First, biological characteristics
South American white shrimp (Penaeus vannamei) is native to the west coast of the Pacific Ocean to the central Gulf of Mexico. Is now recognized as one of the world's highest yield of three excellent shrimp species (the other two for the spot prawns, Chinese shrimp). The shrimp fast-growing, strong resistance to environmental changes, strong resistance to viral diseases, meat flavor, processing meat rate is high, is the main species of shrimp farming in Central and South America, but also the current international aquatic market of shrimp varieties.
South American white shrimp and Chinese shrimp similar in appearance, short head, thin crust, high meat rate, the normal body color is light greenish gray.
South American white shrimp adaptability, can survive in water temperatures of 6 ~ 40 ℃ in the waters, the growth of water temperature of 15 ~ 38 ℃, the optimal growth of water temperature of 22 ~ 35 ℃. High temperature tolerance limit of 43.5 ℃ (gradient amplitude), poor adaptability to low temperatures, water temperature below 18 ℃, its feeding activities that are affected, 9 ℃ below the side lying.
South American white shrimp natural habitat environment depth of 0 to 72 meters, can grow in the salinity of 0.5 ‰ ~ 35 ‰ of the waters, it is reported that 2 to 7 cm of juvenile shrimp , the salinity of the allowable range of 2 ‰ ~ 78 ‰. By salinity domestication, can also be cultured in freshwater ponds. In recent years in the two regions of freshwater ponds and low-salinity water culture has been successful, and achieved very significant economic benefits.
South American white shrimp on the feed of low nutritional requirements, the crude protein content of 25% to 30% of the feed can meet its nutritional needs. The shrimp have the habit of mutual predation, and this habit is more obvious with the growth performance, but the survival rate of pond culture can also reach more than 80%, the shrimp require fresh water, dissolved oxygen in more than 5 mg / l, but tolerate the lowest dissolved oxygen value of 1.2 mg / l, away from the water for a long time to survive, can be transported long distances, you can live shrimp for sale. pH value of 7.0 ~ 8.5, ammonia and nitrogen content is low. The natural environment of seawater, brackish freshwater, river water, reservoir water, pond water and well water, etc., as long as it is not polluted, can be used to raise shrimp.
South American white shrimp fast-growing, large individuals, natural waters can be caught in a body weight of more than 100 grams of adult shrimp, aquaculture body weight up to 60 ~ 80 grams. In reasonable density and feed conditions, water temperature 25 ~ 35 ℃, the local shrimp after 60 days of feeding, can be raised into 10 ~ 12 cm, a weight of 10 ~ 15 grams of commercial shrimp. Cultivation survival rate of up to 80% or more, high yield, up to 200 kilograms per acre, significant benefits of aquaculture.
South American white shrimp is indeed an excellent high-yield varieties of shrimp farming, all over the country can be adapted to local conditions in the sea, freshwater trial farming, and constantly sum up the experience, and must not be a rush, resulting in unnecessary economic losses.
Second, artificial nursery technology
At the end of the 1970s, U.S. researchers have completed the cultivation of South American white shrimp breeding, mating, nursery and high-density breeding of scientific research, in Central and South America has formed industrial development, in July 1988, South American white shrimp introduced into our country by the Chinese Academy of Sciences Institute of Marine Research, Professor Zhang Weiquan, in August 1992, the whole artificial breeding Successful, and in 1994 artificial seedling and mass production success. But the South American white shrimp by the maturation of shrimp and seedling technology, our country has not been able to mass production of seedlings, is now summarized at home and abroad about the South American white shrimp artificial nursery technology is as follows, for reference only.
(a) nursery facilities
South American white shrimp nursery facilities and shrimp nursery in China are basically similar. Its nursery pool is generally made of fiberglass rectangular tanks or cement pools, with a volume of 10 to 15 m 3. Nursery water must be filtered 2 to 4 times, single-cell algae culture water treatment is more stringent. Heating can be done with diesel boiler or coal boiler with hot water circulation. Aerated with a Roots blower.
