Oyster aquaculture cage and method for cultivating oysters

Abstract

[Problem] When oysters are cultivated in an aquaculture cage, the distribution of the oysters in the cage becomes significantly uneven due to the oscillation of waves on the sea surface. [Solution] An oyster aquaculture cage according to the present invention is connected to an aquaculture cable placed on the sea surface, wherein: the upper surface of the aquaculture cage is substantially rectangular in a plan view; the shape of the bottom part of the aquaculture cage has a curved surface that is convex downward in a cross section in a plane perpendicular to the extending direction of the aquaculture cable; the lateral width WBb of the bottom part of the aquaculture cage is 40-70 cm; the height HB of the aquaculture cage is WBb × 1 / 3 to WBb × 2 / 3; the height HBb of the bottom part of the aquaculture cage is WBb × 1 / 4 to WBb × 1 / 2; the downward convex curved surface has a shape that can be approximated to a substantially circular arc or a portion of a substantially circular arc; and the radius RA of the circular arc is 0.48 WBb to 0.63 WBb.

Description

Oyster farming cages and oyster farming methods

[0001] The present invention relates to an oyster culture cage and a method for cultivating oysters.

[0002] Oyster farming has long been a popular aquaculture industry in Japan. In recent years, technological advances in oyster farming have led to the development of more efficient and environmentally friendly farming methods. One such method is cage oyster farming. Cage oyster farming allows oysters to move freely within the cage, which, unlike traditional farming methods, reduces adhesion and pollution to the ocean. Moving the cage allows oysters to roll, resulting in beautifully shaped shells. Furthermore, drying oysters encourages the opening and closing of the oyster cap, cultivating oysters with robust vitality. Strengthening the vitality of cultivated oysters enables long-term storage, enabling the production of oysters suitable for export. While traditional methods are often subject to predation by fish, shellfish, and crickets, cage farming protects oysters from predation by predators. Figure 7 shows an example of a traditional oyster farming method. Oysters are cultivated by hanging cages from rafts floating on the sea surface.

[0003] Patent Document 1 discloses another example of an oyster farming cage. A farming cage 100 is connected to a cable 200. The farming cage is shaped horizontally relative to the cable, making it easier to turn over the cage (Patent Document 1).

[0004] WO 2019 / 151879 (Marlborough Oyster Limited)

[0005] The aquaculture cages described in Patent Document 1 have the problem of oysters being concentrated at the edge of the cage due to the swaying of ocean waves. Figure 8a is an illustration illustrating the problems with conventional aquaculture cages. Figure 8a (A) shows a culture cage when the waves are gentle. The cages are evenly positioned on the sea surface. Figure 8a (B) shows the culture cage tilted significantly due to the waves. The oysters are crowded at the edge of the cage. Once this state occurs, it becomes difficult for the cage to return to its original state. This causes the oysters' growing environment in the cage to vary significantly from one oyster to another, resulting in variations in nutritional intake and growth speed. Oysters compete with each other, hindering their growth. It also makes it difficult for them to roll around properly within the cage. The aquaculture cage in the state shown in Figure 8a (B) is not much different from the conventional cages simply suspended from cables, as shown in Figure 7. Figure 7b is an actual photograph of oysters being cultivated on the sea surface using conventional oyster culture cages. The aquaculture cage in the center of the photo appears to be tilted significantly, with the oysters in it losing their balance. Once tilted significantly, it is difficult to restore balance using only the force of the waves. This can be prevented by installing large floats on the aquaculture cages, but increasing the buoyancy makes the cages more susceptible to the effects of waves, hindering the growth of the oysters. This also makes it difficult for the oysters in the cage to find food. Furthermore, as the cages float, the oysters shake too much, increasing the contact between them and increasing the rate at which their shells are worn down.

[0006] The oyster culture cage connected to the culture cable of the present invention has a front surface, a back surface, an upper surface, and a bottom surface (lower surface), and the front and back surfaces are approximately parallel to a plane perpendicular to the extension direction of the culture cable, the upper surface is approximately rectangular in plan view, and the shape of the bottom surface has a downwardly convex curved surface in a cross section on a plane perpendicular to the extension direction of the culture cable, and the width W of the bottom of the culture cage Ｂｂ is between 40cm and 70cm, and the height H Ｂ Is W Ｂｂ ×1 / 3~W Ｂｂ × 2 / 3, and the height of the bottom of the aquaculture cage H Ｂｂ Is W Ｂｂ ×1 / 4~W Ｂｂ ×½, and the downwardly convex curved surface is a part of a substantially circular arc, and the radius of the circular arc is R Ａ is 0.48W Ｂｂ ~0.63WＢｂ is.

[0007] In the method for cultivating oysters of the present invention, oysters having a total length of 4 cm to 12 cm are placed in the oyster cultivating cages and cultivated.

[0008] The culture cage of the present invention prevents oysters from being unevenly placed at the edge of the cage, which causes a significant loss of balance between the left and right sides, and allows for efficient oyster culture.

