JP2020191819A - Aquaculture method and aquaculture system of asian clam - Google Patents

Abstract

To provide asian clam aquaculture method and system capable of bottoming larvae released from mother shellfishes and growing them to the mother shellfishes in high density.SOLUTION: An asian clam aquaculture method includes a first step of releasing larvae from mother shellfishes, a second step of bottoming young shellfishes, a third step of growing them to mother shellfishes, and a fourth step of growing the mother shellfishes furthermore. The first step comprises a step of releasing the larvae from the mother shellfishes using a first growth container formed of permeable holes and growing them to the young shellfishes. The second step comprises a step of bottoming the young shellfishes in the gravel using a second growth container where the gravel is laid and the permeable holes are formed. The third step comprises a step of growing the young shellfishes to the mother shellfishes using the second growth container. The fourth step comprises a step of further growing the mother shellfishes using a third growth container formed of the permeable holes.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for culturing freshwater clams, and more particularly to a technique for culturing clams that grows larvae released from mother mussels to mother mussels.

There are three types of freshwater clams (蜆) peculiar to Japan: clams (true clams), clams (Seta clams), and corbicula japonicas (Yamato clams). Corbicula japonica and Corbicula japonica live in completely freshwater areas. , Inhabit the steam area. Setashijimi and Yamatoshijimi are male and female aliens like general bivalves such as clams and clams, and release sperm and eggs into water for fertilization, and larvae, juveniles, and adult mussels (also called "parent mussels"). ), While clams are male and female, and are known to spawn and fertilize in the body, release hatched larvae to the outside of the body, and grow into juvenile and adult clams. In addition, for example, in Pale grass blue, larvae grow into larvae through stages such as trochophore larvae, early D-type larvae, and late D-type larvae, but in the present invention, these are not specified unless otherwise specified. Are collectively called "larvae". Setashijimi inhabits only Lake Biwa and the Lake Biwa water system. Pale grass blue inhabits brackish waters all over Japan, and most of the clams on the market are Pale grass blue. Corbicula leana has also inhabited completely freshwater areas such as large and small rivers and waterways in the plains and mountains throughout Japan since ancient times, but now the number of clams has decreased sharply and distribution in the market of clams is not seen. .. Here, a mussel that has grown so that it can reproduce before the adult mussel releases larvae is particularly called a "mother mussel".

There are several reasons why the population of Corbicula leana has decreased sharply, but the absolute population is originally small, and the habitat environment is contaminated with agricultural chemical fertilizers, pesticides, domestic wastewater, etc. There are deterioration, river improvement to prevent flood damage, decrease in habitat where clams can grow due to residential land development, and destruction of ecosystem (gene pollution) due to the introduction of alien species. Such a factor for the drastic decrease in the population of Corbicula leana is not unrelated to Setashijimi and Yamatoshijimi, and there is concern that the population will decrease. In particular, clams are threatened with extinction, and although efforts are being made to protect clams, regardless of individuals, companies, governments, etc., complete aquaculture has not been realized. In addition, it has been widely known from ancient times that freshwater clams improve the function of the liver. In recent years, methionine, ornithine, taurine, vitamin B12, etc., which are abundant in freshwater clams, have been extracted as freshwater clam extracts and commercialized as supplement foods. Is also progressing, and new marketability of freshwater clams is expected. Both the essential amino acid methionine and the non-essential amino acid ornithine have been reported to exhibit liver function enhancing effects. Furthermore, it is also being considered to construct a purification system for rivers, lakes, brackish waters, etc. by utilizing the purification action of bivalve molluscs. In particular, since the breeding period of Corbicula leana is longer than that of Corbicula leana and Corbicula leana. There is a possibility of mass production, and it is expected to be used for purification systems.

By the way, as described above, clams grow from fertilized eggs to larvae, juveniles, adult mussels, and mother mussels, and in particular, it is difficult to increase the survival rate until the larvae become adult mussels. Are known. Hereinafter, the description will be centered on Corbicula leana. After fertilization, the released D-type larvae of Corbicula leana have a body length of about 100 μm to 200 μm, and immediately grow as juveniles and settle on gravel on the seabed. In addition, although there is no clear definition, when a juvenile mussel grows to a body length of about 1 mm, it is called an adult mussel, and it is said that feeding activity is started from this stage. When an adult mussel grows (although there is no clear definition, it has a body length of about 10 mm) and becomes able to reproduce, it is called a mother mussel. Here, the inventor of the present application confirms that the feeding activity starts when the body length of Corbicula leana reaches about 600 μm, and a new growth stage (hereinafter referred to as “small shellfish”) is taken from the juvenile to the adult shellfish. ), And the growth stage of Corbicula leana is larvae (body length about 100 μm to 200 μm), juvenile shellfish (body length about 200 μm to 600 μm), small shellfish (body length about 600 μ to 1 mm), adult shellfish (body length about 1 mm to 10 mm). , Mother shellfish (body length of about 10 mm or more) is considered to be divided into five growth stages.

By the way, various proposals have been made for the cultivation technique of clams, hermaphrodite clams (for example, Corbicula japonica, clams, etc.), but most of them are from the collected juvenile clams to the mother clams. It is related to the technology for growing and the technology for growing mother mussels, and the technology for growing and growing eggs laid from mother mussels to mother mussels has not been proposed so much. In particular, the cultivation of hermaphroditic clams that release larvae There are even fewer proposals for technology. For example, Patent Document 1 states, "For the purpose of providing a shellfish aquaculture device capable of effectively increasing the number of shellfish," a shellfish having a run-down water tank in which growing water flows from upstream to downstream. The aquaculture tank is provided with a mother mussel breeding unit for growing mother mussels and a compartment for communicating with the mother mussels breeding unit via a branch port. The breeding water that branches to the compartment through the branch port is passed through a filter having pores through which an egg laid in the mother mussel breeding section or a floating larva hatched from the egg can pass through. A shellfish farming apparatus characterized by flowing into the shellfish (see "Claim 1").

