CATDOLL : CATDOLL: How to cultivate Sinonovacula constricta? What transportation method should be chosen later?

How to cultivate Sinonovacula constricta? What transportation method should be chosen later?

It is another year of "spring planting and autumn harvest", and the pond will also welcome its first "guest of honor" - the razor clam.

Sinonovacula constricta is one of the four major cultured shellfish in my country. It is commonly known as "razor clam" in Fujian, "dragon clam" in Zhejiang, and "clam" in Shandong, Liaoning, Hebei and other places.

Artificial breeding of Sinonovacula constricta:

1. Seedling raising equipment

It mainly includes circulating water nursery pond, still water nursery pond, bait room and corresponding water supply and water treatment systems.

2. Selection and treatment of broodstock

Select large clams of 1-2 years old that are more than 5 cm long, strong, grow normally, and have well-developed gonads. Since it is difficult to temporarily raise razor clams indoors, broodstock are generally selected from the sea area and induced to spawn on the same day.

3. Preparation before seedling cultivation

(1) Cultivation of bait: The bait for young razor clams is mostly single-celled algae such as Platymonas, Chaetoceros muelleri, and Isochrysis. Cultivation usually begins one month before seedling cultivation. (2) Checking the maturity of the gonads of razor clams: In natural sea areas, razor clams usually begin to spawn in batches from late September to early November. During this period, the maturity of the gonads can be regularly observed to determine the best date for induced spawning.

4. Inducing labor

The effective method of inducing spawning for Sinonovacula constricta is to combine shade drying with running water. The suitable water temperature for inducing spawning is 19℃～23℃, the specific gravity of seawater is 1.008～1.020, and the flow rate is 12 cm/s. 0.5 kg of razor clams with full gonads can produce 30 to 70 million trochophore larvae after one induction of spawning. The density of razor clams placed in 1m3 of water is 1 to 1.5 kg. Specific method: first dry in the shade for 6 to 8 hours, then run water for 2 to 3 hours, and spawn at 3 to 6 am. The efficiency of this method of inducing spawning is 50% to 90%. If spawning is still not seen after 6 am, the induction of spawning is ineffective. If the spawning amount is low, the above method can be used to induce spawning again the next day, and the spawning amount can be increased to more than 95%.

5. Cultivation of planktonic larvae

The larvae culture density is 3-5/ml. The management method is basically the same as the artificial breeding of other bivalve molluscs.

Collection and cultivation of wild razor clam seedlings:

Collecting wild seedlings for cultivation is conducive to improving the survival rate and achieving the purpose of increasing production. Seedlings are collected from the beginning of winter to around the Great Cold. The method of collecting seedlings is to use a seedling bag (120 cm long, 40 cm wide, with a 40 cm × 3 cm trapezoidal bamboo basket at the bag mouth) and a scraper (the scraper for scraping mud is 8 cm wide, 24 cm long, and made of bamboo) to collect. Between the beginning of winter and the Lesser Cold, there are about 200,000 to 300,000 seeds per kilogram of seedlings. The depth of scraping soil is 1 to 3 cm, and then the mud is washed away in water, and impurities are removed, and the clam seedlings are picked. The collected clam seedlings are cultivated in seedling pools. Seedling pools are generally built in high tide areas, where low tides cannot flood, the temperature is high, the water flow is slow, and there is fresh water that can be introduced into the pool. The area is generally about 0.05 acres. After about two months of raising the seedlings in the seedling pool, the seedlings will grow larger and more vigorous. At this time, the environment in the seedling pool is no longer suitable for their growth requirements, and the seedlings need to be moved back to the vicinity of the Central and North Korean area for raising. After another two months of raising, they can grow into seedlings.

Identification of the quality of razor clam seedlings:

The quality of razor clam seedlings directly affects the survival rate and yield of the culture. The identification criteria are shown in the figure below.

Transportation of razor clam seedlings:

Below 20℃, the dry-resistant transportation can last for 48 hours; above 20℃, it can last for about 36 hours. Refrigerated trucks are the best means of transportation. The following aspects should be paid attention to in the long-distance transportation of razor clam seedlings.

(1) Fresh water

The received razor clam seedlings should be washed with seawater on site to remove mud and impurities, and dead and broken seedlings should be picked out as much as possible. Rinse with fresh water once before loading to remove microorganisms on the shell surface and other impurities. Before rinsing, shake the seedling basket several times to shrink the water pipes of the razor clam seedlings so that they do not take in too much water and affect the survival rate. The soaking time should not be too long.

(2) Wet compartment

Before loading the seedlings, rinse the carriage with fresh water and maintain sufficient humidity.

(III) Seedling box

Each box contains 15 kg of seedlings and is loaded in layers. There is a certain amount of space between the upper and lower layers for ventilation.

