Overwintering Management Experience for Broodstock Breeding Ponds in Crayfish Aquaculture

Throughout the entire overwintering period, broodstock basically do not feed and consume a great deal of energy. Therefore, before overwintering, feeding must be intensified to strengthen the broodstock's constitution, store the necessary nutrients for safe overwintering, and increase the overwintering survival rate. When the water temperature drops below 10°C, broodstock basically enter burrows to overwinter and rarely emerge to activity. At this time, the water level should be appropriately raised to ensure there is water or moisture in the burrows, but the water depth must not exceed the burrow entrance; it should be slightly lower than the entrance. Otherwise, the broodstock will emerge from the burrows and choose new places to dig. Once the broodstock have basically entered their burrows, spread a thin layer of plant straw along the water's edge around the pond perimeter, such as rice straw, reeds, cattails, etc. First, to keep warm; second, to provide a hiding and overwintering place for the juvenile crayfish produced before the broodstock overwinter.

After the water level is filled, fertilizer should be applied to maintain a certain fertility of the water quality. Generally, about 100kg of decomposed organic fertilizer per mu is applied, piled in the water at the four corners or around the pond. In winter, water quality is greatly affected by weather and easily becomes clear. According to actual conditions, additional fertilizer may need to be applied when necessary, striving to maintain transparency at around 30cm. The purpose is that fertile water is less likely to freeze, and there will be more plankton in the water. Especially in spring, plankton will rapidly multiply in large numbers. As soon as the juvenile crayfish emerge from their burrows, they can easily obtain nutrient-rich natural feed of suitable size, which increases the survival rate of the juvenile crayfish. There are two types of broodstock burrows. One has the entrance sealed with a pagoda-shaped mound of soil; this type of burrow is commonly called a “sealed-mouth burrow,” and the crayfish remains in the burrow until spring before emerging. The other type has an open entrance, and the crayfish will swim back and forth between the entrance and the bottom of the burrow. When the weather is clear and the temperature rises, the crayfish will emerge and move about near the entrance. Because during the overwintering period, when clear weather and rising temperatures occur, a certain amount of feed should be properly applied near the open burrow entrances at midday for the red swamp crayfish that emerge to feed. At this time, increasing the overwintering survival rate is very necessary. Persist in patrolling the pond multiple times daily to observe the activity of the broodstock. In cold weather, ice must be broken promptly. At the same time, do a good job of keeping various records, especially mortality, including male and female crayfish, numbers, sizes, and weights, which must be clearly recorded. This is helpful for future feeding and estimating seedling quantity.