JP6276104B2 - Useful bivalve reproduction promotion method and bottoming promotion unit - Google Patents

Description

  The present invention relates to a method for promoting the reproduction of useful bivalves and a bottoming promoting unit.

  In order to promote the propagation of clams and the like, conventionally, as described in Patent Document 1, for example, it is known to spread steelmaking slag having a predetermined particle diameter on a beach or the like as a bottoming material. By making the steelmaking slag as the bottoming material into a particle size that the clam larva prefers to bottom, the bottoming property is improved.

JP 2012-055177 A

  However, the above-described conventional example may be reduced in efficiency due to harmful / competitive shellfish.

  For example, common mussels that live in tidal flats with clams can be entangled with each other by foot threads to form a mat-like group covering the ground surface layer, which can adversely affect the sediment environment in which clams inhabit.

  The present invention has been made to solve the above problems, and provides a useful bivalve breeding promotion method capable of preventing the deterioration of the habitat caused by harmful and competing shellfish and making the promotion of breeding clams more efficient. With the goal. Another object of the present invention is to provide a bottoming promoting unit that can promote the bottoming of larvae such as clams by maintaining a good habitat.

According to the invention, the object is
A string-like sweeper 3 that reciprocates due to the flow of seawater is placed on the ground 2 of the inhabited tidal flats of useful clams 1 such as clams, and the inhabited tidal flats regulate the harmful and competing shellfish 4 on the surface of the ground 2 This is achieved by providing a method for promoting the reproduction of useful bivalve 1 that promotes the reproduction of useful bivalve 1.

  For example, it is known that clams 1 have negative phototaxis, so that their larvae dive into the sand that constitutes the bottom sediment when they settle on the ground 2 of the inhabited tidal flat. On the other hand, it is known that the white mussel 4 stays on the surface of the bottom sediment after bottoming because it has positive phototaxis. Therefore, by placing the sweeping body 3 that reciprocates on the ground 2 of the raw tidal flat, the occurrence of the mussel 4 that stops on the surface of the bottom sediment is controlled without significantly affecting the clams 1 that dive into the bottom sediment. be able to. Thereby, formation of the mat-like group mentioned above can be prevented, and the growth environment of clam 1 can be maintained favorable.

  Thus, the useful bivalve 1 in the present invention is a bivalve that is useful for edible purposes and dives in the sediment of the tidal flat, while the harmful / competitive shellfish 4 is harmful to humans or is useful as described above. This refers to shellfish that may compete in the same habitat as the bivalve 1 and that may grow on the ground 2 of the tidal flat and inhibit the growth of the useful bivalve 1.

  In addition, fine mud flowing from the river may accumulate on the tidal flat, but reciprocation by the sweep body 3, that is, sweeping, prevents and suppresses such mud accumulation. As a result, it is possible to satisfactorily maintain the bottoming environment of the larvae of the useful bivalve 1.

  The sweep body 3 is sufficient if it can reciprocate by the flow of seawater, that is, by waves or tides, and prevent the harmful / competitive shellfish 4 from standing on the ground 2 of the tidal flat. As shown in the embodiments described later, it can be made of a material having a specific gravity of about 1.3. In addition, if the movement of the sweep body 3 is such that it reciprocates twice a day due to, for example, tide, there is no fear that the bottoming of the useful bivalve 1 and the action of submersion will be hindered. In addition, the same thing may be said if the tide is filled with the tide and the waves when the tide is pulled are further reciprocated a plurality of times.

  Furthermore, since the sweep body 3 is formed in a string shape, for example, if a weight is attached to one end of the sweep body 3 or is fixed to the ground 2 with an anchor bolt, the sweep body 3 is not flown out of the tidal flat. Further, if both ends thereof are supported so as to be reciprocally movable, it is possible to reliably sweep the predetermined area 2 of the ground at a certain frequency. Note that the direction in which the sweep body 3 can freely move reciprocally matches the direction in which tide fullness occurs as much as possible when importance is placed on the efficient movement of the sweep body 3 by tidal currents or wave fluctuations. Is desirable.

  In addition, if the bottoming promoting base material 6 is sprayed on the ground 2 of the tidal flat where the above sweeping body 3 is arranged in the same manner as the conventional example described above, the bottoming promotion of the larvae by the bottoming promoting base material 6 is promoted. The breeding of the useful bivalve 1 can be further promoted. In this case, if the surface of a large number of bottoming promoting base materials 6, 6,... Is covered with a mesh-like cover 5, the bottoming promoting base material 6 is washed away by sweeping by the sweep body 3. It can be easily prevented and suppressed. In this case, specifically, the cover 5 has a mesh size in which the bottoming promoting base material 6 cannot pass or is difficult to pass. In addition, if the mesh size is made smaller, it is possible to prevent food damage caused by the external enemy without much impeding the entry of the larvae of the useful bivalve 1.

  In addition, in order to cover the surfaces of the large number of bottoming promotion base materials 6, 6,... With the cover 5, the bottoming promotion base material 6 is preliminarily bagged on the mesh-like bag body 7. When packed and laid on the ground 2, the useful bivalve 1 is transferred to an appropriate breeding environment according to the growth stage by carrying or moving the bag body 7, and further, the grown component is further grown. Shells can be easily harvested using the bag 7. When used for harvesting, it is sufficient to make the mesh size smaller than the size of a typical adult shellfish.

  Furthermore, if the sweep body 3 is connected to the mesh-like cover 5, the sweep range of the sweep body 3 is swept to the surface of the cover 5, in other words, to the surface side of the bottoming promoting base 6 by the sweep body 3. It becomes possible to ensure.

