1, broodstock cultivation
The experimental broodstock was introduced from Wuhan and averaged 3.2 cm in size. Choose 100 prawn with strong physique, disease-free and no injury, specifications of 20-50 g and ratio of male to female of 1:1 as broodstock, and choose the broodstock to be reared at 68 l meters covered with fiberglass tile and heating heating system. In the cement pool, the temperature was gradually increased to 26°C on March 15 and freshly chopped “lobster†heads were fed daily at 10% of the body weight of the shrimps. The red of the front part of the red crayfish is red, the color is bright, and the length of the chelonian is longer than the body length; the chelation of the female shrimp is basically blue and the length is less than the body length. The mature male reproductive genitalia is in the shape of a stick at the base of the fifth step; the gonad of the female is open to the base of the third step. Put some washed and sterilized mesh pieces in the rearing broodstock pool as cover for broodstock. Sew and change the water every day, keeping the light 12I:12D (12 hours light, 12 hours dark).
2, mating and spawning
By feeding at 26°C for one month, the broodstock began mating and spawning in late April. The copulation of the red-claw crayfish is soft-shelled mating, and before the mating, the female prawns have to undergo genital oyster shells, and the females begin to lay eggs within 12 hours of male sperm production. The eggs produced by the females are dark yellow after fertilization, adhere to the stomach feet and the fasting hair formed by the tail fan curled inwards. A weighed 326 eggs were held in an egg-holding shrimp weighing 48 grams, and 441 eggs were held in shrimps, and only 27 were in the lower ones.
3, embryonic development
The fertilized eggs of the red clam crayfish are dark yellow, gradually changing to yellow-orange, red-orange, and light gray as the embryo develops. We compared the embryos of shrimps with 4 groups for embryonic development: At 19°C, the embryonic development of shrimp eggs was extremely slow; at 21-23°C, the hatching time was 41 days, and there were 80 days. The larvae were detached from the mother; at 26°C, the fertilized eggs hatched out of the membrane for 30 days and the young prawn detached from the mothers for 52 days; at 29-30°C, the membranes hatched within 25 days and left the mother's body 40 days later.
4, larval rearing
In this experiment, a total of 1731 larvae of red-caught crayfish were hatched. After collection, they were reared in an earthen pond of an area of ​​160 square meters. The larvae of the initial stage of growth were mainly fed with organic detritus and chlorella and other algae. Whether or not organic debris and monosodium algae are abundant in water is of great importance to improve the survival rate of larval of crayfish. If the amount of bait is insufficient, wilting will occur. Through the dissection of juvenile shrimp, it was found that juvenile shrimps had no residue of zooplankton, such as Cladocera, Copepoda, etc., which I believe is mainly due to the poor activity of juvenile shrimp. After 7 weeks of feeding, the larvae have an average size of 7.6 cm.
5, discussion and summary
5, 1 temperature light and reproduction: In mid-March warming, appropriate extension of the light can red shrimp crayfish breeding smoothly. In June, the postpartum broodstock was reared at a constant temperature of 29°C for about 3 months and some of the shrimps re-spawned. Under conditions of temperature, light, feed and dissolved oxygen, it is completely feasible to promote the annual reproduction of red-claw.
Spawning rate and hatching rate of fertilization: 100 pairs of eggs were detected in this test. The spawning rate was 86%, and the fertilization hatching rate was over 90%. The absolute fecundity of red-claw crawfish and the weight of oviposition shrimp were positive. Related. Its suitable embryo development temperature is 22-30 °C.
Feed and reproduction: The fresh animal feed can make the egg size of the broodstock hold eggs neatly, and the embryo development speed is basically the same when hatching.
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