Pond main culture technology of new species of river crab in Wuxi, Jiangsu Province
_Xu Gangchun
River crab scientific name Chinese river crab, also known as hairy crab, hairy crab, is one of the leading species of aquaculture in China. The main culture of river crab is based on the breeding mode of river crab, with a small amount of mandarin fish or perch for biological control of wild trash fish, through the stocking of snails, silver carp and planting aquatic weeds to comprehensively control the water quality of crab ponds. Jiangsu, as the main river crab producing area in the country, breeds adult crabs once a year, usually starting from mid-to-late February to the end of male crab fishing and listing. There are 6 key factors in the main pond breeding process of new species of river crab, namely pond environment, aquatic plant planting, crab seed stocking, water quality regulation, scientific feeding, and breeding management, and the following focuses on the main pond culture technology of the new river crab species "Noah Noah No. 1" participated in by the Freshwater Fisheries Research Center of the Chinese Academy of Fishery Sciences.
First, the pond mouth environment
1. Regular pond mouth The crab pond requires standardization and cleanliness, and the inlet and drainage system is independent and perfect. The area is controlled at 10 to 15 acres, the average water depth is 1 to 1.5 meters, the width of the embankment is 3 to 3.5 meters, the slope ratio of the pond is 1:3, and the bottom of the pond is flat and less silt. After the slope of the pond is leveled, the slope soil is covered with geomembrane, the outer layer is protected by polyvinyl chloride mesh, and the upper edge of the mesh is buried in the soil with soil at both ends of the mesh to ensure that the mesh, geomembrane and the slope are close together, which can prevent the river crab from burrowing on the shore after the seedlings are released and become "old crabs". Plastic plates, nylon films, fiberglass, etc. with a height of more than 60 cm are used around the pond as anti-escape facilities, and buried in the soil for 10 to 20 cm can prevent frogs or toads from entering the pond.
2. Disinfect the pond mouth from November to December to drain the pond water, remove aquatic weeds and pond bottom excessive silt, level the pond bottom, and turn the pond to expose for 20 to 30 days. Filter the water with a sieve bag of 80 mesh and above, and the water level line is 20 cm above the bottom of the pool. Use quicklime 100 to 150 kg/mu, bleaching powder 13 kg/mu or chlorine dioxide 0.25 kg/mu, sprinkle the whole pond after water, clean the pond and disinfect the pond, and kill the wild trash fish and diseases and insect pests at the bottom of the pond.
3. Pond mouth oxygenation At the bottom of the pond, microporous oxygenation equipment is built for oxygenation, and the power of the aerator at the bottom of the microporous pipe per mu is 0.18 to 0.20 kilowatts, and the microporous pipe is configured with 40 to 50 meters (the total gas supply pipe adopts a rigid plastic pipe with a diameter of 60 mm; the branch gas pipe is a microporous rubber pipe with a diameter of 12 mm), which can effectively reduce the risk of large-scale death caused by the lack of oxygen in the pond or the death of aquatic plants and the lack of oxygen in the rainy days in summer and autumn.
Second, aquatic weed planting
On the one hand, aquatic plants provide fresh green feed for river crabs, increase dissolved oxygen through photosynthesis, and on the other hand, create an ideal habitat environment during the molting period of river crabs and avoid enemy molting shells. After the pond is disinfected, aquatic weeds are planted 7 to 10 days later, mainly Elekella, supplemented by bitter grass and yellow silk grass (micro-toothed eye vegetable). Using the method of burrow sowing, the pond is planted, the plant spacing is 1 meter, the row spacing is 1.5 meters, and the rope is pulled in a straight line and evenly spaced when planting.
