Cultivating vannamei shrimp in open-air earthen ponds, these five techniques can double your profits

Cultivating vannamei shrimp in open-air earthen ponds, these five techniques can double your profits

_Sun Zhongxiang, etc

Litopenaeus vannamei is a shrimp family, a genus of shrimp species, native to the waters of the Pacific coast of South America, more concentrated in the waters near Ecuador, is an excellent species of intensive high-yield farming, and is one of the three shrimp with the highest aquaculture production in the world today. The natural habitat area is a muddy seabed, water depth 0~72 m, the most suitable growth temperature is 18~32 °C, salinity 1%~4%, adult shrimp mostly live in coastal waters closer to the shore, juvenile shrimp like to feed and grow in the bait-rich estuarine area, is an omnivorous species, in the case of artificial breeding, can feed on organic debris in the pond.

Penaeus vannamei is one of the main cultured species of shrimp in mainland China, which has the advantages of large individual, fast growth rate, strong disease resistance, strong adaptability to changes in water environment factors, low requirements for feed protein content, high meat yield, long survival time out of water, thin shell and body fat, delicious meat, high meat content and rich nutrition, etc., and is favored by farmers and consumers. In recent years, due to the influence of seeds, environment, diseases and other factors, the success rate of open-air earthen pond culture of vannamei shrimp in South America is low, and the cultivation area of shrimp in small sheds is constrained by the high-pressure situation of environmental protection. Through the promotion of the open-air earthen pond construction standardization, water quality and environment cleanliness, stocking shrimp fry standardization, feed feeding precision and disease prevention and harmless "five" aquaculture technology in Yancheng area, the success rate and ecological, economic and social benefits of P. vannamei clay pond culture have been improved. The aquaculture technology is summarized as follows for the reference of farmers.

1 Shrimp pond construction

1.1 Shrimp ponds

Most of the open-air shrimp ponds in Yancheng are water-lifting ponds with ditches and polders around them. It is necessary to transform the irregular shrimp pond with a large area into a standardized pond with a single pond area of 6 670~13 340 m2. Keep the maximum water depth of the ring ditch 2 m and the beach depth > 1.3 m. The slope of the pond is covered with polyethylene mesh to prevent weed growth and wind and waves from eroding the pond.

1.2 Water sources

There are no pollution sources such as industrial wastewater, agricultural and domestic sewage in the surrounding area. Regularly dredging, completing and inspecting the inlet channel to ensure that the amount of water is sufficient and the water quality meets the "Fishery Water Quality Standards" (GB 11607-89). Build a water pretreatment pond that accounts for about 10% of the total area of aquaculture ponds, and after the source water is treated by precipitation, disinfection, etc., it is connected to each breeding pond through pipelines, and the inlet water is controlled by valves, and the tail water is connected to the tail water purification area through the drainage pipe for centralized treatment.

1.3 Infrastructure

Water, electricity, road, communication equipment is perfect, and areas with abnormal power supply should be equipped with backup generator sets to prevent sudden power outages. Equipped with 1~2 sets of electric submersible pump (about 3 kW) for lifting water into the pool. Construction of facilities such as feed and medicine warehouses, boats, nets, custodial houses and waste collection bins.

1.4 Mechanical Facilities

Install the aeration system at the bottom of the microporous tube, the roots blower is configured according to 0.3 kW per 667 m 2, the diameter of the aeration disc is 80 cm, and 1 aeration disc is generally set up at 300 m 2, and the whole pool is evenly distributed; A waterwheel-type aerator is installed about 10 m diagonally offshore of the pond so that the shrimp pond can maintain sufficient dissolved oxygen and micro-flowing water environment. Farmers with conditions can purchase intelligent unmanned bait throwers to improve the uniformity of bait feeding and reduce waste.

1.5 Tailwater treatment facilities

Build "four ponds and three dams" multi-stage tailwater treatment facilities in the aquaculture area. "Four pools" include sedimentation tank, biological purification tank (biological brush), aeration tank and ecological purification tank; The "three dams" include steady flow dams, overflow dams, and undercurrent wetlands. Through natural settlement, physical filtration, biological adsorption, aeration and ecological purification and other tailwater treatment methods, ensure the recycling of aquaculture tailwater or discharge up to standard.