JP-A-2019-41701 Japanese Unexamined Patent Publication No. 2019-50764

The invention described in Patent Document 1 uses a "filter" to reduce the predation of "eggs or floating larvae" by "zooplankton", and "prevents clogging of the filter member 11". It is described that maintenance such as cleaning work can be easily performed (see FIG. 8) "(see paragraphs" 0039 "and FIG. 8 of the specification of Patent Document 1). Since it is stated that "the mesh size of the pores of the filters 13 and 13'is formed to be approximately 0.5 mm" (see paragraph "0030" of Patent Document 1), the size of this mesh size. Then, zooplankton that cannot pass through the filter, dust contained in the growing water, etc. are likely to cause clogging, and the filter must be replaced frequently, which may reduce the work efficiency. In addition, when the eggs of "zooplankton" pass through the "filters 13 and 13'" and flow into the "juvenile mussel tank 32", the "zooplankton" hatch and grow in the "juvenile mussel tank 32". , There is a risk that the juveniles will be preyed before they grow into mother shellfish, and it will not be possible to "effectively increase the number of shellfish".

Further, in the latest research of the applicant of the present application, instead of laying gravel on the bottom of the mother oyster growing container, slit-shaped or mesh-shaped water-permeable holes are formed on the bottom surface and the side surface of the mother mussel growing container to flow the water flow. It was found that high-density and large-scale cultivation of mother mussels can be realized by aerating from the bottom of the mother mussels growth container and removing the deposits in the mother mussels growth container. It was found that the method of laying gravel on the bottom of the mother mussel growing container is effective for surely landing a large amount of bottom.

The above-mentioned Patent Document 1 is a technical idea of excluding zooplankton with a filter, but in Patent Document 2, the applicant of the present application does not use a filter and optimizes the flow rate of breeding water according to the growth stage of Corbicula leana. We proposed an invention using a technical idea that is completely different from the conventional technology, that is, by making the clams land on the ground and efficiently excluding parasites. Patent Document 2 states, "In a method for culturing clams that live in a freshwater environment, efficient extermination of pests is carried out in order to increase the survival rate of larvae released from the mother clams of clams until they grow into adult clams. "Aim to provide a method for culturing clams" (see paragraph "0028" of the specification of Patent Document 2), "a method for culturing clams that grows larvae released from mother mussels to mother mussels, from the larvae. A method for culturing freshwater clams, which comprises controlling the flow rate of breeding water in a growth tank for growing freshwater clams according to the growth stage up to the mother mussel (see Patent Document 2, "Claim 1"). Has been done. The applicant of the present application has further studied the cultivation technique of Corbicula leana, which grows Corbicula leana at high density and greatly improves the yield.

Therefore, the present invention relates to a technique for culturing mussels that grow in fresh water and are male and female, and in particular, a method for culturing mussels that grows larvae released from mother mussels into juvenile mussels and grows the juvenile mussels into larvae. The purpose of the device is to provide a method and aquaculture system for mussels that can effectively settle the larvae released from the mother mussels and grow and grow the larvae after landing at a high density. And.

Another object of the present invention is to provide a cultivation method and aquaculture system for Corbicula leana, which grows and grows Corbicula leana in a growth tank of Corbicula leana whose structure is optimized according to the growth stage of Corbicula leana.

In order to achieve the above object, the invention according to claim 1 is a method for cultivating a mussel that grows larvae released from a mussel to a mussel, and at least grows the mussel and larvae from the mussel. The first step of releasing the larvae and growing the larvae into juveniles, the second step of landing the juveniles, and the third step of growing the landed juveniles into mother mussels. The first step comprises a fourth step of further growing the mussels, and the first step is to grow the mussels using a first growth vessel having a water permeation hole formed at the bottom in the first growth tank. Including a fifth step of growing, releasing larvae from the mother mussel and growing the larvae to juvenile mussels, the second step is in the second growing tank with gravel laid inside and at the bottom. A sixth step of landing the juvenile mussels grown from larvae on the gravel using a second growth vessel formed with water permeation holes is included.
In the third step, the larvae that have settled down are grown into mother mussels in the third growth tank by using a third growth container in which gravel is laid inside and water permeation holes are formed at the bottom. The fourth step comprises a seventh step, the fourth step comprising an eighth step of further growing the grown mother mussel using a fourth growth vessel having a water permeable hole formed at the bottom. To do.

The invention according to claim 2 is the method for culturing Corbicula leana according to claim 1, wherein the second growth container is used as the third growth container.

The invention according to claim 3 is the method for cultivating mashijimi according to claim 1 or 2, wherein the first step further corresponds to the center of the bottom surface of the first growth container. The fourth step further comprises a ninth step of ejecting air by an aeration means provided at the position to remove the deposits of the first growth vessel, the fourth step further centering on the bottom surface of the fourth growth vessel. It is characterized by including a tenth step of discharging air by an aeration means provided at a position corresponding to the portion and removing the deposit of the fourth growth vessel.

The invention according to claim 4 is a mussel culture system that grows larvae released from a mother mussel to a mother mussel, and at least grows the mother mussel and releases larvae from the mother mussel to produce the larvae. A first growth tank configured to grow to juveniles, a second growth tank configured to settle the juveniles, and the settled juveniles to grow to mother mussels. A first growth tank is provided with a configured third growth tank and a fourth growth tank configured to further grow the grown mother mussel, and the first growth tank has a water permeation hole formed at the bottom. The larvae are released from the mother mussels grown in the first growth vessel, and the larvae are grown into juvenile mussels in the first growth tank. The tank is provided with a second growth vessel in which gravel is laid inside and a water permeation hole is formed at the bottom, and the second growth vessel is configured such that the juvenile mussels land on the gravel. The third growth tank is provided with a third growth container in which gravel is laid inside and a water permeation hole is formed at the bottom, and the third growth container grows the bottomed juvenile mussel to a mother mussel. The fourth growth tank is provided with a fourth growth vessel having a water permeation hole formed at the bottom, and the mother mussels grown in the third growth vessel are further grown in the fourth growth vessel. It is characterized in that it is configured to be used.

The invention according to claim 5 is the clam culture system according to claim 4, wherein the third growth container is used to grow the juvenile mussels grown from the second breeding tank. It is characterized in that the second growth container has been relocated.

The invention according to claim 6 is the machine cultivation system according to claim 4 or 5, which corresponds to the central portion of the bottom surface of the first growth container in the first growth tank. An aeration means is provided at the position so that the deposits in the first growth container can be removed by aeration, and in the fourth growth tank, it corresponds to the central portion of the bottom surface of the fourth growth container. An aeration means is provided at the position, and it is characterized in that the deposits in the fourth growth container can be removed by aeration.