(B) breeding shrimp cultivation
South America and Central America use the majority of South American white shrimp breeder shrimp caught from the natural sea area, but catching seed shrimp to prevent the sperm pods from falling off. Selection of healthy and undamaged, weighing 50 to 60 grams of seed shrimp, male and female ratio (1 to 2):1 into the indoor tank stocking, stocking density of 4 to 5 tails / m 2, the water temperature 26 to 27 ℃, salinity 33 ‰ ~ 35 ‰. Every day, about 50% of the water in the tank was changed and aerated, and the tank was covered with black shade net, and the light level in the tank was less than 100 lux. Feed fresh oysters, squid, frozen sandworms and other bait, daily baiting for about 10% of the weight of the shrimp.
(C) artificial ripening and transplantation of sperm pods
South American white shrimp for the open type of spermatheca type. Its reproductive habits are different from the Chinese shrimp. Male and female shrimp gonads are fully mature before mating. Mating, the male shrimp discharge sperm pods adhering to the female shrimp chest between the third and fourth pairs of footsteps (spermatophore position), a few hours after mating, the female shrimp began to spawn, sperm pods at the same time the release of spermatozoa, in the water to complete fertilization.
South and Central America engaged in South American white shrimp artificial nursery, most of the species to take the shrimp to let its natural mating, and then select the mated female shrimp, into the hatchery tank or cement pool spawning and incubation. This way, although the production of large quantities of shrimp seedlings, but need more seed shrimp. In Central and South America, the South American white shrimp also take artificial ripening, artificial transplantation of sperm pods technology for artificial seedling, the effect is also better. Operational techniques are as follows: collected from the natural sea area of seed shrimp, after a period of stocking, to be completely adapted to the pool after the environmental conditions, that is, artificial squeeze eyeball operations. First of all, the stock shrimp fishing into the inflatable black barrel, and then both male and female shrimp to squeeze the right eyeball, the operation should be carried out in the water. Then put back to the original pool to continue to cultivate the seed shrimp eyeballs. After a period of time, the eyeballs of the seed shrimp will mature one after another, at this time for artificial transplantation of sperm pods. South American white shrimp open type spermatophore is located between the 3rd and 4th pairs of footsteps. Sexually mature male shrimp, its spermatophore is milky white. Artificial transplantation of spermatozoa, must choose high maturity male shrimp, in its 5th pair of footsteps at the base of the thumb several times gently pushed, spermatozoa that is out. The spermatophore is then attached to the spermatophore of the female shrimp. Then carefully place the female shrimp into a small black bucket and wait for her to spawn and fertilize. The bucket should be minimally inflated to prevent the pods from falling out. The bucket should be shaded with a black shade net.
(D) female shrimp spawning and hatching
Artificially transplanted sperm pods of mature white shrimp female shrimp, generally in the middle of the night spawning, fertilization. South American white shrimp pregnant with eggs than the Chinese shrimp much less. General female shrimp spawning only 50,000 to 200,000 grains or so. But its breeding period is longer. After the female shrimp spawning, it will be fished out. After washing the eggs, and then increase the amount of inflation, about 12 to 14 hours, can be hatched out of the jointless larvae. The use of larvae phototropic characteristics, the larvae will be fished into the cultivation pool for cultivation.
(E) larval cultivation
South American white shrimp larval metamorphosis and development is similar to the Chinese shrimp. That is, the same after the jointless larvae, bacchus larvae, mysid shrimp larvae three larval period, and then metamorphosis to the baby shrimp. Larval cultivation of suitable water temperature 28 ~ 30 ℃, salinity 28 ‰ ~ 35 ‰, pH 8 or so. The technical measures for the cultivation of the larvae of the period and the Chinese shrimp are basically similar.
In the larval cultivation stage of the ecological conditions to be relatively stable, the entire nursery period, continuous aeration, in order to maintain sufficient dissolved oxygen.
1. Bait
Bait includes zooplankton and phytoplankton and surimi, etc., zooplankton and plants are cultivated using artificial indoor and outdoor pure culture and fertilization of nursery pools and other methods.
(1) phytoplankton culture: indoor and outdoor artificial cultivation of phytoplankton species are angular hair diatoms, flat algae and seawater chlorella and other three. Indoors with 0.2 tons of water body of glass aquariums and about 10 liters of glass tanks, etc., and outdoors with 0.5 tons of water body of cement pools, respectively, a single pure species and high-density mass propagation of algae to supplement the nursery pool in the urgent need.
