Artificial Seedling and Middle Cultivating Techniques of Fritillaria mirabilis in Gulf of Mexico

Argopectenirradians concentricus is native to the Atlantic coast of North America and has been favored by breeders because of its high meat yield and rapid growth. In December 1995 and December 1997, China introduced two species from the North Carolina coastal region of the United States. Because of its poor low-temperature tolerance, it is not ideal to promote aquaculture on the northern coast, but it is suitable for breeding in the East China Sea. However, the seed supply is extremely limited, which limits the further development of aquaculture production. To this end, in 1996, the Ministry of Agriculture issued the issue of “the introduction of scallops into the Gulf of Mexico population in the north”. In 1999, the Zhejiang Provincial Committee of Science and Technology issued the “Scientific Seedling and Aquaculture Industrialization in the Gulf of Mexico” project. Nearly 600 million young juveniles and 45% of the intermediate breeding rate in the earthen ponds and sea areas are now covered by artificial breeding and intermediate breeding techniques.
First, pro-shell choice and processing
1. Pro-shell choice. As far as possible, shellfish with a shell height of 5.0 cm or more should be selected as pro-shell shellfish. The shell color is bright, and the shell is not damaged and has strong vitality.
2. Pro-shell processing. First remove the attachments on the shell surface, clean the shells with clean filtered seawater, and then treat with 10ppm KMnO4 solution for 5min--10min.
Second, the parent-feeder raises the fattening and promotes the ripening To make the Gulf of Mexico scallops reach the commodity standard that year, should cultivate the early seedlings, buys the pro-beads in the room to carry on the intensive cultivation and promotes the ripeness promptly. The indoor enhanced cultivation and ripening operations are as follows:
1. Parents enter the pool time. Generally in the middle and late March of spring, when the temperature of the water is between 13°C and -15°C, the pro-shellfish can enter the pool, and the pro-shellfish can feed normally after entering the pool.
2. Stocking mode. Put the filtered seawater in the cement pool, put the scallop into the cage, hang it in the pool or store it in a floating cage. When the scallop gonad develops to a certain extent, it can be stored in a single shallow floating cage. In favor of pro-shellfish feeding, especially when pro-shellfish are close to mature, it should not stimulate pro-shellfish, so as not to cause pro-shell early discharge, and is conducive to the removal of dead shellfish and pool bottom contamination.
3. Storage density. Parentfish are placed in cages at a density of 80/m2 to 100/m2.
4. Daily management
(1) Change the water. Change the water once a day in the morning, changing the amount of water each time is 75% - 100%. In the early stage of cultivation, the bottom of the pond is moved to the next day; in the later period of cultivation, the bottom of the sewage is collected on the next day.
(2) Water temperature control. When pro-Bayu enters the pond, it is necessary to first stabilise the water for 2 days - 3 days, then take a daily temperature increase of 1 °C or so, continuously raise the temperature by 3 °C, and then properly stabilize the water body for 2 days - 3 days until the water temperature rises to 22 °C - Stop the temperature rise at -23°C and keep the water temperature constant until the pro-shellfish is fully mature.
(3) feeding. The bait is dominated by artificially cultivated single-cell algae, and the effects of algae, diatom algae, and Phaeodactylum tricornutum are better, supplemented with algal flour, dry yeast, sweet potato powder, etc., and the bait density is maintained at 150,000 feet/ mL - 2577 cells/mL and fed after each change of water.
(4) Others. Light control below 500Lx; use 0.5ppm - 1.0ppm antibiotics to prevent the occurrence of pro-fish disease; timely removal of dead shells in the pool; in the late incubation, often by microscopic examination of promyalve gonad development, found that pro-shellfish has been When mature, we should try to maintain the stability of water and other physical and chemical factors, and prevent dry dew, so as to avoid the stimulation of pro-shellfish and lead to accidental sperm-egg emissions.
Third, oxytocin and hatching
1. Induction. Remove the mature pro-scallops, brush clean with clean seawater, then use 5ppm - 10ppmKMmO4 solution for 5min--10min, dry 2h, sand filter seawater into the cement pool, the water level is controlled at 100cm, the water temperature rises above the pro-nutrient incubation Water temperature 3 °C - 5 °C, inflatable production. Generally, pro-spores can discharge sperm and eggs in a short time. When the quantity of fertilized eggs in the pool water reaches the required density, the pro-scallops are moved into another pool.
2. incubation. After removing the pro-scallops, the fertilized eggs hatch in the original pool, or use the foam sorting method to wash eggs, collect excess sperm, and put 3ppm - 5ppm of EDTA disodium and antibiotics 0.5ppm - 1.0ppm in the hatching pool, the water temperature Controlled at 24 °C - 26 °C, water level increased to full water level, inflated hatch. Generally after 20h - 24h transformed into D-shaped larvae.
Four, planktonic larva rearing
1. The larvae are selected. According to whether the D-shaped larvae hinge is straight or not, the quality of the D-shaped larvae is judged, and in combination with the D-shaped larvae floating situation, the larvae with good vigor and strong floating ability are selected as the production purposes.
