Rescue white shrimp seedlings pay attention to several major points

Penaeus vannamei, also known as the Pacific white shrimp, is one of the top three shrimp species in global aquaculture production. It is primarily found along the Pacific coast of the Americas, ranging from northern Peru to Sonora, Mexico, with the highest concentration along the coast of Ecuador. This species thrives best in temperatures between 18°C and 32°C. When the temperature drops below 16°C, its activity decreases significantly, and growth ceases. The ideal range for optimal growth is 23°C to 30°C. If the temperature falls below 9°C, the shrimp may begin to die. In terms of salinity, Penaeus vannamei prefers a range of 2‰ to 40‰. In recent years, Penaeus vannamei has become a major focus in aquaculture due to its high market demand and profitability. With the successful desalination trials, regions like Doumen and Xinhui in Guangdong have started cultivating this species, importing shrimps from South America. Over the past two years, through direct engagement with on-site producers, the author has gathered valuable insights into both successes and failures in raising this species. Additionally, extensive research was conducted, leading to a comprehensive summary of early stocking practices and key technical elements involved in Penaeus vannamei farming. **Shrimp Selection and Transportation** Selecting high-quality shrimp is crucial for successful breeding. Only healthy shrimp free from pathogens—especially viruses like White Spot Syndrome Virus (WSSV) and Taura Syndrome Virus (TSV)—should be chosen to ensure smooth cultivation. Currently, most shrimps used in Doumen and Xinhui come from Hainan and Zhanjiang. Therefore, it's essential to source them from farms with good water quality and a solid reputation. Visually, healthy shrimp should exhibit strong vitality, swim with clear direction, respond quickly to external stimuli, have transparent bodies, firm muscles, no visible lesions, and no discoloration on their antennae or legs. Their gut should appear full and clear. During transportation, oxygen supply must be maintained, and the density depends on factors such as transport duration, shrimp size, water quality, and temperature. Typically, 70 cm x 37 cm polyethylene bags are used with oxygen. For trips under 10 hours, the water temperature should be between 18°C and 26°C, and shrimp sizes around 0.8–1.0 cm can be transported at about 1,500 per bag. **Pond Preparation and Water Management** Penaeus vannamei requires clean substrate conditions. Excess organic matter in the pond bottom can lead to shrimp mortality. Experts recommend keeping ammonia-nitrogen below 0.5 ppm, nitrite-nitrogen below 0.1 ppm, dissolved oxygen above 5 ppm, and hydrogen sulfide below 0.1 ppm. After dredging, 150 kg of quicklime should be applied, and the pond should be sun-dried if possible. All harmful organisms, competitors, and potential pathogen carriers must be removed before introducing shrimp. A non-leaking plastic woven cloth can be placed in corners to create a separate area for shrimp culture and dilution. Water backflow must be filtered to prevent unwanted debris and predators. Sterilization methods include using lime, bleaching powder, sodium dichloroisocyanurate, hydantoin, chlorine dioxide, quaternary ammonium salts, and iodine-based compounds. **Desalination and Cultivation** Although Penaeus vannamei can grow in freshwater, it requires specific conditions during the seedling stage. The salinity in the pond should match that of the original farm. Typically, it can be diluted to 6‰–10‰, but once introduced to the pond, it should be gradually reduced over 10–15 days to 1‰–2‰. Too rapid a change can hinder growth. The pH level should remain between 8.0 and 8.6 during the larval stage. This species has high nutritional demands, especially during the early stages. Basic feed is critical for success, particularly within the first month after stocking. At this time, shrimp are usually 0.98–1.0 cm in size and grow to 3–4 cm. During this period, they rely mainly on natural bait. The water color should be yellow-green or light brown. Organic fertilizers like chicken, pig, or cow manure are often used, while inorganic fertilizers such as urea and compound fertilizers are also common. Organic fertilizer should be crushed, dried, and fermented before being placed in fiber bags and hung in the pond until the water turns thick. Inorganic fertilizers are typically applied at 1–1.5 kg/acre of urea and 2 kg/acre of compound fertilizer. The timing depends on weather and water temperature—longer in early spring and shorter in summer. Once the water is sufficiently colored, it's the best time to introduce seedlings. Prolonged preparation can negatively impact shrimp growth. Adding beneficial bacteria can also help maintain a healthy microbial balance and reduce disease risk. **Pre-Stocking Precautions** 1. Shrimp should be released on sunny days, preferably around 10 a.m. or in the evening. Avoid planting during rainy days or at noon. 2. Ensure each pond is fully stocked at once to avoid "Kung-sun shrimp" (uneven growth), which affects productivity. 3. Stocking density should not be too high; generally, 40,000–55,000 per acre is recommended. 4. Shrimp should be placed in the wind. Before release, the entire bag should be soaked in the pond for about 30 minutes to allow the water temperature inside the bag to match that of the pond.

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