Shrimp development stage
The stages of growth and development of Penaeus vannamei larvae include fertilized eggs, nauplii, zoea, larvae and prawns. Each stage is subdivided according to different morphologies. For example, zoea can be Subdivided into Phase I, Phase II, and Phase III, the larval stage can also be subdivided into multiple stages such as P1 to P20. According to the introduction of Liang Mao, director of Haimao Saplings Company, the metamorphosis of each stage of growth and development of Penaeus vannamei has certain rules and characteristics. Among them, the nauplii mainly observe the caudal fins, and the juveniles observe the eye points and tail appendages. The squid is observed through the swimming feet. The larvae observe the development of the pupa, but the determination of each stage of the growth and development stages depends on the production experience and the microscope for further observation.
Water treatment system
The treatment process of the water treatment system includes sand filtration seawater, sedimentation tank, chlorine disinfection of Datang, fine sand filtration, protein separation, dark pool, precision filter, ultraviolet disinfection, activated carbon adsorption, and high density fiber filtration. The sea water treated by this complex water treatment system is clean and clear, and water-free organisms and organic matter in the water provide reliable and reliable water for the water for rearing seedlings.
Water quality inspection
Water quality observation and inspection mainly includes water, dissolved oxygen, physical and chemical indicators, and sediment quality improvement. The standard of water quality is “fat, live, tender, and coolâ€. In this state, the water body is refreshed and strong, and the food is rich. Is the best breeding water condition; the change of dissolved oxygen is mainly affected by the photosynthesis of algae and some aquatic organisms and microbial respiration; physical and chemical indicators mainly include ammonia nitrogen, nitrite, pH value and total alkalinity, etc. Changes in indicators should take corresponding measures; Substrate improvement is very important to maintain the long-term stability of the water body, for the bottom quality improvement can be used to change the bottom of biology, chemical reforming, cool change to the bottom and physical change to the bottom (only from a short time Effect, but it can't be fundamentally changed).
The superiority and inferiority of shrimp
High-quality shrimp should have intact body and no damage, smooth surface and no attachment, hepatopancreas clear outline, strong phototaxis, strong anti-stress ability, strong anti-water ability, neat specifications, continuous long-distance swimming, strong bouncing, no body color Red or pale cyan, gastrointestinal full (line black) and so on. However, poorly-prepared shrimp seedlings often show poor anti-stress ability, poor ability to swim against the water, weak adaptability to water temperature and salt concentration, weak activity, unresponsiveness, incomplete shrimp seedlings, body surface scratches or incomplete limbs, abnormal body color, Muscle turbidity, appendix base redness or blueness; silkworms hanging dirty, parasites, algae and feces on the body surface; liver and pancreas atrophy, empty stomach, jejunum and other adverse symptoms.
initial preparation work
The nursery ponds should be cleaned and disinfected 1 week before plant nursery ponds are placed. First, disinfect the cleaning tools and shed cloths, then use methanol or potassium permanganate to sprinkle the nursery ponds (disinfection for more than 12 hours), and then splash around with the methanol and potassium permanganate around the nursery ponds. The nursery ponds were rinsed with fresh water, washed with detergent, and exposed to roof exposure. In addition, the seawater and freshwater should be added to the nursery ponds prior to planting, and the water body temperature (32°C) and salinity (not to be less than 16 ‰, most suitably 22 ‰) should be adjusted. Next, nutrients are added to the water body to cultivate the water bodies. The micro-organisms in the system can be released for 1 week or so.
Fangmiao
Haimao Shrimp Co., Ltd. used Primordium velutipes as a standard for laying seedlings, and put Primo larvae at the stage of nauplii into the nursery workshops. Each nursery pond was allocated 5 million to 6 million (30 cubic meters). ). Through the practice and observation of seedling-laying workshops in each area of ​​Haimao Shrimp Co., Ltd., it was found that the main methods of seedling-laying were direct injection and post-disinfection injection, and the difference in injection methods was mainly based on the selection of technical masters in each district. After the exchange with the technical masters, a more comprehensive understanding of the two seedlings has been achieved. Because of the long-term transport of the nauplii, the shrimp seedlings at this time are relatively fragile, and direct injection can reduce the further damage to the shrimp seedlings. The bacteria and virus may be brought in, and the bacteria and virus are prevented from entering after disinfection, but the shrimp body has certain damage.
Daily management
After the planting, the daily management of the workshop is mainly based on grasping the physical and chemical indicators of the water body, changing the water in the nursery pond, and feeding materials. In addition, the temperature of the water in the nursery pond, the vitality of the shrimp seedlings, and whether there are dead seedlings, inflation, bait, etc. Observe it all. The physical and chemical indicators of water are mainly based on laboratory tests, and the water quality of aquaculture workshops should be tested every day after the seedlings are released. The assessment of indicators (mainly the composition of Vibrio, pH value, ammonia nitrogen, and nitrite, etc.) can be used to judge nursery. Pool water quality and shrimp seedlings situation; nursery ponds change the water is generally every other day for a workshop, generally out of the nursery pond 20 cm water level, when the pumping water to use sieve sieve nets (sieve net mesh size determined by the size of the shrimp) to filter Observe to see if there is a phenomenon of seedling leakage, and then add 20 centimeters (10 centimeters of sea water, 10 centimeters of fresh water) to the nursery pond. However, special treatment is required for some special situations. The specific procedures and operations are mainly arranged by technical masters in each district; Feeding mainly includes vegetal foods and animal feeds, among which larval shrimps are mainly plant foods and chilled artichokes. In the later period, they are mainly animal foods, shrimp and Artemia, and feeding intervals are 4 hours. As the type changed, the ammonia nitrogen and nitrite contents in the nursery pond began to rise, but the impact on the shrimp seedling was not significant. In addition, the color of the water body was also yellowish. As a dark brown discoloration.
Emergence and clear pond
The standard of emergence was mainly P5 stage of prawn, and the whole process of raising seedlings was about 13 days to 15 days. Before the emergence of seedlings, water should be discharged (At this time, care should be taken not to pull out the in-canula directly. Since there is a large difference in the water level between the inside and outside of the pool, direct extraction will cause a great impact on the shrimp seedlings and cause death of the shrimp seedlings) when the water level in the nursery pool When 40 cm to 50 cm are discharged, the cannula can be pulled out to allow the shrimps to enter the net, and then the sieve nets are used to take the seedlings. In addition, when taking the seedlings, attention must be paid to each time. The quantity of seedlings may cause hypoxia and death when there are too many shrimp seedlings. After draining, seedlings are put into double plastic bags filled with 20 liters of cold water and flushed with oxygen. Finally they are placed in foam boxes with ice bottles and packaged and loaded separately according to the method of air transport or motor transport. The transport vehicles are all equipped with a cooling function. The temperature inside the vehicle (about 20°C) should be noticed during the journey. After emergence, the residue of the seedling pool bottom and the four walls are washed with fresh water, and then the bottom of the pool, the four walls, the gas filling pipe, the heating pipe and the gas stone are washed cleanly with the detergent.
After practice, the author concluded that shrimp was successfully picked up from the seedlings.
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