Taihu Lake Silverfish Culture Technology

Taihu Lake Silverfish Culture Technology

Taihu large whitebait is delicious and nutritious, and it is an important traditional export product of China. Nowadays, the transfer of large silverbait in Taihu Lake has become an effective measure for the development of inland waters, and the aquaculture efficiency is continuously improving.

1. Biological characteristics The adult fish of Taihu Lake has about 13-22 cm in length. Its shape is slightly rounded and jade-like. It looks like boneless and intestine. It is delicate and transparent, with silver color.

Taihu Lake has a one-year growth cycle and can reproduce itself in natural waters. During the middle and late December and early September, it is the breeding season. The optimum temperature for the breeding season is 3 to 4°C, and the fertilized egg hatch time is 63 to 65 days, the temperature of the hatched membrane was 6 to 7°C. The normal development temperature of fertilized eggs in Taihu Lake Silverfish is 0～15°C. Fertilized eggs can develop normally in the water with salinity less than 2%. The hatching seedlings can grow normally in the water with less than 0.8% salinity.

The silverfish began to feed on the 7th day after hatching, and the food was mostly phytoplankton. As the individual grows, the bait gradually turns to small zooplankton such as rotifers, cladocera, copepods, and small fish and shrimp.

2. The culture of Taihu Lake is mainly based on the transplantation of inland large surface waters. Although the current research on pond culture has achieved certain results, it has not yet entered the production stage.

(1) Conditions for transplanting waters. The area of ​​transplanted water should be at least 1,000 mu and the water depth should be more than 1.5 meters; the water in the transplanted water should be non-pollution and conform to the fishery water quality standards promulgated by the state; the ecological structure of the transplanted water area should be better, and it needs a certain bait basis; If it is too large, it should be less than 40%. The composition of the fish in the transplanted waters should be as simple as possible. In particular, the number of ferocious meat-eating fish such as fish, pike and horsefish should be small, so that the big silverfish as a kind of “ Filled-type fishes are easy to develop; in addition there must be suitable spawning grounds. In the transplanted waters, leeward suns and depths of 2 to 3 meters must be able to be found. The sediments are hard-boiled, silt-bearing or sand-bottomed breeding grounds. .

(2) Transplantation of large silverbait in Taihu Lake.

1 fertilized egg collection and transportation. Transplantation of Taihu Lake silverfish is generally performed by transplanting fertilized eggs from the Taiyuan region's origin, and then transporting them to their destination. In the Taihu Lake region, from mid-December to early-January of the following year, when the water temperature is 5-8°C, it is the golden age for the breeding of large whitebait. At this time, the broodstock with excellent constitution and mature gonads was selected for dry fertilization. The male to female ratio was 1:1.5. After the fertilized eggs are collected, they can be packaged in two ways. The first method can be used 15cm 15cm plastic bags, add water 250ml, each bag into 30,000 eggs oxygen sealed; the second method is to use 16cm 16 Centimeters of wet gauze, placed in 30,000 incubators and evenly folded. Put the fertilized eggs into a thermos flask with a capacity of 8 liters, put 5 plastic bags or 5 fertilized eggs of warm gauze into each flask, and put ice cubes on every other layer to cover the bottle caps. . Transportation can be by air or train.

2Feeding density and transfer of fertilized eggs. The amount of fertilized eggs laid is determined by the effective area of ​​the transplanted water body. In general, 100,000 effective fertilized eggs need to be placed per thousand mu of water. The oviposition water should be selected before laying eggs. The depth of the oviposition zone should be 5-6 m, and the sediment should be hard mud or sand. There are two ways to serve, the first is direct delivery. After selecting the area to be put into use, multiple delivery points should be selected at the same time so as to avoid improper delivery of the "all army". At the time of release, several ice eyes were opened on the water surface, and then the plastic bag was immersed in the storage water. After the water temperature in the bag was consistent with the temperature of the storage water, the fertilized eggs were slowly and uniformly poured into the storage water. The second method is to sink the cage under the ice. Place several ice eyes of 1m square on the ice and place the fertilized eggs in a 50cm, 50cm and 10cm gauze box. Then slowly sink the cage into the water until the cage sinks. When it is 2 meters deep, it is fixed with wood or plastic floats and floats on the water as a mark. In general, direct delivery is better than hatching.

3 fertilized egg management. After the fertilized eggs are placed in the reservoir, they must be patrolled frequently at the ovulation site within 3 to 4 days to prevent the cages from being taken away by the water surface to cause losses. After every 15 to 20 days, break the ice and lift the cage up to the surface. Use a brush to brush off the attachments on the cage. Use a straw to suck out a certain number of eggs. Check the embryo’s development and survival rate. The box slowly sinks into the water.

4 Examination of transplantation effects and repeated transplantation. In general, after the reservoir moves into the fertilized egg of the giant whitebait, it can see adult fish in the same year, form a population in the second year, and enter the production stage in the third year, resulting in economic benefits. It may be because the number of transplanted objects is very small in the first few generations of migration into new reservoirs, and the transplanted objects are often not seen for a period of time. This phenomenon is the incubation period. The length of the incubation period depends on the number of transplants, methods, reservoir size, and ecological environment. In order to ensure the success of transplantation, it can be transplanted once again in the second year or by artificial insemination.

3. Fishing, processing, and sale of Taihu Lake Silverfish are generally started in the fall. At this time, the weight of the large whitebait has reached the commercial specifications. From this time onwards, the cluster of whitebait fish gradually transitioned to the peak period, peaked before freezing, and achieved the largest daily production. The fishing method generally adopts single or double trawls, and can also be gilled, but the efficiency of the latter is not as high as the former. After harvesting, it is usually processed into quick-frozen 1kg packages and sold domestically or exported.

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