WO2020189105A1

WO2020189105A1 - Bivalve farming raft and farming method

Info

Publication number: WO2020189105A1
Application number: PCT/JP2020/005442
Authority: WO
Inventors: 達郎三保; 弘太郎三保; 憲吾佐々木; 慶子友國
Original assignee: かなわ水産株式会社
Priority date: 2019-03-20
Filing date: 2020-02-13
Publication date: 2020-09-24
Also published as: JP2020150857A

Abstract

The present invention addresses the problem of providing a bivalve farming raft which: can be discarded without being burned; does not use foamed styrol, which is often discarded to drift in the sea; is less likely to cause stress concentration due to external force of ocean waves and tidal current and therefore is less likely to be deformed (e.g., twisted), damaged, and swept away; does not greatly sway due to ocean waves and therefore enables shells being farmed to grow well; has a simple structure; has high durability; and can have a prolonged lifetime. The present invention also addresses the problem of providing a bivalve farming method. The problem can be solved by: a bivalve farming raft for farming bivalves which is provided with a body from which two or more suspended ropes for farming bivalves can be suspended, the body itself having a greater effective buoyancy when floating in water than the total weight-in-water of the plurality of suspended ropes which are directly bound to and suspended from the body; and a bivalve farming method using the raft.

Description

Bivalve aquaculture raft and aquaculture method

The present invention relates to a bivalve aquaculture raft and aquaculture method used when culturing bivalve molluscs.

Sea surface aquaculture includes unfed aquaculture, which cultivates shellfish such as bivalves, which makes it easier to grow by feeding on food such as plankton existing in the sea, and fed aquaculture, which cultivates fish by feeding and raising them. is there.

In the field of non-feeding aquaculture used for bivalve aquaculture as in the present invention, oyster rafts that are generally widely used are, for example, made into a grid in which Meng Soutake is combined vertically and horizontally, and the intersections of the vertical and horizontal directions are fixed with a wire. A raft is made, and the raft is supported from below with a float such as Styrofoam and floated on the surface of the water. The oysters are hung on the raft and cultivated.

In Patent Document 1, a plurality of soft polyethylene tubular pipes or a plurality of pipes in which a plurality of hard polyethylene tubular pipes are connected are used as a parent pipe, and a hard polyethylene tubular pipe is used. Assemble these as child pipes using multiple pipes in a grid pattern, tighten and fix them to the cross part with connecting tools, attach lids to both ends of the child pipes, and float such as foamed polyethylene under the connecting tools. A polyethylene skein for cultivating oysters, which is a double-shelled shell, is disclosed.

In Patent Document 2, a group consisting of floats such as foamed styrol, rails fixed on floats arranged in a row, and rails of each group arranged in parallel are fixed perpendicular to the rails at appropriate intervals. When lying down, it consists of pressers that are fixed at appropriate intervals at right angles when lying on top of the lying down, and a series of seedling collectors or oyster seed attachers to which oyster larvae, which are bivalves, adhere. In the oyster stakes for oyster farming in which the hanging ream is hung in the sea, oyster stakes made of Moso bamboo, of which at least a part of the rails, lying down and presser foots are replaced with Moso bamboo, are disclosed.

On the other hand, in the field of aquaculture for cultivating fish, Patent Document 3 states that a certain sea area is surrounded by a frame, a net is installed in the frame, and a cage for cultivating fish and shellfish in the net is provided. A fish cage in which a frame body constituting the frame is made of a synthetic resin member having a rigid structure is disclosed. The frame has a double structure consisting of a synthetic resin member formed in a pipe shape and a steel core member arranged inside the synthetic resin member, and the frame is formed on a float such as Styrofoam. is set up.

In Patent Document 4, a plurality of annular frames having different outer diameters formed by connecting rod-shaped reinforcing elastic members are used to form a multiple circular structure, and the inner and outer annular frames are elastically deformed at least in the radial direction. A cage frame connected by a possible connecting member is disclosed. The annular frame is installed on a float such as Styrofoam.

In addition, Non-Patent Document 1 discloses that a high-density polyethylene pipe is used for a large open-sea floating and sinking cage in the field of aquaculture in which fish are cultivated.