According to the clam culturing method and culturing system of the present invention, larvae released from mother mussels can be settled by culturing in a growth tank having a structure optimized according to the growth stage of clams. It is possible to grow and effectively settle on the bottom, and it is possible to exert a remarkable effect that the settled juveniles can grow and grow at high density up to the mother clam.

It is a figure explaining the Corbicula leana aquaculture system of this invention. It is a front view of the growth container of this invention. It is a left side view of the growth container of this invention. It is a top view of the growth container of this invention. It is a bottom view of the growth container of this invention. It is a front view of the gantry of this invention. It is a left side view of the gantry of this invention. It is a right side view of the gantry of this invention. It is a top view of the gantry of this invention. It is a front view of the growth container set of this invention. It is a left side view of the growth container set of this invention. It is a top view of the growth container set of this invention. It is a left side view of another growth container set of this invention. It is a figure which shows another gantry of this invention. It is a figure which shows another growth container set of this invention.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, the following embodiments are merely examples that embody the present invention, and the present invention is not limited thereto.

(Embodiment)
[overall structure]
FIG. 1 shows a diagram illustrating a clam farming system according to an embodiment of the present invention. The Masijimi culturing system 1 of the embodiment according to the present invention can release larvae b and settle on the ground while further growing the grown mussel mother mussel a grown on the Masijimi culturing stem 1 as a main configuration. The juvenile clam release tank 2 that grows into juvenile c and releases the grown juvenile c to the juvenile bottom tank 3 in the latter stage (on the right side of the drawing) and the juvenile c that is released from the juvenile shell release tank 2 are laminated. The juvenile mussel bottoming tank 3 and the juvenile mussel c that grew in the juvenile mussel bottoming tank 3 It is provided with a mother mussel growth tank 4 for growing and growing the mother mussel d, and a high density mussel growth tank 5 for growing the grown mother mussel d at a high density and further growing. Further, a breeding water supply tank 18 for supplying breeding water 18a is provided to the juvenile shell release tank 2 and the high-density mother shell growth tank 5.

In the clam farming system 1 of the present embodiment, four of the above-mentioned juvenile clam release tank 2, juvenile clam bottoming tank 3, mother clam growth tank 4, and high-density clam growth tank 5 are used according to the growth stage of clams. The aquaculture tank has been optimized to achieve efficient high-density aquaculture of clams. Traditionally, freshwater mussels are thought to prefer to live on the gravel at the bottom of rivers and lakes, and when culturing, mother shells are laid in gravel so that they are as close to the natural environment as possible. However, as a result of diligent research, the applicant of the present application grows when a juvenile mussel (about 200 μm to 600 μm) grows into a mother mussel (a shell length of about 10 mm). It was found that the survival rate was high even if there was no gravel depending on the conditions, and the growth container 14 having a plurality of water permeation holes formed at the bottom (the lower part of the side surface 14a and the entire surface of the bottom surface 14b) was used to make the juvenile shell release tank 2 and high. It was invented to construct a density mother shell growth tank 5. In the present embodiment, a slit S is formed in the lower side surface of the growth container 14 and a mesh M is formed in the bottom surface of the growth container 14 as water-permeable holes. In the present embodiment, the "bottom" of the growth container 14 is a certain lower region connected to the bottom surface 14b of the side surfaces (four side surfaces on the left, right, front and back) 14a of the growth container 14, and a region of the entire surface of the bottom surface 14b. Shall indicate.

Here, in the high-density mussel growth tank 5, one high-density mussel is used because the purpose is to increase the number of mussels cultivated per single area (or volume), that is, to grow the mussel e at high density. A large amount of mother mussels e will be grown in the growth tank 5 (specifically, one growth container 14 described later). Then, due to the excrement of the mother mussel e, hedro-like deposits are deposited in the high-density mother mussel growth tank 5 (specifically, the above-mentioned growth vessel 14), which lowers the survival rate of Corbicula leana. This deposit needs to be removed. Therefore, the applicant of the present application has invented the removal of deposits by aeration. Normally, it is known that aeration is used for the purpose of increasing the dissolved oxygen amount in the breeding water 18a, but in the present embodiment, since the dissolved oxygen amount is secured by the water flow of the breeding water 18a, the sediment The primary purpose is to remove.

If a large number of aeration means are provided, the effect of removing deposits will be enhanced, but the number of components (air discharge member, air pipe, intake pump, etc.) will increase accordingly, and the manufacturing cost and maintenance cost will also increase. Therefore, the applicant of the present application has invented a configuration capable of realizing a predetermined deposit removing effect by simplifying the configuration most and reducing the cost. That is the high-density mussel growth tank 5 of the present embodiment (the same applies to the juvenile mussel release tank 2). The high-density mussel growth tank 5 is provided with a plurality of growth containers 14 having a plurality of water permeation holes formed at the bottom thereof. Further, in the high-density mussel growth tank 5, the center of the bottom surface of the growth container 14 is provided. The aeration means 11 is provided at a position corresponding to one portion. By providing the aeration means 11 at a position corresponding to one central portion of the bottom surface 14b of the growth vessel 14, it is possible to achieve a remarkable effect of removing deposits and increasing the survival rate of Corbicula leana with a simple configuration. It was. In FIG. 1, the aeration means 11 shows only the air discharge member, and the intake pump for supplying air and the air pipe for supplying air from the intake pump to the air discharge portion are not shown. As the air discharge member, for example, a known air stone can be used.

Further, also in the juvenile mussel release tank 2, since the mother mussel a that releases larvae is similarly grown at a high density, the aeration means 11 is located at a position corresponding to one central portion of the bottom surface 14b of the growth container 14. Was provided.

In the clam farming system of FIG. 1, a configuration in which two growth container sets 7 in which one growth container 14 is suspended on one pedestal 13 is arranged vertically in the juvenile shell release tank 2 is illustrated. There is. No gravel is laid in the growth container 14 arranged in the juvenile shell release tank 2. Similarly, the juvenile mussel bottoming tank 3 is illustrated in a configuration in which one growth container set 8 in which one growth container 14 is suspended on one pedestal 13 is arranged. Unlike the juvenile mussel release tank 2 and the high-density mother mussel growth tank 5, gravel 6 is laid at the bottom of the growth container 14 arranged in the juvenile mussel bottoming tank 3. Further, the mother mussel growth tank 4 is illustrated in a configuration in which three growth container sets 9 in which one growth container 14 is suspended on one gantry 13 are continuously provided. Gravel 6 is laid in the growth container 14 arranged in the mother mussel growth tank 2. Here, the growth container set 9 is provided in advance with no clams (that is, a growth container 14 on which the gravel 6 is laid is suspended on a pedestal 13). The juvenile c, which has grown to a predetermined size after landing in the growth container set 8 of the shell bottom tank 3, may be relocated, or the growth container set 8 itself in which the bottomed / grown juvenile c is grown may be relocated. , It may be relocated to the mother shell growth tank 4 and used as a growth container set 9 so as to grow from the juvenile shell c to the mother shell d.

