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Earthen pond closed shrimp farming mode
In order to prevent the outbreak of shrimp viruses, some aquaculture farms have explored various breeding methods, such as high-density shrimp farming, brine-to-freshwater farming, and industrial-scale shrimp cultivation. However, due to the high initial investment required, many small-scale farms and individual households find it difficult to adopt these techniques. In recent years, the Sanzhonggang Aquaculture Farm in Binhai County, Jiangsu Province, has introduced an earth pond closed-system shrimp farming model. This method is known for its low cost, high efficiency, and high survival rate, making it increasingly popular among local farmers. Below are the key technical details of this model:
1. **Pond Conditions**
The water quality in the area where the ponds are located should be free from pollution caused by industrial wastewater from sugar mills, paper factories, and starch processing plants. The natural water depth should be more than 60 cm, and the annual salinity variation in seawater should not drop below 1 inch. Freshwater can be drawn from well systems.
2. **Intake Gate Setup**
Since the system is a closed-earth pond, there is no need to take in seawater during the later stages of farming. Therefore, only one intake gate is required. For every 10 acres of ponds, a 1-meter-wide intake gate is installed with three separate gates inside the chamber. A filter mesh is placed in the outer tank, while the middle gate is about 20 cm wide, allowing for easy adjustment of water levels. The inner tank is equipped with a conical filtration net.
3. **Preparation Before Stocking**
(1) Drill wells within the ponds to ensure a continuous supply of water. A pump capable of delivering 100 cubic meters per 5 acres of pond should be installed.
(2) After cleaning the pond, fill it with 10 cm of water and apply 80 kg of lime per acre. Once the lime is fully mixed, remove the slurry using a shovel or bamboo raft.
(3) After disinfection, drain the water, install a 60-mesh sieve and a conical mesh bag (8 meters long and 100 meters in total), and secure the bottom of the gate with cotton cloth or sacks to prevent gaps. For the first time, a block is placed behind the gate to prevent excessive water flow that might damage the net. Within 2–3 days, fill the pond to a depth of 60–70 cm and seal the gate with clay to prevent leakage.
4. **Stocking Density**
Depending on the pond depth, the stocking density varies. For a water depth of 1–1.3 m, tiger shrimp should be stocked at 8,000–10,000 per acre, while white shrimp from South America should be stocked at 10,000–12,000 per acre. For deeper ponds (1.4–1.8 m), tiger shrimp larvae should be stocked at 19,900–130,000 per mu, and white shrimp at 13,000 per mu. Seedlings should be of appropriate size: 1–1.2 cm for tiger shrimp, and 0.8–1.2 cm for white shrimp.
5. **Feeding Strategy**
Feed the shrimp in small portions. Before reaching 6 cm in length, feed them three times daily: 30% at 6:30, 50% at 18:00, and 20% at 23:30. After they grow beyond 6 cm, increase feeding to four times a day: 25% at 6:00, 15% at 10:30, 40% at 18:00, and 20% at 23:30.
6. **Water Quality Management**
After introducing the seedlings, add well water every two days, increasing the water level by 5 cm each time until the desired depth is reached. During hot summer months, keep the pond filled to the top. Two days before a rainstorm, fill the pond to the upper limit so that rainwater can overflow naturally through the gate, preventing sudden drops in salinity and pH that could harm the shrimp.
7. **Disease Prevention**
Monitor the water color and bottom condition regularly. Disinfect the pond and improve sediment quality when necessary. Apply 1.5 ppm of bleach every 15 days, and use 20 kg of zeolite or lime mud per mu to enhance bottom conditions. Administer medication courses every 15 days for 3–5 days. Mix feed with 0.3% vitamin C, 2% allicin, and a suitable amount of cod liver oil to boost shrimp immunity.