It is widely distributed in China, Japan, South Korea, Southeast Asian countries, as well as the Indian Ocean and Australia, and In China, it is distributed in the South China Sea region of Zhejiang.
Shrimp is called sand shrimp and mud shrimp in the southern coast of China, and is called "base shrimp" in business. In the classification of crustaceans, decapods, shrimp family, new shrimp genus, is a new species of marine aquaculture, with a wide range of diet, fast growth, wide salinity, low oxygen resistance, strong ability to resist bad environment, shell thin body fat, delicious meat and other characteristics, well received by consumers.
Knife-sized new shrimp farming has a long history in China, Fujian Longhai area has a breeding habit a hundred years ago, but all are cultured in seawater or low salinity seawater waters. From 1986 to 1987, the Wuxi Freshwater Fisheries Research Center was the first successful breeding of desalinated shrimp in pure fresh water.
First, the new shrimp freshwater aquaculture technology of knife forehead
1． Shrimp fry are desalinated
The key to the success of the desalination of the new shrimp with a knife forehead lies in the dilution of the shrimp fry. Dilution is a gradual process that cannot be rushed. The specific gravity of shrimp fry decreased sequentially from 1.020→ 1.015→ 1.010→ 1.007→ 1.005→ 1.003→1.001→1.003→1.001→ 1.005→1.000, the salinity gradient was small, the salinity gradient shrimp fry survival rate was high, and the salinity gradient shrimp fry survival rate was low. Dilution is a process of gradually reducing salinity, generally speaking, the longer the time, the higher the survival rate. It can last no less than one week, preferably in about ten days, and the body length can be increased from 0.4cm to more than 0.7cm during the desalination of shrimp fry. The specific method is: starting one week for the storage stage, the self-propagating or introduced seedlings gradually realize the transition of off-site seawater, and store them for more than one week under the condition of a proportion of 1.018-1.020 seawater, so that some of the larvae that have completed metamorphosis at the end of the metamorphosis can complete the metamorphosis process, and control the light and density during the storage period, adjust the water temperature at 26-30 ° C, and maintain continuous inflation. Fresh water is added every day after storage, each time the amount of water is about 10% of the total water, and the salinity of the pond water is gradually reduced, until the water is full, it is in and out at the same time, so that the water quality is maintained well and the floating head is prevented.
2． Strengthen cultivation
Dig a small temporary pond in the corner of the shrimp pond, the area accounts for about 2-3% of the shrimp pond area, the depth of the pond is 0.8-1m, the shrimp fry required for the shrimp pond is first intensively cultivated for about 15-20 days, and the shrimp fry body length is generally 1-15 cm after the overflow is naturally dispersed to the whole pond, through this method, the adaptability of the shrimp fry to the shrimp pond environment can be greatly enhanced.
3． Shrimp fry stocking
The suitable temperature of the new shrimp is 19-32 °C, and it can be stocked in the middle and lower reaches of the Yangtze River in late May, and can also be temporarily raised in plastic greenhouses in late April. This extends the growth time and improves the specification of the product.
If the purchased shrimp fry is only 0.4-0.5 cm in the middle of the breeding, directly into the shrimp pond, it is necessary to put 80,000-100,000 /0.067hm2, if the shrimp fry size is above 1.5cm, the stocking density is 45,000 /0.067hm2, and the specific stocking density should also be determined according to the conditions and technical aspects of the shrimp pond.
4. Bait and feeding
Penaeus vannamei is an omnivore and prefers animal feed. In the early stage of breeding (before the body length of 3cm), it is mainly based on natural bait culture: about 5 days before the shrimp fry stocking, every 0.067hm2 fertilization of 200-250kg (pig manure and cow manure) and soybean milk to cultivate zooplankton (rotifers, branches and copepods of juveniles) are the mainstay, and the number of zooplankton in the pond decreases after a week of shrimp fry, and when the demand cannot be met, fish pulp and shrimp prefetch should be properly fed, and after 3cm, shrimp pellet feed is mainly based (the crude protein content of the bait is 38-40%). All kinds of nutrients are reasonably composed, and through trial, the bait return effect is good.