Therefore, in the case of unfed aquaculture in which shellfish are cultivated, in order to allow a large number of hanging reams such as ropes and wires with shellfish or aquaculture containers containing shellfish to hang down for the purpose of increasing yield, the interval between the hanging reams. A grid of vertical and horizontal rods is commonly used by those skilled in the art of shellfish farming so that the rods can be hung as narrow as possible, and the rods that make up the net are used for aquaculture. A float such as foamed styrol is an indispensable constituent requirement so that the hanging chain, which is heavier than the net used, can float on the sea surface even if it is hung down. On the other hand, in the case of aquaculture in which fish are cultivated, the surrounding area is surrounded by a net so that the fish do not escape, and in the water area surrounded by the net, there is a fish cage that does not allow the fish to hang down so as not to interfere with swimming. It is commonly used by those who cultivate fish, and the frame of the cage is provided with a net that is lighter in weight than the hanging ream of the double-shelled fish used for non-feeding aquaculture.

New Registration No. 3059919 Japanese Unexamined Patent Publication No. 2008-154466 Japanese Unexamined Patent Publication No. 2004-16123 Japanese Unexamined Patent Publication No. 5-207834

When disposing of the widely used bamboo rafts in a grid pattern, bamboo is incinerated at the beach because there is no proper treatment method for bamboo. Especially in Hiroshima prefecture, about 10,000 units are incinerated. This is a problem because about 2000 oyster rafts are incinerated annually using the oyster farming rafts. In addition, styrofoam floats have become drifting garbage, and waste treatment of oyster rafts made of bamboo in a grid pattern has become a problem.

Since the polyethylene raft for oyster farming in Patent Document 1 and the oyster raft in Patent Document 2 both have a float as a constituent requirement, there is a problem that collection and processing costs at the time of disposal are high when styrofoam is used, for example. It was. Further, since the polyethylene skein for oyster cultivation of Patent Document 1 has a lattice-like form requiring a large number of soft polyethylene tubular pipes or hard polyethylene tubular pipes, the shaving stake of Patent Document 2 is Since a large number of Moso bamboo and a large number of resin pipes are arranged in a grid pattern, all of the inventions have a large lattice pattern, and therefore, the vertical and horizontal intersections of the lattice pattern due to the external force of waves and tidal currents. There is a problem that stress concentration occurs in the cross portion, which causes deformation such as twisting, breakage, and outflow.

In both the inventions of the cage of Patent Document 3 or the cage frame of Patent Document 4, only a lightweight cage net is installed in the annular frame, but the annular frame itself still sinks. Therefore, since the annular frame must be installed on a float such as Styrofoam, there is a problem that if Styrofoam is used as the float, for example, the collection / processing cost at the time of disposal is high. From this, there is a problem that it is difficult to hang the bivalve hanging ream used for non-feeding aquaculture in the frame due to its weight. In addition, there is a problem that the hanging ream for bivalve farming cannot be hung in the water area surrounded by the net, which is an obstacle when fish swim.

The cage of Non-Patent Document 1 is a cage for aquaculture, and a high-density polyethylene pipe is used in a frame surrounding the water surface so that fish do not escape, and a net is installed in the frame, which is surrounded by the net. There was a problem in the water area that it was not possible to hang a hanging net for aquaculture, which would be an obstacle when fish swim. Further, although the frame has a buoyancy that can be supported by installing only a net, there is a problem that a heavy weight-weighted bivalve farming hanging chain cannot be hung.

The present invention was conceived in view of these problems. It does not require incineration at the time of disposal, does not use styrofoam that easily becomes drifting dust, and stress concentration due to external force of waves and tidal currents is unlikely to occur, and therefore deformation such as twisting, It is an issue to provide a styrofoam incinerator and aquaculture method that are less likely to be damaged or run off, have less vibration due to waves, and therefore grow well, have a simple structure, have high durability, and can achieve a long life. And.

The skeleton in the present invention means a main member constituting the raft and having the function of the frame of the raft. Further, the effective buoyancy of the skeleton itself means a value obtained by subtracting the weight of the skeleton itself from the buoyancy when it is assumed that the skeleton itself is completely submerged under the water surface. And, the hanging ream means a material necessary for bivalve aquaculture such as a bivalve, a container for accommodating the bivalve, a rope, a wire, and the like, which is bound to a raft and hung.

The bivalve aquaculture raft according to claim 1 is a bivalve aquaculture raft for bivalve aquaculture, and includes a bivalve aquaculture raft capable of hanging two or more bivalve aquaculture rafts, and the skeleton when the skeleton is floated on the water surface. It is characterized in that the effective buoyancy of itself is made larger than the total underwater weight of the plurality of hanging rafts that are directly bound to the skeleton itself and hung down.

