Artificial breeding technique of crayfish

Parent shrimp selection

Parent shrimp can be selected in September-October of last year or March-April of the same year, with a body weight of 30-50g, complete appendages, health and disease-free, strong activity, and a female-to-male ratio of 2-3:1. Male and female lobsters have obvious characteristics in appearance and are easy to distinguish.

The main results are as follows: 1. when the lobster reaches sexual maturity, the male individual is significantly larger than the female.

2, the male dragon foot is thick, there is a bright red molluscum on the outside of the dragon foot, the female dragon foot is relatively small, most of the female feet do not have red molluscum, even if there is a light color.

3. The male reproductive foramen opens at the base of the fifth pair of footsteps, while the female reproductive foramen opens at the base of the third pair of foot.

4. The abdomen of sexually mature female shrimp is dilated, while that of male shrimp is relatively narrow.

Parent shrimp culture

The area of parent shrimp pond should be about 1200m2, the bottom material should be loam, the water depth is about 1m, the width of the pond is more than 1.5m, there is sufficient and good water source, the injection and drainage outlet is built, and the surrounding ridge is built with plastic film or calcium plastic board to prevent escape wall. 7-10 days before stocking, the pond is disinfected with 50-60kg/ per mu raw lime dry pond. After disinfection, the depth of water injection was about 1m after filtration (preventing wild mixed fish into the pond), and 500-800kg/ mu of rotten livestock and poultry manure was applied to improve the water quality. Put people in the pond for shrimp climbing shelter, such as branches, roots, bamboo tubes, etc., and transplant some aquatic plants.

Parent shrimp ponds can put 40-60kg/ mu of parent shrimp and soak in 3% salt water for 10 minutes before stocking to kill pathogens. In order to make full use of the water body and regulate the water quality, 50-100 silver carp and bighead carp can be mixed cultured at the same time. During the cultivation period, fresh water plants, bean cakes, wheat bran or formula feed can be fed, and some animal feed can be added. Such as chopped snail clam meat, livestock and poultry slaughtering scraps and so on. Daily feed: 2% of the body weight of parent shrimp in March, 4%-5% in April, 6%-8% after May, once in the morning and once in the evening, accounting for 70% of the daily diet. At the same time, the management of water quality should be strengthened, changing fresh water once every 10-15 days, and sprinkling 10-25g/m2 with quicklime every 20 days to maintain good water quality and promote gonadal development of parent shrimp.

Parent shrimp reproduction

From April to May, when the water temperature is above 20, parent shrimp begin to mate. The fertilized eggs are hatched into young shrimps in the belly of female shrimp, and the incubation time is 40-70 days. After hatching, the juvenile shrimp completed the growth and development process under the protection of the mother. As soon as the juvenile shrimp leaves the mother, it can take the initiative to feed and live independently. When it is found that there are a large number of young shrimp in the breeding pond, the seedlings should be collected in time for shrimp seedling cultivation.

Parent shrimp overwintering

The lowest survival water temperature of lobster is 5 ℃. However, when the water temperature is lower than 9 ℃, the mortality rate of shrimp about 3 cm is very high during the overwintering period. Although adult shrimp can survive, there will be a large number of deaths after 2-3 months. Therefore, to do well the overwintering work of parent shrimp and ensure the water temperature of 16 ℃-18 ℃ during the overwintering period is also an important part of the whole breeding work.

The method of overwintering of parent shrimp is the same as that of Macrobrachium rosenbergii, and the commonly used overwintering methods are plastic film covered pool heat preservation method, electric heater heating method, hot spring water overwintering method, factory residual hot water overwintering method and glass chamber overwintering method, which can achieve the safe overwintering effect of parent shrimp.

Seedling raising technique

Although the number of eggs held by lobsters is small, the fertilization rate can be more than 98%, and the hatching rate can reach 80% to 85%. The problem is that the young shrimp grow and molt frequently after emergence, which is easily restricted by environmental conditions and affect the breeding rate. In order to improve the rate of raising seedlings, the key points are as follows:

1. Water quality requirements: during the lobster breeding period, the water body should be kept relatively stable, the water quality should be fresh, and the pH value should be between 6.5 and 8; the temperature difference between day and night should be prevented; and the dissolved oxygen in the water should be kept above 5.6 mg / L.

2. Water environment: there must be water floating lotus on the surface of the water (accounting for 1 up to 3), and there should be water plants at the bottom and hidden caves to increase the molting attachment of shrimp seedlings, and it is also convenient to grasp the emergence time and the growth of shrimp through seedling washing inspection. Fences and filters are added to the water inlet to prevent enemy creatures from entering the pond, to prevent frogs from entering the pond to lay eggs, and to prevent tadpoles from eating shrimp seedlings. At the same time, it is necessary to prevent parent shrimp from clinging to and escaping.

3. Strengthen inspection: persist in checking the emergence of larvae in the morning and evening. When the larvae are free from the mother, catch the parent shrimp in time and return to the parent shrimp pond for re-cultivation, so as to minimize the stocktaking through the pond, and the operation should be especially careful to avoid affecting the parent shrimp holding eggs and the newly hatched shrimp.

4. Guaranteed feeding: timely culture of rotifers and other small zooplankton for newly hatched offspring.