Shrimp and blue crabs belong to the arthropoda, crustacea, and decapoda, and are closely related to taxonomy. The ecological niche is close. Shantou City began shrimp farming in the 1980s when shrimp farmers began to implement polyculture. However, in recent years, it has been found that the green crab may serve as a host for the transmission of shrimp virus, and there is a cross-infection. Therefore, the polyculture model has a lot of academic debate. From the large-scale production development and research projects in recent years, we have concluded that the mixed shrimp in shrimp ponds undoubtedly improves the overall economic efficiency, and it is the key to how to make profits and avoid hazards in production. At present, due to the poor comprehensive conditions of the ponds in the estuary area, the monoculture of prawn disease is serious, and prevention and cure are not yet effective. From a economic point of view, polyculture is better than monoculture prawn. From a production risk perspective, polyculture is safer than monoculture prawn. In fact, after nearly 10 years of exploration and practice in Shantou, a comprehensive set of effective countermeasures has been formed for the polyculture model of shrimp and blue crabs. I. The characteristics of ponds suitable for the implementation of polyculture of shrimps and blue crabs Most estuary low-salt ponds or other sediment-bearing ponds with freshwater sources are suitable. 1. Water quality characteristics Low salinity: Under semi-enclosed water quality management, the salinity of pool water in summer is not less than 1 ‰, and it is no higher than 20 å†¬å£ in winter. In addition to the low salinity suitable for the habit of green crabs, practical observations show that shrimp virus disease is also significantly less. The reason mechanism, some experts believe that the original environment of shrimp white spot virus is high salinity, and the virus virulence is reduced at low salinity. High turbidity, low chroma, and stable pH: The three characteristics of water quality are caused by the polyculture of blue crabs (and fish) to stir up the sediment powder. This kind of water environment is more stable and the turbidity particles are adsorbed. The balance of absorption and release of nutrients in ponds was achieved, maintaining moderate photosynthesis, stabilizing the pH value of pool water, and improving sedimentation and sedimentation pollution. The turbidity can also reduce the damage to shrimps, crabs, crabs, and crabs, as well as their mutual destruction. Whether production can control the achievement of these three indicators at the same time is the key to the success of water quality management. The application of dry grinding marble powder (325 to 600 mesh) for construction has a certain effect. 2. The characteristics of bottom sediments are suitable for sandy or powdered clay sediments, and pure sandy or gravel bottoms are not suitable, and severe acid red mud bottoms are also not suitable. 3, pond structure General shrimp pond structure can be, each pool of 10-40 acres, water depth of about 1 meter, the bottom of the pond is best to dig a ditch or "L"-shaped ditch. Second, the characteristics of polyculture mode 1. Make multiple rounds of catching and catching, catch large grass seedlings in stocking at the beginning of April, with a density of 030-50,000/mu. Afterwards, “squeeze†according to the actual situation to put 2-3 batches, each time 02. - 030,000 tails/mu of black shell seedlings, and about 10,000 shrimps will be given per mu. In the autumn, the total amount of new shrimp is 0.33 per mu. The crabs are stocked with autumn seedlings (August-October) for the main seasonal season. After wintering culture, the spring and summer of the following year are captured and kept small, and then they are appropriately squeezed and released. According to the seed supply status, the batches are added in 2-3 batches. , can also be put in a small amount every day. The annual amount of crab seedlings in 1000-2000 acres, the specific number depends on seed size and quality. Grasshoppers can be harvested and kept small with improved fixed nets. According to the different meshes, the harvesting specifications can be controlled artificially, and the relationship between mesh size and harvesting size: 2. Full-stage breeding, full-year breeding The whole-course breeding means that crab culture is no longer the traditional method of raising and maintaining the ointment, but it is directly stocked with crabs. The whole year of cultivation means that in addition to the wintering of blue crabs, shrimps can also be stocked with Chinese shrimps (low density, 0-10 million per mu) in early spring, and new shrimps and Japanese shrimps will be raised in winter for breeding in the fall. In recent years, newly introduced Penaeus vannamei can also be cultivated throughout the year. 3, supporting the middle of the culture, multi-level breeding supporting shrimp, crab seed intermediate culture is to adapt to the rotation and low salinity requirements, except early spring and late autumn (in this case salinity above 12 å¯) can be stocked seedlings, "The release of seedlings must be subject to "standard crude," and "standard crude" has been developed by a full-time specialized professional intensive intensive care. The multi-level culture generally adopts a small pond supporting a small pool, and the seed is placed in a small pool after the intensive breeding. 