(2) Zooplankton cultivation: the main species of indoor artificial culture of zooplankton are folded arm-tailed rotifers and two kinds of fungus. Rotifers in about 10 liters of large glass tanks to cultivate pure species, in 0.2 tons of glass aquariums in large numbers of breeding rotifers. The main use of lower salinity, warming and aeration, and flat algae, American yeast and other methods of rearing, breeding faster.
The hatching of the eggs of Platyhelminthes is cultivated in 0.2 tons of glass aquariums and 0.6 tons of water in cement pools. There are two methods of their incubation. One is to use high temperature and high salt immersion method, that is, for every 500 grams of eggs, 500 grams of salt mixed immersed in 800 ml of seawater, control the water temperature of 35 ℃, over a period of 6 hours, and then moved into the aquarium or cement pool for heating, aerating, incubation, and take its unarticulated larvae for feeding. Another method is to use filtered seawater with a salinity of 30‰ or more, and put 2 to 3 grams of Eumeces platyrhynchos eggs per liter of water, and then heat the cement pool at 28℃, and inflate and roll the Eumeces platyrhynchos eggs for 20 to 36 hours to hatch out the unseasoned larvae.
In the nursery process, when the South American white shrimp larvae develop to ? Shaped larvae Ⅲ, it began feeding the jointless larvae of the perennial worm, in the mysid shrimp larval period until the 4th day of the baby shrimp, are fed with the jointless larvae of the perennial worm. Feeding the number of general control in each milliliter of water in about 5 of the articulated larvae, and the number of shrimp larvae to give the appropriate increase or decrease.
When the baby shrimp development into the fifth day, are to fish, white shrimp, bivalve meat feeding. Feeding quantity to 300,000 shrimp, 500 grams of fresh bait per day. Above fresh bait by a small meat grinder into minced meat, and then filtered through a 40 to 50 mesh sieve, wash away the viscera, sewage, etc., leaving only the meat residue feeding, to prevent water pollution.
2. Maintain the biological ecological balance of the nursery pool
During the nursery period, there are specialists, every day in the morning and afternoon to determine the number and type of single-cell algae in the nursery pool. When the white shrimp larvae in the nursery pool in the jointless larvae II period, then the introduction of angular hair diatoms, generally 50,000 ~ 100,000 diatoms per milliliter of water, while the application of urea or fertilizer composite, each time to put 5 grams / m 3, 3 ~ 5 days once. Every day, mirror check the number of algae in the nursery pool and the development stage of the larvae, the number of changes in the situation and the climate, sunlight and other changes, the appropriate increase or decrease in the amount of fertilizer to ensure that there is sufficient bait in the nursery pool. If there is an urgent need to replenish the diatoms in the nursery pool, then replenish the pure Angular Hair diatoms propagated indoors and outdoors.
When the nursery pool in the South American white shrimp development to ? When the nursery pool in the South American white shrimp development to ?-like larvae Ⅱ, it will be put into the rotifers, put the number of about 0.1 ~ 1 rotifer per milliliter of water, so that rotifers in the nursery pool natural reproduction, and there is an abundance of algae for bait. When the larvae develop to ? like larvae Ⅲ and mysid shrimp larvae Ⅰ, put in rotifers and the unsegmented larvae of Fennerophora in the nursery pool, generally 5 per milliliter. And according to the results of the daily microscopic examination, a steady stream of supplementation of the annelid unsegmented larvae, until the South American white shrimp larvae development to the shrimp on the 4th day. Litters of shrimp on the 5th day began to feed minced fish as bait.
In the nursery pool of biological ecological balance of integrated nursery technology, is to overcome the indoor and outdoor cultivation of unicellular algae and rotifers and other equipment conditions are not enough to take a more effective nursery methods, but also a save manpower, material resources is more effective measures, and more importantly, to ensure that the larvae of the different stages of development required to ensure that the amount of palatable bait.