(IV) Drying prevention

Cover the top seedling box with 2 to 3 layers of gauze soaked in water to prevent drying. During transportation, spray water every 1 to 2 hours to maintain a moist environment.

(V) Regular observation

During long-distance transportation, it is necessary to stop at regular intervals to check the seedlings, temperature, humidity, etc.

You need to choose the right bait, and you can choose unicellular algae for cleaning. Then, you should pay attention to checking the maturity of Daxin Town, and also properly induce spawning. You can choose to transport by car or ship, and also pay attention to Gabon capping.

Choose a good breeding site. For external coating breeding, choose the area from the lower layer of the mid-tide zone to the low-tide zone when there are 2-3 small ants every day. The bottom of the pond for mixed culture of shrimp and clams must be treated with black mud at the bottom of the pond, and the bottom is preferably a mixture of soft mud and mud and sand. Build a standard model clam field. Whether it is cooked coating or raw coating, external coating breeding must be turned over, raked, and leveled before stocking. The entire clam yard can be divided into small ridges 3-7 meters wide, with small ditches between the ridges. The ridge surface is road-shaped and does not accumulate water. The ridges for mixed culture of shrimp and clams refer to the construction of external coating, and the area is preferably controlled at 1/3 of the total area. The pond must be prepared before stocking clam seedlings. Carefully select and transport clam seedlings. The selection of clam seedlings must be done well, and clam seedlings soaked in fresh water and overnight clam seedlings must be avoided, otherwise the mortality rate will be high.

Transportation: Rinse the carriage with fresh water before loading and maintain sufficient humidity. During long-distance transportation, the vehicle must be stopped at regular intervals to check the temperature and humidity.

After the razor clam seedlings are rinsed, it is best to transport them in 20 kg flat plastic containers, with 15 kg of seedlings per box to avoid overfilling and squeezing the razor clam seedlings. Before loading the seedlings, wet the truck compartment with water to ensure that there is enough humidity in the compartment.

The cultivation methods and precautions of bamboo razor clams The cultivation technology of bamboo razor clams

1. Selection of breeding sites: Breeding should be carried out in the middle and low tide areas, in the inner bay or estuary, on flat and slightly inclined tidal flats. The tide must be smooth and the wind is calm. It can also be cultured in ponds. Razor clams grow 30 centimeters below the sand layer, so they have high requirements for the bottom quality. It is best to have a few centimeters thick soft mud on the surface, a mixture of mud and sand in the middle, and sand at the bottom. At the same time, it has extremely strict requirements for water quality, requiring the specific gravity of seawater to be between 1.010-1.025, the suitable water temperature for growth to be 3-32 degrees, and it likes weakly alkaline water with a pH value of 8.01-8.15.

2. Clam field preparation: After selecting a suitable breeding site, the clam field should be prepared. First, the field should be raked and plowed. Deep plowing should be done in areas with hard bottom. Then, raking and leveling should be done to make the soil soft and suitable for the growth of clams. Before sowing the seedlings, they should be disinfected and sterilized. Bleaching powder should be sprinkled into the water body. After about 2-3 days, the water should be drained. Then tea seed cakes should be used to eliminate small fish, shrimps and snails in the clam field to prevent them from eating the clam seedlings.

3. Seedling sowing: The seedling sowing time is slightly different between the north and the south. The temperature in the south rises quickly, so seedlings can be sown before the Qingming Festival in April, while in the north, seedlings should be sown in late May. Before sowing, put the seedlings in a wooden barrel or plastic barrel, wash the mud and sand with sea water, and then you can sow the seedlings. There are two ways to sow the seedlings: throwing and broadcasting. Throwing is suitable for clam fields with wide courtyards. Gently grab the clam seedlings and throw them on the courtyard. When there is no wind, several people can cross-cast. When there is wind, cast according to the wind. Broadcasting is suitable for clam fields with narrow courtyards. Similarly, gently grab the seedlings and broadcast them on the courtyard.

4. Management of clam yards: Strengthen the management of clam yards after sowing seedlings, conduct regular inspections, check the growth rate and survival rate of clam seedlings, and timely supplement seedlings and take corresponding measures. In the summer, the temperature is high and hot, and the heat dissipation of the mud floor of the clam yard is poor, which is not conducive to the growth of clams. Therefore, sand needs to be added to adjust the temperature so that the clams are in a suitable growth environment. The time for adding sand is before June, generally 1.5 tons of sand per mu, and it is required to be evenly spread on the yard surface. In addition, during storms, attention should be paid to the accumulation of soil and the silt should be moved to other areas in time. When managing clam yards, attention should also be paid to the prevention and control of natural disasters and biological pests to avoid huge losses.