The bivalve aquaculture raft according to claim 2 is characterized in that, in claim 1, the shape of the skeleton is an annular body in a plan view or a shape obtained by combining a plurality of annular bodies.

The bivalve aquaculture raft according to claim 3 is characterized in that, in claim 1 or 2, the shape of the skeleton is a substantially circular shape in a plan view, or a shape obtained by combining a plurality of substantially circular shapes.

The bivalve aquaculture raft according to claim 4 is characterized in that, in claim 1, the shape of the skeleton is a linear body in a plan view or a shape obtained by combining a plurality of linear bodies.

The bivalve aquaculture raft according to claim 5 is characterized in that, in any one of claims 1 to 4, the material of the skeleton is a resin pipe that is not easily corroded by water.

The bivalve aquaculture raft according to claim 6 is composed of a bivalve aquaculture raft according to any one of claims 1 to 5, wherein the bivalve ream can accommodate the bivalve and the entire wall surface is formed in a shape that allows water inflow and outflow. It is characterized by that.

In the bivalve aquaculture method according to claim 7, two or more bivalve culturing hanging reams are hung on the skeleton itself, and the effective buoyancy of the skeleton itself when the skeleton is floated on the water surface is directly bound to the skeleton itself. By making it larger than the total weight of the hanging reams in water, the plurality of hanging reams can be hung only by the effective buoyancy of the skeleton itself.

The bivalve aquaculture raft according to claim 1 or the bivalve aquaculture method according to claim 7 is a case of non-feeding aquaculture in which shellfish are cultivated, but the effective buoyancy of the skeleton itself when the skeleton is floated on the water surface is determined. Since it is larger than the total underwater weight of the plurality of hanging reams that are directly bound to the skeleton itself and hung down, a float such as Styrofoam is not required, so that collection / processing costs at the time of disposal are not required and drifting dust is not generated.

Also, since the only required component of the raft is the buoyant body, which is the skeleton, it is not a complicated shape, so it does not easily collapse due to waves or fast tides. In addition, since Styrofoam is not used, it does not collapse due to strong winds such as typhoons, high waves, and fast tides, and does not scatter as drifting dust.

In the bivalve culture raft according to claim 2, the water surface in the range surrounded by the bivalve skeleton has gentler waves than the outside of the skeleton, so that the external force applied to the bivalve is weakened and the vertical swing of the bivalve is reduced. Since the feeding time of bivalve molluscs becomes longer, the growth of bivalve molluscs is promoted, and the yields of oyster rafts in the case of conventional bamboo rafts and the case of bivalve cultivated rafts in which the skeleton of the present invention is annular are compared by stripping weight. In the case of a bivalve-cultured raft in which the skeleton of the present invention is an annular body, the yield is increased as compared with the case of a conventional bamboo raft.

The bivalve farming raft according to claim 3 has a substantially circular skeleton, so that stress concentration due to external forces of waves and tidal currents is unlikely to occur, and therefore deformation, breakage, and outflow such as twisting are unlikely to occur. When a substantially circular skeleton is used, the yield of bivalve molluscs is higher than that of bamboo oyster rafts, and since there is no stress concentration, the durability of the skeleton is improved and the life is extended.

In the bivalve farming raft according to claim 4, since the shape of the skeleton is linear, the influence of waves applied to the skeleton can be reduced by making the length of the skeleton longer than the size of a plurality of waves. , Can have a positive effect on the growth of bivalves.

The bivalve farming raft according to claim 5 is a material that can be recycled at the time of disposal, so that it has the effect of not causing problems such as incineration and drifting. In addition, since it is a resin pipe made of high-density polyethylene or the like that is not easily corroded by water, it has a useful life of about 6 times that of a bamboo rafts with a useful life of 5 years.

The bivalve aquaculture raft according to claim 6 uses a bivalve aquaculture container in which all the wall surfaces such as the side wall, the bottom wall and the upper surface wall are formed in a shape that allows water to flow in and out. Since the flow of seawater spreads and every bivalve can get a sufficient source of nutrients, all the bivalves have the effect of increasing the growth rate.

