The green bark, commonly known as barnyardgrass and roundworm, is a subtropical species. It is an economical shellfish that is common in the south and north of China and lives in coastal mudflats. Barley is delicious and nutritious, rich in nutrients, contains a variety of trace elements required by the human body, and is one of the quality marine shellfish. According to statistics, the breeding area of ​​the barley of the province is more than 50,000 mu and the annual output is about 45,000 tons. It has become one of the main varieties of marine aquaculture. In the past, most of the young fish were caught in natural sea areas. With the declining natural resources, the young fishes of the young species have become increasingly tense. To this end, Wenling and other provinces in our province have actively carried out research on artificial breeding techniques of indica. Through several years of hard work, we have systematically mastered the technology of artificial breeding of the barley, and carried out large-scale production.
The techniques of artificial breeding of highland barley include pro-shellworm selection, artificial oxytocin production, hatchery selection, larval rearing, attachment base selection and placement techniques, selection and culture of juvenile bait, and feeding techniques; juvenile rearing, management, emergence techniques and seedlings Transportation technology.
I. Basic facilities for raising seedlings
You can use the fish and shrimp crab nursery to carry out the whole artificial breeding of barley. Requires a certain scale of nursery, spawning hatchery, nursery ponds, nursery ponds; single-cell algae cultivation facilities; water, electricity, gas complete; nursery water must be dark precipitation and secondary sand filter.
Second, pro-shell choice and induction hatching
In the breeding season of barley in June-August each year, the glands are full, the females are pink, the males are pale yellow, and the shells are complete and clean. The shells with a shell length greater than 3 cm are used as pro-shellfish. The selected pro-Bei first washed in clean seawater, placed in a cool, dry place, dried 8-12 hours. The oxytocin can be induced by spermatozoa plus water or strong aeration to induce sperm-egg emissions. In the pre-oxygenation spawning pool, clean precipitated seawater filtered by secondary sand was added after dark precipitation. The water level was 80 cm. Heavy metal ions were chelated with 3-5 ppm EDTA sodium salt. The pro-producing pro-scallops were sterilized with 15ppm potassium permanganate for 10 minutes, and then placed in the urine production pool to increase the air-injection volume. Water temperature is controlled at 26-30°C, salinity 18-25, PH8-8.5. Under normal circumstances, large amounts of sperm and eggs will be emitted after 1-1.5 hours. Remove pro-shellfish as soon as possible after oxytocin, and quickly add water to a water level of 130 cm. Use a 100-mesh sieve to scoop up the foam on the surface of the water and the parent waste. The catalytic density is controlled at 10-20 pellets per ml.
Third, the selection of young and larvae cultivation
The fertilized eggs hatched into D-shaped larvae after 16-18 hours, and the upper larvae with strong floating ability were first placed in a separately prepared nursery pond using a 250-mesh sieve net bag. Nursery ponds must be strictly disinfected before use, first washed with 100ppm bleach, then soaked in 20-30ppm potassium permanganate for 15 minutes, rinse with water.
Water temperature during larval rearing was controlled at 26-30°C and salinity was 13-22. Cultivation density should be controlled at 5-10 capsules per ml. D-shaped larvae open mouth food selection of gold algae, enter the shell top phase available golden algae, Chaetoceros, micro-green algae mixed feeding, the effect is good. The feeding density gradually increased from 20,000 to 810,000 per milliliter. Daily feeding 2 times, according to different developmental stages of larvae and the fullness of the gastrointestinal situation to be adjusted.
Strengthen management during the cultivation period, observe and check the larvae's vigor and growth regularly. Appropriate shading, light intensity of 500-1000 lux is appropriate. Microlarging is applied to the larvae to evenly distribute the bait and larvae to facilitate the growth and development of the larvae.
Fourth, attachment abnormalities and nurturing
The larvae began to form with a newborn foot after 48 hours of incubation. At this time, the larva size was 165,180 um. After 72 hours, the plate gradually fell off and began to gradually change from planktonic life to crawling. At this point, the juveniles' attachment pool should be prepared for the argillaceous attachment base. The specific method is to take non-polluted sea mud and reserve it after sun exposure. Before use, put the mud in a plastic basin, add boiling seawater, filter it with a 200-mesh sieve, and evenly distribute it in the attachment pool. The attached pool was filled with 25 cm of water. After the attached base was put into service, it was suspended and precipitated to form a slime bottom at the bottom of the pool. When the pool is poured, collect the larvae with a 200-mesh screen bag and play it evenly in the prepared attachment pool. It is advisable to cultivate a density of 2 to 3 million pieces per square meter. Along with the growth of juveniles, the pools gradually reduce the density of juveniles.
After about 7 days of cultivation, the juvenile water outlet pipe is formed. The average size is 300320 μm after entering the single-pipe period. After 10-12 days of cultivation, it can enter the double-pipe period. At this time, the inlet and outlet pipes are frequently flexed, and the water pipe base is tentacles. Obviously, the average juvenile size is 560600um.
During the cultivation of juveniles, the seedlings are washed once every five days, and sieves may be sieved in different meshes to remove impurities, and the juvenile shells are repeatedly washed by hand until they are clean. Screening of different sizes of juveniles in separate pools is routinely performed using different screens to facilitate simultaneous growth. Change the water daily by more than 80%, shade and inflate. Feeding twice a day, mixed feeding flat Platycladus, Chaetoceros, etc., feeding amount to gastrointestinal fullness prevail. Every day 2ppm oxytetracycline Quanchiposa to prevent disease.
Fifth, out of the pool and transport
After more than 20 days of cultivation, the shell is about 1 millimeter long, and the seedlings can be planted in accordance with the requirements of farmers. When the seedlings are drained, pool water is washed out with seawater, and collected by a 120-mesh sieve bag. The panning can be repeated repeatedly and dry weight method can be used for counting.
When transported, the 100-mesh sieve is used to pack the seedlings, and the seedlings are immersed in sea water and drained naturally. They are transported in plastic buckets or foam boxes. Long-distance transport is carried out with insulated vehicles, and the survival rate is still up to 100% within 10 hours.
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