Gravel 6 having a particle size of about 5 mm to 10 mm is laminated and laid on the bottom of the growth container 14 provided in the juvenile mussel bottoming tank 3. When the larva b (about 100 μm to 200 μm) released from the mother mussel a grows into a larva c that can settle (about 200 μm), the byssus secreted from the byssus glands is entwined with the sediment and settles. However, if the bottom surface 14b of the growth container 14 has only a shape such as a wire mesh or a mesh, it cannot naturally land in the space of the mesh, and the portion that can be landed is limited. On the other hand, if the bottom sediment of the growth container 14 is gravel, the area where the bottom can be settled (the surface of the gravel) increases, so that a large amount of juveniles can be settled as compared with the wire mesh or mesh.

The juvenile mussel release tank 2 is continuously supplied with the breeding water 18a whose flow rate is controlled by the water supply pump P1 from the breeding water supply tank 18. Similarly, the high-density mother mussel growth tank 5 is continuously supplied with the breeding water 18a whose flow rate is controlled by the water supply pump P2 from the breeding water supply tank 18. In the present embodiment, the breeding water supply tank 18 uses the aquaculture pond used for culturing carp, has a certain amount of water storage, and is constantly inflowing natural river water by the water supply pump P3. The breeding water 18a supplied to the shell release tank 2 and the high-density mother shell growth tank 5 contains abundant phytoplankton that feeds the clams. As the breeding water supply tank 18, instead of the above-mentioned aquaculture pond, large and small rivers, waterways, or artificially installed structures for supplying breeding water may be used, but aquaculture is carried out as in the present embodiment. Construction and maintenance costs are lower if you use a pond or a river, an existing pond, or a waterway. Further, instead of the water supply pumps P1 to P3 that require power, the head between the breeding water supply tank 18 and the juvenile shell release tank 2 and the head between the breeding water supply tank 18 and the high-density mother shell growth tank 5 are used. Therefore, the breeding water 18a may be supplied without using power (pump).

Next, each aquaculture tank will be described. The clam farming tank of the present embodiment is provided with four growth tanks, a fry release tank 2 as a first growth tank, a fry bottoming tank 3 as a second growth tank, and a mother mussel as a third growth tank. A high-density mother mussel growth tank 5 is provided as a growth tank 4 and a fourth growth tank.
[Fry shell release tank]
In the juvenile mussel release tank 2 as the first growth tank, the side wall and the bottom wall are formed of concrete, and the growth container set 7 is arranged in two vertical stages inside. One growth container set 7 is configured such that one growth container 14 into which the mother mussel a is put is suspended on one pedestal 13. A slit S as a water-permeable hole is formed on the side surface 14a of the bottom of the growth container 14, and a mesh M (not shown in FIG. 1) as a water-permeable hole is formed on the entire surface of the bottom surface 14b of the bottom. No gravel is laid in the growth container 14, and the mother mussel a is grown by being laminated on the bottom surface 14b of the growth container 14. On the bottom wall of the juvenile mussel release tank 2, the aeration means 11 is arranged at a position corresponding to the center of the bottom surface 14b of the growth container 14. The juvenile mussel discharge tank 2 is connected to the breeding water supply tank 18 via the breeding water supply pipe 15 and the water supply pump P1 whose flow rate can be controlled, and is connected to the juvenile mussel bottoming tank 3 via the juvenile mussel transport pipe 12. Has been done. The discharge port 15a of the breeding water 18a of the breeding water supply pipe 15 is provided near the bottom wall of the juvenile mussel discharge tank 2, and the inflow port 12d of the juvenile mussel c of the juvenile mussel transport pipe 12 is the upper end of the juvenile mussel discharge tank 2. It is provided in the vicinity, and the water flow of the breeding water 18a flows from the bottom wall side of the juvenile mussel discharge tank 2 toward the upper end, and the juvenile mussel c can efficiently flow into the juvenile mussel transport pipe 12. ..

In the juvenile clam release tank 2, the larva b is released from the larva b during the larval release period (the period corresponding to the spawning period of the male and female clams) from April to October while growing and growing the larva a. The released larva b is grown into a juvenile c (the larva b grows into a juvenile c that can settle in about one day), and the grown juvenile c is passed through the larva transport pipe 12 to the second. It is configured to be released into the juvenile clam bottoming tank 3 as a cultivation tank. The inflow of the juvenile c from the juvenile release tank 2 to the juvenile transport pipe 12 is carried out by an overflow method. The water surface ws1 of the breeding water 18a of the juvenile mussel release tank 2 is near the upper end of the juvenile mussel discharge tank 2 and is at the same position as the upper end of the juvenile mussel transport pipe 12.

The juvenile shell transport pipe 12 is configured by connecting the juvenile shell discharge pipe 12b to the tip of the L-shaped pipe 12a. A plurality of juvenile clam discharge holes 12c are opened in the juvenile shell release pipe 12b, and the landable juvenile clams c that have flowed in from the juvenile shell release tank 2 are provided with the breeding water 18a and the juvenile shell release holes 12c. Is released into the juvenile mussel bottoming tank 3.

[Frying shell bottom tank]
Next, the juvenile mussel bottoming tank 3 will be described. The juvenile mussel bottoming tank 3 of the present embodiment is formed of concrete around the periphery (side wall and bottom wall), and a growth container set 8 is arranged inside. One growth container set 8 is configured such that one growth container 14 laid with gravel laminated on the bottom is suspended on one pedestal 13. The juvenile clams c released from the juvenile shell transport pipe 12 of the juvenile shell release tank 2 settle on the gravel 6 and grow until they reach a certain size (shell length is about 1 mm). In addition, a juvenile mussel that has grown to about 1 mm may be referred to as an adult mussel.