[0009] Example of a culture cage of the present invention (bird's-eye view) Example of a culture cage of the present invention (bird's-eye view) Example of a culture cage of the present invention (bird's-eye view) Example of a culture cage of the present invention (front) Example of a culture cage of the present invention (R Ａ Definition of) Examples of parameter values ​​related to the shape of the culture cage of the present invention Example of a culture cage of the present invention (top view) Example of a culture cage of the present invention (side view) Example of a culture cage of the present invention (bird's-eye view) Example of a culture cage of the present invention (front view) Comparative example of a culture cage Comparative example of a culture cage Example of a culture cage of the present invention (front view) Example of a culture cage of the present invention (front view) Example of a culture cage of the present invention (bird's-eye view) Example (A) and comparative example (B) of the culture cage of the present invention: (front view) Example (A) and comparative example (B) of the culture cage of the present invention: (bird's-eye view) Example (A) and comparative example (B) of the culture cage of the present invention: (top view) Example of a culture cage of the present invention (front view / bottom view) Photograph of an example of a culture cage of the present invention Photograph of an example of a culture cage of the present invention Fruits of a culture cage of the present invention Photographs of Examples Photographs of Examples of Aquaculture Cages of the Present Invention Photographs of Comparative Examples of Aquaculture Cages Photographs of Comparative Examples of Aquaculture Cages Example of Aquaculture Cages of the Present Invention (Front) Example of Aquaculture Cages of the Present Invention (Bird's-eye View) Example of Aquaculture Cages of the Present Invention (A1, B1) and Fitting Results (A2, B2) Example of Aquaculture Cages of the Present Invention (Bird's-eye View) Example of Python Code Example of Aquaculture Cages of the Present Invention (Front) Example of Aquaculture Cages of the Present Invention (Front) Photographs of Examples of Aquaculture Cages of the Present Invention Example of Aquaculture Cages of the Present Invention (Front) Example of Aquaculture Cages of the Present Invention (Bird's-eye View) Example of Aquaculture Cages of the Present Invention (Front) Example of Aquaculture Cages of the Present Invention (Bird's-eye View) Example of Aquaculture Cages of the Present Invention (Bird's-eye View) Conventional Oyster Cultivation Methods Issues with Conventional Aquaculture Cages Conventional Aquaculture Cages (Photograph)

[0010] 10 Oyster to be cultivated 50 Arc 51 Center of arc 80 Wave surface 100 Cultivation cage 110 Front surface of the cultivating cage 120 Back surface of the cultivating cage 130 Top surface of the cultivating cage 140 Bottom surface of the cultivating cage (bottom of the cage) 145 Flat part of the bottom of the cultivating cage 150 Side surface of the cultivating cage 160 Joint (front side) 161 Joint (back side) 200 Cultivation cable / cultivation cable 300 Auxiliary member 400 Opening of the cultivating cage

[0011] An embodiment of the present invention will be described using the drawings. The oyster culture cage of the present invention has a mesh structure on its surfaces (top, bottom, front, back, and sides) to prevent oysters, the object of culture, from falling out and to properly circulate seawater inside and outside the cage. This mesh structure is well known. The illustrations explaining the embodiment of the present invention do not specifically illustrate this mesh structure. Figure 3d shows a photograph of an actual culture cage. All surfaces of the culture cage of the present invention have a mesh structure, as shown in the photograph of Figure 3d. When the culture cage is installed in the sea, the surface facing the sun is referred to as the top surface, and the surface facing the seabed is referred to as the bottom surface. An example of an oyster culture cage 100 of the present invention is illustrated in Figures 1a, 1b, and 1c. The culture cage 100 is connected to a culture cable 200 via an auxiliary member 300. The culture cage 100 has a front surface 110, a back surface 120, a top surface 130, and a bottom surface 140. The cage upper surface 130 is approximately rectangular in plan view, and the front surface 110 and rear surface 120 are parallel to a plane perpendicular to the extension direction of the aquaculture cable 200. The shape of the lower surface 140 is a downwardly convex curved surface in a cross section taken along a plane perpendicular to the extension direction of the aquaculture cable 200. Figure 1a is a view from the front (or rear) of the cage. Here, the front (or rear) is a plane approximately perpendicular to the extension direction of the aquaculture cable. The lower surface 140 forms the cage bottom. In the following explanation, the downwardly convex curved shape of the cage bottom will mainly be described using a view from the front of the cage. As shown in Figures 1b and 1c, the cage bottom 140 (lower surface 140) is part of the side of a columnar shape, so the shape of the cage in a cross section taken along a plane perpendicular to the extension direction of the aquaculture cable and at the front of the cage are the same. Note that it is assumed here that the aquaculture cable is arranged so that the distance between the front and rear of the cage is the shortest. When actually cultivating oysters in aquaculture cages, the aquaculture cable is installed on the sea surface or on a ship, and the aquaculture cages are connected to the aquaculture cable. The aquaculture cable and aquaculture cages may be connected on land and then moved to the sea. When used underwater or near the seabed, the aquaculture cable and aquaculture cages are lowered below the sea surface. The oyster culture cages of the present invention may also be used in freshwater, freshwater lakes, brackish water, brackish lakes, estuarine water, saltwater environments, and aquariums. By providing floats to the aquaculture cable or aquaculture cages to adjust buoyancy, the aquaculture cages can be installed on the sea surface, underwater, or near the seabed.The following explanation will mainly focus on examples in which the aquaculture cages are installed near the sea surface, but the aquaculture cages may also be installed in locations other than the sea surface. The aquaculture cages of the present invention can sway around the aquaculture cable as a rotation axis in response to waves and swells. Therefore, the auxiliary member can rotate around the aquaculture cable. In other words, the auxiliary member and the aquaculture cable are not fixed in the rotational direction. The shape of the auxiliary member 300 is not limited to the shape shown in the figure, and various other shapes can be adopted. Furthermore, although the auxiliary member in Figure 1a is located in the center of the top surface 130, it may be located off-center. In this figure, a side surface 150 is present on the bottom 140, but as described below, the side surface 150 may not be present. The top surface 150 in this figure also has an arc-shaped curved surface, but as described below, it may be a flat surface. Although not shown in this illustration, the aquaculture cages are provided with openable and closable windows for inserting and removing oysters into the cages.

