(1) Site selection:

Select a muddy and sandy tidal flat with small wind and waves, smooth tide, and a small amount of fresh water as the cultivation site. The tide level is suitable in the middle and low tide areas, especially near the dry tide line of neap tide. The beach is flat and broad, with a muddy bottom and a sand content of more than 50%. It is opposite to sea water and has a density of 1.010-1.025, preferably 1.015-1.024. There is no industrial pollution, no fish meal processing factory discharge or domestic pollution.

(2) Seed transportation

Clams are a kind of shellfish with strong drought tolerance. They can survive drying for 2-3 weeks in winter, but they can only survive for 2 days in summer. -3 days. For this reason, dry transportation should be used during transportation, but a certain humidity and low temperature must be ensured, and transportation with water must not be carried out.

(3) Breeding methods

1. Temporary cultivation of clams in ponds

(1) Pond construction: Build a pond on flat ground with a depth of 0.5 meters, a flat bottom, an inclination of about 5%, and a rectangular shape. The pool is 1 meter wide and 0.5 meters high. Cement boards or plastic boards are used to protect the slope, prevent advancement and retreat, and prevent soil from flowing into the pool. A pool is defined as 667 square meters, and about 30 cm of tidal sand is laid. Main entrance and drainage channels, and various There are inlet and drainage gates at both ends of the pond.

(2) Temporary cultivation time: Temporary cultivation in ponds is delayed compared to temporary cultivation on tidal flats. Generally, the maximum water temperature on the surface of the pond water does not exceed 25℃, and in winter it is not lower than 5℃. Temporary cultivation can be carried out at the end of October.

(3) Temporary breeding density: The stocking density gradually increases as the water temperature decreases. When the water temperature is 25°C, the amount shall not exceed 2,000 kg per 667 square meters. When the water temperature is 10°C, the amount shall not exceed 5,000 kg per 667 square meters. When the water temperature is 5°C, , can hold up to 6000-8000 kilograms of clams. If the water temperature is high, the temporary raising time should be shortened appropriately. If the water temperature is low, the temporary raising time can be shortened for 1-2 months.

(4) Management: Change the water flexibly depending on the change of water temperature. Generally, change the water once a day, and the daily water change volume is more than 80%. When the water temperature is 25°C, change the water 1-2 times a day, and the water temperature is 10 When the temperature is below ℃, change the water every other day. Where conditions permit, use circular water change. Keep the water depth above 30 cm and beware of "floating heads". The pond water is shallow, the environmental conditions are poor, and moss is prone to occur. It must be removed in time, otherwise the moss covering the surface of the pond will cause the clams to suffocate and die. After each clam harvesting task is completed, the entire pond bottom must be thoroughly loosened and exposed to the sun to keep the pond bottom clean. .

2． Clam seine culture. Clam seine culture is built because clams have the habit of moving with the tide. A block should be set up on the side of the breeding farm with a low tide. There are two types of block: one is to use a double-layer net (both are polyethylene). Ethylene net) is blocked. The inner net mainly prevents clams from escaping. The mesh is small, about 1.5 cm, and the lower edge is buried in the sand. The blocking net is 0.7 meters above the sand surface. The outer net mainly prevents enemies from invading. Its height is at the high tide line. Above, the mesh is larger, about 5 cm, and the blocks are usually fixed with bamboo stakes. The other type only has 1 layer of blocking. The height of the net is 65-100 cm, the mesh is 2-2.5 cm, part of the net is buried in the sand, and the other part is exposed on the beach, and is supported by bamboo poles or wooden poles, the diameter of the wooden poles or bamboo poles is 10-15 cm, and the height is 3 meters. , inserted into the beach to a depth of 60-70 cm.

The appropriate size of the tennis court is about 200×667 square meters.

The main management work during the cultivation period is to repair the nets, prevent "runaway", evacuate piles of clams, and prevent disasters. Because clams have the habit of moving, if the barrier is damaged, the clams are often beaten into piles by the wind and waves after spring tides or strong winds. If they are not evacuated in time, they will die. Especially in summer when the temperature is high, it is more likely to cause a large number of deaths. For harmful organisms, it is necessary to prevent and control them in time to reduce damage.

