to maintaining the normal water temperature, so that the river crabs have a stable water environment for weight gain, fattening and smooth growth.

(3) Daily management: combined with feeding, check the molting growth, diseases and enemy damage of the river crab, check the water quality of the source water, clean up the breeding environment, check the escape prevention facilities and repair the cracks in time.

④ Disease prevention: follow the principle of "prevention first, combining prevention with treatment", adhere to the combination of ecological regulation and scientific drug use, and actively take comprehensive technical measures such as cleaning ponds, planting aquatic plants, breeding crabs by themselves, scientifically feeding and adjusting water quality to prevent and control the occurrence of diseases. Pay attention to the application of microecological agents, adopt the method of "combining up and down", and spread all microbial agents such as photosynthetic bacteria and EM every 7 ~ 10 days to improve water quality. Feeding with biological substrate feed can improve the immunity of river crabs. Because biological bacteria consume oxygen, it is necessary to turn on the aerator when spraying biological bacteria to prevent anoxia in the pond, and do a good job of drug control in advance. The three stages of "prevention, control and protection" should be emphasized throughout the year. From the end of April to the beginning of May, the ciliates were killed with drugs 1 time, and bromine chloride was used every 1 ~ 2 days. Granular bait is made of 1% Chinese herbal medicine, which is fed continuously for 5 ~ 7 days to prevent diseases. At the end of the rainy season, before the high temperature comes, kill ciliates, disinfect water, and take bait orally to control diseases in the high temperature period. In mid-September, ciliates were killed by combining water disinfection with oral bait, and feeding was strengthened at the same time to enhance the physique and disease resistance of Eriocheir sinensis, so as to ensure that Eriocheir sinensis could successfully pass the final weight gain and fattening period.

(5) Sales and transportation

During the period of 10 ~ 1 1, the caught river crabs are put into an escape-proof cage with a cover net for temporary cultivation. Cages should be placed in ponds with fresh water. Submersible pumps should be used to pump water in temporary aquaculture areas to speed up water flow and increase dissolved oxygen. After being kept in a cage for two hours, it will spit mud and get dirty, and then it will be divided into specifications, divided into male and female, bagged, labeled and transported to the market.