缢蛏Factory-wide artificial seedling raising technology

缢蛏 [Sinonovacula constricta (Lamarck)1, commonly known as baby son, mud frog. It is a bivalve marine mollusk. Wenling City, Zhejiang Province is a famous area for pupa (grass seedlings and merchandise). In 2001, the city raised an area of ​​62,000 mu, with a total output of 40,600 tons. Due to the large changes in the marine environment and the constraints of unstable natural conditions, the shortage of seedlings has become a problem. In spite of the proliferation of scientific and technological personnel, the scientific and technical personnel have not been able to meet the needs of a large number of farmers and have restricted the breeding industry to varying degrees. development of. In order to solve this problem, after more than two years of research projects, we have succeeded in the factory-based artificial seedling raising technology. The report is as follows:

I. Pond conditions

1 Outdoor intimacy cultivation pool (using shrimp farming ponds in the vicinity of the beach) an area of ​​308m2, in the high-middle area of ​​secondary cultivation of large seedlings with an area of ​​86.5 acres of earthen ponds, a total of 432 ponds. 2. The indoor small seedling cultivation pool (using cement ponds that are idle during the idle season of shrimps, crabs, and oysters) has an area of ​​850 m2, and is used as a primary seedlings breeding pool, and is equipped with a certain area of ​​feed stocking culture ponds (algae pools). 3. Supporting facilities: First-level sedimentation tanks, second-level high-position filtration tanks, and several reservoir reservoirs. The pumps, power supply units, air supply blowers, pipelines, and lines are all fully configured.

Second, nursery method

1. Artificial in vitro cultivation and fattening of the first-intimate earthworms. Intimate artificial cultivation of fattening is the use of artificial creation of environmental conditions, so that the normal growth and development of the intimacy, gonad maturation, in order to obtain high-quality sperm, eggs. If the infertile gonads are poorly matured, premature delivery, lack of production, or late delivery will not only affect their fertilization rate and hatching rate, but they will also result in poor larval vigor, often causing cilia discs to fall off, leading to the death of nursery. Therefore, in the period of intimacy culture, attention should be paid to the management of the main technical measures such as the storage of water in the cultivation pool, the control of water and the exchange of water, the removal of hostile organisms, and the adjustment of temperature, salinity, and illumination.

2. Intimate indoor ponds for enhanced culture. In general, beginning in mid-September each year, the pro-gills developed from the outdoor culture pool (or on the Bund) are picked up, and after screening, chopped oyster shells are removed, and intact, vitality, and healthy will be intact. Transfer to the indoor pond for intensive cultivation until the frogs can spawn, fertilize, and pick eggs to hatch. The control of hatching density is generally 15 cells/mL-20 cells/mL, and no more than 30 cells/mL.

3. Indoor larvae are raised. With density, D-shaped larvae were cultured at 8 cells/mL. 10/mL is better.

4. Feed supply. The D-shaped larvae initially rely on their own yolk nutrition, and after 24 hours the intestinal tract is formed. The digestive system has been developed and should be fed. The golden-algae feed was the best for the feeds. Not only did the D-type larvae have a high survival rate, but also they grew fast. The daily feeding amount was 10,000/mL to 20,000/mL, and the daily increase was 10,000/day. mL, until the shell grows to 100um ~ l60um, the daily feeding amount is 50,000/mL. The top of the crust is still fed with golden algae in the later period, plus 50000 to 100000/mL of Platymonas suberectus. It is better to mix and feed diatoms. Day and night feeding 3 times - 4 times, depending on the actual observation results may be.

5 strengthen the exchange of water. In addition to D-shaped larvae on the first day plus pool water to 1.40m-1.45m, the next day will have to change the water. In the early days of the shell, the water is changed once a time - 2 times, changing the water volume 1/2; changing the water in the middle of the shell top 2 times a day, changing the water volume by 9/10; the whole pool water can be changed every day in the shell top.

6. Oxygenation. The air stone distribution density is 1/m2, and the air supply volume should be controlled after opening the air supply adjustment switch. The distribution of gas head holes at the bottom of the pool should be vertical and the water flow should be scattered over the water surface and evenly distributed.

7. Drug prevention. Oxytetracycline and other antibacterial drugs can be used, the general amount of 0.5ppm ~ 1.00ppm.

8. Water quality requirements. The quality of water required for hatching and larvae cultivation is fresh and clear. The pH is maintained at 8.0-8.5, the salinity is 18 to 24, the water temperature is 22 to 24, the dissolved oxygen is >5 mg/L, and the ammonia nitrogen is <0.05 mg/L. EDTA is maintained at 5ppm.

