Problems needing attention in freshwater lobster stocking

Freshwater lobster is also called crayfish. In recent years, crayfish has become a pet on the table and its value has doubled. It is predicted that the crayfish market will not be saturated in the next 5 years, and crayfish breeding will be carried out rapidly everywhere. After several years of production practice, the author thinks that the following matters should be paid attention to in crayfish stocking:

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

Thoroughly clear the pond 10 days before crayfish stocking, drain the pool water, use 100 kilograms of quicklime per mu, thoroughly clear the pond. Kill pests and pathogens. 100 kg ~200 kg organic fertilizer is applied per mu to cultivate bait organisms.

Ecological cultivation plants aquatic plants along the shallow water around the pond, accounting for 40%~60% of the pond area. The varieties include bitter grass, Elodea verticillata, Hydrilla verticillata, Eichhornia crassipes, etc., which can not only feed on crayfish, but also be an ideal place for crayfish to hide and inhabit. In addition, the bottom of the pool can also be tied into grass piles, put a pile every 5 meters, each pile of 5 kg ~10 kg, sink to the bottom of the water, put 15 ~20 piles per mu. The haystack is tied with a rope, and the other end of the rope is fixed to the water surface.

Selection of shrimp species is particularly important because artificial propagation of crayfish is not fully mastered at present, and crayfish fry are mainly bred naturally. The time for selecting and stocking crayfish parents is generally from the end of August to the middle of October, and can be caught from culture ponds or natural waters. Male and female parents are required to come from different waters to reduce inbreeding. The parent shrimp should not be out of water for more than 2 hours. In indoor or humid environment, the time can be appropriately long. Male and female identification: ① The first and second gastropods of male shrimp evolve into white, calcareous tubular copulatory organs; the first gastropod of female shrimp degenerates and the second gastropod is feathered. (2) The opening of male genital pore is at the base of the fifth pair of chest feet, which is not obvious, while the opening of female genital pore is at the base of the third pair of chest feet, and a pair of dark round holes are obvious. (3) For adult shrimp with similar body length, male shrimp has thick cheliceps and long and obvious spinous processes on wrist and palm segments, while female shrimp has relatively small cheliceps.

Parental shrimp stocking parent shrimp requirements for physical fitness, complete appendages, uniform specifications, and a full release, avoid batch stocking, can reduce mutual killing. Parental shrimp stocking should be done along the pond around the uniform stocking, uniform distribution. For long-distance transported parent shrimp, the parent shrimp shall be soaked in water for 3 minutes to 5 minutes, and then placed in the pool for 2 minutes to 3 minutes, repeated twice to 3 times, so that the parent shrimp can absorb enough water, and then slowly put the parent shrimp into the pool, which can improve the stocking survival rate. The ratio of female to male of parent shrimp is usually 2~3∶1. Crayfish can mate and lay eggs in autumn and winter. The mating season is generally from September to December. At the beginning of March of the next year, when the temperature rises to 12℃ and the water temperature rises above 10℃, shrimp will leave the cave, come out for feeding and activities. At this time, management should be strengthened and artificial feed should be fed. When the water temperature reaches above 18℃, strengthen feeding. When a large number of young shrimps hatch, they can be caught in cages after breeding.

The stocking density is mainly used to raise crayfish ponds, with 30 kg ~40 kg of seed shrimps per mu, with a specification of more than 30 g/shrimp. After breeding parent shrimps, artificial feed shall be fed in time. In April of the next year, the shrimp cages and cages shall be used to catch the big ones and keep the small ones. The annual yield per mu is 200 kg ~300 kg. In the future, 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. If fishing is overdone, the yield in the coming year will inevitably be greatly reduced. At this time, it is necessary to supplement the seed. The mixed culture pond stocks 10 kg ~20 kg of seed shrimp per mu, with a specification of about 25 g/shrimp. No feed is fed. Natural bait in the pond and residual bait in the fishing pond are mainly used. In April of the next year, the cage fishing is started. The big ones are caught and the small ones are kept. The yield per mu is generally 50 kg ~100 kg.