Pearl culture technology in seawater

1. Artificial breeding 1. Selection and cultivation of parent shellfish (Pinctada martensii) (1) the adult shellfish with strong thickness, good shape, exuberant growth, complete shell, silver-white pearl layer free of diseases and insect pests and full gonads were selected. (2) the parent shellfish needed in the second year should be selected in autumn, and the male and female should be raised separately and hung deeply, and the shallow hanging fattening should be carried out in the early spring, and indoor artificial heating and fattening should be carried out in order to raise seedlings and go to sea early. (3) distant shellfish from different regions and different sea areas should be selected to avoid germplasm degradation caused by inbreeding. In a planned way, the fast-growing, large, thick and disease-free shellfish are selected from Beckham as parent shellfish. 2. Induced labor and artificial insemination. The main results are as follows: (1) the mature degree of sperm and eggs obtained by artificial induction is high, the offspring cultivated are strong, and there is no need to kill parent shellfish, so artificial induction should be used as far as possible to ovulate and lay eggs. Artificial induction methods can be induced by temperature stimulation, open air drying, combination of light and temperature (such as sun exposure), current stimulation, change of sea water specific gravity, change of seawater pH value, ammonia stimulation, ammonia injection, germ cell stimulation and so on. At present, the method of dry and variable temperature combined with ammonia seawater stimulation is commonly used. The method is as follows: dry the parent shellfish for 2-3 hours, add ammonia water to the sea water to make it 0.05-0.07 ‰ ammonia sea water, adjust the temperature with heated sea water, let the parent shellfish soak at 29-30 ℃ water temperature for 20-30 minutes, and then change into normal temperature seawater. (2) if the artificial induction method can not achieve the purpose, the anatomical method will be used for artificial insemination. After washing, cut open the selected parent shellfish, cut off the right shell, cut off the foot silk, mantle and Gill, expose the gonads, wipe off body fluids and sea water with sterilized skimmed cotton, and then absorb sperm and eggs with slender straws. Sperm and eggs are extracted and placed in beakers with filtered sea water. Before insemination, filtered sea water is installed in the insemination tank or aquarium, and the concentration of ammonia seawater is 0.01-0.07 ‰. Then the eggs are filtered through sieve silk and poured into the fertilization tank. After 5-6 minutes, the filtered semen is poured into the sieve silk and fully stirred for fertilization. The ratio of female to male is 3:1. The suitable water temperature for fertilization is 26-30 ℃ and the relative density is 1.0175-1.0240. Direct sunlight should be avoided in the process of insemination and embryonic development, and the water should be changed 2-3 times after fertilization. the ammonia sea water and excess sperm should be removed as far as possible when changing the water for the first time. (3) the density of temporary larvae should be controlled within 50-60 / ml according to air temperature and water temperature. 3. Daily management (1) Culture density: before going down to the pond, the seedling pond pre-placed about 1 stroke 3 filtered sea water, and then moved the larvae into it, and the suitable density was 2-4 D-shaped larvae / ml. (2) add and change water: add an appropriate amount of freshly filtered sea water every day for 3 days, and fill it up on the 3rd day. The water began to change on the 4th day, and the D-shaped period of water exchange was 1 beat 3, which gradually increased to 1 beat 2-2 hand 3 as the individual grew up. The relative density and temperature of sea water shall not be less than 1.0180 before adding water every day, and the temperature difference of water temperature shall not exceed 2 ℃. (3) bait: once every morning after changing water and once at 3-4 p.m. In the D-shaped larva stage, the bait should be less and more refined. The daily feeding amount of Pinctada martensii larvae at different developmental stages is as follows: 300-500 cells / ml of Platymonas subcordiformis at D-shaped stage, 200,500 cells / ml of Isochrysis Zhanjiang, 0.04-0.10ppm of dry yeast, 500-1000 cells / ml of Platymonas subcordiformis at the early stage of shell top, 600-1000 cells / ml, 0.10-0.15ppm of dry yeast. 1000-1500 cells / ml of Platymonas subcordiformis, 1000-1000 cells / ml of Isochrysis Zhanjiang, 0.15-0.20ppm of dry yeast; 1500-2000 cells / ml of Platymonas subcordiformis, 600-1000 cells / ml of Isoflagellate Zhanjiang, 0.20-0.15ppm of dry yeast; 2000-3000 cells / ml of attached and seedling Platymonas subcordiformis, 1000-3000 cells / ml of Isoflagellate Zhanjiang, no dry yeast. 3000-4000 cells / ml of Platymonas subcordiformis from seedling to seedling. Don't vote for the rest. (4) inflating: continuously inflating with an air compressor. (5) other management work: check and observe the activity, feeding, growth and development of larvae every day, keep records, keep good water quality and prevent diseases and enemies. 