(C) the management of larval nursery pool
South American white shrimp larval nursery pool management is a comprehensive scientific management, daily management measures are as follows:
1. Every day, the development of shrimp larvae in various periods of microscopic inspection, counting, and timely mastery of the survival rate of the larvae of various periods.
2. Every day in the morning and afternoon for the species of zooplankton, the number of microscopic examination.
3. Determine the temperature, specific gravity, pH value, dissolved oxygen and other changes regularly in the morning and afternoon every day.
4. According to the development of the nursery pool larvae and shrimp, timely discharge of the old nursery pool sewage, add the appropriate amount of fresh seawater. Shrimp period of water exchange is larger, generally into half or 2/5 of the fresh seawater.
5. Nursery ponds should be timely fertilizer or add a certain amount of phytoplankton, rotifers and arthropod larvae, to ensure that the biological ecological balance of the nursery pond.
6. Maintain a relatively stable water temperature in the nursery pool, to install a thermostat controller to increase the temperature.
7. In order to inhibit the breeding of bacteria in the nursery pool, to promote the normal development of shrimp larvae, put antibacterial drugs such as oxytetracycline, generally 0.5 ~ 1 gram per cubic meter of water.
8. Ensure that the nursery pool pH is relatively stable, reduce the ammonia and nitrogen content of the water, especially the content of non-ionic ammonia toxic factors. Especially from the first day of the baby shrimp, stop diatom placement, switch to flat algae, generally controlled at about 50,000 per milliliter.
9. In the entire larval cultivation stage are kept continuously aerated to ensure that the nursery pool water body has sufficient dissolved oxygen.
Third, aquaculture technology
South American white shrimp is now recognized as one of the world's three highest yielding shrimp species. Temperature and salinity to adapt to a wide range of seawater ponds can be semi-refined and refined, but the growth rate is faster than the spot prawns, the price is also higher. Shrimp fry by freshwater domestication, but also in pure freshwater pond culture. Currently in the United States South American white shrimp finishing yield has reached 355.3 kilograms per mu.
(a) shrimp pond conditions
Shrimp pond construction must take into account economic, practical, safe and easy to operate and other factors. South American white shrimp semi-finishing pool in the existing seawater shrimp pond on the basis of transformation, the area is generally 40 to 50 acres, rectangular, the ratio of length and width of 3:1, the long side of the wind should be parallel with the local perennial direction, depth of 1.5 meters, sandy mud bottom, the width of the pool embankment is not less than 2 meters, set up baiting platform along the inner side of the pool embankment, the bottom of the pool is flat, but inclined towards the drainage outlet, to facilitate sewage, the inlet and outlet should be strictly separate, the greater the distance between the greater the better. The larger the distance between the inlets and outlets, the better. But the intensive pool area should not be too large, generally about 10 acres, pool depth 2.5 ~ 3 meters, sandy bottom pool is better. Where the freshwater ponds can feed Rochester shrimp can feed South American white shrimp, finishing ponds and freshwater shrimp ponds should be equipped with an oxygenator, oxygenator in addition to ensuring that shrimp ponds have sufficient dissolved oxygen as well as fertilizers, medicines can be stirred after the role of the uniformity of the water can be made to a certain rate of flow of water to form a circular flow of dirt in the pool concentrated in the central area of the pool as much as possible for the shrimp to grow to create a clean place of habitats.
(B) water quality conditions
Unpolluted river water, lake water, reservoir water, well water can be pure freshwater pond culture of white shrimp.
The quality of seawater is a direct impact on the growth of white shrimp, survival, yield of the main factors. Determine the merits of water quality, available "a touch, two taste, three smell, four view" method. That is, twisting the water with your fingers, slippery feeling is not good water; mouth taste, bitter and astringent is not good water, salty and no odor is good water; nose smell fishy smell is not good water; eye view of the lack of plankton species in the water composition, the water color is abnormal (reddening, darkening), the amount of foam and with the color of the water is not good, normal seawater foam for the white, the bigger the foam, said seawater eutrophication is more serious.
Feeding of South American white shrimp quality water, the requirements of water quality is fresh, pollution-free, dissolved oxygen for more than 5 mg / liter, pH value of 7.0 ~ 8.5, transparency of 35 ~ 60 cm, NH4 + - N & lt; 0.2 mg / liter.