In a plan view showing a bivalve farming raft having a ring-shaped skeleton of the present invention, (a) is a diagram showing a bivalve farming raft having a substantially circular skeleton, and (b) is a substantially square frame-shaped skeleton. It is a figure which shows the bivalve aquaculture raft which has. It is a figure which shows the bivalve shell farming raft which has a linear skeleton in the plan view of this invention. It is a figure which shows the side view of the bivalve aquaculture raft which has the skeleton of the linear body of this invention. It is a figure of the plan view of the bivalve aquaculture raft which combined the linear body of this invention. It is a plan view which shows the bivalve aquaculture raft of the shape which combined the two substantially circular skeletons of this invention. It is a top view which shows the bivalve aquaculture raft of the shape which combined the three substantially circular skeletons of this invention into substantially concentric substantially circular shapes. It is a plan view which shows the bivalve aquaculture raft of the shape which combined the three substantially circular skeletons of this invention in substantially parallel. It is a figure which shows the state which hung the culture container containing the bivalve on the bivalve culture raft which has a substantially circular skeleton. It is a figure which shows the state which hung the culture container which contained the bivalve on the bivalve culture raft which has a linear body. It is a front view view of the hanging chain in which aquaculture containers containing bivalves are laminated. It is a figure which shows an example of the material which comprises a skeleton. It is explanatory drawing of the plan view which shows an example of the case where the skeleton is a combination of substantially quadrangular ring bodies.

The bivalve culturing raft 1 of the present invention is suitable for cultivating bivalve oysters 12 such as oysters, scallops, and pearl oysters, which are surface-cultured and carry out unfed aquaculture.

The bivalve aquaculture raft 1 of the present invention is a bivalve aquaculture raft 1 for bivalve aquaculture, and includes a bivalve 2 capable of hanging two or more bivalve aquaculture rafts 10 for bivalve aquaculture, and when the skeleton 2 is floated on the water surface. The effective buoyancy of the skeleton 2 itself is made larger than the total underwater weight of the plurality of hanging reams 10 that are directly bound to the skeleton 2 itself and hung down.

The hanging ream 10 is directly hung on the skeleton 2 itself by using a restraining means such as a rope 4.

Since the effective buoyancy of the skeleton 2 itself when the skeleton 2 is floated on the water surface is larger than the total underwater weight of the plurality of hanging reams 10 hanging on the skeleton 2, a float such as styrofoam is required. It is an extremely simple structure because only the skeleton 2 is required as a constituent requirement of the raft.

Further, in the bivalve culture cage 1, the shape of the skeleton 2 is, for example, an annular body (

skeletons

2a, 2b) in a plan view as shown in FIGS. 1 (a) and 1 (b), or, for example, as shown in FIG. A shape in which a plurality of annular bodies are combined in a plan view (

skeleton

2g, 2f), or a linear body (skeleton 2c) in a plan view as shown in FIGS. 2 and 3, for example, as shown in FIG. It is a shape in which a plurality of linear bodies (2d, 2e) are combined in a plan view. In the case of the linear body, it is preferable to make the length of the skeleton 2 longer than the magnitude of the plurality of waves in order to reduce the influence of the waves applied to the skeleton 2.

When a plurality of linear skeletons 2c as shown in FIG. 2 are combined, they are restrained by the restraining means 3a made of the same material as the skeleton 2c. The material of the restraining means 3a may be made of resin or metal, but is preferably made of resin in consideration of durability in marine use.

In the case of unfed aquaculture used for bivalve aquaculture, in general, in order to increase the yield of bivalve 12 as much as possible, the rafts are hung on the bamboo laid vertically and horizontally. In other words, when considering the composition of the skein, it is the idea of a person who cultivates shellfish to hang a large number of hanging reams in the center of the skein, so in the skeleton of a ring or striatum, In the case of an annular body, it is considered that nothing can hang down in the central water area, and in the case of a linear body, it is considered that the number of hanging reams that can be hung down is reduced, and the yield of the double shell 12 is considered to decrease. Those who cultivate shellfish generally do not think of making it into a shape. The inventor was able to come up with a ring-shaped or linear skeleton 2 for the first time with a strong desire to realize a bivalve farming raft that does not require styrofoam.

In the case of the annular body, for example, in the case of a polyethylene pipe, both ends of the bent skeleton are brought into close contact with each other for butt fusion, and in the case of the linear body, for example, in the case of a polyethylene pipe, a linear skeleton A polyethylene lid is brought into close contact with both ends and bat fusion is performed. In any case, if the skeleton is a pipe, water does not enter the internal cavity, and the construction is performed by a joining method suitable for the material of the pipe or the like. This creates buoyancy in the skeleton.

