First, the choice of aquaculture waters
(1) Site selection
1, the pond culture area is adapted to local conditions, the small pond is 3 ~ 5 mu, the large pond is from 10 mu to dozens of mu, and the water depth is 1.5 ~ 2 m, so the water quality is generally fat and rich in feed organisms. Grass carp, bighead carp and crucian carp can be mixed in the pond, and the stocking density is 100 ~ 200/mu. It is not suitable to stock or raise a very small amount of carnivorous fish, such as chain fish, nor to stock carnivorous fish such as herring and snakehead.
2. Pollution-free rivers have sufficient oxygen, fresh water, living water and material exchange, which is suitable for the growth of Hyriopsis cumingii.
3. Large waters, such as lakes and reservoirs, have a large water area. Pearl culture is carried out in the shallow water area on the shore or at the corner, which is characterized by high water fluidity, thin water quality and rich dissolved oxygen. Environmental factors are complex, and management and operation are inconvenient.
(2) Ecological environment
1, water quality conditions, water depth1.5 ~ 2.5m is more suitable. A certain speed of running water is extremely important for the growth of pearl mussels and the cultivation of pearls. The pH value of pearl culture water should be kept in neutral and slightly alkaline range, and 7 ~ 8 is appropriate. Acidic water with low pH value is not conducive to the growth of pearl mussels and the formation of pearls, which can be adjusted by sprinkling quicklime water in pearl water. High pH value can inhibit the growth of pearl mussel, which can be controlled by applying organic fertilizer.
2. Calcium salt is the most needed salt for pearl mussels. The main component of mussel shell is calcium carbonate. The growth of pearl mussel and pearl synthesis depend on the absorption of calcium. The content of Ca2+ in water can be kept above 1.5mg/l, and the calcium source can be supplemented by applying calcium fertilizer. Magnesium, silicon, manganese, iron, etc. It is not only an essential element for the growth of pearl mussels, but also for the growth of food organisms. These nutrients are supplemented by applying organic fertilizer and inorganic fertilizer. Rare earth can promote the pearl secretion of pearl mussels and accelerate the formation of pearls. Among the rare earth nutrition sources, nitrate rare earth has the best effect and the pearl grows fastest. In the growing season of pearl mussels, rare earth nutrient sources are applied once a month to make the concentration of pond water 0.1mg/L.
3. The most suitable bait organisms for Hyriopsis cumingii are diatoms, golden algae, green algae, gymnosperms and so on. , followed by organic debris such as small zooplankton and bacteria. Therefore, it is very important to cultivate rich bait organisms for pearl culture. The fatness of water body and the abundance and shortage of food organisms can be reflected by the color of water. The color of the water body should be yellow-green, and the transparency should be about 30 cm, so as to keep the pearl water body "fat, lively, cool and tender".
Second, the selection of pearl mussels
(1) Investigate the source of mussels.
If there are diseases in the mussel farms or nearby pearl farms, even cheap mussels can't be bought to prevent the spread of germs. It is best to collect cultured mussels from wild mussels in natural waters, and it is best to select females and males from different waters to ensure the quality of germplasm and improve the pearl culture performance of future generations.
(2) Transportation and temporary support after transportation
1. Dry transportation is suitable for low temperature transportation of 1 ~ 10℃. When the temperature is higher than 25℃, mussels are easy to die of hypoxia, and when the temperature is lower than 0℃, they are easy to freeze to death. The shorter the transportation time, the better, not more than 3 days. Attention should be paid to the following points during operation: ① Before transportation, let the operating mussels absorb enough fresh water and put it into a laundry list, straw bag or bulk. (2) Lay mussels flat to prevent water loss. ③ During shipment, the accumulated height of the operating mussels is less than 20cm. ④ Spray fresh water frequently on the way to keep mussels moist. Ensure the safety of water use.
2. Wet transportation is suitable for long-distance transportation. ① A large number of mussels can be transported by running water, and sewage and lack of oxygen should be avoided during transportation. (2) The other is to transport mussels in a closed box at low temperature. The water in the box is kept at a low temperature with packed crushed ice to reduce the metabolism of the operated mussels, and oxygen is supplemented at the same time to ensure the survival rate of the operated mussels during transportation.
After long-distance transportation, the operation mussel is weak, so it must be temporarily raised and rejuvenated before operation. The damaged mussels are hoisted separately and then used for surgery after recovery. The temporary rearing time of mussels transported in winter is about 65438 0 weeks; The temporary rearing time of mussels transported in spring and summer is longer than 1 month; Mussels transported in autumn are temporarily kept for about 20 ~ 30 days.