(C) cultivation of basic bait organisms
Cultivation of basic bait organisms include: clearing ponds → natatorium → fertilizer → introduction of seeds, these regular steps in the pond must be thorough, natatorium, the mesh of the inlet gate is usually 40 mesh, and then can not be too small, the pool should be reasonably applied to organic fertilizer or chemical fertilizer.
After winter exposure to the shrimp pond silt removal 10 to 20 cm, about 15 days before the release of shrimp fry with quicklime 50 to 70 kg / mu, or bleaching powder 8 kg / mu disinfection shrimp pond. Pond cleaning can take different methods according to local conditions. After clearing the pond to about 10 days before the release of seedlings, into the water 50 cm, the application of organic fertilizers and fertilizers to cultivate the basic bait organisms, the application of chemical fertilizers for urea 3 kg / mu, calcium superphosphate 0.5 kg / mu. Make the water yellowish green or tea brown. Pond water transparency 25 to 40 centimeters, pH 8.0 or so. The amount of fertilizer should be flexible according to the fat and thin shrimp pond substrate.
In short, before the shrimp fry into the pool, to cultivate enough basic bait organisms, because the basic bait organisms palatable, nutritionally comprehensive, is any artificial bait can not be replaced, is to improve the survival rate of shrimp fry, shrimp fry to enhance the physical and accelerate the growth of shrimp fry the most important material basis. At the same time, bait organisms, especially phytoplankton on water purification, absorption of ammonia, hydrogen sulfide and other harmful substances in the water to reduce shrimp disease hazards and stabilize water quality will play an important role.
(D) shrimp fry stocking
1. Selection of shrimp fry
South American white shrimp fry to choose robust and lively, elongated body segments, uniform size, clean body surface, full of muscle, intestinal full, responsive to external stimuli, swimming in an obvious direction (not circling swimming), the carapace of transparency (muscle is not cloudy), the whole body without foci (appendages are intact, large tentacle whip), the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the body of the shrimp, the shrimp and the shrimp. No redness, gills do not turn black) and so on. The most effective way is to resist leaving the water test: from the nursery pool randomly take out a number of tail shrimp fry, wringing out a wet towel to bury them, 10 minutes after taking out and put back to the original pool, such as shrimp fry survived, it is a high-quality shrimp fry, otherwise it is a poor quality seedlings.
Stocking high-quality shrimp seedlings is to improve the survival rate of shrimp farming and an important guarantee of high yield. Stocking of South American white shrimp specifications is best more than 2 cm, generally 1 ~ 1.2 cm, at this time the shrimp fry on the adaptability of the external environment is stronger, raised the survival rate is high, too small to raise the survival rate is low. However, the current South American white shrimp seedlings have not formed a large-scale production, shrimp fry far from meeting the needs of aquaculture, most of the shrimp seedling imported, the specifications are generally small, generally only 0.6 centimeters, the survival rate of only 35% or so, less than high-yield and efficient purpose. If stocked about 2 cm shrimp seedlings, raised into a survival rate of about 85%.
3. Timely release of shrimp seedlings
South American white shrimp optimal growth of water temperature of 22 ~ 35 ℃, in this water temperature range to put shrimp seedling culture, fast growth, feeding, strong body, strong disease resistance. South American white shrimp living in the environment of low water temperature is small intake, weak, slow growth, thus raising the survival rate is low. Therefore, South American white shrimp stocking time in the south of China is more appropriate in April to May.
4. Reasonable stocking density
General semi-finishing conditions, due to poor artificial control conditions, simple facilities, so the stocking density of shrimp fry generally put 6,000 to 10,000 tails per acre, finishing pond seedling density of 30,000 to 40,000 tails / acre. In accordance with the current high density of Rochester shrimp finishing, take the method of rotational fishing, stocking density of up to 50,000 ~ 60,000 tails / mu, mu yield has reached more than 500 kilograms, mu of net profit of up to 4,468 yuan. Of course, the culture of South American white shrimp profits relative to Rochester shrimp much higher.