A drainage port is formed at the lower end of the side wall of the juvenile mussel bottoming tank 3, and this drainage port is connected to the lower end of the side wall of the mother mussel growth tank 4 by a water level adjusting drainage pipe D1. The water level adjusting drain pipe D1 has a configuration in which an elbow pipe is connected to a cylindrical pipe, and the elbow pipe having a drain port is configured to be rotatable in a plane perpendicular to the paper surface of FIG. 1 to rotate the elbow pipe. With, the height of the drainage position can be adjusted. For example, when the elbow pipe is rotated so that the drainage port is close to the bottom wall of the mother shell growth tank 4, the water surface ws2 of the breeding water 18a is lowered, and the elbow pipe is rotated so that the drainage port is far from the bottom wall of the mother shell growth tank 4. Then, the water surface ws2 of the breeding water 18a rises. By such water level adjustment, the water surface ws2 of the breeding water 18a of the juvenile mussel bottoming tank 3 and the water surface ws3 of the breeding water 18a of the mother mussel growth tank 4 are adjusted to be at the same height. The water surface ws2 of the breeding water 18a of the juvenile mussel bottoming tank 3 is set below the upper end of the growth container 14, and the water surface ws3 of the breeding water 18a of the mother mussel growth tank 4 is above the upper end of the growth container 14. It is set.

In the juvenile mussel bottoming tank 3, the breeding water 18a supplied from the upper juvenile mussel transport pipe 12 passes between the gravel 6 laid in the growth container 14 and is discharged from the water level adjusting discharge pipe D1. Has been done. Therefore, the juvenile clam c supplied together with the breeding water 18a can efficiently settle on the gravel 6.

Although the gravel 6 is laid on the entire bottom of the juvenile clam bottom tank 3, only a part of the gravel 6 laid is shown in the figure. In the juvenile clam bottoming tank 3 of the present embodiment, gravel 6 having a particle size of 5 mm to 10 mm is laid, and the gravel 6 has a much wider landing area (gravel surface) than, for example, a wire mesh. Moreover, since the gravel 6 is close to the natural growth environment of Corbicula leana, a large amount of juvenile mussels can be effectively settled.

[Mother shell growth tank]
Next, the mother shell growth tank 4 will be described. In the mother mussel growth tank 4 as the third growth tank, the side wall and the bottom wall are formed of concrete, and the growth container set 9 is arranged in three horizontal stages inside. One growth container set 9 is configured such that one growth container 14 laid with gravel 6 laminated on the bottom is suspended on one pedestal 13. In the growth container 14, the juvenile clams c that have settled on the gravel 6 in the juvenile clam bottoming tank 3 and have grown to a certain size are grown and grown until they become mother clams (shell length is about 10 mm or more). Preferably, the growth container set 8 of the juvenile mussel bottoming tank 3 in which the juvenile mussels c grown to a certain size after landing is moved to the mother mussel growth tank 4 is configured as a growth container set 9. It is more efficient to do it. In that case, a new growth container set 8 may be arranged in the juvenile mussel bottoming tank 3. In the mother mussel growth tank 4, a water level adjusting drain pipe D2 is provided at the lower end of the side wall facing the water level adjusting drain pipe D1. Similar to the water level adjusting drain pipe D1, the water level adjusting drain pipe D2 has a configuration in which an elbow pipe is connected to a cylindrical pipe, and the elbow pipe having a drain port can rotate in a plane perpendicular to the paper surface of FIG. By rotating the elbow pipe and adjusting the height of the drainage position, the height of the water surface ws3 of the breeding water 18a of the mother shell growth tank 4 can be adjusted.

In the mother mussel growth tank 4, since the water flow of the breeding water 18a flows in the lateral direction (from the left side to the right side in FIG. 1), the excrement of freshwater clams is likely to accumulate, and pests such as midges are also likely to occur. Therefore, the water flow is set to be about 12 m / min. At this flow velocity, juvenile mussels (adult mussels) grown to about 1 mm do not flow out together with the breeding water 18a, the influence of sediments is small, the occurrence of pests is small, and the mother mussels d (shell length is about about). The clams can grow until they reach 10 mm).

[High-density mussel growth tank]
Next, the high-density mother mussel growth tank 5 will be described. In the high-density mother mussel growing tank 5 as the fourth growing tank, the side wall and the bottom wall are formed of concrete, and the growing container set 10 is arranged in two horizontal stages inside. The structure of one growth container set 10 is different from that of the above-mentioned growth container sets 7 to 9, and four growth containers 14 are suspended on one pedestal 20. In the growth container 14, the clams that have grown into the mother mussel d in the mother mussel growth tank 4 are grown at a high density to grow into a larger mother mussel e. As described above, a slit S as a water permeable hole is formed on the side surface 14a of the bottom of the growth container 14, and a mesh M (not shown in FIG. 1) as a water permeable hole is formed on the entire bottom surface 14b of the bottom. Has been done. Further, as in the case of the juvenile mussel release tank 2, no gravel is laid in the growth container 14, and the mother mussel e is laminated on the bottom surface 14b of the growth container 14 and is grown at a high density. On the bottom wall of the mother mussel growing tank 5, the aeration means 11 is arranged at a position corresponding to the center of the bottom surface 14b of the growing container 14. The breeding water 18a is continuously supplied to the high-density mother oyster growing tank 5 from the breeding water supply tank 18 connected via the breeding water supply pipe 16 and the water supply pump P2 with the flow rate controlled.

In the high-density mother mussel growing tank 5, a water level adjusting drain pipe D3 is provided at the lower end of the side wall on the side facing the discharge port of the breeding water supply pipe 16. The water level control drainage pipe D3 has the same configuration as the water level control drainage pipes D1 and D2, and by rotating the elbow pipe and adjusting the height of the drainage position, the water surface of the breeding water 18a of the high-density mother shell growth tank 5 The height of ws4 can be adjusted. The water level ws4 of the breeding water 18a of the high-density mother oyster growing tank 5 is adjusted so as to be above the upper end of the upper growing container 14. In the high-density mother oyster growing tank 5, only mother mussels having a shell length of about 10 mm or more are grown, so that they are not affected by pests.