Multi-species composite aquatic grass can diverge during the growth period, keep the pond water fresh, and provide a good ecological environment for the growth of river crabs. The best planting time for Elekella is from late January to early February, the planting time of bitter grass is generally in late February, and the planting time of yellow silk grass is from mid-April to early May, covering about 60% of the pond bottom area, and the water level is maintained at 10 cm above the grass head. During the peak growth period of summer aquatic plants, they should be mowed several times to avoid lack of oxygen due to luxury. In the high temperature season, Elastane is prone to death and decay, and should be fished out in time to avoid spoiling the water quality. When encountering wild growth of aquatic grass and cannot be treated, the water weeds on the esophagus of the river crab should first be cleaned out, so as not to hinder the river crab from eating.
Third, crab species are stocked
At the end of February and the beginning of March, you should avoid the freezing cold period, the water temperature is 3 ~ 10 ° C, according to the weather forecast, choose sunny weather to prepare for seed release. The crab species source selects the "Noah No. 1" (species registration number: GS-01-005-2016) high-quality crab species bred by the Freshwater Fisheries Research Center of the Chinese Academy of Fishery Sciences. The main characteristics of "Noah No. 1" are: (1) fast growth rate, 20% faster than the common breed of river crab in the same period ;(2) The large size rate of crabs has been significantly improved. The proportion of male crabs with more than 200 grams per adult crab and more than 41% of female crabs of 150 grams per adult crab reached more than 41%, which was 21% and 18% higher than that of ordinary river crabs in the same period.
The choice of the origin of crab species should follow the principle of proximity and avoid long-distance transportation to improve the survival rate of entering the pool. When screening the appearance of crab species, it is required to have neat specifications, bright individual colors, sound limbs, quick response, rapid action, no attachment organisms and parasites on the body surface, no disease spots, no small size and precocious individuals. Crab species are sterilized using potassium permanganate solution or normal saline before stocking. Crab species can be released at one time, the stocking density is about 800 crab species / mu, the crab species specifications are 100 ~ 160 / kg, can be from the artificial punch boat to the middle of the pond along the pond to slowly move forward, so that the river crabs can climb freely into the pond on the floating board.
Fourth, water quality regulation
1. Water source purification Set up an ecological purification area for inlet water sources, adopt the pond circulating water breeding mode, introduce purification ponds into the outer river water, plant aquatic grasses in the purification pond, stock snails, silver carp, etc. to form a small ecosystem, inject purified water into the breeding pond, and provide fresh water for water exchange and water addition in the high temperature season.
2. Prevention and control of moss Crab pond aquaculture in the early stage of the water body is thin, easy to grow moss, a small amount of moss can bear the same effect of aquatic weeds, should not be one-sided use of aquatic weeds, river crabs have greater harm to the moss removal agent to kill. After manual removal of most of the moss, combined with fertilizer hydroponic algae, promote the growth of aquatic grasses to inhibit moss, biological control.
3. Prevention and control of zooplankton In the early stage of breeding, zooplankton grow rapidly with the growth of algae, which not only consumes more oxygen but also has a greater impact on the growth of algae, it is recommended that 2/kg of silver carp be stocked 2/kg per mu for biological control and control.
4. Water quality monitoring during river crab breeding often measured ammonia nitrogen, nitrite, pond water ammonia nitrogen, nitrite content standards are ≤ 0.2 mg / l and ≤ 0.1 mg / l, when exceeding this standard, it will be harmful to river crabs, and the higher the temperature, the greater the toxicity of ammonia nitrogen and nitrite.
5. Water level control The water level control principle is shallow spring, high summer and moderate autumn. On the eve of heavy rain and typhoons, the water level can be appropriately reduced by 10 to 15 cm, and the water level exceeding the conventional water level after the rainfall needs to be drained immediately to prevent the river crab from going to the top of the grass and having difficulty breathing oxygen.
6. Regulate water quality Crab pond fertilization should use green bio-organic fertilizer (such as fermented soybean meal, rape meal, etc.); stocking snails to purify water bodies; supplement chlorella, cultivate beneficial algae to absorb excess nutrient salts in water bodies; regularly use EM bacteria (water diversion No. 1) to transfer water to change the bottom, cultivate beneficial bacteria in water, accelerate the ammonization and nitrification process of organic matter, and reduce ammonia nitrogen concentration and harm.