2 Water environment

2.1 Soil quality

The bottom of the pool is required to be flat, sandy soil or loam soil is the best, and the thickness of silt at the bottom of the pool is 5~10 cm.

2.2 Water Quality

During the growth of shrimp, the pH value was 7.5~8.5, ρ (dissolved oxygen) ≥ 5 mg/L, ρ (ammonia nitrogen) ≤ 0.1 mg/L, ρ (nitrite nitrogen) ≤ 0.1 mg/L, pool bottom ρ (organic matter) ≤ 5 mg/L, ρ (hydrogen sulfide) ≤ 0.1 mg/L, transparency 25~35 cm.

Keep the pool water with a certain fertility, adjust the composition of algae in the water through proper water replenishment and fertilization, so that green algae and diatoms become dominant populations to facilitate algae photosynthesis and oxygen. During the breeding period, properly add water and change water, avoid large drainage and irrigation, and prevent causing shrimp stress reaction. Scientific and reasonable use of aeration equipment, standard rough stage, maintain 24 h continuous oxygenation; In the cultivation stage, flexibly grasp the traditional principle of "three openings and two openings", and start the machine at noon and at night in the early stage; Later turn on all day (stop for 0.5 h when baiting).

2.3 Microbiological preparations

7~10 days after stocking shrimp fry, use 1 microbial preparation (according to the product instructions) to degrade toxic and harmful substances in the pool; In the middle and late stages, biological bacteria such as bacillus, EM bacteria, photosynthetic bacteria, lactic acid bacteria and other biological bacteria were alternately applied every 15~20 days (according to the product instructions) until the end of breeding. In the later stage, the substrate improvement products (according to the product manual) are regularly used to improve the substrate environment and always keep the water body fertilizer, live, cool and tender.

3 Stocking shrimp fry

3.1 Shrimp fry

Select shrimp seedlings produced by large-scale fine seed nurseries with production qualifications, credibility and good after-sales service, and test them by authoritative institutions to ensure that they do not carry specific viruses (WSSV, TSV, IHHNV, etc.), and the number of acute hepatopancreatic necrotic Vibrio bacteria (VPAHPND) and attached cilia does not exceed the standard. Choose shrimp fry with agile swimming posture, clean body surface, no attachment, long body shape, thick and obvious intestines, and black and white heads.

3.2 Hold-up Care

Commonly known as standard rough, a special high-level standard thick pool can be built next to the pool, and a corner of the shrimp pond can also be blocked by canvas, color strip cloth, etc., and a temporary standard rough pond can be built to improve the adaptability of shrimp seedlings through standard thickness, eliminate weak and inferior seedlings, and reduce the incidence of diseases in the future.

Select a sunny day with a water temperature above 20 °C to release seedlings in the morning or evening, and after appropriate temperature treatment, the water temperature difference between the standard coarse pond and the breeding pond is < 2 °C. After the shrimp fry enter the pond, do a good job in the management of baiting, oxygenation, heat preservation and water change, and drugs such as allicin, vitamin C and microecological preparations (according to the product instructions) can be added to the feed to improve the anti-stress ability and immunity of the shrimp fry. The standard thickness time was 15~25 days, and after the shrimp fry were about 4 cm long, the seedlings were moved and cultured in separate ponds.

3.3 Density

The greater the stocking density of shrimp in open ponds, the higher the yield, the more difficult the management, the more factors that deteriorate the water quality, the higher the probability of disease occurrence, and the lower the success rate of aquaculture. Therefore, the stocking capacity of shrimp fry should be 2 30,000~50,000 per 667 m.

3.4 Polyculture

After 1 month of stocking of shrimp fry, 3~5 disinfected 500~600 g silver carp were stocked every 667 m2, and 100 kg of washed live snails were stocked, which could purify the water quality of shrimp ponds and feed organic debris and bait.

4 Feed feeding

4.1 Quality

The feed is required to have good stability and palatability, and the protein content and particle size in the compound feed are selected according to different growth stages, and its quality meets the "Feed Hygiene Standard" (GB 13078-2017) and the "Safety Limit of Pollution-free Food Compound Feed for Fisheries" (NY5072-2002). All feeds are required to be fresh, unspoiled, with good physical properties and stable nutrients.