In the high-density mother oyster growing tank 5, a large amount of mother oyster e grows at high density, so that there is a possibility that deposits mainly on the excrement of the mother mussel e are deposited in the growing container 14, and in particular, the upper stage. There is a concern that the excrement of the mother mussel e from the growth container 14 of the above will be deposited in the growth container 14 in the lower stage. As described above, the growth container 14 is formed with water-permeable holes at the bottom (the lower part of the side surface 14a and the entire surface of the bottom surface 14b), so that the area near the bottom peripheral edge of the growth container 14 is caused by the water flow of the breeding water 18a. Can be discharged to the outside without accumulating the excrement of the mother shell e. Therefore, on the bottom wall of the high-density mother mussel growth tank 5, an aeration means 11 is provided at a position corresponding to one central portion of the bottom surface of the lower growth container 14. By providing the aeration means 11 at a position corresponding to one central portion of the bottom surface 14b of the growth vessel 14, it is possible to achieve a remarkable effect of removing deposits and increasing the survival rate of Corbicula leana with a simple configuration. It was. If the number of growth container sets 10 is further increased and arranged, a larger amount of mother mussels e can be grown at high density.
In the present embodiment, the growth container sets 7 to 9 and the growth container set 10 have different configurations, but the growth container sets 7 to 9 may have the same configuration as the growth container set 10.

[Growth container set]
Next, the detailed configuration of the growth container set will be described with reference to FIGS. 2 to 15. The growth container set includes a growth container and a pedestal on which the growth container is suspended. The growth container uses the same growth container 14 in the growth container sets 7 to 10 and 50, and the gantry is the growth container set 7. In ~ 9, the gantry 13 is used, and in the growth container sets 10 and 50, the gantry 20 is used.
[Growth container 14]
First, the growth container 14 will be described. FIG. 2 is a front view of the growth container 14, FIG. 3 is a left side view of the growth container 14, FIG. 4 is a plan view of the growth container 14, and FIG. 5 is a bottom view of the growth container 14. Is. As shown in the figure, the growth container 14 is a tray-shaped container having a rectangular shape in a plan view with an upper opening, and includes a side surface 14a connected to the left, right, front and back, and a bottom surface 14b connected to the side surface 14a. The material is synthetic resin. A plurality of slits S having an opening width of about 3 mm and an opening length of about 16 mm are formed in the lower portion of the side surface 14a. Further, as shown in FIGS. 4 and 5, a mesh M having a plurality of square opening portions having an opening width of about 3 mm and an opening length of about 3 mm is formed on the bottom surface 14b. The slit S and the mesh M are used as water-permeable holes. A collar portion 14c is provided on the upper edge portion of the growth container 14, and the collar portion 14c is hooked on the gantry 13 or the gantry 20 hooking member described later, whereby the growth container 14 is attached to the gantry 13 or the gantry 20. Can be suspended. A reinforcing ridge 14d for strength reinforcement is formed on the bottom surface 14b, and a plurality of reinforcing ridges 14e for strength reinforcement are formed on the back side of the flange portion 14c.

The growth container 14 is also shared with the juvenile mussel bottoming tank 3. In the juvenile mussel bottoming tank 3, a growth container 14 on which gravel 6 is laminated is suspended on a gantry 13, and juvenile clam c is released from above together with breeding water 18a to land the juvenile clam c on the gravel 6. .. The water surface ws2 of the breeding water 18a is set so as to be maintained below the upper end of the growth container 14. This is to prevent the breeding water 18a from overflowing from the upper end of the growth container 14 and being discharged, and at the same time, the juvenile clam c may be discharged before landing on the gravel 6. Further, the uppermost layer of the gravel 6 to be laid is set lower than the water surface ws2. The juvenile c is able to land on the gravel 6 because it is the gravel 6 laid in the water and the juvenile c cannot land on the gravel 6 laid above the water surface ws2. .. Then, the breeding water 18a passes through the slit S and the mesh M from above the growth container 14 and is discharged downward.

Here, if the slit S is formed up to the vicinity of the upper end of the growth container 14, an opening portion of the slit S exists between the water surface ws2 and the uppermost layer of the gravel 6, and the slit S grows from this opening portion. The juvenile clams c discharged to the outside of the container 14 may be generated, and the bottoming rate of the juvenile clams c may decrease. Therefore, in the present embodiment, the opening length is set so that the upper end of the opening portion of the slit S is lower than the uppermost layer of the gravel 6. If the opening width of the slit S is narrowed so that the juvenile clams c are not discharged, the passage rate is lowered due to clogging due to deposits and the like, and the deposits are accumulated in the growth container 14, and the survival rate of the juvenile clams is increased. It may decrease. Since the gravel 6 is laid on the bottom surface 14b on the entire surface, there is no particular problem in discharging the juvenile clams c. As described above, the lower portion of the side surface 14a and the lower surface 14b of the growth container 14 are referred to as the bottom portion.

[Mount 20]
Next, the gantry 20 constituting the growth container set 10 used for the high-density mother mussel growth tank 5 will be described. 6 is a front view of the gantry 20, FIG. 7 is a left side view of the gantry 20, FIG. 8 is a right side view of the gantry 20, and FIG. 9 is a plan view of the gantry 20. The gantry 20 is made entirely of stainless steel, and has a rod-shaped strut and an L-shaped cross-section hooking member so that a total of four growth containers 14 are suspended on one pedestal 20, two each in the vertical and front and rear directions. Are appropriately connected to form a frame. A pair of left and right front vertical columns 21L and 21R are provided at the front end, a pair of left and right central vertical columns 29L and 29R are provided at the center, and a pair of left and right rear vertical columns 30L and 30R are provided at the rear end. There is. The front vertical column 21L on the left side, the central vertical column 29L on the left side, and the rear vertical column 30L on the left side are welded to and connected to a pair of left horizontal columns 22L and left horizontal column 23L. The front vertical column 21R on the right side, the central vertical column 29R on the right side, and the rear vertical column 30R on the right side are welded to and connected to the horizontal column 24R on the right side.

Further, the pair of left and right front vertical columns 21L and 21R are welded and connected to the left and right end portions of the pair of upper and lower front hooking members 25T and 25B. The pair of left and right central vertical columns 29L and 29R are welded to the left and right ends of the pair of upper and lower central hook members 26T and 26B and the left and right ends of the pair of upper and lower central hook members 27T and 27B. Has been done. A pair of left and right rear vertical columns 30L and 30R are welded to both left and right ends of a pair of upper and lower hooking members 28T and 28B.

