After 2000, the culture of P. vannamei grew rapidly. Especially in East China, most of the areas where Macrobrachium rosenbergii was cultured have been reared to Penaeus vannamei. So far, East China (two provinces and one city) has cultivated an area of ​​about 500,000 mu of white shrimp. The main culture areas have been concentrated in Nanhui and Fengxian in Shanghai, Kunshan and Wujiang in Jiangsu, and Haining and Xiaoshan in Zhejiang.

The culture of South American white prawns in East China is based on semi-intensive intensive culture of fresh water, and the yield is mostly around 1000 kg/mu. The farming conditions and technology levels vary widely across regions, and the success rate is high or low. Compared with Guangdong, Hainan and other places, the annual temperature in East China is lower, and the suitable growth period of shrimp is shorter, and the water quality of sediment is also different. Therefore, it is of great significance to explore and develop the related technologies of freshwater culture of Penaeus vannamei in East China.

Introduction of the South American White Prawn Culture Model in East China

In general, the culture mode of Penaeus vannamei in East China is mainly semi-intensive intensive culture in freshwater earthen ponds, and the yield is mostly around 1000 kg/mu, and intensive culture, crude samples, and polyculture are relatively few. However, in the same semi-intensive mode, the investment, management, and output of the regions vary from place to place, and they are divided by the time and density of planting. There are mainly greenhouse direct seedlings, greenhouses and seedlings, and direct seedlings. There are several types of ponds, such as ponds and ponds. Putting seedlings in greenhouses refers to the mode of raising shrimp seedlings into pre-built greenhouses when the temperature is still relatively low in mid-to-late March. Compared with the stocking of greenhouses after May, the greenhouses are put in greenhouses. The seedlings have the characteristics of long breeding time, early listing of shrimps, high yield, and high risks. Regardless of whether the greenhouses are stocked or stocked in Datang, the stocking has two different types of direct seedling seedlings and desalinated seedlings. The difference is that the shrimp seedlings are transported into the pond after being transported by air from the south to the farming area. Dilution is to first subordinate the dilution in the professional fading field. Regardless of the stocking method adopted, the basic breeding techniques are similar, and they are introduced separately.

Pond preparation

Regardless of which stocking mode is used, the preparation of shrimp before stocking is basically the same. The shrimp culture in East China is basically an earthen pond. Due to the low temperature in winter, there is a longer time for dredging and drying ponds. We often find in the technical services that many farmers do not pay much attention to the work of dredging and drying up the ponds in the early stage, and waste the winter season as a slack season. In fact, good shrimp pond conditions are particularly closely related to the success of shrimp farming. In particular, there are many ponds in East China that have been reared by four home fish ponds. These ponds commonly suffer from problems such as aging ponds, sediment deposits, and different pond depths. Therefore, it is imperative that the preparation of the shrimp pond be done before the shrimp is stocked.

1, clear the entire pool

After the shrimps are harvested in the autumn, the accumulated water in the culture ponds must be drained in time to clean the drying ponds. Where conditions permit, excavators can be used to deepen the pond. Avoid silting the pond directly on the pool, so that when it rains during cultivation, the sludge will flow back to the pond and pollute the water. At the same time, it is necessary to carefully inquire into ponds and carry out repairs for dams, sluice gates, etc. Where there are many sediments in the bottom of the pool, it should be sun dried or washed with water to promote the full decomposition and discharge of organic matter.

Disinfection and disinfection: The sewage clearing pond should be carried out in autumn and winter. During the past 20 years before shrimps are stocked, the enemy organisms, pathogenic organisms, and pathogenic intermediate hosts in the ponds should be removed. The best medicine for clear ponds is quicklime, which can be sprinkled and sprinkled with 30-40cm of water. The amount of quicklime is generally increased or decreased depending on the pH of the bottom soil, and is sterilized with water, mostly at 75-100kg/mu. Tea bran 2-3kg/mu can also be used to soak and soak in the pool water after soaking for 3-4 days. At this time, bleaching, bleaching, etc. are not recommended for cleaning.

2, water and fertilization

From the time of clear ponds to about 10 days before planting, 60 cm of water can be added and fertilization can begin. The influent water must be screened with a 60-80 mesh screen to prevent wild fish, aquatic insects, and earthworms from entering the culture tank. After entering the water, according to water quality conditions can choose whether to disinfect the water body (mainly with povidone iodine and other disinfectants), such as good water quality conditions without disinfection, direct fertilization culture basic food. Cultivating basic food organisms can use organic or inorganic fertilizers. Currently used inorganic fertilizer urea and superphosphate.