Further, when the shape of the skeleton 2 is an annular shape, the height of the waves on the inside surrounded by the skeleton 2 is lower than that on the outside, and the speed of the tidal current is slower. Therefore, the bivalve 12 housed in the hanging chain 10 It can be expected that the yield of bivalve molluscs 12 will increase as the feeding time increases.

The annular body may be any shape such as a substantially circular shape, a substantially quadrangular shape, a substantially triangular shape, and a substantially polygonal shape in a plan view. Further, the annular bodies may be arranged in a plan view, for example, as shown in FIGS. 5 to 7, 12 in different sizes. Further, the combined shape of the linear bodies is a shape in which the linear bodies are combined so as to form a quadrangle with the linear bodies as sides even if the shape is vertically and horizontally configured as shown in FIG. The shape may be a combination of the linear bodies as sides so as to be polygonal, or may be a shape in which the quadrangular or polygonal shapes having different sizes are arranged. However, it is provided that the effective buoyancy of the skeleton 2 itself when the skeleton 2 is floated on the water surface is made larger than the total underwater weight of the plurality of hanging reams 10 which are directly bound to the skeleton 2 and hang down. Must be.

Further, in the bivalve aquaculture raft 1, the shape of the skeleton 2 is substantially circular (skeleton 2a) in a plan view as shown in FIG. 1 (a), or as shown in FIGS. 5, 6 and 7. , It is a shape that combines a plurality of substantially circular shapes. The skeleton shown in FIG. 5 is a skeleton in which two substantially

circular skeletons

2f and 2g are concentrically combined, and the skeleton shown in FIG. 6 is a skeleton in which three substantially

circular skeletons

2f, 2g and 2h are concentrically combined. It is a skeleton, and the skeleton shown in FIG. 7 is a skeleton in which three substantially circular skeletons 2i are combined in parallel. The combination of substantially circular shapes includes a combination of a plurality of circular shapes having different diameters, a combination of a plurality of concentric circular shapes having different diameters, a combination of a plurality of circular shapes in series, parallel, and an oblique row. Any arrangement may be used, such as a combination of a plurality of circular shapes in series, in parallel, or in a plurality of diagonal rows.

Further, the

skeletons

2f and 2g shown in FIG. 5 are tightened by the restraining means 3b of the resin member made of the same material as the skeleton 2, and the

skeletons

2f, 2g and 2h shown in FIG. 6 are fastened together with the resin member made of the same material as the skeleton 2. It is tightened by the restraining means 3c, and the skeletons 2i shown in FIG. 7 are tightened by the restraining means 3d made of a resin member made of the same material as the skeleton 2. As a result, the distance between the individual skeletons is made constant.

The skeleton 2 is concentrically combined with three substantially

circular skeletons

2f, 2g, and 2h as shown in FIG. 6, and the

linear skeletons

2d and 2e are combined vertically and horizontally as shown in FIG. As shown in 12, the

skeletons

2j, 2k, and 2n of the annular bodies having different sizes are combined so as to be triple in a plan view and fixed by the restraining means 3e, so that the hanging points of the hanging ream 10 can be expanded. It is possible to increase the yield of bivalve molluscs 12.

Next, the material of the skeleton 2 is a resin pipe that is not easily corroded by water. The type of the resin pipe may be, for example, a high-density polyethylene pipe, a low-density polyethylene pipe, a polypropylene pipe, a polyvinyl chloride pipe, or the like, but a high-density polyethylene pipe having excellent hardness and strength is preferable. ..

From the above, the skeleton 2 capable of hanging two or more hanging reams 10 for bivalve culture is provided, and the effective buoyancy of the skeleton 2 itself when the skeleton 2 is floated on the water surface is hung on the skeleton 2. In order to make it larger than the total underwater weight of the 10 units, the total underwater weight of the hanging series 10 is calculated in advance, and the calculated effective buoyancy of the skeleton 2 itself is larger than the calculated underwater weight. 2. Set the shape of the annular body, the linear body, or a combination thereof, the size such as the pipe diameter and length, and the material.