[0012] Figure 1b is an illustration of the culture cage 100 viewed from below. As mentioned above, the bottom 140 of the culture cage is part of the side of a cylinder. Furthermore, its cross section is part of an arc, like the front surface 110 of the culture cage. Figure 1c is an illustration of an oyster culture system using culture cages and a culture cable, where five culture cages 100 are arranged on a culture cable 200. In actual culture on the sea surface / underwater / above sea, two or more culture cages 100 are arranged on the culture cable 200 to efficiently culture a large number of oysters. Figure 1d is an illustration of the culture cage 100 viewed from the front side (a plane perpendicular to the extension direction of the culture cable). The symbols in the figure refer to Figures 1a and 1b. The cage bottom 140 has the shape of part of an arc.

[0013] Figure 1e is an illustration of a cross section of the aquaculture cage 100 as seen from the front side (however, the aquaculture cable 200 and auxiliary member 300 are not shown). Here, the cross section refers to a plane parallel to a plane perpendicular to the extension direction of the aquaculture cable. The cross shape of the cage bottom 140 is a part of a circular arc 50. The cross mark in the figure indicates the center of the arc. This figure illustrates the definition of parameters for defining the shape of the aquaculture cage. Here, the parameters are the radius R of the arc (circle), Ａ , height of the basket H Ｂ, width of the basket bottom W Ｂｂ , height of the bottom of the basket H Ｂｂ is.

[0014] The width W of the basket bottom of the present invention Ｂｂ The width of the cage bottom is 40 cm or more and 70 cm or less. As will be described later, if the width of the cage bottom is too small, it will be difficult to cultivate the oysters in the cage in a balanced manner. Also, if the width of the cage bottom is too large, it will be difficult to rotate the culture cage. More preferably, it is 40 cm or more and 60 cm or less. More preferably, it is 45 cm or more and 55 cm or less.

[0015] The cage bottom 140 has a shape of a part of a circular arc, and the radius of the circular arc is defined as "radius of the circular arc" R Ａ Let's say. R Ａ is the distance from the center of the arc to the inner surface of the cage bottom as shown in Figure 1e. Ａ If the radius is large, the curved surface of the cage bottom will be gentle. If this radius is small, the curved surface of the cage bottom will be too sharp. If the curved surface of the cage bottom is too gentle or too sharp, it will be impossible to cultivate oysters in the cage in a balanced manner, as will be described later. Ａ is 0.48W Ｂｂ Over 0.63W Ｂｂ For example, the width W of the bottom of the basket Ｂｂ When is 50 cm, the arc R Ａ is between 24.00 cm and 31.50 cm.

[0016] The height H of the aquaculture cage of the present invention Ｂ Is W Ｂｂ ×1 / 3 or more W Ｂｂ × 2 / 3 or less. For example, the width W of the bottom of the basket Ｂｂ When the height of the aquaculture cage is 50 cm, Ｂ The height H of the aquaculture cage is 16.67 cm or more and 33.33 cm or less. Ｂ If the temperature is too low or too high, it will be impossible to cultivate in a balanced manner.

[0017] The height H of the basket bottom of the present invention Ｂｂ Is W Ｂｂ ×1 / 4 or more W Ｂｂ × 1 / 2 or less. For example, the width W of the bottom of the basket ＢｂWhen the height of the bottom of the aquaculture cage is 50 cm, Ｂｂ The height H of the aquaculture cage is 12.50 cm or more and 25.00 cm or less. Ｂｂ If the ratio is too low or too high, it will be difficult to achieve a balanced culture. Ａ 0.9R Ａ

[0018] To summarize the above, the width W of the bottom of the aquaculture cage of the present invention Ｂｂ is between 40cm and 70cm, and the height H Ｂ Is W Ｂｂ ×1 / 3 or more W Ｂｂ × 2 / 3 or less, and the height of the bottom of the aquaculture cage H Ｂｂ Is W Ｂｂ ×1 / 4 or more W Ｂｂ × 1 / 2 or less, and the radius R of the arc at the bottom of the basket Ａ is 0.48W Ｂｂ ~0.63W Ｂｂ FIG. 1f shows an example of a variation in the shape of the culture cage of the present invention. The width W of the bottom of the culture cage Ｂｂ The radius R of the arc at the bottom of the basket when the value is changed by 1 cm from 40 cm to 70 cm. Ａ、 Width of the basket bottom W Ｂｂ , height of the basket H Ｂｂ For example, the width W of the bottom of the aquaculture cage Ｂｂ When is 50 cm, the arc R Ａ is 24.00 cm or more and 31.50 cm or less, and the height H of the bottom of the aquaculture cage Ｂｂ is 12.50 cm or more and 25.00 cm or less, and the height H of the aquaculture cage Ｂ is between 16.67 cm and 33.33 cm.

[0019] 1g is a plan view of the culture cage 100 of FIG. 1a as seen from the top surface 130. The shape of the top surface may be flat or curved, as will be described later. In either case, the shape of the top surface is approximately rectangular in plan view. The length of the cable of the culture cage 100 in the extension direction is the length L of the culture cage. Ｂ The length of the aquaculture cage is L Ｂ The length of the aquaculture cage L is not particularly limited as long as it functions as a culture cage. Ｂis 0.4W Ｂｂ 1.2W or more Ｂｂ More preferably, it is 0.7 W or less. Ｂｂ More than 1.0W Ｂｂ For example, the width W of the bottom of the basket Ｂｂ When the length of the aquaculture cage is 50 cm, Ｂ The length L of the aquaculture cage is preferably 20 cm or more and 60 cm or less, and more preferably 35 cm or more and 50 cm or less. Ｂ is the width of the bottom of the basket W Ｂｂ If the cable is too long, it becomes difficult to rotate the cages around the cable, while if it is too short, the cages will become elongated and the distribution of oysters in the cages will become significantly uneven.