In the cultivation of Penaeus vannamei, the ideal water color is yellow-green or dark brown formed by green algae and diatoms. However, in freshwater aquaculture in East China, it is relatively difficult to cultivate diatoms, so farmers should not pursue the color of diatoms in the water. In general, when the ratio of nitrogen to phosphorus in fertilizers is 7:1 (instead of 3-4:1 in mariculture), it is easier to cultivate green algae. At the same time, due to the low water temperature in eastern China, the growth of algae in fertilizers is very slow, and the ratio of fertilizer to nitrogen to phosphorus ratio is also difficult to match, so it is necessary to use specialized peicidin in the fertilizer and water process. At the same time as fertilizer and water, probiotics, such as photosynthetic bacteria and EM bacteria, should also be used at the same time. Probiotics can only be used as probiotics in ponds in the first instance in order to adjust the water color during the cultivation process. The role of water quality.

The selection and delivery of shrimp

1, shrimp selection

The quality of shrimp seedlings directly affects the vital interests of shrimp farmers. The success of shrimp farming must be based on healthy seedlings. As the seedlings of Penaeus vannamei are mainly concentrated in Guangdong, Hainan, Fujian and other places, the farmers in East China are basically air-fed seedlings from these regions. There are also specialized desalination plantations to take aircraft seedlings. Desalt and sell to farmers. In any case, farmers should understand the basic situation of seedling breeding farms through various channels: First, they should understand the qualifications of nursery farms, purchase shrimp seedlings from certified farms that are certified by the national or provincial level, and second, understand the species of shrimps. The source, preferably SPF broodstock imported from Hawaii, USA, or the second generation female parent of different strains, must resolutely eliminate the use of seedlings raised by broodstock of unknown origin; thirdly, it should be understood during the breeding process. The larvae are cultivated, transported and their success rate. Understand the conditions of water temperature and food in the breeding process, and do not buy shrimp seedlings that use high-temperature seedling breeding techniques. Try to use biological baits such as Artemia and rotifers in the breeding process. More shrimp seedlings.

Second, farmers must observe the status of the shrimp before they can get the shrimp. In general, the size of South American white shrimp aircraft seedlings is about 0.8cm, and the desalinated shrimp seedlings are more than 1.2cm in size. At this time, the shape and activity status of the shrimp seedlings can be clearly observed with the naked eye, and the quality is good. Shrimp should have the following characteristics: (1) Individual size of the shrimp seedlings is uniform, transparent and strong. (2) The shrimp body surface is clean, without parasites and damage. (3) The stomach of the shrimp is full, the ratio of the width of the abdominal segment to the width of the intestine should be greater than 4:1. The intestinal tract should be straight and the ankle should be clean. (4) The tentacles of the shrimp seedlings should be put together and put forward. The tail fan should be fully opened and the abdominal section should be relatively slender. (5) In the clean water state, most of the shrimp seedlings have the phenomenon of top water after being in the state of volt. The activity is strong, and it is sensitive to external stimuli. When swimming, there is obvious directionality (do not play round motion), and the body is leveled in. , countercurrent strong touch. (6) In case of water resistance test, several tail shrimps were randomly taken out of the nursery pond and the shrimps were buried in a wrung wet towel. After about 5-8 minutes, they were taken out and put back into the raw water. If the shrimp seedlings survived, they were high quality seedlings. Or poor quality seedlings. If observing shrimp body thin, no swimming top flow ability, body color red, white muddy are unhealthy shrimp. Some shrimps have condensed insects on the body surface and should be observed many times and carefully selected.

2, shrimp seed desalination

After the quality shrimp is selected, it can be air-fed with pure oxygen in a plastic bag. Within 24 hours, the shrimp can maintain a good survival rate. After the shrimp seedlings from the south arrive at Jiangsu, Zhejiang and Shanghai, they must go through desalination to enter stocking. There are two ways to desalt the shrimp: First, professionalize the seedlings planting field, build cement pool greenhouses, and concentrate the desalination of the shrimp seedlings. After the desalination of the shrimp seedlings, the specifications can reach 1.2cm or more, and the salinity can be sold to the farmers in 3‰. Put it into Datang for secondary desalination and aquaculture; Second, farmers use the earthen pond to desalinate themselves. During March-April, ditches and plastic sheds can be dug in the earthen pond, and the salinity of the water in the shed can be adjusted. The earthworms are similar to the salinity of aircraft seedlings, and they are warmed by earth boilers. After the temperature has stabilized in May, farmers can directly use a simple desalination tank with a striped cloth around 100 square meters in the aquaculture pond, adjust the salinity in the desalination tank to 15 Torr, and then put the seedlings. The exchange of the pool water inside and outside the stripe cloth will achieve desalination. After the desalination is completed, stripe cloth can be removed and the shrimp can be placed in the pond for breeding.