Three. Matters needing attention in pearl culture operation
Pearl culture operation is the key to pearl production, and every link must be carefully done to improve the survival rate of mussels after operation, avoid diseases and increase the proportion of high-quality pearls.
(A) the season of pearl farming operations
It is suitable to carry out pearl culture in March ~ May and 9 ~ 10. At this time, when the water temperature is 15 ~ 25℃, the pearl oyster has vigorous metabolism, high survival rate of cell slices, rapid wound healing, rapid formation of pearl sacs and good pearl quality. When the water temperature exceeds 30℃, although the surgical wound heals quickly and the pearl sac forms quickly, the survival time of cell fragments is short, the survival rate is low, the wound is easy to fester, infected with diseases, and the pearl mussel dies. If pearl culture is carried out in high temperature season, it must be carried out in a cool, ventilated and shady place, and the operator must have skilled skills to complete the whole operation process in a very short time. When the water temperature is lower than 5℃, Hyriopsis cumingii enters hibernation. At this time, although the probability of infection is reduced, the wound is not easy to heal and the cell fragments are easy to freeze to death.
(2) Selection of operation mussels
Choose healthy, disease-free and harmless Hyriopsis cumingii. The growth line is broad and obvious, the axe foot is full of fat, and the mantle is yellowish.
(3) Matters needing attention in the operation process
1, during the operation, all tools should be strictly disinfected and cleaned to avoid bacterial operation. Soak or scrub all operating tools with 70% alcohol. If conditions permit, the operation can be performed under aseptic conditions. Operators are not allowed to operate with bacteria, and wash their hands before operation.
2. The production operation should be carried out in a cool and windless environment, so as to avoid the small pieces being blown dry by the wind, and to avoid the cell pieces from reducing their vitality due to direct ultraviolet irradiation.
3. Treating the cell chip with mixed nutrient solution can improve the survival rate and disease resistance of the chip, and improve the yield and quality of pearls. Formulas of several mixed nutrient solutions: ① polyvinylpyrrolidone (PVP) nutrient solution formula: adding 0.5 ml 1 liter of 0.4% physiological saline. ② formula of lecithin nutrient solution: add 0.5g lecithin, 0.02g potassium chloride (KCl) and 0.02g sodium bicarbonate (nahco3) into 1l 0.4% brine. ③ Formula of cobalt chloride nutrient solution: add 1.5g cobalt chloride (COCl) into 0.4% saline. ④ Formula of chlortetracycline nutrient solution: Add chlortetracycline 1g into 0.4% physiological saline.
4. The width of the shell opening shall not exceed 0.8 cm, so as to avoid pulling or breaking the adductor muscle, resulting in the postoperative death of the operative clam.
5. The wound area of the nuclear implant should not exceed 5% of the total area of the mantle, so as not to cause serious hydrops in the tissues and organs of the operated mussel and die.
6. Try to avoid inserting nuclei in the visceral mass, so as not to damage the digestive tract and lead to heart erosion and death of the operative clam.
7. Operators must be skilled and fast. The shorter the operation time, the better. The whole operation process should not exceed 8 minutes, so as to ensure the survival rate of cell fragments and pearl mussels.
(Source: China Xingnong. com)
Cultivation techniques of pearl mussels
Release date: (2006-10-1215:12: 00) Number of visits: 150.
1. How are pearls formed?
Answer: Pearl is a valuable ornament and a valuable Chinese herbal medicine, which has high economic value. Pearl industry is often called "treasure house", so it has a bright future. Pearls are cultivated by mussels. Mytilus belongs to Mollusca, Lamellibranchia, with a wide variety and rich resources. In the pearl industry, mussels, crested mussels and pearl mussels are often used for breeding.
There are two softwares in the clam shell called mantle. After being stimulated, it will rapidly divide and proliferate, gradually surround the stimulus source, form a complete pearl sac, and secrete nacre layer by layer with the stimulus source as the center, and finally form pearls. Natural pearls are occasionally invaded by small sand grains, eggs and other foreign bodies, and the epidermal cells of the mantle divide to form pearl sacs, which wrap the foreign bodies and secrete mother-of-pearl to form nucleated pearls.
Second, what season is good for pearl cultivation surgery?
A: Late spring or early autumn is the best time for pearl breeding surgery. Due to the high temperature in midsummer, mussels dehydrate quickly after leaving water, and the wounds are prone to inflammation and ulceration. In winter, mussels almost go into a dormant state, and the surgical wound is not easy to heal, and it is easy to spit and rot.
Pearl mussels are usually caught from wild waters. It is not advisable to pile up for too long after coming out of the water. If it cannot be operated immediately due to transportation or other reasons, it should be temporarily raised in small waters. Temporary ponds can be set up if conditions permit, and the collected mussels can be fattened before operation to improve the success rate of operation.