4. The “artificial ecosystem†culture is a more mature model. In addition to the mixed green crabs, it also contains polyculture fish, mainly salmon, blue fish, carp, etc., forming a pond “artificial ecosystemâ€. “Cultivation and utilization of combined fish control ponds have resulted in eutrophication due to closed culture, balancing the ecological environment and reducing disease. Third, disease prevention and control technical points 1. Multiple rotations make the shrimps in a low-density state for a long period of time. The probability of cross-infection between shrimps and crabs, shrimps and shrimps is relatively low. Infected shrimps can be farmed to harvest specifications under good conditions. If a certain batch of shrimp died as a result of disease in production, generally some of them survived, and they also caused less deaths in rotation. In one or two tidal periods (15 to 30 days), shrimp harvested quickly. 2, using grass shrimp in the sparse, low-salt environment, growth and size differentiation obvious phenomenon, the implementation of arrested, catching big stay small. In this way, the capacity and density of pond shrimp at any one time can be reduced by “pressingâ€. Generally, the first batch of grass shrimp is farmed for 50-60 days, and commodity shrimp with a size of 15 g or more can be harvested. After harvesting starts, they are harvested daily. Shrimp, according to the growth and disease status of shrimp, the flexible change of nets is an important disease prevention measure. Shrimp infestation usually occurs through the “tick periodâ€, “lag period†until death, and shrimp can be harvested during the “incitement periodâ€. Reduce losses and further infections. 3. In the peak season of shrimp disease, the amount of blue crab feeding was controlled, and the green crab was used to ingest the weak shrimp to control the spread of shrimp disease. By observing the shrimps harvested daily by the fixed nets, the situation of the shrimps in the pond can be roughly understood. If there are signs of illness, the feeding amount of blue crabs should be reduced immediately, or even feeding should be stopped. A large number of production examples and control experiments showed that the incidence of shrimp disease was inversely proportional to the amount of polyculture of green crabs in the pond during the peak of shrimp disease in May of each year. 4, reduce shrimp - crab virus cross infection. Blue crabs will ingest the weakly-dead prawn. The production of white crabs can be observed in production (markedly different from brown spot, brown spots, brown spots, and armor piercing. White spot and gray spot but not ulcerated penis). , but white crabs generally do not die. Only the number of dead shrimps in the pool is greater than the total food intake of blue crabs. The infestation of dead shrimps by green crabs will trigger the development of blue crabs. However, because we took rounds of catch on the shrimp repeller, a large number of dead shrimps are generally rare. The timely application of 3-5ppm bleaching powder or 5-10ppm tea bran cake in addition to disinfection can also stimulate the early death of some diseased shrimp in the pool and be eaten by the green crab, which can reduce the concentration of death. This is in line with other shrimp disease prevention and aquaculture. The measures are obviously different. On the other hand, to prevent diseased crabs from infecting prawn and picking out diseased crabs in time is the key. This task can be combined with the harvest of green crab each day. Fourth, other corresponding supporting technology 1. The technology of clear ponds at intervals shows that the ponds have no dry pond clearing period due to the realization of year-round breeding and round-rotation arrests. To solve the problem of bottom quality, we have adopted shallow interval technical measures, that is, the use of large flows in multiple pond combinations. Axial flow pump is forced to lightly or dry (pool bottom ditch not) pool of water, and the extracted water is added to other ponds. The heavy water is firstly returned to the “old water†and then “new water†is added. To be implemented alternately at each pond, this measure should strictly grasp the timing and duration of the dry pool according to the conditions of shrimp, crabs, weather, and seasons in the pool. The dry season is generally 1-2 days in summer, 5-10 days in winter and 5-10 times in a year. Good operation does not damage shrimp and crab, and the effect of improving sediment quality is obvious. The winter dry pool can also promote the green crab cave. Dry pool should be promptly matched with the pond. 2, the middle of the detoxification technology must be cleared during the breeding process of white-tailed prawns and multiple generations of low-value hybrid fish (such as longevity fish, carp, etc.). We must avoid damaging the ponds and crabs. Clear delta tail shrimp can use deltamethrin (pesticide trade name "enemy" water agent). The order of biosensitivity in the pond during the application was: white tailed shrimp> long-armed shrimp, giant shrimp> Moji shrimp, long-haired shrimp> prawn Penaeus> blue crab> fish. After application, the ridge-tailed white shrimp patrols quickly along the edge of the pool and uses a dense mesh to set the net to attract. Should pay attention to master the drug concentration, generally 5 ml per 10 acres of pool, with less stimulation of other shrimp, crab as a limit. V. Conclusion It is true that shrimp-crab polyculture is not disease-free and healthy breeding. However, for large-area estuary low-salt ponds, the conditions are poor in all respects. It is still unrealistic to implement high-density and healthy breeding. If this mode of production is adopted and the management is conducted well, the annual output value of mu can reach 5,000 yuan and gross profit ( Does not contain pond rent, 300-800 yuan / mu varies from place to place up to 1500-2000 yuan. Similar to other polyculture modes of shrimp, shellfish, algae, and shrimp, fish and fish are still of practical significance. Automatic Air Hose Reel,Auto Rewind Air Hose Reel,Self Retracting Air Hose Reel,Air Compressor Retractable Hose Reel NINGBO QIKAI ENVIRONMENTAL TECHNOLOGY CO.,LTD , https://www.hosereelqikai.com