9. Larval metamorphosis. Both the larval metamorphosis and the juvenile breeding period require the timely delivery of larvae attachment, living substrates, and conditioning the bottom of the nursery. In general, the tidal flats of natural tidal flats (abundant benthic diatoms) that are free of pollution and smooth on the surface should be selected when large tides are flooded, shaved, sun exposed, dried into cakes, and then crushed into powder. Use a 200-mesh sifter to filter and spill it evenly into the pool to allow it to settle. The thickness of sediment is 3mm-5mm. After the juveniles are attached, the distribution density of the juveniles is 60 x104/m 2 -220x104/m 2 at the bottom of the pond.

Water temperature is maintained at 20 °C - 23 °C, salinity 20 ‰ ~ 24 ‰, the daily water exchange rate is controlled at 100% - 200%, and should be appropriate water. Feeding of bait was also based on golden algae and Platymonas philippinarum, and some small diatoms were assisted in feeding. The daily feeding amount was: Xanthomonas 5.0xl04/mL—7x104/m L, Platycladiia 0.4104/mL— 0.7104/mL.

10. The outdoor secondary breeding of the seedlings (overwintering for the seedlings). When the indoor cement pool raises the seedlings to a shell length of 500um-800um and the young shell shape approximates into a shell shape, it can be discharged in time and transferred to an outdoor earth pond for culture.

The location selection of secondary soil nursery for large-scale seedlings should be based on different seasons and emergence time. For example, the seedlings cultivated in the indoor pool should be kept in the high tide area (small tide period is 1-2 days) if they are out of the pool before and after the beginning of winter. Wherever they arrive, the seedlings during the period from light snow to snowfall should be temporarily raised in the upper part of the middle tide area (from the first 70m to 80m in the lower part of the first batch of indoor wintering stocking ponds).

The construction specifications for the secondary soil nursery for large seedlings, generally 16m to 20m in length and 7m to 8m in width, are suitable for an area of ​​about O, 20 mu to 0.25 mu per well, and the average pond depth is 20cm to 30cm. The width of the earth dam foundation is wide. 1.0m~1.2m, top width 0.35m—0.40m, height 0.6m—0.7m, keep slope surface smooth, and excavate a water inlet and outlet at the tide surface, width about 1.5m-2 .0m. If the slope of the beach is too large, the earthen pond dyke can be properly reduced, but it is required that the upper dyke be slightly higher than the lower levee, so that the dyke will be washed away by the current when the tide is low, affecting the normal growth of seedlings in the earthen pond.

Winter holding ponds have a water depth of 35cm to 45cm in winter and a depth of 20cm to 30cm in spring. The stocking density of seedlings during wintering is generally 50 x 104/mz-60 xl04.
/m2.

Third, discuss

1. Intimate culture can be comprehensively used in shrimp ponds in middle and side beaches. However, attention should be paid to the removal of harmful organisms, and shrimp bait should not be directly fed in the culture area to avoid eutrophication of the culture medium. It should be strengthened. The cultivation period maintains water quality, fresh, fertile and free from pollution. The regulation of frogs should also be combined with water storage and dry dehydration, which is conducive to the growth of pro-growth and gonadal development, and access to healthy, high-quality pro-frogs for nursery production.

2. In order to ensure the quality of pro-spawning, it is necessary to grasp the maturation of intimacy and development, so that artificial stimulation of production should be appropriate, otherwise it is difficult to ensure the quality of eggs.

3, picking eggs hatch. Due to the fact that it is difficult to distinguish male and female from the outside, in order to ensure the quality of the fertilized egg, males can discharge the sperm first, and then the female releases the egg in the same way. In the state of still water, use the mesh or the net. Fertilization, it is better to sink the discharged eggs in a short period of time from the discharge layer. If the original pond is hatched and cultivated, the water in the upper part (drainage layer) must be drained, then oxygenated and agitated, and the excess sperm and other harmful floating materials should be stirred into foam to remove and agitate the pool water for incubation.

4. Larvae are grown. Due to the planktonic life of D-type larvae, their foraging is more passive. Therefore, it is better to use algae such as Isochrysis galbana, nutrient-rich, easily digested and absorbed algae as the open bait, such as golden algae, chlorella, and planktonic algae. Mixed feeding, nutrition is comprehensive.

5. Perverted attachment. It is difficult to turn the larvae gradually from the flood season to the attachment period. From the current situation, the bottom plane adhesion layer must be evenly laid with a 3 mm to 5 mm thick active mud mud. Because larvae grow from seedlings, larvae metamorphosis to juveniles (seedlings) is a complex process from larval formation, ecology, physiology, and a series of changes. The individuals are very fragile and must be artificially created to create a good ecological environment. Only by strengthening scientific management can we improve the survival rate of juveniles (seedlings) and produce healthy and high-quality seedlings.





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