The desalination pool is adjusted for salinity, and near the seashore, seawater can be extracted and transported to adjust the salinity of the pond. In areas farther away from the sea, salt brines or salt can be used in conjunction with other trace elements (the proportion of which is to be adjusted according to the composition of sea salt) to adjust the salinity. The salinity of the initial desalination tank must be consistent with the salinity of the transported shrimp seedlings. The salinity error is within 3 inches and the temperature difference is within 2°C. In the first 2-3 days of desalination, mainly fresh water with suitable temperature is added to the desalination tank. Afterwards, the brine in the desalination tank may be partially withdrawn and fresh water may be added. Generally, after 8 to 10 days of desalination, the required salinity requirement can be achieved. In the desalination should pay attention to, first, desalination of the pool water must have a certain color, and second, must be fed Fengnian insects or other professional shrimp feed to feed, in order to enhance the vitality of shrimp seedlings.

If it is desalination, when the salinity of the shrimp falls to within 3 inches, it can emerge. If the fishermen desalinate themselves, they can continue to desalinate until the salinity is 0, continue to grow greenhouses, or put them into the pond for breeding.

3, shrimp feeding

If the shrimps are desalted directly in the greenhouses or desalinated in the desalination tank surrounded by the color strips, the desalination can be completed and the water temperature can be appropriate. The greenhouses and color strip cloths can be removed and the shrimps can be placed in the ponds for breeding. However, when shrimps are transported by air or from the desalination plant to the farm, they must be oxygenated using plastic bags.

During transportation, the degree of sealing of the plastic bag and the health condition of the shrimp must be taken into consideration. If the shrimp seedlings gather in a plastic bag or the muscles are opaque, it indicates that stress has occurred during transportation. Before the shrimps and shrimps are transported to Tangkou, they should test the water to check whether the toxicity of the disinfectant in the pond disappears and whether the viability of the shrimp in the pond is the same as in the nursery pond. For the test water, a cage of about one square metre can be designed, about 100 shrimps will be placed in the pond and placed in the pond for 24 hours and then counted again. If the survival rate is above 95%, it indicates that the shrimp larvae are healthy and the pond water quality Meet the requirements of shrimp seedlings.

Shrimp should be placed on a sunny morning. After long-distance transport, the shrimp should be aware of the temperature difference between the plastic temperature of the shrimp and the temperature of the pond water. The plastic bag can be placed in the pool until the water temperature is approximately the same. Open and let shrimps swim into the pond by themselves.

The density of shrimp ponds should be determined in accordance with the farming pattern, pond conditions, shrimp seedlings specifications, health status, and expected yield, and the differences are also large everywhere. In general, if the pond yield per mu is required to be more than 1,000 pounds, the seedling density of the aircraft seedlings should be more than 100,000. If the large-sized seed that has been desalinated, the seedling density can be controlled at 70,000 to 80,000/mu.

When desalinating or growing in the middle of a greenhouse, the density of young shrimp can be appropriately increased, but generally it cannot exceed 3000 tails/cubic body of water.

In addition, whether it is a greenhouse investment seedlings or direct investment seedlings in Datang, it is very easy to attack 3-4cm shrimp when it is cultured for about 30 days. When the farmers control the death of shrimp through water quality control or drug means, they can fill in some shrimp into the pond to make up for the density of shrimp that died of disease in shrimp ponds.

4, aquaculture management

The daily management of postponed shrimp includes water quality regulation, feed feeding and regular patrol ponds.

(1) Water Quality Management

The quality of water quality management is one of the key factors for the success or failure of shrimp farming. The water quality indicators during the entire culture period should be controlled in the following standards: dissolved oxygen above 4mg/l, at the bottom of dissolved oxygen above 3mg/l; pH value of 7.5-8.6; ammonia nitrogen: non-ionic ≤ 0.1mg/L, total ammonia nitrogen ≤ 0.6mg/ L; Transparency: The maximum height under fresh water conditions can not be less than 20 cm; water color is green or yellow-green. It is important to note here that freshwater shrimp has different water and transparency requirements than seawater. Seawater requires a transparency of 20-30cm. In fact, it is difficult to achieve at the later stage of breeding. Freshwater is even more difficult to achieve. There is no problem with the low transparency, as long as the water is tender, smooth, cool, and live. In addition, the sea water color requires brown water (more diatoms), but the best water color for freshwater farming is green water because green algae can maintain the stability of the algae system under freshwater conditions.