The front hooking member 25T, the central hooking member 26T, the central hooking member 27T, and the rear hooking member 28T have the same height, and the front hooking member 25B, the central hooking member 26B, and the center The portion hooking member 27B and the rear hooking member 28B have the same height. The distance between the front hook member 25T and the front hook member 25B is such that when the growth container 14 is suspended, the bottom surface 14b of the growth container 14 suspended in the upper stage and the growth suspended in the lower stage are respectively. The distance between the container 14 and the collar 14c is set so that the breeding water 18a can appropriately pass when the growth container set 10 is arranged in the high-density mother oyster growth tank 5, and this distance is 40 mm or more. Is desirable. Further, the distance between the front hooking member 25B and the lower end of the gantry 20 is such that when the growth container set 10 is arranged in the high-density mother oyster growth tank 5, the growth container 14 suspended on the lower stage of the gantry 20 The distance between the bottom surface 14b and the bottom wall of the high-density mother oyster growing tank 5 is set so that the breeding water 18a can appropriately pass through, and this distance is preferably 40 mm or more. In addition, "the breeding water 18a can pass through appropriately" means that the sediment can be appropriately discharged by the water flow when the breeding water 18a passes through.

The left horizontal column 22L has a height substantially equal to that of the front hooking member 25T, and is connected to the front vertical column 21L, the central vertical column 29L, and the rear vertical column 30L. The left horizontal column 23L has a height substantially equal to that of the front hooking member 25B, and is connected to the front vertical column 21L, the central vertical column 29L, and the rear vertical column 30L. The left horizontal column has a two-piece structure of 22L and 23L, in order to secure the strength of the gantry 20. The height of the left horizontal strut 22L is substantially equal to that of the front hooking member 25T, the central hooking member 26T, 27T, and the rear hooking member 28T when the growth container 14 is suspended on the gantry 20. Or, this is to prevent the growth container 14 from falling off from the gantry 20 by coming into contact with the left horizontal column 22L after being suspended. The same applies to the relationship between the left horizontal support column 23L, the front hooking member 25B, the central hooking member 26B, 27B, and the rear hooking member 28B. However, on the other hand, this configuration makes it inconvenient to attach / detach the growth container 14 from the left side of the gantry 20. Therefore, in the present embodiment, the right horizontal column 24R is used as one, and the right horizontal column 24R is connected to the upper ends of the front vertical column 21R, the central vertical column 29R, and the rear vertical column 30R. did. With this configuration, a space portion that can easily attach and detach the growth container 14 is formed on the right side of the gantry 20. This space portion is expressed as a detachable space portion DS.

[Growth container set 10]
Next, the growth container set 10 used for the high-density mother mussel growth tank 5 will be described. 10 is a front view of the growth container set 10, FIG. 11 is a left side view of the growth container set 10, and FIG. 12 is a plan view of the growth container set 10. As shown in the figure, in the growth container set 10, the front hook member 25T of the gantry 20 and the central hook member 26T arranged to face each other have the collar portion 14c of one growth container 14. The collar portion 14c of another growth container 14 is suspended from the front hooking member 25B of the gantry 20 and the central hanging member 26B arranged to face each other, and the center of the gantry 20 is suspended. The collar portion 14c of another growth container 14 is suspended from the portion hooking member 27T and the rear hooking member 28T arranged to face each other, and the central portion hooking member 27B of the gantry 20 and A flange portion 14c of another growth container 14 is suspended from a rear hooking member 28B disposed so as to face each other. That is, a total of four growth containers 14 are suspended on one pedestal 20, two front and rear, two upper and lower. As described above, since the attachment / detachment space DS is provided on the right side of the gantry 20, the growth container 14 can be smoothly attached / detached. Further, the distance between the bottom surface 14b of the upper growth container 14 and the collar 14c of the lower growth container 14 and the distance between the bottom surface 14b of the lower growth container 14 and the lower end of the gantry 20 are fixed distances (40 mm or more). Since it is set to (desirable)), when the growth container set 10 is arranged in the high-density mother shell growth tank 5, the water flow of the breeding water 18a passing through effectively disperses deposits such as mother shell excrement. It can be discharged to the outside of the high-density mother shell growth tank 5.

As a method of cultivating Corbicula leana known as a conventional technique, there is a method of laying gravel in a waterway to grow mother mussels. As an example of this method, a waterway having a width of 30 cm and a length of 12 m is created and weighs 5 kg. When the mother mussels were added and grown, the survival rate of the mother mussels was 50%. However, as an example of this embodiment, 24 growth vessels 14 having a width of 30 cm and a length of 50 cm are used to form a high-density mother oyster growth tank, and 5 kg of mother oysters are charged per growth container 14. The survival rate was 95%. Therefore, the aquaculture method and the aquaculture system of Mashijimi of the present embodiment have a yield of about 46 times that of the above-mentioned conventional technique when comparing the yield per unit area, and can realize the high-density aquaculture technique of Mashijimi. It can be said that it was done.

[High-density growth container set 50]
As described above, the combination of the gantry 20 and the growth container 14 may be appropriately changed. FIG. 13 is a left side view of the high-density growth container set 50. The high-density growth container set 50 has a configuration in which a pedestal 20 on which the growth container 14 is suspended is arranged in a plurality of stages in the front-rear and vertical directions. With this configuration, a larger amount of mother mussel e can be grown and grown at high density.
[Other growth container set]
FIG. 14 shows another gantry 13, and FIG. 15 shows a growth container set 7 using the gantry of FIG. The gantry 13 and the growth container set 7 are used for the juvenile mussel release tank 2, the juvenile mussel bottoming tank 3, and the mother mussel growth tank 4. The configuration of the gantry 13 is as follows in the configuration of the gantry 20: left horizontal support 23L, front suspension member 25B, central suspension member 26T, 26B, 27T, 27B, rear suspension member 28B, central vertical support 29L, 29R. The lengths of the front vertical columns 21L and 21R, the central vertical columns 29L and 29R, and the rear vertical columns 30L and 30R are appropriately adjusted, and the gantry 13 has only one growth container 14. Suspended. The gantry 13 is also provided with a detachable space DS.

In the present embodiment, the configuration, shape, material, size, combination, etc. of the growth container set 7 to 9,50 composed of the gantry 13 and the growth container 14, the growth container set 20 composed of the gantry 20 and the growth container 14 and the like. However, these configurations, shapes, materials, sizes, combinations, etc. can be variously modified and modified without departing from the technical scope of the present invention.

