Technical measures
I. Geographic Conditions The Doumen District is located at the mouth of the Xijiang River in the Pearl River Delta. Most of the farming ponds in the region are freshwater ponds. There are a lot of saline stains in the strata under 10 meters or more. Drilling holes can be used to extract salt water. The salinity is 15‰-20. Hey.
Second, the pond conditions The ponds reared by Penaeus vannamei are mostly ponds that were originally cultured with Macrobrachium rosenbergii. Each area is 6-8 mu and the water depth is 1.5-2 meters. The pond is pumped and drained with a pump.
Third, the stocking operation
1. Clear pond culture water can be used by conventional methods. For example, 150 kg lime dry pond is used per acre, 0.5 meter water is used, and then 30 g/m3 bleach is used to disinfect once, and then the cells can be promoted by single-cell algae. Compound fertilizer culture water. However, "washing ponds" should be used between the two rivers. After the ponds are used, the silt is washed away with water pumps. The conditional year-end rest pond, after exposing to use the bulldozer to clear away the pond bottom sludge.
2. Adjusting the salinity of pond water P. vannamei has a wide salinity, and it can grow in fresh water with little salinity, but it has a higher salinity in the early stage of cultivation and gradually fades out later. Adjust to more than 5 inches. There are three methods of adjustment: firstly, digging wells, adjusting the salinity of the pond water with underground saline water; secondly, adjusting the salinity with seawater transported by ship; and adjusting the salinity with sea salt or seawater.
The adjustment of the salinity of the shrimp ponds is not consistent with that of the whole pond. The salinity of the small water bodies used for the crude seedlings used in the ponds is higher than that of the outside, which serves to save the cost of water transfer and gradually dilute the water.
3, after the original pond desalination standard rough seedlings shrimp pond disinfection, fertilization and regulation of salinity, but also on the side of the convenience of management with a sealed plastic cloth to surround a small water body of 10-15 square meters, a small body of water The salinity should be adjusted to be close to the salinity when the shrimp seedlings are desalinated, generally more than 8 。. The shrimp seedlings should be healthy and lively, and require to be diluted to less than 10‰ on departure, with 50,000 seedlings per mu. The returned shrimps should first be kept in a small body of water for about 10 days. The benefits are not only centralized, but also facilitate the management of feeding, but also play a role in continuing to dilute and improve the survival rate.
Shrimp will gradually decrease its salinity during the holding of small water bodies. After 10 days, the cloth will be removed and the shrimp will grow into big ponds.
When temporarily raising the standard crude shrimp seedlings in small water bodies, multiple oxygen enrichment heads should be placed to prevent the shrimp seedlings from being intensively deficient in oxygen; appropriate feed of microparticle feeds or shrimp slices should be adopted to promote the growth of shrimp seedlings.
4. Use of beneficial microbial preparations Apply a microbial preparation every 15 days from the start of seedling injection, each time about 1 kilogram, pay attention to prevent conflict with the disinfectant (refer to product instructions). Microbial preparations have the effect of degrading ammonia nitrogen and can be used in combination with simple algae stimulating hormones to keep the water fresh. Avoid excessive water changes, reduce spending on salting, and keep shrimps growing steadily.
5, other management to maintain adequate dissolved oxygen, in addition to the water cultured with good green algae, every 3 acres of water to install a 1.2-kilowatt aerator; feed pellet feed, bait coefficient of about 1, the previous can use higher protein Special feeds for shrimp, and feeds for Macrobrachium praecox in the later period are acceptable. The pH of the culture water is preferably maintained at 8.0-8.5, and more than 9.0 shrimps are easy to develop. If the water quality in the breeding process is not particularly corrupted, it is generally not necessary to change the water in order to maintain the water. The salinity and beneficial bacteria content; under normal circumstances the pond water does not have to be disinfected, each use of antibiotics brings destruction of the aqueous phase, increase the possibility of shrimp stress illness.
6. Timely harvest In the summer and autumn, the breeding period will reach 100 pigs per kilogram in 70 days, which can be selected for market. The breeding time is up to 70-80 tails per kilogram for 100 days. Usually the listing is completed. Timely listing can avoid the loss due to the deterioration of the aquaculture environment in the later period.
Conclusion and analysis
I. Comparison of the cultivation of P. vannamei in freshwater ponds after aquaculture with aquaculture in coastal seawater ponds may be due to avoidance of lateral transmission of similar viruses from crustaceans and copepods in seawater and blocking of P. vannamei from Seawater induces toxic disease causes, so as to obtain stable production. This point has also been proven in the production of this region. In the distribution of South American white shrimps throughout the region, the more disease near the beach, the more disease and the lower the yield. In 2001, there were only 84 tons of shrimp in 3000 acres of shrimp ponds. The average yield per mu is only 28 kilograms, and there is only 8 kilograms of per annum near the southernmost pond. More than 500 kilograms of production are in the pure freshwater pond area in the north.
Second, controlling drug use is one of the effective ways to prevent shrimp outbreaks. Penaeus vannamei can cause morbidity for many reasons. At this time, if a large number of antibiotics are used to disrupt the balance of the culture water, such as the death of algae, the degree of stress in the shrimp will increase, which will further worsen the disease. The correct approach is to pay attention to maintaining the stability of water quality when there is not a lot of shrimp, and there should be no sudden changes to recover; if the disease expands, some milder drugs such as bromochlorohydantoin can be used to disinfect and treat the disease. It is not necessary to repeatedly administer drugs to prevent the disease from expanding. After 3-5 days of application, microbiological preparations should be re-introduced to create a good water quality environment in order to alleviate the disease.
High-yielding aquaculture technology of white shrimp in Hekou area
Doumen District, Zhuhai City, is located at the mouth of the Pearl River and is rich in freshwater resources. It adopts “dilution + beneficial microorganisms†to implement semi-enclosed cultivation of Penaeus vannamei. It has been harvested in large areas for three consecutive years, providing some useful references for aquaculture areas with similar conditions.
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