How can yields be increased during freshwater shrimp (Macrobrachium nipponense) farming?
Question: How can freshwater shrimp yields be increased?
At present, freshwater shrimp are mainly reared in ponds. If the average yield per unit area can be raised to 80 kg/mu, relatively good economic returns can be achieved. The key techniques for increasing the yield per unit area of pond-reared freshwater shrimp are described below:
1. Pond conditions. (1) Water source. The water source must be abundant, clean and pollution-free, meet fishery water standards, and allow convenient intake and drainage. (2) Shrimp pond. The area should not be too large; 0.201-3.35 hectares is preferable. (3) Pond slope and water depth. The slope should be 1:2.5-1:3, and the water depth 1.2-1.5 m. (4) Bottom substrate. The mud should not exceed 10 cm, and the bottom should slope somewhat toward the drainage outlet.
2. Preparatory work before stocking. (1) Pond clearing. Seven to ten days before stocking, slake 75 kg of quicklime in water and splash it over the whole pond to thoroughly eliminate wild trash fish and pathogens. (2) Filling with water. Four days after pond clearing, fill with water to 50 cm. (3) Applying base fertilizer. Before filling with water, apply 300-400 kg of fermented organic fertilizer per mu. (4) Planting aquatic plants. Plant aquatic plants such as tape grass (Vallisneria), Elodea, and Potamogeton malaianus in the shallow-water zones around the pond; the planted area should account for about 40% of the shrimp pond area.
3. Stocking model (two crops of stocking). (1) The first crop yields about 50 kg per unit. Stocking takes place from late July to early August, with 40,000-50,000 shrimp fry about 2 cm in size stocked per mu. Stocking should be done in the early morning or evening on clear days, avoiding direct sunlight during the day, and should be completed in a single stocking. To regulate water quality and control autumn breeding, fish such as bighead carp must be stocked in combination. There are two polyculture methods: first, polyculture with overwintered bighead carp, stocking 30 bighead carp of 0.3 kg each per mu; second, polyculture with bighead carp and blunt snout bream summer fry, stocking 800 of each per mu. The first crop ends with pond draining in December. (2) The second crop is stocked from December to January with young shrimp about 3 cm in size, at 20 kg per mu. This is monoculture, without polyculture of fish. It ends by the end of June the following year.
4. Feeding and management. (1) Water quality. During the rearing period, good water quality and a suitable water level must always be maintained. According to the water color and transparency of the shrimp pond, water should be added or drained in a timely manner to regulate water quality, keep dissolved oxygen in the pond water sufficient and the water fresh, and promote the growth, development, and molting of the shrimp. In the later rearing stage, the water should be changed frequently. If frequent water changes are not possible, an appropriate amount of photosynthetic bacteria and bottom-improving agents can be splashed periodically. During the rearing period, quicklime and phosphate fertilizer should also be applied at the right time according to the pH of the pond water and its calcium and phosphorus content. The amount of quicklime each time is 10-20 kg per mu, and the amount of superphosphate each time is 8-10 kg per mu. Generally, apply once every 15 days or so. (2) Feeding and fertilizing. The feed should be based mainly on pelleted feed for freshwater shrimp, supplemented by fresh live bait such as snails, clams, and small trash fish. The protein content of the pelleted feed must reach more than 35%. The suitable feeding temperature for freshwater shrimp is about 25°C. Feeding should follow the "four fixeds" (fixed time, fixed quality, fixed quantity, and fixed person). In the early rearing stage, suitably sized feed should be splashed over the whole pond; later, it should be placed on the shallow shoals around the pond and on feeding strips, with one feeding point set every 1-2 m. The number of feedings is generally 2 times per day; when the water temperature is 25-30°C, they should be fed 3 times per day. In the morning, feed 1/3; in the afternoon, feed 2/3. Feeding should be uniform so that all shrimp in the pond can eat and eat their fill. The daily feeding amount of artificial compound feed can first be trial-fed at 2.5-5% of the body weight of the shrimp in the pond, and then adjusted according to the feeding situation of the shrimp. Generally, the feed should be consumed within 1-2 hours after feeding. The standing stock of freshwater shrimp in the pond can be roughly estimated from the average number per unit area and the average body weight of the shrimp. To increase natural food organisms in the pond, additional fertilizer should be applied at the right time and in the right amount according to the water color and transparency of the shrimp pond. A yellow-green or tea-brown water color is relatively suitable, and the transparency should preferably be maintained at about 30 cm. (3) Aquatic plants. According to the growth of the aquatic plants, promptly splash fertilizer solution in the planting areas. The concentration of the fertilizer solution should not be too high, so as to avoid fertilizer damage. (4) Daily management. The shrimp pond must be managed by dedicated personnel, with 3-4 pond patrols every day, and corresponding measures taken promptly when problems are found. Pay attention to the environmental sanitation of the shrimp pond and strengthen the prevention and control of diseases and insect pests of freshwater shrimp.
