With the continuous innovation and development of marine aquaculture, the polyculture of shrimp, serrata and bluegrass has emerged along the coast of Zhejiang, and the area for aquaculture has increased year by year. A new pattern of high-yield, high-efficiency breeding has been established on a large scale. According to many years of practical experience, the following links should be properly grasped for the polyculture of shrimp, blue crab, and quail.
I. Pond selection For ponds with shrimps, blue crabs, and oysters, in addition to the basic requirements for common shrimp ponds, there must be separate intake and drainage systems, with convenient inlet and outlet water, and a water exchange capacity of more than 20%. At the end, argillaceous soil is better for growth. Each pond must also have a shoal (water depth 30 cm to 40 cm) that accounts for more than 25% of the pond area in order to build an oyster. The water quality requirements are non-polluting. The specific gravity of seawater is 1.010 to 1.020, the pH value is stable at 7.8 to 8.4, the ammonia nitrogen content is less than 0.6 milligrams per liter, and the bottom sediment hydrogen sulfide is less than 0.01 milligrams per liter. Adjacent to the best fresh water sources, in order to facilitate the regulation of salinity.
Second, preparation before stocking
1. The dredging and renovation ponds must be completely dredged and the embankments, gates and other facilities must be repaired before stocking.
2. Jianou, circling nets for prevention If it is in Xintang, 20 days before sowing, cattle should be used as a shoal to build rakes. The depth of ploughing will be 20 cm to 30 cm. The conditions of the pond may vary depending on the width of the pond, which ranges from 2m to 3m, with shallow ditch on both sides of the pond. The area accounts for 20% of the total area of ​​the pond. The turned over mud is then crushed with bovine chopped water and soaked in water. Laotang only needs a little trimming. Lastly, 21 nylon nets must be placed on the gills, with a mesh size of 3.5 cm to 4.0 cm. The net edges around the gills must be pressed tightly so as to prevent the blue crabs from entering the digging area, causing unnecessary losses. Anti-escape net adopts 40-mesh sieve net, and then fixed by small wooden stakes. The spacing of wooden stakes is 50 centimeters, and the height from the ground is 40 centimeters. However, the upper edge of the screen mesh must be flattened toward the inside to make the width of the fold. It is 20 centimeters to avoid crab crawling to escape.
3. In the two weeks prior to the disinfection and stocking of clear ponds, 15 kg of bleaching powder or 15 kg of tea seed cake was used for clear pond disinfection per acre of the pond. After 3 days, the water was drained and then filtered into natural seawater filtered through a 80 mesh sieve.
4. Culture of plankton The inoculation of seedlings into the water 20 cm to 30 cm 10 days before stocking, and the algae cultivation after biological and physical treatment of water quality and sediment. This can change the traditional fertilizer manure ponds, resulting in excessive residual mud conditions.
Third, seedling stocking
1. Seedling stocking seedlings to choose the shell is jade white, shiny, robust, shell is not broken, the specifications of high quality seed. The simple method to identify the advantages and disadvantages of seedlings is to shoot the baskets by hand after mounting the seedlings. The sound produced by the seedlings when the shells are closed by surprise is the better the seedlings, and vice versa. The stocking time is generally after the Ching Ming period. The average stocking density is 300 to 350 grains per square meter, and the stocking area does not exceed 20% of the total pond area.
2. Shrimp stocking There are many varieties of shrimp that can be raised at present, such as Chinese shrimp, P. monodon, P. new penaeus, Penaeus vannamei and so on. Election varieties should also be based on the life habits of the shrimp to determine the time of stocking, but considering that as a polyculture, the density must not be too high, generally the amount of seedlings per mu is 10,000 to 15,000.
3. The selection and breeding of blue crabs The crabs generally have four seasons. Spring and autumn seedlings are preferred. The current crab seedlings are mainly from artificially harvested natural seedlings. The seedling size varies from 1 cm to 3 cm. We must choose hard, neat and well-matched specifications and appendages, at least crabs that cannot be missed by chewing feet and swimming feet. The stocking density can be determined according to the conditions of the water body. Generally, the pond along the coast of Sanmen County in Zhejiang Province should have no less than 1,000 mu per mu. The seedlings should not be thrown into the water directly. They should be placed on the shore near the water, so that they can go into the water so as to avoid drowning and cause the survival rate to decline.
