Large silverfish transplantation and proliferation technology

First, broodstock fishing The broodstock is selected during the spawning season to ensure successful reproduction. These fish are captured using ice-sinking gill nets, and it's crucial to collect them within two hours of capture to maintain viability for fertilization. The timing is critical, as delays can reduce the success rate of spawning. Second, dry artificial insemination Mature broodstock is carefully selected. For females, the gonads are gently squeezed to release eggs into a dry fertilization container. Meanwhile, male fish are handled by squeezing their crescent-shaped, milky-white testes near the vent to release sperm. The semen flows along the dorsal fins and is introduced to the eggs. After three males are processed, the anal and caudal fins of both sexes are gently stirred to mix the gametes. Next, 20 ml of 0.7% physiological saline is added to activate the sperm, followed by continued stirring for one minute, then allowing it to rest for 1–2 minutes before transferring the mixture to the hatching tray. Once enough 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 number of fertilized eggs, different incubation methods are used. 1. Container incubation: Clean, rinsed eggs are placed in fresh water-filled trays, kept at a depth of 2 cm. A density of 500,000 to 1 million eggs per square meter is ideal. The eggs are stirred every two hours, and water is changed daily, with dead eggs removed promptly. 2. Pool incubation: A rectangular hatching pond, 1.5 meters wide and 3 meters long, is constructed on a concrete floor using bricks or wood. A plastic sheet is laid on the bottom, and 1 to 2 million eggs are placed per square meter. Water depth should be 4 cm, with a temperature maintained between 2–5°C. Water is changed daily, not exceeding one-third of the total volume each time. 3. Fertilization rate calculation: Throughout the hatching process, the development of the embryos is observed under a microscope or dissecting scope. The fertilization rate is determined once the eggs reach the midgut stage. Fourth, handling fertilized eggs 1. Location selection: Choose a sheltered, sunny area with stable water conditions, a depth of 1.5–2.5 meters, rich zooplankton for food, few predators, and a hard or sandy bottom. The water should be clear and suitable for egg survival. 2. Transportation: Eggs are transported in sealed nylon bags with oxygenation. Each liter of water should contain 50,000–100,000 eggs. The transport water temperature must match that of the incubation environment to avoid shock. 3. Dispersal: Slowly submerge the egg bag into the water until the temperatures equalize. Then, open the bag and spread the eggs evenly. Stir gently with a wooden board or stick to prevent clumping and ensure even distribution. Fifth, monitoring silverfish growth After the fertilized eggs are released, the growth, feeding behavior, and gonadal development of the whitebait should be regularly measured. Water quality and food availability are also monitored frequently to support healthy development and provide accurate data for resource assessment. This ongoing observation helps ensure the success of the breeding program and supports sustainable management practices.

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