CATDOLL : CATDOLL: How are clams raised in supermarkets? What is the salinity of the brine?

1. How are clams raised in supermarkets? What is the salinity of the salt water?

Clams can survive normally when the salinity of brine is between 1.004 and 1.027, and grow best when the salinity is between 1.015 and 1.020.

1. Water temperature: Clams are euthermic shellfish. In natural sea areas, they can adapt to water temperatures ranging from 0 to 36 degrees Celsius. They grow normally when the water temperature is 5 to 35 degrees Celsius, and grow fastest when the water temperature is 18 to 30 degrees Celsius. The upper limit of the suitable temperature for clams is 43 degrees Celsius. When the water temperature rises to 44 degrees Celsius, the mortality rate reaches 50%; when the water temperature rises to 45 degrees Celsius, all of them die.

2. Dissolved oxygen: Clams can live normally in seawater with a dissolved oxygen content of 1 mg/L. Therefore, the dissolved oxygen content of normal seawater can meet the living needs of clams.

How to spit sand out of clams:

To make the clams spit out sand and dust quickly and cleanly, you can put iron spoons, iron nails, etc. in the container. Shellfish have the habit of spitting out sand and mud when they smell iron, which will prompt the clams to spit out sand automatically. You can also put the clams in an iron pot, leave it for an hour or two, and then wash it with clean water, which can also achieve the same effect.

In addition, you can also put some salt in the container where the clams are placed. Generally speaking, 1 spoon of salt is enough for 1 kilogram of clams, which can also make the clams spit out sand faster.

30 bar, specific gravity 1.020 is fine. That is 1L water 30g salt

Wouldn't it be better to use seawater essence directly? Ask the seller when you buy it.

Available at seafood stores

2. When cooking clams, there are always many that remain unopened. What is the reason?

Clams are molluscs and are distributed along the coast of my country. Liaoning is the main producer, followed by Guangdong, Fujian and other places. Clams are tender and delicious, and are the best among shellfish seafood, with medicinal and edible value. According to legend, the earliest consumption of clams in China was two or three thousand years ago, and they are known as the freshest in the world. Clams are produced in large quantities in my country, and are semi-artificially farmed in coastal sand and mud. Most of the clams sold on the market today are artificially farmed. Before eating clams, it is usually necessary to soak them in light salt water in advance to remove the sand and mud. When boiling clams, put cold water and clams in the pot together, heat slowly over low heat until they open, and then remove and wash them. The meat is very tender and delicate, and it can be cooked quickly when it is put into the pot, so it is usually boiled in hot water. Because if you use cold water to boil them, it will take some time for the water to boil, and the cooking time will be relatively long. The clams will become old and woody, not fresh at all, and will have a strong fishy smell. Therefore, it is advisable to use cold water to boil clams.

Use hot water to boil clams, but be careful not to cook them for too long. After the water in the pot boils, add two slices of ginger and a handful of green onions, then pour the clams into the pot. After the clams are fully opened, season them and serve. The clams cooked in this way not only have no fishy smell, but also have a more tender texture. Because the clams are just cooked, they taste original and the soup is also very delicious. If there are any that have not opened, pick them out.

In addition, when buying fresh clams, we should not buy those with their mouths open. Those are usually dead clams. After buying the clams, we must feed them first to make them spit out the sand and mud. The most common method is to use salt water to spit out the sand, but this method is relatively slow. We can add a little white vinegar to the water, which can stimulate the clams to spit out the sand faster. Remember to change the water in the middle to ensure that the sand is spit out cleanly.

If you want it to open, you have to put it in cold water and cook it slowly, then it will open by itself. If you put it in boiling water and boil it to death, how can it open?

Clams are alive when you buy them. If they die before cooking, they will not open when cooked and such clams are inedible.

It is possible that some necrotic ingredients were mixed in when purchasing, or it is possible that they were not cooked thoroughly or for insufficient time.