[0020] 1a and 1e is an illustration of the culture cage 100 seen from the side. In this embodiment, the cage has a side surface 150, but as will be described later, the side surface 150 may not be present.

[0021] Figure 1i illustrates an opening 400 in the bottom 140 of the embodiment shown in Figure 1a for removing oysters. The opening is provided with a lid, which is closed during aquaculture. Figure 1i shows two openings 400 symmetrically located on the left and right sides of the bottom 140, but either one can be used. Providing the opening 400 in the bottom 140 allows oysters to be easily inserted and removed without removing the aquaculture cage 100 from the aquaculture cable. Oysters can be easily removed from the aquaculture cage on an offshore work site (raft) or a ship by simply rotating the aquaculture cage 100 slightly around the aquaculture cable as its axis of rotation. Furthermore, the opening 400 can be attached not only to the bottom 140 but also to the side 150 or top 130. The aquaculture cage can be made of synthetic resin such as plastic, but other materials are also acceptable. The thickness of the inner and outer surfaces of the cage is approximately 2 to 3 mm, but this can be selected appropriately depending on the cage's specifications and purposes. The thickness can be generally 1.5 mm or more and 10 mm or less, more preferably 1.5 mm or more and 6 mm or less, and more preferably 2 mm or more and 4 mm or less.

[0022] Examples of the present invention are described using the drawings. <Example 1> In Figure 2a, a culture cage 100 of the present invention is connected to a culture cable 200 placed at sea level via an auxiliary member 300. Floats may be provided on the culture cable or the culture cage to keep the cage afloat. Figure 2a(A) shows a state in which the cage 100 is not rocking due to calm waves. Figure 2a(B) shows a state in which the cage 100 is tilted by waves. Figure 2a(C) is an illustration showing oysters rolling downward from the state shown in Figure 2a(B). When the cage 100 is tilted by waves (Figure 2a(B)), gravity acting on the oysters 10 escapes sideways as a drag, making the oysters in the cage prone to rocking and rolling even in small waves. It is known that moderate rocking of the oysters in the cage is effective for efficient oyster cultivation. Furthermore, in Figure 2a(C), as in Figure 2a(A), the oysters are arranged without crowding. In reality, the oysters in the cage are hidden on the surface of the cage, so they do not look like this from outside the cage. The illustration of the oysters in the cage is intended to clearly show the state of the oysters in the cage.

[0023] Figure 2b is a comparative example of the present invention. The aquaculture cage 100 in Figure 2b has a flat bottom, and the bottom and sides are vertical. Figure 2b (A) shows a case where the waves are calm. Oysters 10 placed in such a aquaculture cage 100 have nowhere to move to and it is difficult for the oysters to roll away, even if the cage 100 is tilted by waves (Figure 2b (B)), because the bottom and sides are vertical.

[0024] Figure 2c is a comparative example of the present invention. The aquaculture cage 100 in Figure 2c has a flat bottom, with both ends of the bottom arced. Figure 2c (A) shows the case when the waves are calm. When the cage 100 tilts due to waves, the oysters 10 move to the arc at the bottom edge, but as shown in Figure 2c (B), the oysters end up crowded at the edge of the cage. Once the oysters are crowded at the edge of the cage, they lose their balance on the left and right sides. Even if strong waves come, the cage does not regain its balance, and the tilted state shown in Figure 2c (B) continues. When oysters are crowded together, their growth becomes inefficient.

[0025] Figure 2d shows an embodiment of the present invention. Figure 2d(B) is an illustration of the case when the waves are calm. Figures 2d(A) and 2d(C) are illustrations of the case when the culture cage is tilted by the waves. As shown in Figure 2a, even if the culture cage of the present invention is tilted left or right by the waves, the oysters roll along the curved surface of the bottom of the cage and move downward. However, if the oysters are large or the waves are too small, the oysters will not move, as shown in Figures 2d(A) and 2d(C). Even in such cases, the oysters are arranged in the cage without being crowded together, as in the state of Figure 2d(B), so this is not a particular problem. In any case, using the culture cage of the present invention can prevent the oysters in the cage from being unevenly arranged at the edges of the cage.

