First, raft culture.
Choose the sea area with stable tidal current, rich bait, calm wind and waves and water depth of more than 4m as oyster raft breeding ground. Oysters near the river should be selected near the estuary with low salinity; Oysters in Dalian Bay should be selected in high salinity waters far from the estuary. Pacific oyster and pleated oyster are in between. There are two main ways of development:
⑴ Rope-hanging culture: It is suitable for oysters with shells as a fixed base. There are two kinds of culture methods: one is to string the shells for fixing oyster seedlings with ropes, separate them with bamboo tubes of about 10cm in the middle, and hang them on a raft frame; Secondly, the shells containing oyster seedlings are clamped in the twisted seams of polyethylene ropes with a diameter of 3-3.5 cm, and every 10cm is clamped 1 shell, and hung on the floating raft. Generally, each rope is 2 ~ 3m long. You can also use rubber tires to clamp seedlings and hang them.
⑵ Cage culture: Cage culture in scallop net. Put the anchorless oyster fry or the oyster fry fixed on the shell together with the shell into the scallop cage and hang it on the floating raft. Generally, there are 65,438+10,000 oyster seedlings per 667㎡. Using shells as seedling picker can hang about 10000 shells per 667 ㎡. Oyster seedlings are stocked in May-June and harvested at the end of the year, and the output per 667 square meters can reach more than 5,000 kilograms.
Second, beach planting.
1. site selection: the inner bay with small waves, gentle tidal current and no pollution should be selected for sowing and seedling raising in tidal flat, and sandy beach or tidal flat is suitable as the bottom material. The intertidal zone should be selected in the lower part of the middle tidal zone and near the low tidal zone.
2. Sowing season: It is generally suitable to sow from mid-March to mid-April. Seedlings can be planted in the middle of May at the latest.
3. Sowing method:
1). Dry tide sowing: sowing in the dew on the beach after low tide. Before sowing seedlings, the beach surface should be leveled, or a bed-like foundation should be built before sowing seedlings. Dry-tide sowing seedlings should try to master the rising tide after sowing seedlings, so as to shorten the exposure time of oyster seedlings to the air and avoid sowing seedlings in the sun at noon.
2) Water seedling raising: after the high tide, raise seedlings by boat. Before sowing seedlings, cut the beach into strips and insert bamboo poles, wooden poles, etc. As a sign, and after the high tide, the oyster seedlings were scattered on the boat with a shovel. Because the distribution of oyster seedlings cannot be directly observed, the seedlings sown with water are often uneven. Sowing density should be determined according to beach quality and fat water. There are about120,000 plants per 667㎡ of the first-class beach, about 100 plants in the middle, and the general difference is 60,000-80,000 plants.
3. Mixed culture of oysters and prawns
1. Selection of shrimp pond: The bottom material of shrimp pond with mixed culture of oysters is silt or muddy sand, and the water depth is above1.3m. The average daily water exchange rate should reach about 50%. The transparency is controlled at 40 ~ 50~60cm in the early stage and 50~60cm in the middle and late stage.
2. Site layout: Before stocking oyster seedlings, the silt should be thoroughly dredged, and the bottom of the pond where oyster seedlings are sown should be leveled and compacted with bulldozers and other tools to make it slightly convex and slightly higher than the surrounding bottom surface, so as to prevent oyster seedlings from sinking and being buried by mud to death.
3. Seedling raising: Under the premise of ensuring the normal stocking density of prawns, it is appropriate to sow and raise oyster larvae at a speed of about 30,000 per 667 ㎡. The sowing date should be in early April, and the specifications of seedling seed player should be above 2cm. Sowing seedlings are stressed evenly, avoiding the low-lying areas of the ring ditch and the feeding area. The sowing area accounts for 1/4 ~ 1/3 of the pool bottom area.
Fourth, throwing stones to engage in aquaculture.
Stones used as oyster seedling pickers have now become oyster breeding equipment. Shells with short growth period can be cultivated in situ in seedling collection field; Oysters near the long-growing river will be moved to farms for breeding. There are three main ways to cultivate students: starry sky, plum blossom and determinant;
1, the stars in the sky: oysters and stones are lying around.
2. Plum blossom style: generally 5-6 pieces of oyster stones are 1 group.
3. Determinant: row width is 0.5 ~ 1m, row spacing is 0.6 ~1.5m. Deep-water culture can be carried out without any management after riprap and seedling collection.
V. Bamboo cultivation
The collected oyster seedlings were sparsely planted in situ by the method of inserting bamboo and picking seedlings. When cultivated, oyster bamboos can be arranged in two ways:
⑴ Direct insertion: 150 ~ 179 Oysters and bamboos are inserted directly in rows, with a length of 3 ~ 5m or rows of 100 ~ 120 Oysters and bamboos, leaving 2 ~ 3 gaps in the middle of rows to make the water flow smooth.
