Crayfish can breed all the year round, with the peak period from May to September. Crayfish are hermaphroditic and have obvious secondary sexual characteristics. It can be distinguished from the shape of abdominal swimming limbs. The abdominal swimming limbs of male shrimp are specialized as intersecting spines, while those of female shrimp are specialized as spermatic holes. Secondly, there are obvious differences between the two pincers. The male pincers are thick, and there is a bright red wart on the outside of both ends of the pincers, while the female pincers are small and the wart is not obvious. Thirdly, the claw feet of male shrimp are bigger than those of female shrimp, and the individual is bigger than that of female shrimp.
The ovarian development of crayfish lasts for a long time. Usually, after mating, depending on the water temperature, the ovary needs to develop for another 2-5 months before it matures. In production, we can observe the joint between the breastplate and the abdomen, judge the degree of gonad maturity according to the color of the ovary, and divide the ovarian development into pale, yellow, orange, brown (brown) and dark brown (bean paste color) stages. Among them, pale color is the gonad of immature young shrimp, which is small and takes several months to reach maturity; Orange is a basically mature ovary, and it takes about 3 months to ovulate after mating; Brown and brown-black are mature ovaries, which are ideal types for breeding parent shrimp. The testis is small and generally matures synchronously with the ovary in a culture pond. In the main crayfish production areas in the United States, the method of gradually draining the pond water is generally used to stimulate the gonad maturity of crayfish and promote the mating and spawning of parent shrimps.
Crayfish can mate almost all the year round, but the peak is in spring every year. Mating is generally carried out in an open area in water, and the mating water temperature ranges from 15℃ to 3 1℃. During mating, the male shrimp injects sperm into the seminal vesicle of the female crab (shrimp) through mating thorns, and the sperm can still be fertilized by storing it in the seminal vesicle for 2-8 months. After mating, female shrimps dig holes one after another, and when the eggs mature, they complete the process of ovulation, fertilization and larval development in the holes.
The breeding of crayfish is quite special, and most of the breeding process is completed in caves, so it is difficult to see egg-holding shrimps in ordinary production. Ovary needs 2-5 months after mating to mature and ovulate and fertilize. The fertilized egg is purple sauce color and adheres to the bristles of the swimming limbs in the abdomen. The egg-bearing shrimp often holds the abdomen close to the water in the hole to keep the egg in a moist state. The fecundity of crayfish is small. According to different specifications, the fecundity is generally 100-700, with an average of 300. The incubation time of eggs is about 14-24 days, but the incubation period can be as long as 4-5 months at low temperature. During the development of crayfish larvae, there is no need for any external nutrition supply, and the newly hatched larvae need to stay in the abdomen of the parent shrimp for several months before they leave the mother. If the conditions are not suitable, you can stay in the cave for several weeks without eating or drinking. When the pond is filled with water, the larvae and parent shrimps climb out of the cave one after another and naturally distribute in the pond. Sometimes, the parent shrimps will bring their larvae into the water and then release them. Although crayfish hold less eggs, the survival rate of larvae hatching is very high. Because of the scattered reproductive habits of crayfish, the large-scale production of larvae is limited, which has adverse effects on intensive production.