[0026] 2e (A) to (D) show examples of variations in the shape of the aquaculture cage of the present invention. The shape is as seen from the front of the cage. The width W of the bottom of the aquaculture cage Ｂ , height of the aquaculture cage W Ｂ , height of the bottom of the aquaculture cage H Ｂｂ , the radius of the arc at the bottom of the aquaculture cage R Ａ is defined as shown in the figure. Figure 2f shows an overhead view of various shapes of aquaculture cages 100 (100A, 100B, 100C, 100D). The aquaculture cages 100A, 100B, 100C, and 100D in Figure 2f correspond to the aquaculture cages 100 in Figures 2e(A), 2e(B), 2e(C), and 2e(D), respectively. The aquaculture cage 100 in Figure 2e(A) has a shape similar to that in Figure 1a, with both ends of the arc-shaped bottom 140 connected to the side surfaces 150. The top surface 130 is an upwardly convex arc. In reality, it is part of the side surface of a cylinder, as in the aquaculture cage 100A in Figure 2f. The center of the arc of the bottom surface 140 is located slightly above the top surface of the cage, as shown in the figure. By placing the aquaculture cable 200 in this vicinity, the aquaculture cage 100 can swing around the aquaculture cable 200 as a rotation axis in response to waves and swells on the sea surface. The arc of the bottom 140 of the aquaculture cage 100 in Fig. 2e(B) is semicircular. The radius R Ａ is the width W of the bottom 140 ＢｂThe aquaculture cage 100 in Fig. 2e(C) has a semicircular bottom 140, similar to that in Fig. 2e(B), and the radius of the arc is about half of that of the bottom 140. There are no side surfaces 150, and the end of the bottom 140 is connected to the top surface 150. The center of the arc of the bottom 140 is located slightly below the top surface of the cage, as shown in the figure. Ａ is the width W of the bottom 140 Ｂｂ The top surface 130 is flat. The center of the arc of the bottom surface 140 is located on the top surface of the cage as shown in the figure. The culture cage 100 of Figure 2e (D) does not have side surfaces 150, and the end of the bottom surface 140 is connected to the top surface 150. The radius of the arc of the bottom surface 140 is larger than in Figures 2e (A) to (C). The center of the arc of the bottom surface 140 is located above the top surface of the cage as shown in the figure. In the cage 100 of the shape of Figures 2e (A) to (D), the width W of the bottom 140 Ｂｂ The other parameters of the culture cage 100 when the width W of the bottom 140 is set to 50 cm are shown in Table 1. Ｂｂ is not limited to 50 cm, and any value between 50 cm and 70 cm can be selected.

[0027] Figure 2g illustrates the advantages of the present invention using illustrations of an embodiment of the present invention and a comparative example. (A1) and (A2) are embodiments of the present invention, while (B1) and (B2) are comparative examples. Figure 2h is an overhead view of the aquaculture cage 100. The aquaculture cage 100 in Figure 2h(A) corresponds to Figure 2g(A1) and (A2), and the aquaculture cage 100 in Figure 2h(B) corresponds to Figure 2g(B1) and (B2). Figures 2g(A1) and (B1) show the appearance of the cage 100 when the waves are calm. In both cages 100, the oysters 10 remain at the bottom. (A2) and (B2) show the situation when the waves are slightly strong. In the embodiment of the present invention (A2), the aquaculture cage 100 is slightly tilted due to the swaying of the waves, while in the comparative example (B2), the aquaculture cage 100 hardly tilts even in strong waves. In Examples (A1) and (A2), the cage bottom is semicircular and the top surface is flat. On the other hand, in Comparative Examples (B1) and (B2), the cage bottom and top surface form a circle. The shape of the bottom 140 of the aquaculture cage 100 of this Comparative Example and the radius R of the arc of the bottom Ａ The height H of the culture cages in the comparative examples (B1) and (B2) is the same as that in the examples.Ｂ is the width W of the bottom 140 Ｂ In the comparative examples (B1) and (B2), the distance from the aquaculture cable 200 to the bottom of the cage (the dotted arrow in the figure) is R Ａ 2g (B1 (B2)) is simply hung from the aquaculture cable 200, which is not very different from the conventional aquaculture method of simply hanging the aquaculture cage from a raft. On the other hand, in the present invention, the bottom of the cage is part of a circular arc, and the height H Ｂ is the width W of the bottom 140 Ｂ Since the radius of the bottom arc R Ａ (Since the values ​​for σ and σ are set to appropriate values, the aquaculture cage 100 of the present invention can sway from side to side around the aquaculture cable 200 even in small waves, and the oysters in the cage can roll moderately. When the oysters roll moderately, they come into contact with each other, strengthening their shells and improving their shell shape. It should be noted that if the front and back of the aquaculture cage have a symmetrical shape, such as a circle, it will be less likely to sway in the presence of waves or swells.

[0028] The top surface of the culture cage of the present invention is approximately rectangular in plan view. Figure 2i(A) shows an embodiment in which the top surface of the culture cage is approximately rectangular in plan view. Figure 2i(B) shows a comparative example in which the top surface is not approximately rectangular. If the top surface of the culture cage is approximately rectangular in plan view and the length of the culture cage in the direction of the culture cable 200 is the same on all sides, when the culture cage 100 swings left and right around the culture cable 200 as the axis of rotation, the oysters in the cage can also swing left and right smoothly. If the length of the culture cable 200 in the direction of the culture cable 200 varies depending on the location, as in Figure 2i(B), the oysters cannot move smoothly.

[0029] An example of an oyster cultivation method using the present invention is shown in Figure 2j. 300 oyster juveniles are placed in a cultivation cage and cultivation begins on the sea surface. After that, the oysters are sorted according to their size. For example, an oyster with a total length of 6 cm (volume of about 50 cm) is cultivated. ３) or larger are selected and left in the cage. In Figure 2j (A1), oysters with a total length of approximately 6 cm are placed in the cage. (A2) is an illustration seen from directly below the culture cage. In (B1), the oysters have grown further to a total length of 7 cm. As the oysters grow from (A1) to (B1), they also increase in width and height. The bottom of the culture cage of the present invention is arc-shaped with a moderate curvature, so even as the oysters grow larger, they can be placed at a moderate density as shown in illustration (B1). (C1) is an illustration of oysters that have grown further to a total length of approximately 8 cm. (D1) is an illustration of oysters that have grown further to a total length of approximately 10 cm. By using the culture cage of the present invention, it is possible to culture oysters in the cage only once, from juvenile oysters to oysters large enough to be shipped. In the oyster farming method using the farming cages of the present invention, it is preferable to farm oysters with a total length of 4 cm to 12 cm in the cages.Furthermore, in the oyster farming method using the farming cages of the present invention, it is preferable to farm oysters with a total length of 4 cm to 12 cm in the cages, with oysters of 2 kg to 10 kg per cage.