4.2 Varieties

In the standard coarse stage, it is mainly fed with No. 0 shrimp special compound feed, and it is best to feed Fengnian insect meal in the first 1 week, and gradually increase the proportion of compound feed until all Fengnian insect powder is replaced.

4.3 Feeding

Feed feeding adheres to the principle of "timing, positioning, quality and quantification", and determines the amount of baiting, the increase or decrease of feed according to factors such as weather, water environment, shrimp molt, survival rate, health status, medication, biological bait amount, etc., and takes the eating time and checking the fecal results as the judgment standard. 5~10 days after stocking, feed 4~5 times a day, and feed 10,000 shrimp fry 5~10 g each time, with a daily increment of 20%; Morning and evening feeding accounted for 70% of the daily feeding volume, and noon and early morning accounted for 30%. Install the bait table to observe the eating of shrimp, and feed the shrimp fry in sufficient quantities before 30 days of stocking, and it is appropriate to eat them in 2 hours; 30~45 d feeding time is 1.5 h; After 45 days, the feeding time is 1 h. Less or no feeding on rainy days and when the disease occurs, and 30% reduction in feeding when shrimp molt a lot.

5 Disease control

5.1 Pond disinfection

After the end of 1 breeding cycle, drain the pond water, remove the silt, make the bottom of the pond be frozen and exposed to white and cracked, and then use quicklime, bleaching powder, tea seed cake and other drugs to thoroughly disinfect to achieve the purpose of killing predators and pathogenic bacteria and improving the pond environment. Disinfection method of quicklime + tea seed cake: 2 weeks before seedlings, use 100~150 kg of quicklime every 667 m2, add water to dissolve and evenly sprinkle the whole pool; After a few days, use 50 kg of tea seed cake every 667 m2, soak for a day and night, splash the whole pool, and then dry the pool for 3~5 days after releasing the disinfectant water.

5.2 Daily disease prevention

Implement the disease prevention policy of "comprehensive prevention and active treatment", so as to select good seedlings, manage water, feed good materials, and improve the bottom, so that shrimp will get less sick and do not get sick violently. Before stocking shrimp fry, detoxification products should be selected in the pool water according to disinfection drugs, and anti-stress agents should be splashed in time after release to relieve the stress response of sshrimps. In the process of aquaculture, it is especially necessary to seize the dangerous period of "3.6" (that is, 6 cm in the 6th month of the lunar calendar, 6 cm in shrimp body length, and 60 days in the pond of shrimp fry), starting from feeding management, and implementing measures such as strengthening water quality control, reducing stress reactions, preventing pathogen invasion, and enhancing immunity. Once it is found that the shrimp is eating and activities abnormal, it should immediately stop feeding or reduce the feed, take targeted measures such as water change, algae cultivation, and oxygen increase, and find that the shrimp is sick, and promptly ask a technician for diagnosis and symptomatic treatment.

5.3 Standardize medication

The use of drugs in the whole process of aquaculture should comply with the Regulations on the Administration of Veterinary Drugs and the Guidelines for the Use of Fishery Drugs for Non-Pollution Food (NY 5071-2002). Select high-efficiency, low-toxicity and low-residue fishery drugs, and it is strictly forbidden to use fishery drugs that have not obtained licenses, approval numbers, and product implementation standards. It is necessary to use non-drugs with caution, and cannot rely solely on the one-sided publicity and feeling of the factory to use or increase the dosage, so as not to cause irritation and harm to shrimp. A quality and safety traceability system should be established from the seedling stage to product sales, and real-time tracking and testing should be implemented to ensure the safety of product quality.

6 Conclusion

"Five modernizations" aquaculture technology is to apply new aquaculture achievements, new technologies, new machinery, new concepts, through the standardized transformation of ponds, create a good ecological environment, pay attention to pond water quality regulation, achieve tail water discharge up to standard, purchase and cultivate excellent seedlings, control suitable density, select high-quality feed for precise feeding, scientific disease prevention to ensure the quality and safety of aquatic products, so that P. vannamei achieves the purpose of ecological, environmental protection and healthy aquaculture, and ensures the comprehensive economic benefits of farmers.

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