Introduction to freshwater crayfish (freshwater crayfish) breeding technology

Freshwater lobster, scientific name is crayfish, also known as lobster, giant lobster, and giant red shrimp. This shrimp is native to the United States and was introduced to my country from Japan during World War II. It is now widely distributed in the middle and lower reaches of the Yangtze River. This shrimp is a warm-tropical freshwater shrimp with strong adaptability, high reproductive rate, mixed feeding habits, fast growth, disease resistance, high temperature tolerance, low oxygen tolerance, and will not die after being out of water for several hours. Shrimp meat is tender, nutritious, and contains 8 essential amino acids for the human body. It has lower fat content, more tropomyosin and paramyosin, and a higher edible portion. It is deeply loved by domestic consumers, the export volume is also increasing day by day, the sales and purchase prices are rising, and the breeding prospects and benefits are promising.

Freshwater lobsters live widely in freshwater lakes, rivers, ponds, ditches and rice fields. Benthic organisms, plankton and various aquatic plants are all palatable food and grow well in these waters. Young shrimps live in shallow water areas or near pools, and like to live in caves. They sometimes hide in the shelter of gravel and aquatic plants. Usually, shrimp holes are dug on the banks of the large water surface, where there is a lot of clay and swamps, where reeds and reeds are thick. The shrimp holes are generally round. , slopes downward, is about 30 cm deep, and twists in different directions. Freshwater lobsters often move seasonally in their habitats. In spring, when the water temperature rises, shrimps mostly move in shallow water. In midsummer, when the temperature is not high, they move to deep water. In winter, they overwinter in caves. Freshwater lobsters also molt, grow and reproduce in caves to prevent harm. The shrimp prefers shade and is afraid of light, crawling out of the cave when the light is weak or dark. During the rainy season, freshwater lobsters often climb onto land. This shrimp also has a strong ability to withstand hunger, and can generally withstand starvation for 3 to 5 days; in autumn and winter, it generally does not starve to death without eating for 20 to 30 days. The optimal temperature for feeding is 25~30℃; when the water temperature is below 15℃, the activity weakens; when the water temperature is below 10℃ or exceeds 35℃, feeding is significantly reduced; when the water temperature is below 8℃, it enters the overwintering period and stops feeding. The lifespan of freshwater lobster males is generally 20 months, and the lifespan of females is 24 months.

Freshwater lobsters usually mate and lay eggs from the end of October to March of the following year. The mating time varies in different waters. If you mate too early, the eggs are often immature, while if you mate too late, the eggs will be overly mature and aging. The suitable water temperature for mating is 22~25℃. It is best not to fish during the mating season and allow them to hold eggs, hatch and reproduce. Freshwater lobsters mate in spring, summer, and autumn and can lay eggs 3 to 4 times a year. Generally, a broodstock with a body length of 7 to 10 cm and a weight of 15 to 30 grams can carry 220 to 270 eggs, depending on the individual size. Different, there is a big difference in the amount of eggs they can carry. Under normal circumstances, after mating and spawning, the egg-bearing shrimp needs to hatch for 1 to 2 months (i.e., embryonic development), which requires a lot of physical strength. Therefore, the nutrition and cultivation of the egg-bearing shrimp must be strengthened. The suitable water temperature for egg-bearing shrimp to hatch is 22~27℃, and the incubation time is 6~10 weeks. Before shrimp larvae are cultivated, ponds need to be cleaned and disinfected, the incoming water filtered, and organic fertilizers applied to cultivate natural food organisms for the shrimp larvae to feed on. Generally, the stocking density of shrimp larvae is 150,000 to 200,000 when cultivating shrimp larvae. If the "soy milk" method is used to cultivate, the stocking density can be 160,000 to 180,000.

2. Lobster breeding technology

Lobsters can be cultured in ponds where Macrobrachium japonicus is generally cultured. Ordinary ponds can also be cultured. The culture technology after the release of larvae is similar to that of Macrobrachium japonicum. are similar, including preliminary preparations, feed placement and water quality management, etc., but attention must be paid to their burrowing habits, and anti-escape measures also need to be strengthened. Lobsters have strong endurance, and their breeding output is high. The current market demand is also large, and the economic benefits of breeding are considerable. The most common shallow water rice field farming is now introduced as an example. Other farming methods can be referred to.

3. Freshwater lobster cultured in rice fields

Freshwater lobster cultured in rice fields generally yields 400 to 500 kilograms per acre, and can reach 600 kilograms at high yields. Raising shrimp in rice fields can eat weeds and other aquatic organisms that consume fertilizer in the fields. It not only saves the labor of weeding, but also eliminates mosquitoes and flies that harm people and livestock. Moreover, shrimps are constantly moving and foraging in the rice fields, which not only helps the rice fields to loosen soil, provide running water, and ventilate the rice fields, but also increases the amount of dissolved oxygen in the field water. At the same time, they excrete a large amount of feces through metabolism, which has the effect of maintaining and increasing fertilizers.

1. Selection of rice fields

To raise freshwater lobsters in rice fields, the water source should be sufficient, not affected by droughts and floods, the water quality should be fresh and pollution-free, the soil should be fertile, the water retention performance is good, and the sun should be sufficient. Although the water quality of some mountain streams or springs is relatively poor and the water temperature is relatively low, if it can have a long flow or pass through the rice fields where shrimps are not raised, and then flow into the shrimp farming rice fields, the water temperature will increase and it is also suitable for shrimp farming. .

2. Transformation of rice fields

In order to facilitate production management and daily feeding, the area between drainage channels is generally regarded as a breeding area. Dig a circulation buffer ditch with a depth of 0.5~0.6 meters and a width of 1.0~1.2 meters 0.6 meters away from the inner side of the surrounding ridge, and turn all the soil onto the side ridge, so that the side ridge reaches a height of 0.8~1.0 meters and a top width of 0.6~0.8 rice. The side ridges should be compacted, the inner slope should be leveled, and a plastic film should be used to enclose a closed protective wall on the inside of the ridge top. The height of the fence above ground is 0.4~0.5 meters, and it is buried 0.1~0.2 meters underground. Anti-escape nets should be set up at the upper and lower inlets and drainage outlets.

In order to facilitate shallow irrigation, drying, application of chemical fertilizers, pesticides or fishing in rice fields, shrimp ditches and shrimp ponds must be dug in shrimp farming rice fields.

The shrimp ditch can be dug after transplanting the rice seedlings. The method of digging should depend on the shape and size of the field and the direction of the drainage outlet. If the rice field is small, it can be opened in the shape of a "field"; if it is a long and large field, it can be opened in the shape of an inner "well" or an inner "field". The width and depth of the ditch are preferably 0.3 to 0.4 meters respectively. Shrimp ponds can be opened at the intersection of shrimp ditches or at the four corners of the field, connected to the shrimp ditches. Shrimp ponds are generally 1.0 meters square and 0.8 to 1.0 meters deep.