4. selection and delivery of attachments: it is best to use darker plastic plates, such as black or red ones. The attachments should be soaked in filtered sea water for a week, and then sterilized with 5/1000000 bleach or potassium permanganate before use. The attachment begins when about 20% of the larvae appear pigment spots. 100-150 pieces per cubic body of water shall be cast in 2-3 batches within 3-4 days. 5. Seedling harvesting: only 20-30 days after the attachment of shellfish seedlings, the individual 2mm-3mm can meet the commercial specifications. It is required that the seedlings should be caged and farmed in the sea on the same day. Second, the management and culture of pearl shellfish is an important link in pearl culture and production, which is related to the quantity and quality of core shellfish and the output and quality of pearls. 1. Site selection: choose the middle part of the bay with good windbreak conditions, smooth tidal current and plankton-rich bay or the bay mouth with little wind and waves; in the utilized aquaculture layer, the water temperature is not lower than 12 ℃ in winter and not higher than 31 ℃ in summer, it is best to have an appropriate amount of fresh water injected into the bay, but the specific gravity of seawater in the rainy season is not less than 1.0150. The lowest tide water depth of bamboo raft culture is 5m, the lowest tide water depth of float longline raft culture is 7m, the lowest tide water depth of fixed vertical culture is 2m, the bottom material is sand or sand mud, there are few harmful organisms, and there is no adverse effect of factory or municipal sewage. 2. Management and culture of all kinds of pearl shellfish (1) shellfish seedlings (shell length below 3cm): this is an important stage of mother shellfish culture. In management, it is necessary to do diligent inspection, diligent prevention and control, frequent cleaning of shellfish seedlings and cages, and timely dredging and changing cages. When there is a great disparity between the size of shellfish seedlings, it is best to adopt floating raft culture in order to separate them from each other. (2) small shellfish (shell length 3. 1-6.9cm): do a good job of dredging and changing cages, remove attachments to promote growth, and strive to develop large shellfish in a short period of time. (3) large shellfish (shell length 7cm or above): this is another important stage of pearl shell culture, which determines the quantity and quality of core shellfish. Be sure to choose sites with smooth flow, rich bait, wind, cold, heat, light, insect pests and other conditions, and use suitable water layers for management and cultivation. (4) recuperation: the purpose of rest and recuperation is to restore the health of the shellfish and prevent the death of the shellfish. Through rest and recuperation, the pearl nucleus does not or rarely move before the transplantation of small pieces of pearl sac, so as to prevent enucleation and the occurrence of vegetable beads and deformed beads. The recuperation period is 20-25 days. The rest and recuperation site requires calm waves, smooth flow, little change in water temperature and sea water density, water depth (lowest tide) more than 3m, hard bottom material, relatively low water temperature, so it is best to adopt floating raft culture. The resting cage uses double-loop net cage and the bottom of the cage is covered with net cloth, which is raised in the water layer below 2.5m. The stocking density is slightly higher than that of the same type of shellfish. (5) breeding pearl shellfish: it is the final stage of the success or failure of pearl culture. it is necessary to select the best sea area site, strengthen the health management of breeding pearl shellfish and grasp the quality management of pearls, grasp the most suitable water layer for culture, clean up attachments and sludge frequently, and move briskly during operation. The exposed space should be short, and the shellfish on land should not be taken. Third, the purpose of preoperative treatment is to inhibit the surgical shellfish physiologically and avoid the poor effect of nuclear implantation caused by full gonads. After preoperative treatment, the mortality rate is lower and the pearl quality is better. The main results are as follows: 1. The method of inhibiting gonadal development should be recovered for a period of time after the breeding period of the previous winter before operation, and then treated. Commonly used cage treatment method: the shell is treated with 30-mesh polyethylene mesh bag, mesh 2mm, mesh bag length 100cm, wide 50cm. The shellfish cage was covered with a net cloth bag, with 2 shellfish in each bag and 40 shellfish in each cage. The mouth of the net cloth bag was fastened with rubber silk rope and raised in a water layer 1-2 m deep under the floating raft. 2. The method of promoting gonadal maturation to release sperm and eggs in advance is contrary to the inhibition