Fifth, scientific feeding
In the main breeding mode, the new river crab species mainly adopts the precision feeding method of intensive breeding. Start feeding when the water temperature reaches above 10°C. Feeding once a day in the evening, according to the scientific bait principle of "pre-fine, intermediate green, late meat", to ensure that the bait is fresh and palatable, does not rot and deteriorate. The bait is mainly based on full-price river crab compound pellet feed, supplemented by plant-based feeds such as corn and pumpkins and animal feeds such as small trash fish and river mussels. The daily amount of bait is about 1% of the body weight of the pond crab in March to April, 3% to 5% in May to June, and 5% to 10% in July to October. The actual feeding volume increases or decreases according to the season, weather and feeding conditions.
6. Aquaculture management
Under the main breeding mode of new river crab species, the prevention method of "ecological prevention and control is the mainstay and drug prevention and control is supplemented". If sick crabs and dead crabs are found, they should be fished out in time, check the cause and cause of death, and carry out harmless treatment. On the basis of adhering to the traditional principle of "four determinations, four looks", it is necessary to strengthen the construction of scientific and technological fisheries, from online water quality analyzers to full video surveillance, the advantages of digital fisheries should be used as appropriate. At the same time, do a good job in production management records, easy to analyze and summarize, and guide the next year's production.
The market catch of river crabs generally begins with the "June Yellow" after the three-hull and can be sold in small quantities; adult crabs are caught since late September and are listed in batches according to the law of "nine females and ten males" in the lunar calendar. Fishing is mainly carried out by setting up cages in ponds, but also on pond mounds, and finally dry ponds.
After the river crab is dried up, the aquatic weeds during the breeding process and after the harvest are concentrated. Aquaculture tailwater treatment mainly adopts "in situ repair + ectopic repair" technology, first of all, the "grass-fish-snail-bacteria" ecosystem in the pond is repaired in situ, and then the pond water is discharged into the primary sedimentation purification pond of the purified water quality of silver carp and snails for ectopic repair, and after sedimentation, it enters the secondary purification area full of aquatic grasses through the overflow dam, and purifies through the secondary purification area, and the water quality test meets the standard before it can be discharged into the surrounding waters.
#pgc-card .pgc-card-href { text-decoration: none; outline: none; display: block; width: 100%; height: 100%; } #pgc-card .pgc-card-href:hover { text-decoration: none; } /*pc 样式*/ .pgc-card { box-sizing: border-box; height: 164px; border: 1px solid #e8e8e8; position: relative; padding: 20px 94px 12px 180px; overflow: hidden; } .pgc-card::after { content: " "; display: block; border-left: 1px solid #e8e8e8; height: 120px; position: absolute; right: 76px; top: 20px; } .pgc-cover { position: absolute; width: 162px; height: 162px; top: 0; left: 0; background-size: cover; } .pgc-content { overflow: hidden; position: relative; top: 50%; -webkit-transform: translateY(-50%); transform: translateY(-50%); } .pgc-content-title { font-size: 18px; color: #222; line-height: 1; font-weight: bold; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; } .pgc-content-desc { font-size: 14px; color: #444; overflow: hidden; text-overflow: ellipsis; padding-top: 9px; overflow: hidden; line-height: 1.2em; display: -webkit-inline-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; } .pgc-content-price { font-size: 22px; color: #f85959; padding-top: 18px; line-height: 1em; } .pgc-card-buy { width: 75px; position: absolute; right: 0; top: 50px; color: #406599; font-size: 14px; text-align: center; } .pgc-buy-text { padding-top: 10px; } .pgc-icon-buy { height: 23px; width: 20px; display: inline-block; background: url(https://lf1-cdn-tos.bytescm.com/obj/cdn-static-resource/pgc/v2/pgc_tpl/static/image/commodity_buy_f2b4d1a.png); }
River Crab Farming Q&A & Illustration Crab Breeding Key Techniques Crab Breeding Bait Recipe Book Crab ¥49 Purchase