How to raise clam

How to raise clam should pay attention to the following aspects:

Transportation of Meretrix meretrix seedlings

When the seedlings reach the commercial specifications (white seedlings, medium seedlings and large seedlings), they can be transplanted or sold, and the time for washing seedlings depends on the climate and tide. The first day of the lunar calendar and twelve o'clock (midnight and noon) are spring tides. And the time difference of full tide every day is about 50 minutes. Generally, it is carried out when the weather is cool, not rainy or low tide, so that the washed seedlings are strong and have high survival rate in transportation and cultivation. Seedling production area and cultivation area are often not in the same area, so transplanting seedlings requires a transportation process. Because of its strong adaptability to the environment, Meretrix meretrix can withstand hours or even days without drying up and dying. There is a certain amount of seawater in the body cavity, which can play a regulating role after fishing and bring some benefits to storage and transportation, but it will still directly affect the quality of shellfish, such as sorting time, packaging and transportation. In the process of transporting seedlings, we should also pay attention to the following issues:

1) Short-distance transportation: generally transported by car or ship. The transportation time is less than 24 hours, so there is no need to take cooling measures.

2) Long-distance transportation: The transportation time exceeds 24 hours, and refrigerated trucks are needed. Seedlings and ice packs are staggered and separated by bamboo pieces. When the temperature is controlled at about 3℃ and the transportation time is 80h ~100h, the survival rate is over 95%.

3) Generally, the seedlings are packed in net bags, each bag is about 30kg, and the mesh size is subject to no leakage of seedlings.

4) Take the Meretrix meretrix seedlings on the same day, wash them clean, and have no debris such as sediment.

5) The transportation time is best in the north wind, the temperature is relatively low, and the survival rate is high. The weather in the south is easy to die, so it is best to wash the seedlings on the same day, transport them on the same day, and sow them on the same day. From emergence to sowing, it should not exceed three tides at the latest to improve the survival rate of sowing.

6) During seedling washing and handling, we should try our best to avoid damaging Meretrix meretrix seedlings and breaking their shells, resulting in death and mutual infection, which will affect the survival rate of transportation.

7) All vehicles and ships must be transported in Gabon to avoid death caused by sun and rain, but they must not be covered tightly to prevent suffocation.

8) Before transportation, the tide in the stockyard must be accurately calculated to determine the departure time. If it is stocked in the low tide area, it is necessary to transport the seedlings in the spring tide, otherwise, when the seedlings arrive, the land will not be exposed and it will be impossible to sow.

Culture of Meretrix meretrix in intertidal zone

(A) the selection conditions of farms

The mussel breeding farm should choose the middle and low tide area with relatively calm wind and waves, gentle tidal current, flat terrain, more sand and less mud (sediment concentration is 70% ~ 90%); The specific gravity of seawater is 1.0 10 ~ L.025, and the most ideal specific gravity is1.012 ~1.020. The flow rate is 40~ 100 cm/s.

(2) whole ridge sowing

1. Sowing season: Sowing season varies greatly according to individual specifications of seedlings. White seedlings, usually planted in April-May; Most of the middle seedlings were sown in June+February, 5438, and in some places, due to cold weather and other reasons, sowing was postponed to the next spring; Large seedlings are usually sown before spawning.

2. Leveling: Leveling is mainly to build a dike with Miscanthus to prevent the loss of Meretrix meretrix seedlings at the edge of the embankment near the harbor road and the subtidal zone. The dike is 30 ~ 40 cm wide and about 25 cm high. Large tidal flats should also be enclosed with Miscanthus and divided into several pieces for easy management. Then pick up the stones and sundries on the embankment, fill the depression with sand and level the embankment. If the embankment is soft, the drainage ditch must be excavated to prevent the area from being flooded. Finally, one week before sowing seedlings, use bleaching powder (15 kg/mu) or tea seed cake (8 kg/mu) to splash ridges to kill enemies and pests.

3. Sowing methods: Sowing methods include dry sowing and wet sowing.

(1) Dry sowing: When the low tide reaches the dew, unload the Meretrix meretrix seedlings from the seedling carrier parked on the land. When sowing seedlings, it is required to sow evenly to prevent accumulation. If the tide is high, it is impossible to continue sowing seedlings or if the sowing is not completed, the clam seedlings should be unloaded and soaked in water until the next high tide.