[0030] 3a, 3b, 3c, and 3d are photographs of an embodiment of the aquaculture cage of the present invention. Ｂｂ is 51.5 cm, and the height of the aquaculture cage H Ｂ is 27 cm, and the height of the bottom of the aquaculture cage H Ｂｂ is 16.7 cm, and the radius R of the arc at the bottom of the aquaculture cage Ａ is 27 cm. That is, R Ａ / W Ｂｂ = 0.52, H Ｂ / W Ｂｂ = 0.52, H Ｂｂ / W Ｂｂ = 0.32. Figure 3b is a photograph of the culture cage viewed from the side. The length of the culture cage L Ｂ is 40.5 cm, and L Ｂ / W Ｂｂ= 0.79. Figure 3c shows the aquaculture cage 100 being inverted. When the aquaculture cage 100 is placed underwater, it may be inverted around the aquaculture cable 200 as a rotation axis to drain the aquaculture cage 100. With the aquaculture cage of the present invention, the aquaculture cage 100 can be easily inverted even at sea. Figure 3d shows the state when actual oysters are placed in the aquaculture cage. Figure 3d(B) shows a state in which the waves are calm and the cage is balanced left and right. Figures 3d(A) and (C) show states in which the cage is tilted. Even if the aquaculture cage is tilted by waves on the sea surface, the aquaculture cage will continue to rock with the waves, causing the oysters inside to roll left and right, returning to a roughly balanced state (Figure 3d(B)).

[0031] Fig. 3e is an actual photograph of a comparative example. When the culture cage 100 is placed in the sea, the culture cage may tilt due to the influence of waves, as shown in Fig. 3e, and lose its balance from side to side, making it difficult to return to its original balanced state.

[0032] Figure 3f is an actual photograph of another comparative example. Ｂｂ is 27 cm, and the height of the aquaculture cage H Ｂ The size of the cage is 15cm, so there is insufficient free space in the cage, making it difficult for the oysters to roll around inside.

[0033] <Example 2> In Example 1, the culture cage bottom 140 was a part of a circular arc. The shape of the culture cage bottom 140 can be slightly modified as long as the culture cage can swing moderately around the axis of the culture cable and the oysters in the cage can roll moderately. For example, the lowest part of the culture cage bottom 140 may be flat as shown in Figure 4a. Figure 4a is a view of the culture cage 100 from the front. This flat part is called the culture cage bottom flat part 145. If the flat part is too long, the balance will be poor when rocked by waves, as in the conventional cage. Furthermore, if the flat part is too long, the oysters will have difficulty rolling. Therefore, the width W of the culture cage bottom flat part 145 in the present invention ＢＦ is the width of the bottom of the aquaculture cage W Ｂｂ That is, 0≦W ＢＦ ≦W Ｂｂ × 0.3. For example, W ＢｂIf is 50 cm, W ＢＦ The radius R of the arc of the bottom of the culture cage 100 having such a flat portion is preferably 0 to 15 cm. The bottom of the culture cage 140 having such a flat portion can be considered to be a downwardly convex curved surface, which is approximately a part of a circular arc. The other symbols in FIG. 4a have the same meanings as those in the previous embodiments. In the culture cage 100 having such a shape, the radius R of the arc of the bottom of the culture cage Ａ is the radius of the arc defined by the arc-shaped portion of the culture cage bottom 140 as shown in Figure 4a. Figure 4b is an illustration of the culture cage 100 as seen from above and below. In Figure 4b(B), the flat portion 145 of the culture cage bottom extends along the extension direction of the culture cable 200.

[0034] <Example 3> In Example 1, the culture cage bottom 140 was a portion of a circular arc. In Example 2, the culture cage bottom 140 was a portion of a circular arc with a flat bottom. The shape of the culture cage bottom 140 can be slightly modified as long as the culture cage can swing appropriately around the culture cable and the oysters in the cage can roll appropriately. As long as the overall shape of the culture cage bottom 140 of the present invention can approximate a circular arc, the culture cage bottom 140 may have four or more flat portions 145. Examples are shown in Figures 4c (A1) and 4c (B1). In (A1), there are five flat portions 145, and in (B1), there are four flat portions 145. Figures 4d (A) and 4d (B) are overhead views corresponding to Figures 4c (A1) and 4c (B1), respectively. The culture cages are viewed from below. The symbols in the figure have the same meanings as those explained above. Ｂ , height of the aquaculture cage W Ｂ , height of the bottom of the aquaculture cage H Ｂｂ is defined as shown in Fig. 4c (A1) (B1) as before.

[0035] In Example 3, the radius R of the arc at the bottom of the aquaculture cage Ａis calculated by approximation using the least squares method. A large number of coordinates of the culture cage bottom 140 are extracted. Some of the coordinates of the cage bottom 140 in Figures 4c(A1) and (B1) are shown as black circles in Figures 4c(A2) and (B2), respectively. While 21 and 17 coordinates are extracted in Figures 4c(A2) and (B2), more coordinates may be extracted to improve the accuracy of the approximation. The general equation of a circle is calculated for the extracted data points using the least squares method, with X² + Y² + AX ​​+ BY + C = 0. The circles in Figures 4c(A2) and (B2) are the results obtained by approximation using the least squares method. The radii of the circles are 24.43 cm and 25.90 cm, respectively. For reference, the Python code used to calculate the circle in Figure 4c(A2) is shown in Figure 4d. The width W of the culture cage bottom in the examples of Figures 4c(A1) and 4c(B1) is calculated by approximation using the least squares method. Ｂｂ Table 2 shows the size of the culture cage when the height is set to 50 cm. Of course, the width of the bottom of the aquaculture cage W Ｂｂ The range is not limited to 50 cm and can be selected from 40 cm to 70 cm.