Fourth, daily management
1. The feeding of feedstuffs to shrimps, blue crabs, and cockroaches should be based on feeding seedlings. In the middle and later stages of polyculture, the feeding of blue crabs should be the main method. The fed amount of fresh feed and compound feed should be flexibly controlled according to the weight of shrimps, crabs, quails, feeding activities, water temperature, and water quality. It is better to eat less than enough food. Feeding should be evenly spread and should not be fed regularly to prevent shrimps and crabs from competing for food.
2. Regulation of Water Quality The regulation of water quality in shrimp, blue crabs, and oysters directly affects the benefits of the entire culture because è› likes to grow in algal rich areas, with relatively low transparency requirements for water bodies, and for middle and late stages of shrimp and blue crabs. The growth has higher water quality requirements. According to this feature, in the early stage of aquaculture, the water quality should be adjusted so as to facilitate rapid growth, but care should be taken not to overuse the chemical fertilizer so as to avoid causing excessive levels of heavy metal ions and death due to poisoning.
3. The inspection of the patrol ponds will be carried out twice a day in the morning and evening. The inspection will include poolsides, anti-escape facilities, shrimp and crab shells, food intake, and growth. If any problems are found, prompt remedial measures should be taken. To prevent the crabs from escaping and digging up foods? It is an important part of day-to-day management and must not be taken lightly. The blue crabs are mostly active at night, and it is more important to strengthen night-time inspections. During the culture process, the growth of shrimps, crabs, and clams should be periodically checked and determined, providing a reference for the daily management measures adjustment.
4. Disease Prevention and Control The prevention and treatment of diseases adopts the principle of “prevention first, prevention and control combined†to carry out comprehensive prevention and control. It is necessary to use dibromohydantoin, bromochlorohydantoin and quaternary ammonium salt every 10 days to 15 days. Iodine and other cross-spray disinfection.
I. Pond selection For ponds with shrimps, blue crabs, and oysters, in addition to the basic requirements for common shrimp ponds, there must be separate intake and drainage systems, with convenient inlet and outlet water, and a water exchange capacity of more than 20%. At the end, argillaceous soil is better for growth. Each pond must also have a shoal (water depth 30 cm to 40 cm) that accounts for more than 25% of the pond area in order to build an oyster. The water quality requirements are non-polluting. The specific gravity of seawater is 1.010 to 1.020, the pH value is stable at 7.8 to 8.4, the ammonia nitrogen content is less than 0.6 milligrams per liter, and the bottom sediment hydrogen sulfide is less than 0.01 milligrams per liter. Adjacent to the best fresh water sources, in order to facilitate the regulation of salinity.
Second, preparation before stocking
1. The dredging and renovation ponds must be completely dredged and the embankments, gates and other facilities must be repaired before stocking.
2. Jianou, circling nets for prevention If it is in Xintang, 20 days before sowing, cattle should be used as a shoal to build rakes. The depth of ploughing will be 20 cm to 30 cm. The conditions of the pond may vary depending on the width of the pond, which ranges from 2m to 3m, with shallow ditch on both sides of the pond. The area accounts for 20% of the total area of ​​the pond. The turned over mud is then crushed with bovine chopped water and soaked in water. Laotang only needs a little trimming. Lastly, 21 nylon nets must be placed on the gills, with a mesh size of 3.5 cm to 4.0 cm. The net edges around the gills must be pressed tightly so as to prevent the blue crabs from entering the digging area, causing unnecessary losses. Anti-escape net adopts 40-mesh sieve net, and then fixed by small wooden stakes. The spacing of wooden stakes is 50 centimeters, and the height from the ground is 40 centimeters. However, the upper edge of the screen mesh must be flattened toward the inside to make the width of the fold. It is 20 centimeters to avoid crab crawling to escape.
