Thick-shelled mussel seed marine area seedling preservation method and raft culture method
Gu Zhongqi and so on
Thick-shelled mussels belong to the order Offinchoptera, pterodactyls, mussels, mussels, mussels, naturally distributed in the East China Sea, Yellow Sea, Bohai Sea, is an important marine aquaculture shellfish in China. The market price of thick-shelled mussels is higher than that of purple mussels, and the breeding benefits are good, which is highly respected by breeding owners. Since the breakthrough of industrial artificial seedling technology, the scale of cultivation of thick-shell mussels in the shengsi sea area of Zhejiang province has increased rapidly. At present, Shengsi County, Zhejiang Province has become an important production area for thick-shell mussel culture in China, and the breeding method is mainly raft culture. The raft culture technology of thick-shelled mussels is introduced as follows.
First, the selection of breeding sites
Thick-shelled mussel culture is generally selected in sea areas with a water depth of 10 to 20 meters, sedimenty bottom, smooth water flow and small wind and waves. The water quality of the breeding area is excellent, the bait organism is abundant, the water temperature is 5 ~28 °C, and the salinity is 25~30.
2. Transport of seedlings
1. Dry resistance Thick-shelled mussel seedlings have strong drying resistance under the condition of low temperature and large humidity; the temperature in the foam box is controlled at about 10 °C for about 24 hours without death.
2. Transportation method The seedlings with an average shell length of 2 mm are loaded into a 60 mesh mesh bag into a foam box, and cooled down with an ice pack (the ice pack is wrapped with a towel to prevent direct contact between the ice pack and the seedling). The time from the time the shells are packed to the destination sea area is controlled within 24 hours.
Third, the structure and setting of the floating raft
The structure of the raft includes the floating silk (large silk), the sleigh, the cable, the float and other parts.
1. The floating rope is a polyethylene rope, the diameter is about 2.6 cm, the length of the floating silk is 100 meters, and the spacing between the floating silk is 4.5 meters.
2. The sleigh is made of moso bamboo, with a length of 4 to 5 meters and a diameter of 15 to 20 cm.
3. Sleigh cable: The material of the sled cable is the same as the floating silk, but the diameter is slightly thicker than the floating silk. The length of the cable is twice the depth of the full tide in the aquaculture sea area, and it is at an angle of 30° to the seabed.
4. The float is made of plastic foam, cylindrical, 60 cm high, 35 cm in diameter, the float coat is mesh coated, and one end is connected with a polyethylene sling with a diameter of 0.7 cm, hanging on the float, and each row hangs 80 to 120 floats.
Fourth, thick-shelled mussel seedling seed marine area preservation method
1. Early temporary rearing Of shell seedlings with an average shell length of 2 mm, they are temporarily raised in 40 mesh polyethylene mesh bags. The size of the mesh bag is 30 cm×40 cm, each bag puts 10,000 shells, and the net bags are strung together one by one with a sling rope, each 10 bags are 1 string; the sling is polyethylene material, 0.4 cm in diameter and 3 meters long, and the sling is hung on the floating rope, and the end is tied with a pendant. In terms of daily management, remove the floating mud and other attachments outside the seedling bag every 10 to 15 days to keep the water flowing smoothly in the seedling bag and ensure the normal growth of the baby shells. After 2 to 3 months of temporary rearing, the average height of the shell of the shell reaches 0.5 cm, and the seedlings can be wrapped at this time.
2. Pack seedlings
(1) Wrap the shells on the seedlings with 20 mesh polyethylene mesh pieces, and remove the nets after 10 days (pay attention to the large tide flood seedlings, small tide floods to remove the mesh pieces, avoid the tide is too urgent, prevent the shells from squeezing each other and causing injury to the seedlings). Before wrapping the seedlings, disperse the clustered shellfish seedlings, remove the predators, and wash off the floating mud on the shellfish seedlings to enhance the attachment strength.
(2) The number of seedlings per rope is about 15,000. When wrapping seedlings, the seedlings should be evenly scattered on both sides of the seedling rope, and try to avoid the situation that the number of seedlings around the seedlings is different, so as to avoid the occurrence of loose and inconsistent seedlings after attachment and affect the normal life of thick-shelled mussels. When suturing, it is required to be tight and suitable, too tight shellfish is not easy to attach, too loose is easy to cause shellfish to accumulate.
(3) The seedling rope of the seedling is polyethylene rope, with a diameter of 3 cm and a length of 2.2 meters. The upper end of the rope is attached to the floating rope by a sling rope, which is also a polyethylene rope with a diameter of about 0.6 cm and a length of 1.5 m.
3. Protection and management
(1) During the nursery period, the seedlings are fragile due to their small size and are prone to abnormalities or deaths. Generally, every 5 days to the sea to observe the growth of seedlings, if there is an abnormality, it is necessary to make timely adjustments.
(2) Wind and waves are easy to cause a certain impact on seedlings, therefore, before the arrival of cold waves or typhoons, it is necessary to do a good job in advance, carefully check whether the breeding facilities are firm and damaged, and prevent unexpected situations such as inverted rows and broken ropes.
(3) Daily management should be carried out diligently, often to the aquaculture sea area to check whether the float has fallen off, whether the suspension rope is loose, whether the seedling bag is damaged or entangled with each other, etc., and the problems should be dealt with in time.
Fifth, thick-shelled mussel raft culture method
1. Seedling release time The seedling release time is generally 4-5 months.
2. Seedlings Seedlings the length of the seedling shell for growing up is about 0.5 cm, and the density of seedlings is 1500 grains/string. When wrapping seedlings, first lay out the net sheet, rub the group of seedlings, evenly scatter on the net, and then put on the growing rope to wrap tightly and sew solidly. The grow-out rope is a polyethylene rope with a diameter of 3 cm and a length of 2.2 m, and the upper end is connected to the floating rope by a sling. The time to dismantle the net depends on the size of the shellfish and the water temperature, and the mesh can be removed in 5 to 10 days.
3. Hanging the seedlings The grow-out rope of the wrapped seedlings should be hung to the sea in time. The row spacing is 4.5 meters, and the rope spacing is 50 to 70 cm.
4. Daily management
(1) Inspection. Frequently go to the sea to inspect the safety of the raft frame and the growth of thick-shelled mussels, adjust the tightness and uniformity of the floating silk and sleigh cables, maintain the balance of force, and prevent the pulling of piles and broken ropes.
(2) Adjust the aquaculture water layer. In the early stage of growing, less floats are hung, the water layer is appropriately lowered, and the attachment of other organisms is reduced. In the middle and late stages of growing, the floats are added in time according to the growth situation.
(3) Eliminate predators. Carnivorous gastropods on the seedling rope are observed regularly and removed in time; a certain number of crab cages are hung in the breeding area to remove crabs from the sea area.
(4) Typhoon prevention. Before the typhoon comes, do a good job of reinforcement, transfer and other work; you can also take methods such as deflation to sink the raft and recover after the typhoon has passed.
(5) Harvest. From November to December of the following year, the shell can be harvested when the shell length reaches more than 6 cm.