[0036] Example 4 Example 4 is an example that further limits Examples 1 to 3. The aquaculture cage of Example 4 has a distance L between the center of the aquaculture cable and the center of the arc at the bottom of the aquaculture cage. Ｃ is 0.25 x R Ａ More preferably, it is 0.20×R Ａ More preferably, it is 0.18×R Ａ More preferably, it is 0.16×R Ａ More preferably, it is 0.14×R Ａ More preferably, it is 0.12×R Ａ More preferably, it is 0.10×R Ａ Here, R Ａ is the radius of the arc at the bottom of the aquaculture cage. Ａ is 0.48 W as in the previous examples. Ｂｂ Over 0.63W Ｂｂ The range is as follows: Ｂｂis the width of the bottom of the aquaculture cage. If the center of the aquaculture cable is close to the center of the radius of the arc, the swinging path of the bottom of the aquaculture cage will be closer to the curved surface of the cage bottom, making it easier for the aquaculture cage to swing more smoothly. This embodiment will be explained using Figures 5a to 5d.

[0037] The explanation will be given using the illustration in Fig. 5a. Fig. 5a shows the front of the aquaculture cage 100 (or a cross section in a plane perpendicular to the extension direction of the aquaculture cable 200). The aquaculture cage 100 in Fig. 5a(A) is the same as the aquaculture cage 100 in Fig. 2e(D). The width W of the bottom of the aquaculture cage Ｂｂ is 50 cm, the radius R of the arc 50 along the outer periphery of the bottom 140 of the aquaculture cage Ａ The center of the arc is located above the top surface of the aquaculture cage and the aquaculture cable 200. The distance L between the center of the aquaculture cable 200 and the center of the arc at the bottom of the aquaculture cage is Ｃ is 4 cm. Therefore, L Ｃ / R Ａ = 4 / 30 = 0.13.

[0038] Figure 5a (B) shows an example in which the height of the auxiliary member 300 in Figure 5a (A) is slightly increased. In this embodiment, the center of the aquaculture cable 200 and the center of the arc 50 are almost coincident. As in this example, the height of the cage can be adjusted using the auxiliary member 300 to keep the distance between the center of the aquaculture cable and the center of the radius of the arc within an appropriate range. This is also true for other embodiments of the present application.

[0039] The shape of the aquaculture cage 100 in Figure 5b is the same as that of the aquaculture cage 100 in Figure 2e (B). The two differ in the location of the aquaculture cable attachment. In Figure 5b, the aquaculture cable 200 is located below the top of the cage. The aquaculture cable passes through the front and back of the cage. The width W of the bottom of the aquaculture cage Ｂｂ is 50 cm, the radius R of the arc 50 along the outer periphery of the bottom 140 of the aquaculture cage Ａ The distance L between the center of the aquaculture cable 200 and the center of the arc at the bottom of the aquaculture cage is 25 cm. Ｃ is 2 cm. Therefore, L Ｃ / R Ａ= 2 / 25 = 0.08. Figure 5c is a photograph of an actual example. The aquaculture cable 200 is located below the top of the cage as shown in Figure 5b. There are holes in the front and back of the cage through which the aquaculture cable passes.

[0040] The shape of the aquaculture cage 100 in Fig. 5d is the same as that of the aquaculture cage 100 in Fig. 2e(A). The two differ in the location of the aquaculture cable attachment. In Fig. 5d, the aquaculture cable 200 is located to the left of the center on the top surface of the cage. The width W of the bottom of the aquaculture cage Ｂｂ is 50 cm, the radius R of the arc 50 along the outer periphery of the bottom 140 of the aquaculture cage Ａ The distance L between the center of the aquaculture cable 200 and the center of the arc at the bottom of the aquaculture cage is 27.5 cm. Ｃ is 6.39 cm. Therefore, L Ｃ / R Ａ = 6.39 / 27.5 = 0.23.

[0041] <Example 5> Figure 6a shows an example in which joints 160, 161 are provided on the culture cage 100. The joints are used to connect the auxiliary member 300. In Figure 6a, the recesses of the joints 160, 161 are connected to the protrusions of the auxiliary member 300, but the method of connecting the joints 160, 161 to the auxiliary member 300 is not limited to this. The joints 160, 161 are provided in the examples described above using photographs such as Figures 3a and 5c. In Figure 6a, the culture cages 100 are connected in series to a single culture cable 200. However, as shown in Figure 6b, the culture cages 100 may be connected to a culture cable 200 that connects two parallel culture cables. This example can be applied to all of the examples described above.