3. In the two weeks prior to the disinfection and stocking of clear ponds, 15 kg of bleaching powder or 15 kg of tea seed cake was used for clear pond disinfection per acre of the pond. After 3 days, the water was drained and then filtered into natural seawater filtered through a 80 mesh sieve.
4. Culture of plankton The inoculation of seedlings into the water 20 cm to 30 cm 10 days before stocking, and the algae cultivation after biological and physical treatment of water quality and sediment. This can change the traditional fertilizer manure ponds, resulting in excessive residual mud conditions.
Third, seedling stocking
1. Seedling stocking seedlings to choose the shell is jade white, shiny, robust, shell is not broken, the specifications of high quality seed. The simple method to identify the advantages and disadvantages of seedlings is to shoot the baskets by hand after mounting the seedlings. The sound produced by the seedlings when the shells are closed by surprise is the better the seedlings, and vice versa. The stocking time is generally after the Ching Ming period. The average stocking density is 300 to 350 grains per square meter, and the stocking area does not exceed 20% of the total pond area.
2. Shrimp stocking There are many varieties of shrimp that can be raised at present, such as Chinese shrimp, P. monodon, P. new penaeus, Penaeus vannamei and so on. Election varieties should also be based on the life habits of the shrimp to determine the time of stocking, but considering that as a polyculture, the density must not be too high, generally the amount of seedlings per mu is 10,000 to 15,000.
3. The selection and breeding of blue crabs The crabs generally have four seasons. Spring and autumn seedlings are preferred. The current crab seedlings are mainly from artificially harvested natural seedlings. The seedling size varies from 1 cm to 3 cm. We must choose hard, neat and well-matched specifications and appendages, at least crabs that cannot be missed by chewing feet and swimming feet. The stocking density can be determined according to the conditions of the water body. Generally, the pond along the coast of Sanmen County in Zhejiang Province should have no less than 1,000 mu per mu. The seedlings should not be thrown into the water directly. They should be placed on the shore near the water, so that they can go into the water so as to avoid drowning and cause the survival rate to decline.
Fourth, daily management
1. The feeding of feedstuffs to shrimps, blue crabs, and cockroaches should be based on feeding seedlings. In the middle and later stages of polyculture, the feeding of blue crabs should be the main method. The fed amount of fresh feed and compound feed should be flexibly controlled according to the weight of shrimps, crabs, quails, feeding activities, water temperature, and water quality. It is better to eat less than enough food. Feeding should be evenly spread and should not be fed regularly to prevent shrimps and crabs from competing for food.
2. Regulation of Water Quality The regulation of water quality in shrimp, blue crabs, and oysters directly affects the benefits of the entire culture because è› likes to grow in algal rich areas, with relatively low transparency requirements for water bodies, and for middle and late stages of shrimp and blue crabs. The growth has higher water quality requirements. According to this feature, in the early stage of aquaculture, the water quality should be adjusted so as to facilitate rapid growth, but care should be taken not to overuse the chemical fertilizer so as to avoid causing excessive levels of heavy metal ions and death due to poisoning.
3. The inspection of the patrol ponds will be carried out twice a day in the morning and evening. The inspection will include poolsides, anti-escape facilities, shrimp and crab shells, food intake, and growth. If any problems are found, prompt remedial measures should be taken. To prevent the crabs from escaping and digging up foods? It is an important part of day-to-day management and must not be taken lightly. The blue crabs are mostly active at night, and it is more important to strengthen night-time inspections. During the culture process, the growth of shrimps, crabs, and clams should be periodically checked and determined, providing a reference for the daily management measures adjustment.
4. Disease Prevention and Control The prevention and treatment of diseases adopts the principle of “prevention first, prevention and control combined†to carry out comprehensive prevention and control. It is necessary to use dibromohydantoin, bromochlorohydantoin and quaternary ammonium salt every 10 days to 15 days. Iodine and other cross-spray disinfection.
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