Third, how to choose the surgical clam?
A: Surgical mussels are divided into producing mussels and inserting mussels. The mussels used to make small pieces of instant mussels and cultivate pearls are all inserted in mussels. Before the operation, according to the ratio of 1: 1, select producers and insert mussels and put them into a basin filled with water. The production of mussels should be 3 years old and the insertion of mussels should be 4 years old. When mussels are young, the pearl secretion function is strong, the pearl formation speed is fast, and the pearl quality is good, but when mussels are old, it is the opposite.
Fourth, please introduce the manufacturing method of the insert.
A: The production of the insert is divided into four steps: cutting mussels, peeling the mantle, peeling the skin, and shaping and slicing. Insert the mussel cutter into the front and rear ends of the mussel, cut off the adductor muscle before and after, and then cut off the joint between the two cloaca and internal organs, taking care not to damage the cloaca, which is clam cutting; Then use tweezers to gently turn the edge film inward along the mark, tear a small mouth at its front or rear edge, clamp the inner epidermis with small tweezers, and put the other tweezers between the inner epidermis and the outer epidermis at the small mouth to separate the inner epidermis from front to back, that is, peel off the outer membrane; Then use a blade or scissors to cut off the outer skin of the edge film along the coating mark, and lay it on a glass plate with one side facing upward to remove the outer skin; Finally, cut off the colored edges with a slicing knife, trim both sides and cut into square pieces with a side length of 0.5 cm. Drop a little chlortetracycline solution with a concentration of 0. 1% on the small piece, which is the edge-cutting piece. It should be noted that the trimmed small pieces should not be stored, so as not to affect the cell vitality.
5. How to insert the insert?
Answer: First, gently insert a bottle opener between the two shells of mussels, so that the shells are scattered, and fix them with plugs, with the opening not exceeding 1. 1- 1.4 cm, and dip a sponge in water to clean the dirt on the epidermis and internal organs in the central membrane; Then insert 3-4 rows into the mantle from the gill line away from the gill base 1 cm, with the row spacing of 0.8 cm and the spacing of 1- 1.5 cm. Inserts should be arranged evenly, which can be plum blossom-shaped, and it is appropriate to insert about 40 pieces. Then tilt the needle, place the needle in the center of the front of the tablet, wrap the tablet evenly on the needle with crochet, puncture the inner epidermis of the mantle with crochet, and send the tablet into the connective tissue between the inner epidermis and the outer epidermis at one time from the opening, with a general depth of about 0.6cm, then press the sent small pieces outside the mantle with crochet, and then pull out the needle to leave the small pieces inside; After the small pieces are sent in, the small pieces are arranged into a drum-shaped protrusion on the inner surface of the mantle with a crochet, and then the other side of the clam is operated. After the operation is completed, the date of the operation is engraved on the mussel shell and sent to the water for pearl culture.
6. How to breed mussels?
A: Single hanging culture is better. That is, a small hole is drilled in the mussel crown, and each mussel is hung and fixed on a bamboo frame or a live Zhi Zhu frame with a row spacing of about 1m and a spacing of about 3cm, and about 1000 mussels are raised per mu. The environment of mussel water area requires ventilation to the sun, with no tall buildings and trees around, water depth of 1m, no aquatic plants, weak running water and neutral water quality, so toxic sewage should be prevented from entering pearl farms.
Mytilus has no predatory organs, but only feeds on the water flow formed by gill cilia activities, so it should be kept in the water layer with the richest food. When the water temperature is 10-30℃ in spring and autumn, it should be hung 20-30 cm above the water surface, and it should be hung 70 cm above the water surface in midsummer and severe winter. Fertilization is not needed in aquaculture waters in winter, and inorganic fertilizer and organic fertilizer should be applied in spring and autumn to improve water quality, promote plankton growth and provide rich food for mussels. When the temperature is high in summer, inorganic fertilizer should be applied, and the fertilizer should be applied several times.
Seven, how to harvest pearls?
A: Pearl mussels can be harvested after 2-3 years of cultivation. Pearls can be picked when the water temperature is lower than 20℃, because the pearls are delicate and shiny at this time. When selecting pearls, cut the anterior and posterior adductor muscles with a knife, lift the pearls on the mantle with your fingers, gently wash them with clear water, then absorb the moisture with flannel, polish them with white silk, and then sell them in different grades. Mytilus meat can be eaten raw or dried into scallop meat. The outer layer and middle layer of mussel shell can be used as shell powder of livestock and poultry, and the inner layer can be used as pearl powder, which is an important raw material for cosmetics, medicines and food.