⑵ Oblique insertion: 1 pile inserts 23 ~ 26 oyster bamboos, with a bottom width of 45 ~ 60 cm, a top width of 33 ~ 36 cm and a pile spacing of 20 ~ 25 cm. 1 row is composed of 5-6 piles, with a row spacing of about 2.5m, and 8000 ~ 10000 branches of oyster bamboo can be inserted every 667m2.
Sixth, the bridge culture
After the seedlings are picked by bridge method, the stone strips are rearranged and cultivated in a sparse way. Generally, 6-7 stone bars are 1 group, and each group is connected into 1 column by stone bars. Group spacing is 50 ~ 60 cm, and column spacing is 1 ~ 2m. During the culture period, the front and back sides of the stone strips should be exchanged to make the oysters grow evenly on both sides.
Seven, vertical stone culture
After the seedlings are collected by standing stone method in the mid-tidal area, as long as the amount of seedlings is appropriate, they can grow naturally without any management until harvest. This method is mainly used for breeding pleated oysters.
Eight, grid culture
This culture method is to set a fixed grid frame in the inner bay after the water depth is 2 ~ 4m and the wind and waves are calm, and the grid frame is the same as the grid seedling collection. Oyster seedlings are mostly supported in series by fixed bases such as shells and cement tiles, and hung in strings on grid frames. The length of each chord is 1 ~ 1.5m, and the chord spacing is 0.5 ~1m. The culture density should not be too high to prevent bottoming out, so as to avoid the invasion of natural enemies of some benthic organisms.
IX. Management of Cultivation Period
1. Turn the stone (move the stone): it is to move the position of the oyster stone. Turning stones can prevent oysters from being suffocated by mud, stir floating mud, increase nutrients in bait and promote the growth of oysters. Generally, turning stones 2 ~ 3 times during the cultivation period.
2. Flood control: In rainy season, attention should be paid to prevent flood inflow, or to dig ditches around dikes to fight floods, or to move oysters to deep-water areas with high salinity for breeding.
3. Overwintering: Oysters cultured in Dalian Bay and near rivers in the north usually go through 2-3 winter freezing periods. Check 1 time before freezing, and transplant oysters that may be threatened into deep water to make them overwinter safely.
4. Fattening: Before harvesting in1~ February, move the oysters to an excellent fattening farm for fattening, so as to increase production.
5. Prevent human trampling: Oysters sown on the beach can only filter water and feed on the surface of the beach. Once trapped in mud, they can't live normally and suffocate. It is forbidden to trample on the beach at will, and managers should March along the ditch when they get off the beach.
6. Clear the channel: always check whether the drainage channel is clear, and try not to flood the beach area after the low tide, so as to avoid the oyster from dying because of the high water temperature, the enemy lurking and the deep floating mud.
7. Pest control: Oysters have many enemies, which should be removed by turning over stones. July-September is the peak breeding season for red snails and litchi snails, so it is necessary to dive to catch their parent shells and egg bags. In the season of frequent crab activities, strengthen management and catch enemies.
8. Windproof: The typhoon has caused great damage to the aquaculture facilities, and it will also roll up sediment to bury the fixer and oysters. Therefore, after the typhoon, it is necessary to rescue in time, repair the raft frame and support the fallen or buried anchor.
X. Prevention and control
1. Larvae bacterial canker: The pathogens are Vibrio anguillarum and Vibrio alginolyticus. This disease may occur during the cultivation of various oysters. After being infected, the floating larvae sink and fix, or their mobility decreases, and suddenly a large number of them die.
Prevention and control methods:
1) Keep the water clean;
2) Discard the diseased larvae immediately when they are found;
3) The single-celled algae are free from Vibrio pollution;
4) Disinfect the seedling water by filtration, ozone and ultraviolet alone or in combination;
5) Spray 50 ~100g compound streptomycin or10g chloramphenicol per cubic meter of water in the whole pool for 3 ~ 5 days.
2. Oyster onychomycosis: The pathogen is Parkinsonian. Pasteurellosis is one of the most serious diseases of oysters. The disease is widely distributed in geography. It mainly attacks oysters for more than one year. The death of oysters occurs in summer and early autumn (August-September), and then with the cold weather, the water temperature drops and the death decreases. The occurrence of epidemic diseases is related to high water temperature (30℃) and high salinity (30‰). When the salinity is lower than 15‰ or the water temperature is lower than 20℃ or higher than 33℃, oysters will not die even if there are Chrysopa parasites. With chronic infection of oyster, the body gradually becomes emaciated, the growth stops, and the gonad development is also hindered. Seriously infected oysters will die with their shells open, especially when the environmental conditions are unfavorable.
Prevention and control methods:
1) Avoid using infected oysters as fry;
2) Before the oyster larvae are fixed and metamorphosed, thoroughly clean the fixtures, thoroughly remove the old oysters, and remove any objects attached to live oysters between oyster beds, and the oyster beds should not be too dense;
3) When oysters grow to a proper size, harvest them as soon as possible to avoid diseases;
4) Oysters cultured in low salinity (1.5 ‰) can inhibit the development of diseases.