3. Newbies ask for help: What should I pay attention to when raising clams?

When raising clams, you should pay attention to the following aspects:

Transport of clam seedlings

When the seedlings grow to commercial specifications (referring to white seedlings, medium seedlings, and large seedlings), they can be transplanted for cultivation or sold. The time for washing seedlings should also be determined by the climate and tides. The high tides are at 12 o'clock on the first and fifteenth day of the lunar calendar (midnight and noon). The time difference of high tide every day is about 50 minutes. It is usually carried out in cool weather, non-rainy days, and non-low tides. In this way, the washed seedlings are strong, and the transportation survival rate and cultivation survival rate are high. The seedling production area and the cultivation area are often not in the same area, so transplanting seedlings requires a period of transportation. Because the variegated clams have a strong ability to adapt to the environment, they can withstand several hours or even days without drying up or dying. A certain amount of seawater is stored in the body cavity, which can play a regulating role after fishing, which brings certain benefits to storage and shipment, but the sorting time, packaging, transportation and other factors of shellfish will still directly affect their quality. In the process of transporting seedlings, the following issues should also be noted:

1) Short-distance transportation: Generally, it is transported by car, but it can also be transported by ship. If the transportation takes less than 24 hours, no cooling measures are required.

2) Long-distance transportation: Transportation lasts more than 24 hours and requires a refrigerated truck. The seedlings and ice packs are arranged alternately and separated by bamboo strips. The temperature is controlled at about 3°C. The transportation takes 80 to 100 hours and the survival rate is more than 95%.

3) Seedlings are usually packed in mesh bags, with each bag weighing about 30 kg. The mesh size should be such that no seedlings leak through.

4) The clam seedlings should be collected on the same day, and the seedlings should be cleaned and free of mud, sand and other debris.

5) The best time for transportation is on a north windy day, when the temperature is relatively low and the survival rate is high. In south windy weather, the seedlings are prone to death. It is best to wash the seedlings, transport them on the same day, and sow them on the same day. The time from seedling removal to sowing should not exceed 3 tides at the latest, so as to improve the survival rate of sowing seedlings.

6) During the process of washing and transporting the seedlings, try to avoid damaging the clam seedlings or breaking their shells, which may cause death, mutual infection, and affect the survival rate during transportation.

7) Whether transporting by car or ship, it must be covered to avoid death caused by sun and rain, but it must not be covered tightly to prevent suffocation.

8) Before transportation, the tide of the stocking ground must be accurately calculated to determine the departure time. If the seedlings are stocked in a low-tide area, they should be transported during high tide. Otherwise, when the seedlings are transported, the ground will not be dry and sowing will be impossible.

Intertidal zone culture of clams

(I) Selection conditions of breeding farms

The breeding farms for adult clams should be selected in the mid- and low-tide areas with relatively calm waves, smooth tides, flat terrain, more sand and less mud (sand content is 70% to 90%); the specific gravity of seawater is 1.010 to 1.025, and the most ideal specific gravity is 1.012 to 1.020; the flow rate is 40 to 100 cm/second.

(II) Preparation and seedling planting

1. Seedling planting season: The seedling planting season varies greatly depending on the size of the individual seedlings. White seedlings are generally planted in April and May; medium seedlings are mostly planted in December, and in some places, due to cold weather and other reasons, the planting is postponed to the spring of the following year; large seedlings are generally planted before egg laying.

2. Land preparation: Land preparation mainly involves building embankments with Miscanthus near the harbor and the edge of the subtidal zone to prevent the loss of clam seedlings. The embankment is 30 to 40 cm wide and about 25 cm high. Large tidal flats should also be surrounded by Miscanthus dikes and divided into several blocks for easy management. Then pick up the stones and debris on the surface of the land, fill the depressions with sand, and level the surface of the land. If the land is soft, drainage ditches must be dug to prevent water accumulation in the land. Finally, one week before sowing seedlings, sprinkle the land with bleaching powder (15 kg/mu) or tea seed cake (8 kg/mu) to kill harmful organisms.

3. Seedling sowing method: There are two methods of seedling sowing: dry sowing and wet sowing.

(1) Dry seeding: When the land is dry after low tide, unload the clam seedlings from the seed transport boats moored on the land. When sowing the seedlings, spread them evenly to prevent them from clumping. If the tide has risen and it is impossible to continue sowing the seedlings or if the sowing is not completed, unload the clam seedlings, immerse them in water, and wait until the next tide to sow them again.