Fifth, feeding management
Feeding management is good or bad, directly related to the South American white shrimp breeding survival rate, production and economic benefits. Therefore, in the South American white shrimp throughout the breeding process, the pond water quality, feed, daily work to carry out scientific management.
(a) water quality control
1. Pond water color control
The ideal water color for shrimp farming is formed by green algae or diatoms yellow-green or yellow-brown, these green algae or diatoms is a benign biological communities in the pond micro-ecological environment, play a purifying role in water quality. Therefore, it is necessary to consciously regulate this ideal water color in the breeding process. At present, the most conventional method is to apply nitrogen and phosphate fertilizers in proportion to the water in the pond, such as thin water ponds early in the application of organic fertilizers, fertilizer depending on the pond water transparency, pH, water color and other flexible grasp, once a week fertilizer. To the breeding of late due to residual bait and shrimp excreta increased, the general water color becomes darker, at this time should take the appropriate amount of water or apply a certain amount of zeolite powder or quicklime to control the water color measures.
In the shrimp pond put beneficial micro-organisms, such as photosynthesis bacteria, EM bioactive bacteria, etc., can timely degradation of organic matter into the water column, such as animal carcasses, bait, etc., to reduce the organic oxygen consumption, stabilize the pH value, and at the same time can be balanced to the unicellular algae photosynthesis to provide nutrients to balance the algal phase and the bacterial phase, to stabilize the water color of the pond.
2. Pond water pH, dissolved oxygen, transparency control
South American white shrimp suitable pH value of 7.8 to 8.5. But the breeding of the middle and late had a peak of 9.2, therefore, in the breeding process should pay special attention to the regulation of pH, should not be too high, otherwise it will increase the toxicity of ammonia and nitrogen, inhibit the growth of shrimp.
In the South American white shrimp farming process, with the growth of shrimp, the demand for dissolved oxygen in the water is also growing, so in the early stages of aquaculture depending on the water quality to take the intermittent opening of the oxygenator. Later, with the growth of shrimp gradually extend the time to open the oxygenator, finishing ponds and high-density high-yield breeding ponds, to the breeding of the mid- to late-stage need to be turned on 24 hours a day when necessary to ensure that the dissolved oxygen in the pool water is more than 5 mg / l, the bottom layer of the pond dissolved oxygen in the more than 3 ml / l, the minimum can not be less than 1.2 mg / l, so, to buy a rapid water quality meter, at any time to monitor the pool of water pH, dissolved oxygen, ammonia and nitrogen! and other changes to ensure that shrimp farming is foolproof.
In the early stage of aquaculture, the transparency of the pool water to maintain 25 ~ 40 cm, breeding in the middle and late, the transparency of the pool water should be maintained at 35 ~ 60 cm, if the transparency of less than 20 cm should be changed, add water or application of zeolite powder or quicklime, if the transparency is too large, can be applied to the nitrogen and phosphorus fertilizers.
In pure freshwater pond culture of South American white shrimp can take silver and bighead carp, used to regulate the pond water quality.
(B) scientific baiting
Semi-intensive ponds are generally fed cheap chilled fish paste or small shellfish, but also put some with the feed, with the feed can be artificially prepared, with the feed ingredients containing 17% fishmeal, 40% of soybean cake, 28% of gluten, 10% of the second meal, 3% of the bone meal, 2% of additives.
Relative to the Chinese shrimp and spot prawns, South American white shrimp on the bait protein requirements are not high. Both to ensure that the shrimp to eat, eat well, but also to take into account the breeding environment and reduce feed costs. Culture of South American white shrimp feed coefficient of 1.45, than the culture of spotted shrimp feed coefficient of 1.6 to 1.8 low, so now commercially available shrimp feed is also suitable for the nutritional needs of South American white shrimp. Feed particle size should also be based on the different growth stages of shrimp to choose, too small or too large particles will cause unnecessary waste, thus causing the bait coefficient of increase. Breeding pre selection of particle size 0.05 ~ 0.5 mm of granular feed, medium-term selection of 0.5 ~ 1.5 mm of feed, late selection of 1.5 ~ 2.0 mm of feed, the best use of puffed sinking granular shrimp feed.