White seedlings are often sown in this way because they are light and easy to be swept away by the tide.

(2) Wet sowing: Wet sowing refers to transporting Meretrix meretrix seedlings to the marked land by boat and sowing them evenly in the marked area before the ebb tide leaves the dike. Sowing should be carried out at low tide or low tide to avoid the loss of clam seedlings.

Wet sowing method increased sowing time, improved work efficiency and improved the survival rate of Meretrix meretrix seedlings, but the sowing was uneven. This method is only suitable for medium and large seedlings.

4. Sowing density: Sowing density directly affects the growth rate and yield of Meretrix meretrix. If the sowing density is too high, the growth of Meretrix meretrix is slow; The sowing density is too thin, the cultivation area is not fully utilized, and the yield per unit area is low. Therefore, it is very necessary to master the appropriate sowing density. The amount of seedlings sown depends on the size of individual mussels, the level of intertidal zone, sediment conditions and other factors (table 19-6): individual mussels are large and have high survival rate, so less sowing can be done; In the low tide zone, the larvae of Meretrix meretrix feed for a long time, grow fast, and have more natural enemies, so the larvae of Meretrix meretrix should be multicast appropriately. The hard substrate has good stability and can also be multicast.

In addition, it should be increased or decreased according to the quantity and flow rate of bait organisms in the sea area.

Table 19-6 Relationship between Seedling Density, seedling size and Site Conditions.

3) Cultivation management

As the saying goes, "three seedlings, seven tubes." Doing a good job in the management of cultivation period is an important measure to ensure the increase of production.

1. Migration: The main purpose of migration is to transfer the intertidal zone of culture, evacuate the culture density and promote growth.

(1) Large and sparse seedlings: The tidal zone of sowing seedlings is higher. After 6-7 months of culture, the number of individuals increased significantly, the food intake increased, and the culture density was relatively too dense; At the same time, the physique of Meretrix meretrix is gradually enhanced, and its adaptability to the external environment is strong. Therefore, we should move to the low tide area for stocking and reduce the breeding density appropriately to accelerate the growth of Meretrix meretrix.

(2) Transplanting in different seasons to improve the survival rate of Meretrix meretrix seedlings: according to the characteristics of good thermal insulation of mud layer, difficulty in freezing to death in winter, large storage capacity of sand ridges, low temperature and difficulty in dying in summer. With the different seasons, it can be transplanted to different places to improve the survival rate. Harvesting and transplanting can be adopted.

(3) Accelerate the recovery of physical strength of the mother mussel after delivery, and transplant it to promote growth: After laying eggs and ovulating, the mother mussel has poor adaptability to environmental factors and is prone to death. Therefore, before the breeding season comes, the parent shellfish should be transplanted to the low tide zone, where the bait is rich and calm, so as to restore their physique and accelerate their growth.

2. Disaster prevention and defense against enemies: Natural disasters that seriously threaten Meretrix meretrix, mainly floods and typhoons. In the land vulnerable to typhoon, we should strive to harvest or transplant to a safe area before the typhoon season comes; Similar measures should be taken on flooded land; For the victims who haven't had time to harvest and transplant, they must be rescued in time, remove the sediment covering the embankment, collect the lost clam and reduce the loss.

The natural enemies of Meretrix meretrix and their control measures are described above. During the breeding period, it is necessary to kill insects frequently to reduce losses.

3. Strengthen daily management: After the seedlings of Meretrix meretrix are sown, we should often patrol the embankment to check whether the seedlings of Meretrix meretrix are lost, the growth speed and survival rate of Meretrix meretrix, and the harm of the enemy, so as to replenish the seedlings in time or take corresponding measures. At the same time, it is necessary to dredge ditches, fill dikes and repair dams. In particular, the newly bred parent mussels are weak in constitution, and most of them float on the embankment. If people trample on it, the death rate is even greater. Therefore, after the breeding season, management or transplantation should be strengthened.

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