Large silverfish transplantation and proliferation technology

First, broodstock fishing The broodstock is carefully selected to spawn during the spawning season. They are caught using ice-sinking gill nets, and it's crucial to collect them within 2 hours of capture to ensure viability before fertilization. The timing is critical to maintain the quality of the gametes. Second, dry artificial insemination Mature broodstock is chosen, and the female’s gonads are gently squeezed to release eggs into a dry fertilization container. Meanwhile, the male’s crescent-shaped, milky-white testes near the vent are squeezed, allowing the milt to flow along the fins toward the eggs. After three males have been used, the anal and caudal fins of both sexes are gently stirred to mix the sperm and eggs thoroughly. Next, 20 ml of 0.7% physiological saline is added to activate the sperm, and stirring continues for one minute before letting it rest for 1–2 minutes. The mixture is then transferred into a hatching tray. Once enough fertilized eggs are collected, they are rinsed several times with clean water and filtered to remove any debris or tissue fragments. Third, incubation management Depending on local conditions and the quantity of fertilized eggs, different incubation methods are applied. 1. Container Incubation: After rinsing, the fertilized eggs are placed in fresh water trays at a depth of 2 cm. A density of 500,000–1,000,000 eggs per square meter is maintained. The eggs are stirred for two hours, and the water is changed daily while dead eggs are removed. 2. Pond Incubation: A rectangular hatching pond, approximately 1.5 meters wide and 3 meters long, is constructed on a concrete floor using bricks or wood. A plastic sheet is laid as a base, and 1–2 million fertilized eggs are placed per square meter. The water depth is kept at 4 cm, with a temperature between 2–5°C. Water is changed daily, with no more than one-third of the volume replaced each time. 3. Fertilization Rate Calculation: During the hatching process, the development of the embryos is observed under a microscope or dissecting scope. The fertilization rate is calculated when the egg reaches the midgut stage. Fourth, handling fertilized eggs 1. Location: Choose a sheltered area with stable water, a depth of 1.5–2.5 meters, rich zooplankton, fewer predators, and a hard or sandy bottom. The water should be clear and suitable for egg survival. 2. Transportation: Eggs are transported using sealed nylon bags with oxygenation. The concentration is 50,000–100,000 eggs per liter of water. The transport water temperature must match the incubation temperature to prevent shock. 3. Dispersal: Slowly submerge the egg bag into the water until the temperatures equalize. Then, open the bag and evenly spread the eggs in the water. Stir gently with a wooden paddle to avoid clustering and ensure even distribution. Fifth, monitoring the growth of silverfish After the release of fertilized eggs, the growth, feeding habits, and gonadal development of the whitebait should be monitored regularly. Water quality and food availability are also checked periodically to support healthy development and provide data for resource management decisions.

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