The calculation / setting example will be described. As shown in FIG. 8, it was decided to use a high-density polyethylene pipe as shown in FIG. 11 as the material of the skeleton 2a, and the bivalve aquaculture raft 1 made of the circular skeleton 2a was used to hang the hanging reams 10 n times. I will let you. As shown in FIG. 8, the underwater weight of one hanging chain 10 is W (kg). The density of the material constituting the material 20 used for the skeleton 2a is α (kg / m ³ ), the total length of the material 20 used for the skeleton 2a is L (m), and the density of water is β (kg / m ³ ). .. Since the skeleton 2a is a pipe, if the outer diameter is 2R (m) and the inner diameter of the skeleton 2a is 2r (m) in the cross section of the pipe as shown in FIG. 11, the portion that generates the buoyancy of the material 20 used for the skeleton 2a. The weight A (kg / m) per unit length of the material 20 used for S (m ² ) and the skeleton 2a is expressed by the following formula.
S = πR ² (1)
A = π (R ^2- r ² ) × α (2)

The underwater weight W (kg) of the hanging chain 10, the number of hanging numbers n of the hanging chain 10, the cross-sectional area of the portion of the material 20 used for the skeleton 2a that produces buoyancy is S (m ² ), and the buoyancy of the material 20 used for the skeleton 2a. The density of the entire portion producing the above is α (kg / m ³ ), the density β of water is known, and the effective buoyancy U (kg) of the skeleton 2a itself is directly bound to the skeleton 2a itself and hung down. The total length L (m) of the material 20 used for the skeleton 2a is calculated and obtained so as to be larger than the total underwater weight (W × n) of the hanging series 10. The underwater weight W (kg) of the hanging ream 10 is such that the hanging ream 10 is submerged in water, the weight at that time is measured, and the value is taken as the underwater weight.

The buoyancy F of the skeleton 2a, the weight w of the skeleton 2a, and the effective buoyancy U of the skeleton 2a are expressed by the following equations.
U = Fw (3)
The buoyancy F of the skeleton 2a is expressed by the following equation from the equation (1).
F = S × L × β = πR ² × L × β (4)
The weight w of the skeleton 2a is expressed by the following formula from the formula (2).
^{w = A × L = π (} R 2 -r 2) × α × L (5)
From equations (3), (4), and (5), the effective buoyancy U is expressed by the following equation.
U = πR ² × L × β-π (R ^2- r ² ) × α × L (6)
The relationship between the effective buoyancy U of the skeleton 2a, the underwater weight W of the hanging stations 10 and the number of hanging stations n (ream) is expressed by the following equation.
U> W × n (7)
Rewriting equations (6) and (7),
π R ² × L × β-π (R ^2- r ² ) × α × L> W × n (8)

Therefore, from the equation (8), the total length L of the skeleton 2a is expressed by the following equation.
L> W × n / (πR 2 × β-π (R 2 -r 2) × α) (9)

The underwater weight W of the hanging chain 10 is 50 kg, the hanging number n of the hanging chain 10 is 50 stations, the outer diameter 2R of the pipe cross section of the skeleton 2a is 0.2 m, the inner diameter 2r of the pipe cross section of the skeleton 2a is 0.16 m, and the skeleton 2a. The total length L of the skeleton 2a when the density α of is 950 kg / m ³ and the density β of water is 1000 kg / m ³ is applied to Eq. (9).
L> 30.25m (10)
Since workers may get on the skeleton 2a, the safety factor is increased by 1.5 times. The total length L of the skeleton 2a at this time is obtained.
L = 46m (30.25 × 1.5) (11)
The diameter R1 of the circular skeleton 2a is obtained from the plan view at this time.
R1 = 15m (46 / π) (12)

Therefore, from the calculation result equations (10) to (12), the underwater weight W of the hanging chain 10 is 50 kg, the hanging number n of the hanging chain 10 is 50 stations, the outer diameter 2R of the skeleton 2a is 0.2 m, and the skeleton 2a When the inner diameter 2r is 0.16 m, the density α of the skeleton 2a is 950 kg / m ³ , and the density β of water is 1000 kg / m ³ , the circular diameter of the skeleton 2a in a plan view is 15 m. Therefore, in the case of producing a bivalve farming raft 1 capable of hanging about 50 hanging rafts 10 having an underwater weight W of 50 kg, a circular shape with a diameter of 15 m using a pipe having an outer diameter of 0.2 m and an inner diameter of 0.16 m of high-density polyethylene. The skeleton 2a may be manufactured.

