(a) The water temperature required for spawning by selected broodstock during spawning is above 18°C. In the middle and lower reaches of the Yangtze River, from mid-April to mid-September, from June to July, it is the peak of spawning, with the peak period from mid-June to mid-July.
(b) Spawning and Hatching In spawning groups, broodstock are spawned from June to July. Individuals are relatively large. This is the oldest shrimp after wintering. The broodstock that spawn after July 7 are smaller. The shrimp that grew after the breeding year. The entire process of spawning and hatching takes place in cages. The cages are divided into incubators and incubators. The incubator is made of polyethylene net cloth with a mesh of 196 meshes/cm2. The specification is 10 meters and 667 meters and 1.7 meters. The bottom of the box and the upper mouth of the box are each equipped with a polyethylene chain rope. The cage is open and floating. When the cage has 0.3 meters exposed to the surface to prevent shrimp escape. Place 1-2 wood-dyed small cages for hatching in the box, and make them with a mesh of 12 mesh/cm2 polyethylene mesh with a specification of 1.7 meters and 1 meter of O.5 meters. Expose the cage when installed. The water surface is 5 centimeters in size, and is a small brick in each corner of the bottom of the box.
The broodstock should be moved to the incubator for fattening before spawning. When the water temperature reached 18°C, broodstock mated and eggs were laid within 24 hours after mating. When the female is pregnant, the abdomen extends and flexes, and the back is raised. The eggs produced were oval in shape, with many yolks, and clumping in the abdomen of the female bristles l-4 pairs of appendages. After the winter, the aged shrimp can spawn two times in succession. The second spawning is after the egg hatched for the first time. The number of spawns in the shrimp is related to the age and body length of the broodstock, and the aged shrimp after wintering. Up to 5,000 eggs can be laid, and the shrimp that matured that year have a body length of 3 cm and a maximum of 700 eggs.
When the eggs appear compound eyes, the female eggs should be placed in hatching cages, 700-1000 per cage. After 6-7 days, the larvae can break the membrane and fall out of the broodstock and fall into the incubator. At this point, the incubator should be taken out of the cage together with the hatched broodstock.
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