1. Pond conditions. (1) Water source. The water source must be abundant, clean and pollution-free, meet fishery water standards, and allow convenient intake and drainage. (2) Shrimp pond. The area should not be too large; 0.201-3.35 hectares is preferable. (3) Pond slope and water depth. The slope should be 1:2.5-1:3, and the water depth 1.2-1.5 m. (4) Bottom substrate. The mud should not exceed 10 cm, and the bottom should slope somewhat toward the drainage outlet.
2. Preparatory work before stocking. (1) Pond clearing. Seven to ten days before stocking, slake 75 kg of quicklime in water and splash it over the whole pond to thoroughly eliminate wild trash fish and pathogens. (2) Filling with water. Four days after pond clearing, fill with water to 50 cm. (3) Applying base fertilizer. Before filling with water, apply 300-400 kg of fermented organic fertilizer per mu. (4) Planting aquatic plants. Plant aquatic plants such as tape grass (Vallisneria), Elodea, and Potamogeton malaianus in the shallow-water zones around the pond; the planted area should account for about 40% of the shrimp pond area.
3. Stocking model (two crops of stocking). (1) The first crop yields about 50 kg per unit. Stocking takes place from late July to early August, with 40,000-50,000 shrimp fry about 2 cm in size stocked per mu. Stocking should be done in the early morning or evening on clear days, avoiding direct sunlight during the day, and should be completed in a single stocking. To regulate water quality and control autumn breeding, fish such as bighead carp must be stocked in combination. There are two polyculture methods: first, polyculture with overwintered bighead carp, stocking 30 bighead carp of 0.3 kg each per mu; second, polyculture with bighead carp and blunt snout bream summer fry, stocking 800 of each per mu. The first crop ends with pond draining in December. (2) The second crop is stocked from December to January with young shrimp about 3 cm in size, at 20 kg per mu. This is monoculture, without polyculture of fish. It ends by the end of June the following year.
4. Feeding and management. (1) Water quality. During the rearing period, good water quality and a suitable water level must always be maintained. According to the water color and transparency of the shrimp pond, water should be added or drained in a timely manner to regulate water quality, keep dissolved oxygen in the pond water sufficient and the water fresh, and promote the growth, development, and molting of the shrimp. In the later rearing stage, the water should be changed frequently. If frequent water changes are not possible, an appropriate amount of photosynthetic bacteria and bottom-improving agents can be splashed periodically. During the rearing period, quicklime and phosphate fertilizer should also be applied at the right time according to the pH of the pond water and its calcium and phosphorus content. The amount of quicklime each time is 10-20 kg per mu, and the amount of superphosphate each time is 8-10 kg per mu. Generally, apply once every 15 days or so. (2) Feeding and fertilizing. The feed should be based mainly on pelleted feed for freshwater shrimp, supplemented by fresh live bait such as snails, clams, and small trash fish. The protein content of the pelleted feed must reach more than 35%. The suitable feeding temperature for freshwater shrimp is about 25°C. Feeding should follow the "four fixeds" (fixed time, fixed quality, fixed quantity, and fixed person). In the early rearing stage, suitably sized feed should be splashed over the whole pond; later, it should be placed on the shallow shoals around the pond and on feeding strips, with one feeding point set every 1-2 m. The number of feedings is generally 2 times per day; when the water temperature is 25-30°C, they should be fed 3 times per day. In the morning, feed 1/3; in the afternoon, feed 2/3. Feeding should be uniform so that all shrimp in the pond can eat and eat their fill. The daily feeding amount of artificial compound feed can first be trial-fed at 2.5-5% of the body weight of the shrimp in the pond, and then adjusted according to the feeding situation of the shrimp. Generally, the feed should be consumed within 1-2 hours after feeding. The standing stock of freshwater shrimp in the pond can be roughly estimated from the average number per unit area and the average body weight of the shrimp. To increase natural food organisms in the pond, additional fertilizer should be applied at the right time and in the right amount according to the water color and transparency of the shrimp pond. A yellow-green or tea-brown water color is relatively suitable, and the transparency should preferably be maintained at about 30 cm. (3) Aquatic plants. According to the growth of the aquatic plants, promptly splash fertilizer solution in the planting areas. The concentration of the fertilizer solution should not be too high, so as to avoid fertilizer damage. (4) Daily management. The shrimp pond must be managed by dedicated personnel, with 3-4 pond patrols every day, and corresponding measures taken promptly when problems are found. Pay attention to the environmental sanitation of the shrimp pond and strengthen the prevention and control of diseases and insect pests of freshwater shrimp.