What should be paid attention to in freshwater crayfish stocking?

In recent years, crayfish has become a pet on the table, and its price has doubled. It is predicted that the crayfish market will not be saturated in the next five years, and crayfish farming in various places will be carried out rapidly. After several years of production practice, the author thinks that the stocking of crayfish should pay attention to the following points:

Tangkou choose to cultivate crayfish Tangkou, the area should be moderate, generally in 20 mu ~ 50 mu. The ratio of pond to slope is larger, at 1 ∶ 2.5 to 1 ∶ 3, which is convenient for crayfish to live and reproduce, and at the same time reduce the escape of crayfish. The pond is rich in natural bait organisms and aquatic plants.

Thoroughly clear the crayfish 10 days before stocking, drain the pond water and clean the pond thoroughly with 100 kg of quicklime per mu. Kill enemy organisms and various pathogens. 100 kg ~ 200 kg organic fertilizer per mu was applied to cultivate bait organisms.

Ecological cultivation plant water plants in the shallow water around the pond, accounting for 40% to 60% of the pond area, including bitter grass, Elodea, verticillium verticillata, hyacinth, water floating lotus and so on, which can be eaten by crayfish and is an ideal place for crayfish to hide and live. In addition, the bottom of the pond can also be made of water grass into a haystack, put a pile every 5 meters, each pile 5 kg ~ 10 kg, sink at the bottom, put 15 ~ 20 piles per mu. The haystack is fastened with a rope, and the other end of the rope is fixed to the water.

Selection of shrimp species because artificial propagation of crayfish is not fully mastered at present, crayfish seedlings are mainly natural reproduction, so the selection of shrimp species is particularly important. The time for selecting and releasing crayfish parent shrimp is generally from the end of August to the middle of October, and can be fished from culture ponds or natural waters. Male and female parent shrimps are required to come from different waters to reduce inbreeding. The parent shrimp should not leave the water for more than 2 hours, and the time can be longer in indoor or humid environment. Male and female identification: the first and second gastropods of ⑴ male prawns evolved into white, calcareous tubular connectors; the first gastropods of female prawns degenerated and the second gastropods were pinnate. The reproductive foramen opening of ⑵ male shrimp is not obvious at the base of the fifth pair of chest feet, while that of female shrimp is at the base of the third pair of chest feet, showing an obvious pair of dark round holes. For adult shrimp with similar body length of ⑶, the chelate foot of male shrimp is thick, and the spinous process on carpal and metacarpal segments is long and obvious, while that of female shrimp is relatively small.

Parent shrimp stocking requires strong physique, complete appendages, uniform specifications, and a full foot at a time to avoid batch release, which can reduce the killing of each other. When stocking parent shrimp, it is necessary to keep them evenly along the pond and distribute them evenly. For the parent shrimp transported over a long distance, soak the parent shrimp in water for 3 ~ 5 minutes, then put the parent shrimp next to the pond for 2 ~ 3 minutes, repeated 2 ~ 3 times, after allowing the parent shrimp to absorb enough water, and then slowly put the parent shrimp into the pond, the survival rate can be improved. The female-to-male ratio of parent shrimp is usually 2-3 ∶ 1. Crayfish can mate and lay eggs in autumn and winter, and the mating season is usually from September to December. In early March of the following year, when the temperature rises to 12 ℃ and the water temperature rises to more than 10 ℃, shrimp will leave the cave to feed and move. At this time, management should be strengthened and artificial feed should be given. Strengthen feeding when the water temperature is above 18 ℃. When a large number of young shrimps hatch, cages can be used to catch parent shrimps that have been bred.

The stocking density is mainly raised in crayfish ponds, with 30 kg ~ 40 kg per mu and more than 30 g / mu. After parent shrimp is released, artificial feed is fed in time, and fishing in cages and cages begins in April of the following year, with an annual yield of 200 kg ~ 300 kg per mu. From now on, it will only be harvested every year, and there is no need to plant seeds. It should be noted that fishing should not be overdone, such as overfishing, the yield in the coming year is bound to be greatly reduced, at this time the need for supplementary planting. The mixed culture pond breeds shrimp 10 kg ~ 20 kg per mu, the specification is about 25 g / mu, without feed, mainly with natural bait in the pond and residual bait in the fishing pond. the cage fishing begins in April of the following year, and the yield per mu is generally 50 kg ~ 100 kg.