Because white seedlings are small and light, they are easily carried away by the tide and lost, so this method is often used for sowing seedlings.

(2) Wet seeding: Wet seeding is to transport clam seedlings to the marked land by boat before the tide has receded from the pond, and then evenly spread the seedlings within the marked area. Seeding should be done at low tide or when the tide is slow to prevent the seedlings from being lost.

The wet sowing method increases the sowing time, improves the work efficiency and the survival rate of clam seedlings, but the sowing is less uniform. This method is only suitable for the sowing of medium and large seedlings.

4. Seedling density: Seedling density directly affects the growth rate and yield of clams. If the seedling density is too high, the clams will grow slowly; if the seedling density is too sparse, the cultivation area cannot be fully utilized and the yield per unit area is low. Therefore, it is necessary to master the appropriate seedling density. The seedling quantity should be determined according to factors such as the size of the clam seedlings, the height of the tidal zone and the bottom conditions (Table 19-6): If the clam seedlings are large, the survival rate is high and less seeding can be done; if the tidal zone is low, the clam seedlings have a long feeding time and grow fast, and at the same time there are more enemies and pests, the clam seedling damage rate is high, so more seeding should be done appropriately; the bottom of the pond with hard soil has good stability and can also be sown more.

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

Table 19-6 Relationship between clam seedling sowing density, seedling specifications and site conditions.

3) Cultivation and management

As the saying goes, "three parts seedlings, seven parts management". Doing a good job of management during the growth period is an important measure to ensure increased yields.

1. Transplantation: The main purpose of transplantation is to transfer the breeding area, disperse the breeding density and promote growth.

(1) Seedlings are enlarged and transplanted sparsely: The tide zone where seedlings are sown is high. After 6 to 7 months of cultivation, the individuals are significantly enlarged and the food intake increases. The stocking density is relatively too dense. At the same time, the clams' physical fitness gradually improves and their ability to adapt to the external environment is stronger. Therefore, they should be moved to a lower tide zone for stocking and the stocking density should be appropriately reduced to accelerate the growth of clams.

(2) Transplant in different seasons to improve the survival rate of clam seedlings: Based on the good thermal insulation of the mud layer, the clam seedlings are not easily frozen to death in winter, and the sand court has a large water storage capacity and low temperature, so the clam seedlings are not easily sun-dried to death in summer. With different seasons, they can be transplanted to different sites to improve the survival rate. The method of harvesting and transplanting can be adopted.

(3) Accelerate the recovery of the clams after spawning and promote growth by transplantation: After spawning and ejaculation, the clams are weak and have poor adaptability to environmental factors, which can easily lead to death. Therefore, before the breeding season, the clams should be transplanted to a place with low tide, abundant bait, and calm water to restore their physical condition and accelerate their growth.

2. Prevent disasters and enemies: The natural disasters that seriously threaten clams are mainly floods and typhoons. In the acreages that are vulnerable to typhoons, efforts should be made to harvest or transplant them to safe areas before the typhoon season arrives; similar measures should be taken in the acreages threatened by floods; victims who are not harvested or transplanted in time must be rescued in time, the mud and sand covering the acreage surface must be cleared, and the scattered clams must be gathered to reduce losses.

The pests of clams and their control measures are as mentioned above. During the culture period, the ponds should be frequently cleaned to reduce losses.

3. Strengthen daily management: After the clam seedlings are released, it is necessary to frequently inspect the ponds to check whether the clam seedlings have been lost, the growth rate and survival rate of the clams, the damage caused by enemies, etc., so as to replenish the seedlings in time or take corresponding measures. At the same time, it is necessary to dredge the ditches, fill the pond surface, and repair the dams. Especially the parent clams that have just reproduced are weak and most of them float on the surface of the pond. If they are trampled by people, the mortality rate is even greater. Therefore, after the breeding season, management should be strengthened or transplantation should be carried out.