[Aquaculture method]
Next, a method for culturing clams using the clam culturing system 1 having the above-described configuration will be described. First, in the clam farming system 1, when the mother mussel a grown in the juvenile clam release tank 2 reaches the larval breeding season (generally known as the spawning season, breeding season, etc. for clams other than clams), the mother. Corbicula leana larva b is released from shellfish a. The released larva b slowly floats in the breeding water 18a from the bottom to the top of the juvenile release tank 2 and grows into a juvenile c that can settle in about one day, and transports the juvenile together with the breeding water 18a. It flows into the pipe 12 and is discharged to the juvenile mussel bottoming tank 3. The juvenile clams c released into the juvenile mussels bottoming tank 3 settle on the surface of the gravel 5 laminated and laid in the juvenile mussels bottoming tank 3, and shift to benthic life to grow.

When the bottomed juvenile clam c grows, it is transferred to the mother clam growth tank 4. At this time, the grown larvae c may be selected and transferred to the breeding set 9 arranged in the mother mussel growth tank 4 in advance, or the larvae may be released and settled during this period in a cycle of at least one month. As the bottom period, the growth container set 8 of the juvenile mussel bottoming tank 3 may be relocated to the mother mussel growth tank 4 and used as the breeding container set 9. After the growth container set 8 of the juvenile mussel bottoming tank 3 is moved to the mother mussel growth tank 4, a new growth container set 8 is arranged in the juvenile mussel bottoming tank 3.

In the mother mussel growth tank 4, the relocated juvenile mussels c are grown to the size of the mother mussel d (about 10 mm), and when the size of the mother mussel d is reached, they are sorted and the high-density mother mussel growth tank 4 is used. It is relocated to No. 5 where it is grown in large quantities at a higher density, and even larger mother mussels e are grown. In addition, some mother mussels are transferred to the juvenile mussels release tank 2 and grown for further growth, and are used for releasing larvae b.

As described above, according to the clam culturing method and the culturing system of the present invention, the clams are released from the mother mussels by culturing in a plurality of growth tanks having a structure optimized according to the growth stage of the clams. It has a remarkable effect that the larvae can be grown into larvae that can settle and effectively settle in large quantities, and the larvae that have settled can be grown and grown at high density to the mother mussels. Can be done.

1 Masijimi culture system 2 juvenile shell release tank 3 juvenile bottoming tank 4 mother shell growth tank 5 high-density mother shell growth tank 6 gravel 7, 8, 9, 10, 50 growth container set 11 aeration means 12 juvenile transport piping 12a L-shaped pipe 12b Juvenile discharge pipe 12c Juvenile discharge hole 12d Juvenile inflow hole 13,20 Stand 14 Growth container 14a Side surface 14b Bottom surface 14c Collar 14d Reinforcing ridge 14e Reinforcing projectile 15, 16, 17 Piping 15a Breeding water outlet 18 Breeding water supply tank 18a Breeding water 21L, 21R Front vertical support 22L, 23L Left horizontal support 24R Right horizontal support 25T, 25B Front hook member 26T, 26B, 27T, 27B Central part Hook member 28T, 28B Rear hook member 29L, 29R Central vertical support 30L, 30R Rear vertical support a, d, e Mother shell b Larval c Young shell D1, D2, D3 Water level control drain pipe M mesh P1, P2 P3 Water supply pump S Slit ws1, ws2, ws3, ws4, ws5 Water surface of breeding water

Claims (6)

It is a method of culturing clams that grows larvae released from mother mussels to mother mussels.
At least, the first step of growing the mother mussel, releasing the larva from the mother mussel, and growing the larva into the juvenile, the second step of landing the juvenile, and the landed juvenile. The third step of growing the mother mussel and the fourth step of further growing the grown mother mussel are provided.
In the first step, a mother mussel is grown in a first growth tank using a first growth container having a water permeation hole formed at the bottom, larvae are released from the mother mussel, and the larvae are larvae. Including the fifth step of growing to shellfish
In the second step, the juvenile mussels grown from larvae are attached to the gravel using a second growth container in which gravel is laid inside and a water-permeable hole is formed at the bottom in the second growth tank. Including the sixth step to bottom out
In the third step, the larvae that have settled down are grown into mother mussels in the third growth tank by using a third growth container in which gravel is laid inside and water permeation holes are formed at the bottom. Including the 7th step
The fourth step is a method for culturing Corbicula leana, which comprises an eighth step of further growing the grown mother mussel using a fourth growth container having a water-permeable hole formed at the bottom. The method for culturing Corbicula leana according to claim 1, wherein the second growth container is used as the third growth container. In the first step, air is further discharged by an aeration means provided at a position corresponding to the center of the bottom surface of the first growth container to remove the deposits of the first growth container. Including steps
In the fourth step, air is further discharged by an aeration means provided at a position corresponding to the center of the bottom surface of the fourth growth container to remove the deposits of the fourth growth container. The clam farming method according to claim 1 or 2, wherein the method comprises steps. It is a clam farming system that grows larvae released from mother mussels to mother mussels.
At least, a first growth tank configured to grow a mother mussel, release larvae from the mother mussel, and grow the larvae to juveniles, and a second growth tank configured to settle the juveniles. A third growth tank configured to grow the larvae that have settled down to the mother mussel, and a fourth growth tank configured to further grow the grown larvae. Prepare,
The first growth tank is provided with a first growth container having a water-permeable hole formed at the bottom, and larvae are released from the mother mussels grown in the first growth container, and the larvae are grown in the first growth vessel. It is configured to grow into juveniles in the tank,
The second growth tank includes a second growth container in which gravel is laid inside and a water permeation hole is formed at the bottom, and the second growth container is such that the juvenile mussels are landed on the gravel. It is composed and
The third growth tank is provided with a third growth container in which gravel is laid inside and a water-permeable hole is formed at the bottom, and the third growth container extends the bottomed juvenile to the mother mussel. It is configured to grow
The fourth growth tank is provided with a fourth growth container having a water permeation hole formed at the bottom, and is configured to further grow the mother mussels grown in the third growth container in the fourth growth container. A clam farming system characterized by this. The clam according to claim 4, wherein the third growth container is a relocation of the second growth container in which the juvenile mussels grown from the second growth tank are grown. Aquaculture system. In the first growth tank, an aeration means is provided at a position corresponding to the center of the bottom surface of the first growth container, and the deposits in the first growth container can be removed by aeration.
In the fourth growth tank, an aeration means is provided at a position corresponding to the central portion of the bottom surface of the fourth growth container, and the deposits in the fourth growth container can be removed by aeration. The clam farming system according to claim 4 or 5, wherein the clams are cultivated.

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