method, which is to promote gonadal maturation to release sperm and eggs in advance to obtain operative shellfish. The commonly used layer changing method is as follows: after the water temperature rises to 17 ℃ in spring, the sparse female shellfish is raised in the 1.5m water layer with higher water temperature, which can promote the gonad maturation. After the water temperature is 22-24 ℃, the shellfish is put into a cage with a smaller mesh and raised in a 5m water layer to make it in a static state. Before performing the operation on a sunny day, change to the 1m water layer, soon discharge the sperm and eggs, and lower it to the depth of 5m the next day after 5-7 days, and then carry out a second shallow suspension to induce labor in the climate and sea conditions. At this time, about 60-80% are available for operation, and those that are temporarily unavailable can be stored in the water depth below 5m to prevent the gonads from developing again, and raise the 2m water layer to the day before use to induce labor. In addition to the variable layer method, there are pool water induced labor method, ground sowing method, sun method, electric stimulation method. 3. After treatment, the physiological status and gonads of the shellfish have basically met the requirements, but the shellfish is very weak and has to go through a recuperation period. The rest period is usually about a week. During the rest and recuperation, different measures should be taken according to the specific conditions of the shellfish, so that the shellfish can be properly restored. Fourth, nuclear insertion is an important link in pearl culture and production, which is directly related to the output and quality of pearls. The time of nuclear insertion should be carried out when the water temperature rises above 18 ℃ in March of each year. In the process of nuclear insertion, if the water temperature exceeds 31 ℃ and the sea water density is less than 1.0150, the operation should be suspended. 1. Scallops and bolts: the attachment should be removed 2-3 weeks before shellfish platoon, and the floating mud should be washed away before shellfish platoon. Scallop time is generally 2-4 hours, scallop time is not enough, can not be forced to open shellfish. When using methods such as running water, we should pay attention to shortening the time. The bolted mouth should be able to see the nuclear position clearly and facilitate the operation without damaging the adductor muscle. 2. The choice of surgical shellfish and small shellfish: the suitable age of surgical shellfish is 2-3 years old, and the shell length is above 7cm. The suitable age of small shellfish is 2-3 years old, the shell length is more than 7cm, the pearl layer on the inner surface of the shell is rainbow color or silver, the thickness of the mantle is moderate, the edge pigment and leukoplakia are not much, and the shell body is strong. 3. Preparation of small slices: the procedure of preparing small slices is as follows: take the tablets-spread them on wet gauze-wipe them-cut into strips-soak in the mixture of PvP (or other drugs) and red mercury for 3 minutes + cut into squares, filter the seawater and raise the tablets-use. 4. Core insertion (1) incision location: the right edge of the shell body should be at the base of the foot (that is, at the junction of black and white). The knife edge on the left side of the shell body (when the foot nucleus position is inserted) should be at the 1mm from the foot base, the knife edge is curved, the width is slightly smaller than the diameter of the pearl nucleus, the knife edge should be thin, be careful not to cut the foot gland, and pay attention to cleanliness and hygiene during the operation. (2) the width of the channel is slightly smaller than the diameter of the pearl nucleus, and the depth must not exceed the nuclear position. (3) Nuclear position: there are left pocket, right pocket and lower foot. (4) Ten needles should be punctured at the front of the small piece when sending the film. The outer side (front) of the small piece must all be attached to the pearl nucleus, and the small piece should be glued to the intestinal tract behind the pearl nucleus or to the opposite side of the foot constrictor. (5) Nuclear delivery: when the pearl nucleus enters the knife edge, use a small nuclear feeder to send the pearl nucleus to the nuclear position. (6) the amount of nuclear implantation depends on the size of the shellfish and the specification of the nucellus. Generally, there is one for each 8-1Omm nucellus, and 2 for the nucellus below 8mm. Fifth, the rest and recuperation of operative shellfish and pearl harvesting pearl shellfish suffered greater trauma during nuclear implantation, and if not handled properly, it will cause death. Therefore, it takes more than ten days to a month to recuperate after the operation, in order to facilitate the wound healing and restore normal physiological activities. Before the pearl harvest, the pearl shellfish should be sampled and inspected. If the thickness of the pearl layer reaches the standard, the pearl can be opened and collected.