3． Polyculture of clams and shrimps

(1) Polyculture pond: The polyculture pond is based on the principle of providing suitable environmental conditions for the polyculture species. The pool shape is preferably rectangular, and the size is (30-60) )×667 square meters is appropriate. It is easy to enter and drain, and the depth of the pool is 1.5-2 meters. A pond bottom with a ring groove is better than a flat bottom pond bottom. The ring groove can separate the shrimp feeding platform and the clam living area (central platform). The bottom of the polyculture pond should contain more than 60% sand. If the sand content of the bottom of the pond is low, fine sand can be added appropriately. Clam seedlings enter the pond earlier than shrimp seedlings in polyculture. The pond should be cleaned before placing clam seedlings (old ponds should be decontaminated), and the bottom of the pond should be plowed for 20-20 years. 30 cm deep, after disinfection, crush and rake it flat. Commonly used drugs for disinfection of clear pools mainly include rotenol, bleaching powder and quicklime.

(2) Intake of water and fertilizer: Water should be introduced in time after the bottom of the polyculture tank is sorted. The seawater put in needs to be filtered through a 60-80 mesh sieve to prevent harmful organisms from entering the pool. The appropriate water depth is 20-30 centimeters. After entering the water, apply fertilizer. Commonly used fertilizers include chicken manure, cow manure, human manure and inorganic fertilizers. Base fertilizer should be enough.

(3) Sowing seedlings: Seedlings should have a shell length of 2.5-3.0 centimeters and a seeding density of 250-500 kilograms per 667 square meters. Seedlings should be sown evenly.

The surface of clam shells cultured in shrimp ponds is black, which is caused by long-term dehydration and does not affect the quality of clam meat. If you need to decolorize, you can rinse it and dry it in the shade for 2-3 days. The black color can be removed. You can also use non-toxic and odorless oxidants for rapid decolorization.

4． Proliferation of clams

(1) Beach closure and proliferation: During the clam breeding season, establish a clam protection zone to ensure broodstock reproduction.

According to the habit of shell seedlings inhabiting the mid-tide area, the lower section of the high-tide area and the upper section of the mid-tide area are designated as seedling areas, and beach closures are implemented for beach conservation; the lower section of the mid-tide area and the low-tide area are designated as breeding areas, and rotational fishing operations are adopted to catch large larvae. Measures such as staying in a small school.

(2) Transplant culture: Choose a mid- to low-tide area with calm seas, smooth water flow, flat and stable bottom, sand content of 60%-80%, and not affected by floods to transplant clams and stock them. Shell seedlings with a body length of 1 cm should be stocked at 150-200 kg per 667 square meters; shell seedlings with a body length of 1.5 cm should be stocked at 100-150 kg per 667 square meters. At the same time, daily management work such as leveling the beach surface and clearing enemies must be done.

(4) Death and prevention of clams

1. Death symptoms: Generally, they first emerge from the beach (commonly known as "floating head"), the adductor muscle relaxes, the water outlet pipe is unable to spray water, the luster of the shell fades, the fleshy part turns from milky white to pink, or even black, and the two shells open and die. From a small number of "floating heads" and dead clams, the beach should be leveled to prevent stagnant water and local high temperatures.

2． Causes of death

(1) Season: Most of the deaths of Jiangsu clams occur in the high temperature season from August to September. At this time, after the clams lay eggs and ejaculate, their bodies are weak, and there is more rain and the relative density of sea water. In seasons where the beach temperature is low and the beach temperature is too high, large numbers of deaths are likely to occur. Particularly in areas with uneven tidal flats and stagnant water, high temperatures are most likely to occur and cause death.

(2) Area: The tidal area is higher, the bottom is harder, and the places with larger mud are most susceptible to death. Especially the tidal flats in the high tide area during the neap tide season are prone to death if they remain dry for too long.

(3) Microorganisms: It is easy to cause death due to environmental deterioration. The soft parts of dead clams quickly rot and pollute the tidal flats. Due to the action of microorganisms, the death of clams spreads from the higher tidal flats to the low tide areas and even subtidal zones, causing a large number of clams to die in the entire sea area.

3． Prevention methods

(1) Transplantation and sparse culture: Move clams from higher tidal areas to low-tide areas for cultivation. This not only frees up the seedling collection area, but more importantly, prevents clams from dying due to lower salinity and excessive beach temperature after spawning.

(2) Polyculture with shrimps: In shrimp culture ponds with large sand content, polyculture of clams and shrimps can not only effectively prevent the death of clams, but also facilitate the growth of clams. It can also purify sea water and promote the growth of shrimp.

(3) Pond temporary culture: Use pond temporary culture to prevent the death of clams during high temperature periods.

(4) Strengthen management: The stocking density should be reasonable, the interval between harvesting and stocking should be controlled, piled clams should be evacuated in a timely manner, and "floating heads" and dead clams on the tidal flats should be promptly removed. Level the beach to prevent stagnant water and local high temperatures.