Feeding is done along all sides. 1/3 of the total amount of feeding during the day, 2/3 of the feeding at night (evening), 2 times of erbium feeding, and one more injection in the middle of the night during the peak growth period. The daily feeding amount is determined by the total amount of shrimp body estimated on the day, the early control is 6-8%, the middle and late stage is controlled at 4-5%, the smaller the individual, the higher the percentage of feeding, and conversely, the lower the percentage of feeding. The standard is based on the fact that more than 2/3 of the shrimp body reaches a full stomach and a semi-full stomach within 1 hour after each feeding or eats within 1.5-2 hours.
5． manage
Daily examination
(1) Check the eating situation during the daily inspection of the pond, observe whether the feed on the feed table is finished, or use the mesh to check whether there is any feed left in the feeding place. Adjust the feeding amount according to the inspection.
(2) Observe whether the shrimp is abnormal, whether there is a lack of oxygen floating head, such as the floating head should be opened in time.
(3) Every half a month or so, the length of the shrimp should be measured, and a record should be made to determine whether the shrimp growth is good.
Water quality management
The main methods of water quality management are fertilization to cultivate water quality and water injection and water exchange, as well as mechanical oxygenation. Fertilization (base fertilizer is mainly organic fertilizer, topdressing is mainly chemical fertilizer) should be moderately regulated according to the water quality fertilizer, control the water color is yellow-green or tea brown, the transparency is mastered at 30-35cm, and regular water quality analysis. According to incomplete statistics, each shrimp pond is fertilized with 200-250 kg of base fertilizer (pig, cow manure) and 5-10 kg of fertilizer (urea and calcium superphosphate) per 0.067 hm2. On average, it is injected once a week, and the amount of water exchanged in half a month is about 1/5, and its water exchange requirements are significantly lower than those of other shrimp. The substrate requirements of the shrimp pond are higher than those of other shrimp, so low-quality improvement is very important. Irregular use of quicklime (10-15kg/0.067hm2) has a certain effect on improving water quality and substrate.
6． disease control
In practice, we have found that the disease of the new shrimp with a knife forehead is more common than other freshwater shrimp, and the treatment is worse after healing, so it is necessary to find and treat it in time, and more importantly, it is mainly based on prevention. Prevention and control of shrimp disease, mainly used for the prevention of strong chlorine whole pond sprinkling disinfectant water and adding drugs to bait, most of the shrimp ponds have received good preventive effects.
7． Fishing techniques
Capture knife-fronted shrimp using general shrimp catching methods such as pulling nets, releasing water dry ponds, etc. are difficult to work, we according to its living habits, in the night shrimp pond around, four corners fixed knot net (cage net (shrimp easy to enter and difficult to out) the catch rate is higher, especially in the shrimp pond outlet slowly release water net to catch (or form a small water flow in other places) and above the net as a light lure (light does not need to be too strong), shrimp fishing is very easy, convenient, and simple operation, generally several times in a row (dusk and early morning maximum) can be basically full net fishing, We used this method, which ended in early September to mid-October, and the recapture rate was 36% in terms of stocking.
8． transport
The new shrimp with a strong dry tolerance can survive 48 hours away from the water, and die after 60 hours. This feature is conducive to long-distance transportation and the sale of live shrimp. Therefore, the new shrimp farmed or caught in China is mostly sold as live shrimp, which increases the economic value of the shrimp.
Second, the development prospects of freshwater aquaculture of new shrimp with knife forehead
Freshwater aquaculture of penaeus shrimp has created a gratifying situation, can it be further developed in the future, and how to develop it? It is related to the overall situation of the adjustment of the variety structure. Although the level of yield is not high, the output between ponds and ponds is unbalanced, and the size difference is also very large, but it should be noted that with the continuous improvement of breeding technology, today's local high-yield and high-income shrimp ponds are the prelude to achieving comprehensive high-yield and stable production tomorrow. From the perspective of development, the new shrimp will have a better development in the coming period. In accordance with the established policy of steady, coordinated and healthy development, we will actively, steadily, and systematically guide and promote freshwater aquaculture of new shrimp with a knife forehead, prevent blind swarms, continue to explore and summarize in the course of development, obtain mature experience, and seek further development in the process of becoming more and more mature. It should be seen that the knife-sized new shrimp is a kind of marine medium-sized shrimp, the production is impossible to reach the high level of large shrimp, coupled with the current high price of fry, which is an obstacle to the development of knife-sized new shrimp, to build a certain scale of enterprise professional nursery, to provide enough seed, to promote the further development of freshwater aquaculture of knife-sized new shrimp.