During the hot season, the weather becomes extremely warm, with intense sunlight and high temperatures. This leads to poor water quality, which negatively affects shrimp feeding and molting processes, and can even result in high mortality rates. Based on the practical experience of 21 households, including Liang Chunlin and Zhai Youbin, located in the coastal area of Dalian Pulandian City where the Yellow Sea meets the Bohai Sea, effective management during this period requires four key strategies.
First, it is essential to control water temperature and increase oxygen levels. As water temperature rises and shrimp grow, the water depth should be gradually increased. In the middle to late stages of aquaculture, the water level should reach 1.8 to 2 meters, and during peak heat periods, it should be maintained above 2.2 meters. During high tide, daily water exchange should be carried out. In low tide or dry seasons, mechanical irrigation and drainage are necessary to ensure that about 50% of the water is exchanged. During the hottest times, the pond should be fully filled to keep the water temperature below 30°C, maintain a water clarity of around 35 cm, and stabilize dissolved oxygen at approximately 5 mg/L. This helps promote faster growth and better quality of shrimp. When changing water, it's important to prevent the entry of harmful viruses, so it's recommended to filter incoming water using a 60-mesh net.
Second, feeding should be done in phases based on the size of the shrimp. When shrimp reach 4 cm in length, feed snails, oysters, and other low-cost shellfish bait at a rate of 6-8 kg per 10,000 shrimp daily. At 8 cm, increase the feed to 50 kg per 10,000 shrimp. When they reach 12 cm, provide 100 kg per 10,000. If small shellfish are insufficient, switch to compound feed: 1.5 kg per 10,000 shrimp when they are 4 cm or larger. For every 0.5 cm increase in size, add 0.3–0.5 kg per 10,000. Once shrimp exceed 10 cm, increase by 0.7–0.8 kg per 10,000. If using chilled fish, replace 1 kg of compound feed with 2.5 kg of fish. Shrimp are nocturnal, so feeding should occur twice a day—once before sunrise and once after sunset, with 1/3 in the morning and 2/3 in the evening. The feed must be placed around the pond’s edges so all shrimp can access it. Follow the "Four More and Two Less" principle: feed more when shrimp are in the early growth stage, less in later stages; feed less in the morning, more in the evening; feed less during low tides, more during high tides; feed less when shrimp are molting, more during normal growth. Avoid feeding if the food is spoiled or if feeding in deep water or ditches.
Third, it's crucial to prevent disease outbreaks during the high-temperature season. Shrimp activity decreases, metabolism slows, and the water environment deteriorates, creating favorable conditions for pathogens. To prevent disease, avoid overfeeding and ensure feed isn't too concentrated, as this can cause spoilage. Live bait is especially prone to decay in hot weather. Regular water changes are necessary to reduce pollution. Also, adjust shrimp density to maintain sufficient active space for them.
Fourth, to prevent shrimp from floating and dying due to low oxygen levels, conduct daily inspections in the morning and evening to monitor shrimp behavior and food availability. Adjust the type and amount of feed accordingly. When shrimp molt heavily, add high-protein compound feed to prevent cannibalism. Oxygen levels drop significantly before midnight and just before dawn, making these the most dangerous times for shrimp to suffocate. If you notice white shrimp floating or small fish gathering at the pond edge, it's a sign of floating head. In such cases, start the aerator or change the water immediately.