CATDOLL : CATDOLL: How long is the life span of freshwater shrimp? What should we pay attention to when raising shrimp?

1. How long is the life span of freshwater shrimp? What should we pay attention to when raising shrimp?

The life span of green shrimp is relatively short, generally 14 to 18 months, and the life span of male shrimp is shorter than that of female shrimp. Green shrimp that have overwintered generally die in July or August of the following year.

During the breeding process of freshwater shrimp, it is important to catch them in batches. Starting from September of the current year, large shrimps over 4 cm in length should be caught continuously, and small shrimps should be kept for breeding. The adult shrimps of the following year should be caught and put on the market before June or July. The reasons are as follows:

(1) Freshwater shrimp grow very fast. There is a saying that "it takes 45 days to catch up with the mother shrimp". It means that after 45 days of growth, the body length of the young shrimp can catch up with the length of the mother shrimp, reaching about 3 cm. Generally, the young shrimps hatched in June each year, in October of the same year, the male shrimps can reach 4 to 5 cm in length and weigh 3 to 5 grams. After one year of growth, the male shrimps can generally reach a length of more than 7 cm, and the female shrimps can reach a length of 5 to 6 cm. A few male shrimps can reach a length of more than 10 cm and weigh about 10 grams, while the female shrimps can reach a length of more than 8 cm and weigh about 7 grams.

However, green shrimps mature early and have strong reproductive capacity. Female shrimps can lay eggs many times. Green shrimps with large individuals and well-developed gonads can reproduce offspring in September and October of the same year. Therefore, even if shrimp fry of the same size are released, the result will still be several generations in the same pond. There are differences in the feeding competition ability between green shrimps, coupled with the uneven artificial feeding and the individual differences between female and male shrimps, which bring difficulties to the effective control of breeding density and the cultivation of adult shrimp ponds. If a part of the adult shrimps that have reached the market size can be caught in time according to the growth of green shrimps, so that the shrimps left in the pond can continue to grow, it will also be conducive to the balanced listing of live shrimps, preventing the market from "no shrimps to eat" in the middle of breeding, and concentrated listing in the late stage of breeding, resulting in "difficult to sell shrimps", which is conducive to improving social and economic benefits. It is also conducive to capital turnover, reducing costs, and creating conditions for expanding reproduction.

(2) Increasing production is the ultimate goal of shrimp farming. Under dense conditions, the growth of freshwater shrimp should be promoted so that the size of freshwater shrimps out of the pond is basically the same, and the production per unit area is increased. Only by fishing in batches and multiple times can the density be thinned out in time, the restriction of excessive density on group growth can be alleviated, and a more appropriate density can be maintained to promote the growth of freshwater shrimps. Practice has shown that the yield of one-time fishing is 40% to 50% lower than that of multiple fishing in batches, or even lower.

(3) After wintering, the shrimp will mate and reproduce in the spring. The male shrimp will die soon after mating, and the female shrimp will also die one after another after the reproduction is over. Therefore, clearing the pond in time and catching the big ones and leaving the small ones is a good way to reduce losses and improve economic benefits.

2. How to stock freshwater shrimp in a pond once and cultivate them all year round?

The one-time stocking and year-round shrimp farming model is a shrimp farming method designed based on the habit of green shrimps to reproduce in the pond. It has the advantages of simple operation and commercial shrimps can be caught and sold all year round.

(1) Breeding process

In December, clean the shrimp pond, fertilize and cultivate the water → stock shrimp (also stock silver carp and bighead carp) → spring shrimp farming and management → catch shrimp in stages in May and June → keep shrimp fry in the pond in June → stock summer fish → fall shrimp farming and management → catch large ones and keep small ones from September to December → dry the pond in December to complete the production. (2) Seed source and stocking

Choose high-quality shrimp species with pure varieties. It is best to buy them from original fine shrimp seedling farms. Generally, around December, 2,000 to 3,000 shrimp seeds/kg are stocked per mu, with 15 to 20 kg of shrimp seeds, and about 200 silver carp and bighead carp seeds of 25 grams/tail are stocked in mixed culture. Shrimp are caught in stages in May and June and some shrimp are left in the pond to reproduce shrimp seedlings on their own, which will be used as shrimp seeds for autumn shrimp farming. (3) Do a good job in daily feeding and management

We must grasp every link of shrimp farming, strengthen feeding management, and promote the rapid growth of shrimp.

① Transplanting water plants: Water plants can provide a hidden place for the growth of freshwater shrimp, improve the three-dimensional space, and can also regulate water quality and reduce water temperature. Mainly plant floating plants such as water peanuts and water spinach. Water plants should be managed according to different growth periods, and they should account for 20% to 30% of the pond in spring and 50% to 60% of the pond in autumn.

② Scientific feeding: As the activity range of freshwater shrimp is small, multiple feeding points should be implemented in the freshwater shrimp habitat, and the "four determinations" and "four observations" feeding method should be adhered to. After entering November, the weather gradually gets colder, and appropriate feeding should be given, and feeding should not be stopped early.

③ Disease prevention and control: There are few diseases in shrimp farming, but ciliate disease is a common disease in shrimp. If it is not prevented and controlled in time, it will cause bacterial gill rot and black gill disease. Therefore, around mid-April and mid-August every year, it is necessary to use drugs once in full, use ciliates killer to kill ciliates, and then use chlorine dioxide and other disinfectants. After 1 week, use EM bacteria, photosynthetic bacteria, Bacillus and other biological agents to adjust water quality. During the frog breeding season in spring, it is necessary to patrol the pond more often and remove frog eggs in the pond in time. Usually, the water should be filtered with an 80-mesh silk sieve to prevent wild fish from entering the pond.

④ Adjust water quality: The water level should be adjusted flexibly according to different seasons and periods. The water quality should also be adjusted in time according to different growth stages to maintain a certain degree of water quality.

3. How to carry out rotational catch and release in shrimp farming?

Some high-yield fish farming areas all implement a method of catching and releasing in rotation, and the stocking of freshwater shrimp is no exception. To increase the yield per unit area and improve economic benefits, it is necessary to implement a method of catching and releasing in rotation so that a more reasonable stocking density can be maintained in the pond throughout the entire breeding period, which is conducive to the growth of freshwater shrimp and fully tap the production potential of the pond.

For this reason, shrimp fry are generally stocked in two batches.

The first batch of juvenile shrimps that overwinter the following year are released in March and April each year and harvested in July. The stocking density is 20,000 to 25,000 shrimps per mu, and the size of the juvenile shrimps is generally 2,000 to 3,000 shrimps per kilogram.

The second batch of shrimp fry bred that year, with a density of 40,000 per mu, was released after the first batch of shrimps were caught, which was around July.

The second batch of shrimp fry are raised and harvested at the end of the year. The big ones are caught and the small ones are kept. The big ones are put on the market as commercial shrimps, and the small ones are used as shrimp seeds for the next year.

This article is from: China Agricultural Press "Medicinal Plant Cultivation and Animal Breeding Encyclopedia"