As shown in FIG. 10, the hanging chain 10 is composed of aquaculture containers 11 capable of accommodating bivalves 12 and having all wall surfaces such as side walls, bottom walls, and top walls formed in a shape that allows water to flow in and out. There is. Since the aquaculture container 11 is composed of a grid-like wall, the food of the bivalve 12 such as plankton existing in the sea easily flows in and out of the aquaculture container 11, and the growth of the bivalve 12 is promoted.

Next, in the bivalve aquaculture method, the effective buoyancy of the bivalve 2 itself when the bivalve 2 is floated on the water surface is applied to the bivalve 2 itself by hanging two or more bivalve aquaculture hanging stations 10 on the bivalve 2 itself. By making it larger than the total underwater weight of the plurality of hanging reams 10 that are directly bound and hung, the plurality of hanging reams 10 can be hung only by the effective buoyancy of the skeleton 2 itself. That is, the bivalve aquaculture method is a method of cultivating the bivalve 12 using the bivalve aquaculture raft 1.

Then, as shown in FIG. 8, the bivalve aquaculture raft 1 is used by directly binding a plurality of hanging chains 10 to the substantially circular skeleton 2a itself with a rope 4a and hanging them, and as shown in FIG. 9, the water surface 8 is used. A linear skeleton 2c is floated on the skeleton, and a plurality of hanging reams 10 are directly bound to the skeleton 2c itself by a rope 4b and hung.

Next, an example of a bivalve aquaculture raft will be described. For 65 days from November 22, 2018 to January 24, 2019, aquaculture was carried out at a oyster farm managed by the Fukae Fisheries Cooperative in Etajima City, Hiroshima Prefecture, using aquaculture containers 11 as shown in FIG. The bivalve farming raft 1 used had a

skeleton

2f and 2g as shown in FIG. Further, as a comparative example, aquaculture was carried out using a conventional bamboo raft in the same aquaculture container 10 at the same aquaculture place at the same time as in the examples. The bivalve 12 of the same lot as at the start of the measurement was hung on the bivalve culture raft 1 and the bamboo raft using the skeleton 2 of the present invention for test culture. The cultivated oysters were stripped and the stripped weight was measured. The results are shown in Table 1.

From Table 1, when compared by the weight of the stripped meat, the average value is 9.63 g in the case of the conventional bamboo raft, whereas the average value is 12.05 g when the

skeleton

2f and 2 g of the present invention are used. An increase in yield of about 1.3 times was obtained. It can be inferred that this is because the bivalve 12 has a longer feeding time because the height of the waves and the speed of the tidal current are suppressed in the inside of the

skeleton

2f and 2g as compared with the outside of the

skeleton

2f and 2g. ..

1 Bivalve aquaculture raft 2 Frame 3 Restraint 4 Rope 8 Water surface 10 Hanging ream 11 Culture container 12 Bivalve 20 Material

Claims

A bivalve farming raft for bivalve farming
Equipped with a skeleton that can hang two or more hanging reams for bivalve aquaculture
A bivalve aquaculture raft characterized in that the effective buoyancy of the skeleton itself when the skeleton is floated on the water surface is made larger than the total underwater weight of the plurality of hanging rafts that are directly bound to the skeleton itself and hung down.
The bivalve aquaculture raft according to claim 1, wherein the shape of the skeleton is an annular body in a plan view or a shape obtained by combining a plurality of annular bodies.
The bivalve aquaculture raft according to claim 1 or 2, wherein the shape of the skeleton is a substantially circular shape in a plan view, or a shape obtained by combining a plurality of substantially circular shapes.
The bivalve aquaculture raft according to claim 1, wherein the shape of the skeleton is a linear body in a plan view or a shape obtained by combining a plurality of linear bodies.
The bivalve aquaculture raft according to any one of claims 1 to 4, wherein the material of the skeleton is a resin pipe that is not easily corroded by water.
The bivalve aquaculture raft according to any one of claims 1 to 5, wherein the hanging ream is composed of a bivalve aquaculture container formed in a shape capable of accommodating bivalve molluscs and all walls can flow in and out of water.
Two or more bivalve aquaculture hangings are hung on the skeleton itself.
By making the effective buoyancy of the skeleton itself when the skeleton is floated on the water surface larger than the total underwater weight of the plurality of hanging reams that are directly bound to the skeleton itself and hung down, only the effective buoyancy of the skeleton itself is obtained. A method for cultivating bivalve molluscs, which comprises allowing a plurality of the hanging reams to hang down.