The amount of bait should be based on the size of the shrimp, survival rate, water quality, weather, feed quality and other comprehensive factors, but practical production experience is also very important. Breeding medium-term (shrimp body length of 3 to 10 cm), the daily bait for shrimp wet weight 6% to 8%, late breeding (shrimp body length of 10 cm or more), the daily bait for shrimp wet weight of 4% to 5%. Pre-culture feeding twice a day, feeding period were 7:00, 19:00; mid-culture baiting three times, feeding time for 7:00, 19:00, 23:00; culture in the late stage of feeding four times, feeding time 7:00, 12:00, 19:00, 24:00, evening feeding accounted for 50% of the total amount of daily baiting. The feeding method is uniform feeding along the edge of the pool.
(C) patrol
Every morning, evening, midnight patrol, observe the water color changes and whether the shrimp floating head, with the help of light observation and fishing net to check the two methods of observation of the shrimp's activities, growth and satiation rate to regulate the amount of bait and whether or not to open the oxygenator.
(D) timely harvest
Shrimp collection methods and nets are generally similar to the spot prawns. One-time shrimp collection should generally pay attention to: when the cold wave attack, the temperature suddenly lowered (more than 8 ℃) can not collect shrimp, when the temperature rises and then collect shrimp; sudden deterioration of water quality, as soon as possible, early collection of shrimp; shrimp growth stagnation, the beginning of shrimp disease should be a surprise collection of shrimp. High-yield intensive shrimp ponds to take the method of rotational fishing, when some of the shrimp grow to commercial specifications when the sub-sparse start, several times harvest.
Six, shrimp disease control
This summer, the Guangdong coast and outbreaks of large-scale shrimp disease, early shrimp serious reduction in production, which has been plagued by the Guangdong shrimp aquaculture industry in recent years, another outbreak of disease. Recently, the Guangdong aquatic community are paying close attention to the South American white shrimp with strong disease resistance, so shrimp disease is less, the growth rate is faster than the spot prawns, for a time, Guangdong shrimp farmers have high hopes for the South American white shrimp.
The 80s is the heyday of the world shrimp aquaculture industry, but also the beginning of large-scale outbreaks of epidemic shrimp disease. 80's, known as the world's grass shrimp Kingdom of Taiwan Province in the shrimp disease blow under the devastation of the helpless in the hope of the introduction of a strong resistance to the South American white shrimp to revitalize the shrimp industry, but the good times do not last long, the storm clouds in 1998, South American white shrimp aquaculture boom in less than a year and the collapse of the shrimp. Less than a year and the collapse of the time, disease in all directions. And the current needs of Guangdong, South American white shrimp fry most of the introduction from Taiwan Province, and shrimp pathogens brought into Guangdong, should cause leaders at all levels to pay close attention to the import of shrimp fry for strict quarantine.
In fact, in the artificial culture environment, shrimp are likely to occur four kinds of shrimp disease, namely, viral infections, bacterial infections, rickettsial infections and parasitic infections. The South American white shrimp mainly cause viral infections are: TSV (Taola virus), WSSV (white spot virus), IHHNV (subcutaneous and hematopoietic necrosis virus), BP (shrimp baculovirus), YHV (yellow head virus) and so on. Above various viruses are limited to the regional area of the epidemic, and with the seed shrimp, shrimp fry import and export breakthroughs across national borders, the consequences are endless. And white spot disease is now the most widespread worldwide virus.
Our province in recent years the introduction of South American white shrimp and breeding gradually increased, but the South American white shrimp disease epidemic is not optimistic, nearly 70% of the shrimp ponds to varying degrees began to appear. Therefore, the South American white shrimp disease to prevent than cure.
South American white shrimp aquaculture began, the pond splash 2 mg / liter of hygromycin in the water column; every other week thereafter, change the application of 1 ~ 1.5 mg / liter of furacilin once, regularly add a feed or even a variety of drugs to enhance the shrimp's ability to resist disease, bait mixing drugs with vitamin C, E, allicin, hygromycin, chloramphenicol, etc., the shrimp pond for the scientific management of shrimp ponds, so that the shrimp ponds Continuously maintain the biological ecological balance, balanced shrimp pool algae and bacteria phase, effective prevention and control of shrimp disease in South American white shrimp.