[0042] Here, we will explain the general steps for cultivating oysters using cages. (1) Selecting an Appropriate Cultivation Site: When selecting an appropriate cultivation site, it is important to confirm that the water quality, seabed conditions, and tidal currents are suitable for oyster growth. In particular, water quality that is rich in nutrients and low in pollutants is desirable. Seabed conditions are also important, with areas with little mud or sand accumulation being preferable. (2) Obtaining Oyster Sprouts: Oyster sprouts can be collected from the wild or purchased from specialized farms. When collecting from the wild, it is important to choose the appropriate season and location. When purchasing from a farm, purchasing from a reliable supplier will ensure high-quality sprouts. (3) Preparing the Cages: Cages are generally made of plastic or metal, and materials that are resistant to rust and corrosion are preferable. The size and shape of the cages are selected based on the conditions of the cultivation site and the type of oysters. The mesh size of the cage is also important; if it's too small, growth will be hindered, while if it's too large, there's a risk of the oysters falling out. (4) Placement of the juvenile oysters: It's important to place the juvenile oysters in the culture cages at appropriate intervals. Care must be taken, as overcrowding can lead to competition between oysters and hinder growth. Also, securing the juvenile oysters in the cages can promote growth. (5) Underwater Cage Installation: When installing the culture cages in the sea, there are two methods: floating them on the surface using swim bladders or buoys, or sinking them to the seabed using weights. The method chosen depends on the environment of the culture area and the type of oysters. The cages are installed at an appropriate location and height, taking into account the effects of tides and waves. Floating cages are called floating culture cages, and are characterized by rapid growth because the oysters are exposed to nutrient-rich water layers. However, they are susceptible to the effects of waves and wind, and require regular inspection and maintenance. On the other hand, the method of sinking the cages to the seabed is called bottom-based cage cultivation, and because the cages are installed stably, they are less susceptible to the effects of waves and wind. However, depending on the condition of the seabed and the currents, the accumulation of mud and sand can become a problem. (6) Regular inspection and cleaning It is important to inspect the cages regularly and check the growth of the oysters. It is also advisable to clean the cages regularly to prevent the proliferation of algae and other organisms inside.By removing mud, sand, algae, etc. that have become stuck in the mesh of the cages, water flow is ensured and an environment suitable for oyster growth is maintained. (7) Harvesting and Shipping Once the oysters have grown to a harvestable size, they are removed from the cages and shipped to market. Oysters usually grow from juveniles to a harvestable size in 1 to 3 years. The harvesting period is decided at an appropriate time, taking into consideration the variety, the conditions of the farming area, market demand, etc. Generally, oysters are cultivated using cages according to the above steps. This method is becoming popular around the world because it has little impact on the natural environment and allows for efficient farming.

[0043] This invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the invention. For example, the opening for removing oysters can be located anywhere within the cage. Although the aquaculture cable 200 is located in the center of the top surface, it can also be connected to a location off-center. The surface of the aquaculture cage of the present invention is meshed to prevent oysters from falling out of the cage and to allow seawater to circulate inside and outside the cage. However, any material that performs a similar function can be used. The shape and size of the holes can be selected appropriately depending on the purpose of the aquaculture. Furthermore, in the aquaculture system using the aquaculture cages and aquaculture cables of the present invention, floats can be provided on the cages to stably position the cages on the sea surface. It should be noted that providing excessive buoyancy to the aquaculture cages can cause excessive shaking. Furthermore, while the examples described above have all shown the same width at the bottom of the cage as the entire cage, these do not necessarily have to be the same. For example, when viewing the aquaculture cage 100 from the front, as shown in Figure 5e, a shape in which the width of the top of the cage is slightly wider than the width of the bottom is also an embodiment of the present invention. The aquaculture cable of the present invention is used to connect aquaculture cages underwater, and there are no restrictions on its specific shape or material. It is appropriate to select the cable taking into account the size and weight of the aquaculture cages and the number of aquaculture cages to be connected. The material of the aquaculture cable may be natural or synthetic. The length of the aquaculture cable is selected depending on the intended use. While the figures shown so far show a short cable, in reality, it can be 50 cm or more, or even as long as 300 m. The diameter is approximately 1 cm to 20 cm, but other sizes are also possible. The cross-sectional shape does not necessarily have to be circular.

Claims

1. An oyster culture cage connected to a culture cable has a front surface, a back surface, a top surface, and a bottom surface (lower surface), the front surface and the back surface are approximately parallel to a plane perpendicular to the extension direction of the culture cable, the top surface is approximately rectangular in a plan view, the shape of the bottom surface is a downwardly convex curved surface in a cross section perpendicular to the extension direction of the culture cable, and the width W of the bottom of the culture cage is Ｂｂ is between 40cm and 70cm, and the height H of the aquaculture cage is Ｂ W Ｂｂ ×1 / 3~W Ｂｂ × 2 / 3, and the height of the bottom of the aquaculture cage H Ｂｂ W Ｂｂ ×1 / 4~W Ｂｂ × 1 / 2, the downwardly convex curved surface is a part of a substantially circular arc, and the radius of the circular arc is R Ａ is 0.48W Ｂｂ ~0.63W Ｂｂ These are oyster farming cages.

2. Length L of the aquaculture cable in the aquaculture cage in the extension direction Ｂ is 0.4W Ｂｂ 1.2W or more Ｂｂ 2. The oyster culture cage according to claim 1, which is as follows:

3. An aquaculture cage as described in claims 1 or 2, which, when connected to the aquaculture cable, is adapted to sway around the aquaculture cable as an axis of rotation in response to waves and swells.

4. An aquaculture cage as described in claims 1 or 2, characterized in that a connecting member for connecting to an aquaculture cable can be installed on the upper surface.

5. An aquaculture cage as described in claims 1 or 2, characterized in that the front and back surfaces are provided with through holes for allowing aquaculture cables to pass through.

6. A culture cage as described in claims 1 and 2, characterized in that the bottom of the culture cage has an opening for putting oysters in and taking them out.

7. Distance L between the center of the aquaculture cable and the center of the arc ｃ is 0.25 x R Ａ 3. The culture cage according to claim 1 or 2, characterized in that:

8. A method for cultivating oysters, comprising placing oysters having a total length of 4 cm to 12 cm in the oyster culture cage described in claim 1 or 2.

9. A method for cultivating oysters by placing oysters having a total length of 4 cm to 12 cm in the oyster culture cages described in claims 1 and 2, in an amount of 2 kg to 10 kg per cage.

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