2. Larvae cultivate ecological conditions. Water temperature 24 °C - 26 °C, salinity 20 ‰ -30 ‰, pH 7.8 - 8.5, light 1000Lx - 5000Lx, dissolved oxygen is greater than 5mg / L. The nursery water is sand filtration seawater filtered by a 1000-mesh filter bag. The culture pond water is treated with 3ppm-5ppm EDTA disodium, 0.5ppm--1.0ppm antibiotics to prevent diseases, and the pool water is continuously inflated throughout the incubation period.
3. Larvae breed density. In the pre-culturing period, the larval density was 10 cells/mL--12 cells/mL, and the mid-to-late days of the crust were reduced to 5 cells/mL--8 cells/mL.
4. Change the water. The cultivation pool began to change the water the next day after the selection of the D-shaped larvae, 2 times a day. The amount of water changed every time in the previous period was 30% of the original pond water, and the shell top increased to 50%-70% of the original pond water in the middle and later periods.
5. Feeding. Can be fed to gold algae, Phaeodactylum tricornutum, small diatoms, and later in the same period, plus the investment of Platycladus diels, the effect is better, and fed after each change, according to microscopic larvae stomach fullness and food organisms in the water The quantity was used to determine the amount of feeding. In the early stage of incubation, small diatoms and Phaeodactylum tricornutum were kept at a density of 30,000 cells/mL to 50,000 cells/mL, and 5000 cells/mL-10000 cells/mL of MP were added during the later period of incubation.
Fifth, abnormal attachment and juvenile cultivation
1. Perverted attachment. The larvae entered the metamorphosis period after 10d--13d incubation. When 30% of the larvae were observed to have eye spots, the size of the larvae was between 180 μm and 200 μm in shell length. The attachment base is a polyethylene mesh sheet (size 27cmx40cm), and 0.8kg--1.0kg attachment base per cubic meter of water. Attachment bases are first suspended at the bottom of the pool, and are inflated during the period of attachment. The water is changed twice a day, and the amount of water exchanged is 1/2--4/5. The number of feedings and the amount of feeding are appropriately increased depending on the density of the algae in the water.
2. Nurturing
(1) Ecological conditions cultivated. Incubation with planktonic larvae.
(2) Change water and feed. When the juveniles are all attached, increase the water exchange volume, change the water twice a day, every time 3/4--4/5, change the water and feed it, and control the feeding amount according to the density of the algae in the water body to increase Platymonas The amount of feeding.
(3) Others. To maintain the stability of the water temperature in the pool, use 0.5ppm--1.0ppm antibiotics to prevent the occurrence of disease.
6. Incubate the middle juveniles for 13 days to 15 days. When the juvenile shells reach about 1.0 mm in length, they can be moved to earth ponds or sea areas for intermediate cultivation until the shell length is 0.5 cm--1.0 cm. Develop.
1. Earthen pond cultivation
(1) Site selection and preparation. The area near the site is free of pollution, easy to enter and drain, seawater salinity between 20 ‰ and -30 ,, pH value 7.8--8.5, after pond clearing, bleaching powder (30mg/L) or quicklime before entering the water ( 50kg/Mu - 75kg/Mu Clear pond. After the medicinal property of the drug disappears, the pond can be filled with water. When entering the water, it is filtered with a 60-mesh sieve to prevent pests from entering.
(2) broadcast seedlings. The juveniles are discharged into a 20 mesh--30 mesh polyethylene mesh bag. The mesh bag size is 30 cm x 40 cm. Two mesh seedling curtains are placed in each mesh bag, and the mesh bags are hung in the pool.
(3) Water level adjustment and water quality control. Holding ponds generally control the water level of 60cm - 100cm, and regular water quality determination, the general requirements to maintain dissolved oxygen in the water above 5mg/L, pH value between 7.8 - 8.5.
(4) bait management. Mixed ponds with shrimp do not need to be fertilized. In intensive culture ponds, when food organisms are lacking, they should be fertilized and fed with food organisms. Fertilizers should be made of urea, superphosphate, or active liquid fertilizer. The water color is yellowish green or brownish. . When the food organism is too rich, it can easily cause the pH of the water to rise, and the water should be changed in time.
2. In the middle of the sea area
(1) Site selection. Choose sea areas with small winds and tides, unimpeded tides, rich food organisms, sea water temperature of 16.2°C - 28.5°C, salinity of 27‰ - 30‰, and pH of about 8.2. Sand is good for piling and floating.
(2) Let go of seedlings. The juveniles are loaded into a 20 mesh--30 mesh polyethylene mesh bag, the mesh bag size is 30 cm x 40 cm, 2 mesh seedling curtains are placed in each mesh bag, and the mesh bags are hung on the floating raft, 10 bags per string. , Each float can hang 100 strings - 200 strings.
(3) Daily management. Always check the safety of floating rafts, float balls, slings, and cages during the cultivation period. Wash cages regularly to remove silt and attached organisms. When the seedlings reach the seedling specification, seedlings should be divided in time to facilitate the extension of the scallop growth period. When the shellfish grow to 1.5cm above the shell length can be divided into seedlings for the development.