In order to maintain a sufficient amount of algae in the water, appropriate nitrogen and phosphorus fertilizers should be applied in the early stage of cultivation (the ratio of nitrogen and phosphorus is 7:1 is good). In the middle and later stages of shrimp rearing, the food intake increases, and the amount of residual baits and excrement increases. The transparency of the water is very low. The deposited organic matter is easily decomposed into ammonia nitrogen, organic acids, etc., which can cause an increase in oxygen and ammonia in the water. At this time, the amount of water should be changed. , Add water or apply zeolite powder (25 kg/mu); Zeolite powder absorbs harmful substances such as ammonia and nitrogen in water, acidity in neutralizing water, increases calcium ion in water, promotes molting of shrimp, and is beneficial to the growth and development of white shrimp. . In the whole culture process, zeolite powder is applied once every 15 days or so to help the growth of white shrimp molting. During the cultivation period, quicklime should be used regularly to adjust the acidity and alkalinity and improve the quality of the bottom soil. Generally, it should be used once every 20 days, and each time 10 to 15 kg per mu. It should not be used during the clam shell. In addition, beneficial live bacteria, such as photosynthetic bacteria and EM biologically active bacteria, should be administered every 15 days to improve the water quality of shrimp ponds and to maintain the water quality.

Within one month after stocking, a small amount of water is added instead of a lot of water. Generally add 5-10cm of water every 2-3 days until the water depth reaches more than 1.5 meters. In the middle and later stages of culture, the following conditions are encountered: When the pH of the water body fluctuates more than 0.5 or exceeds the range of 7-8.5; When the water is too transparent (greater than 80cm) or too cloudy (less than 20cm), the color of the water is significantly darkened When the amount of inorganic suspended matter increases; when the pond surface appears stable foam; when the pool water ammonia nitrogen, hydrogen sulfide, etc. exceeds the standard; can be appropriate to change the water 15-20%, should not be large row irrigation, prevent shrimp stress reaction.

In addition, the aquaculture machine is equipped with an aerator, which is usually started at noon for two hours in the early days, and turned on for two to four hours before dawn. The boot time can be gradually increased in the early days, and the high-yield tangs in the middle and late periods should be turned on almost continuously.

(2) Feeding of bait

Feed is the most important cost investment in shrimp farming, so choosing high-quality and environmentally friendly feed has a very important role in the success of the breeding and cost savings. Due to the relatively short growth period of shrimps in East China, the feed quality of shrimps is relatively high in order to accelerate the growth of shrimps. Practice has proved that with low-priced low-grade feed, the cost of raising shrimp does not necessarily follow. Only by choosing high-end branded feed can shrimp's success be guaranteed.

In addition, scientific feeding of feed can also effectively increase the economic efficiency of shrimp farming. In the process of desalination or intermediate cultivation of shrimps, they are usually fed four times a day. The daily feeding amount is as follows: A, 1 cm shrimp seedlings: 100 g per 100,000 tails; B, 2 cm shrimp seedlings: 200 g/100,000 tails; C, 3 cm shrimp: 300 g / 100,000 seedlings were fed and adjusted later. When the shrimp grows to more than 3cm and it is transferred to the pond for breeding, the number of feedings is generally 4 times a day. The feeding time was 6:00, 11:00, 19:00, and 23:00. Daily feeding amount: 3-10 cm shrimp daily feed amount is 6-8% of shrimp body weight. Individuals weighing more than 10 cm feed about 4% of their body weight. Feeding should be evenly distributed along the shallow water area around the pond, accounting for about 60% of the total amount of material in the afternoon and evening. Do not open the aerator when feeding.

In addition, in order to facilitate the scientific feeding management of white shrimp, it is required to set 3-4 food tables around the pond in order to check the feeding conditions of white shrimp. Generally, after one hour of feeding, the satiety of the sampled shrimps should be as good as 50-70%, and less than 50%, it is proved that the amount of feeding is insufficient; there are still leftovers after checking the food table 3 hours after feeding. The material proves that the feed is fed too much. It is necessary to grasp the amount of daily feeding and make comprehensive analysis and adjustment based on the size of the shrimp, pond water quality, water temperature, weather, and the amount of residual baits.

5, disease prevention

When Penaeus vannamei was introduced into East China, due to the low salinity, relatively less disease was observed in white shrimp reared in the South. However, in the last two years, with the gradual expansion of the aquaculture area, the incidence of white shrimp disease has increased. Therefore, it is very important to understand the law of occurrence and prevention and treatment of P. vannamei disease. Until now, the disease of P. vannamei detected in East China is basically the same as that in South China, with viral diseases, bacterial diseases, parasitic diseases, and Rickettsia infections.

Frozen Tube&tentacle Squid

frozen tube&tentacle squid

Frozen Squid,Tube Tentacle Squid,Frozen Tube Tentacle Squid,Fresh Frozen Tube Tentacle Squid

Zhoushan Junwei Aquatic Products Co., Ltd. , https://www.junweiaquatic-intl.com