In addition, the bottoming promotion unit A that can be used in the above-described method for promoting the growth of useful bivalves and can promote the bottoming of larvae such as clams by maintaining a good habitat,
A large number of bottoming accelerating base materials 6 can be packed in the mesh bag body 7 and the sweep body 3 can be movably connected on the surface of the bag body 7.

In this case, when the inside of the bag body 7 is divided into a plurality of parts, it becomes possible to prevent a large number of the bottoming promoting base materials 6 from being biased in the bag body 7, and a good bottoming environment can be obtained. In addition to being able to be secured easily in a wider range, when the bag body 7 is placed on the ground 2, the thickness of the boundary portion of the section not filled with the bottoming promoting base material 6 is thinner than other portions. In addition, a so-called gravel on the ground 2 of the tidal flat can be formed in a pseudo manner, and the bottoming property of the useful bivalve 1 can be improved. That is, a minute unevenness is formed on the ground 2 of the tidal flat, and the seawater flows over the tidal flat 2 to generate a wave shielding effect, more specifically, a large and small vortex is generated in the recess, thereby causing the horizontal In addition to the change in the flow velocity in the direction, a region where such a change in flow velocity change is small is also formed. Experience has shown that clam bottoming is high in these areas.

  As is clear from the above explanation, according to the present invention, it is possible to prevent the deterioration of the habitat environment due to harmful and competing shellfish, and to make the promotion of reproduction of useful bivalves more efficient. The resource recovery and regeneration of useful bivalves can be efficiently achieved.

It is a figure which shows the installation state of a bottoming promotion unit, (a) is a top view, (b) is the 1B-1B sectional view taken on the line (a), and is a figure explaining the reproduction promotion function of a useful bivalve.

  FIG. 1 shows an embodiment of the present invention. In this embodiment, as shown in FIG. 1A, the bottoming promoting unit A has a sweep body 3 that is supported by a support 11 so as to be reciprocally movable at both ends.

  The sweep body 3 is formed by stringing a material having a specific gravity of 1.3. In this embodiment, for example, a synthetic resin material such as vinylon is used as such a material. At both ends of the sweep body 3, a connector 12 connected to the support body 11 is attached. In this embodiment, the connector 12 enables the sweeper 3 to return more. For example, the connector 12 can be constituted by a return (monkey ring). In this case, one ring is swept. It is attached to the end of the body 3.

  On the other hand, the support 11 is a pair of parallel cord-like members, for example, wires, in this embodiment, and the cord-like members 11, 11 are spaced at the same distance as both ends of the sweep body 3. Accordingly, the above-described connecting tool 12 is connected to each cord-like member 11, for example, by passing the cord-like member 11 through the other return ring, the cord-like member in a posture in which the sweep body 3 is orthogonal to the cord-like member 11. 11 is supported so as to be reciprocally movable in the longitudinal direction.

  Further, as shown in FIG. 1B, the bottoming promotion unit A has a large number of bottoming promotion base materials 6 arranged in the reciprocally movable region of the sweep body 3 described above. The bottoming promoting base material 6 is provided with an appropriate size capable of promoting the bottoming of the clam 1 larvae by being spread on the ground 2 of the tidal flat. Is formed in a cylindrical shape having a diameter and a length of about 10 mm each.

  Further, the bottoming promoting base material 6 has a bulk specific gravity in the range of 1.1 to 1.7 which is not buried when the bottom of the tidal flat is liquefied by a strong wave generated when a large low pressure strikes, in other words, It has an underwater bulk specific gravity smaller than sand. In the present embodiment, the bottoming promoting base material 6 is formed by crushing, molding, and firing a mixture of porcelain clay and a specific gravity adjusting material at a ratio of about 80% and about 20%. More specifically, Kibushi clay is used for the porcelain clay, and shells are used as the material for adjusting the specific gravity. Crushing is performed using a ball mill to reduce the clay to 30 microns or less, and the shells to 300 microns or less. After adding water to muddy and filtering and dehydrating with a filter press, kneading with a kneader, extrusion molding with an extrusion molding machine, drying the resulting molded body, and baking at high temperature with a rotary kiln or the like Made.

Further, as shown in FIGS. 1 (a) and 1 (b), the bottoming promoting unit A has a mesh-like bag body 7 that accommodates many of the above-described bottoming promoting base materials 6, and this bag body 7 as a predetermined body. It has the fixing member 13 for fixing to the position. The bag body 7 is formed, for example, by weaving synthetic fibers into a mesh size bag shape through which the above-described bottoming promoting base material 6 does not easily pass, and has a rectangular shape in plan view. At least four corners of the bag body 7 are formed with attachment portions 7a for attachment to the fixing member 13 described above. This attachment part 7a can be comprised with a string, for example.

  Further, the inside of the bag body 7 is partitioned into a plurality of blocks 7b, 7b,. For example, the bag body 7 is formed to have a length of about 1 meter in a plan view, and the partition is formed by partitioning the interior of the bag body 7 in parallel with a specific side. Thereby, each block 7b is formed long in a fixed direction.

  On the other hand, in this embodiment, the fixing member 13 is a rectangular frame member 13a that is slightly larger than the size of the bag body 7 in plan view, and for fixing the rectangular frame member 13a to a predetermined position. And anchor bolts not shown. The frame member 13a can be formed, for example, by framing a PVC pipe with a joint. On the other hand, the anchor bolt can be configured, for example, by bending the rear end portion of a metal bar with a sharp tip so that it can be locked to the frame member 13a.

  In addition, as shown in FIG. 1 (a), the bottoming promoting unit A connects a plurality of the above-mentioned frame members 13a to each other to form a lattice-like frame, and each bag body 7 is placed inside the eye. Attached and formed. Further, as the bag body 7, that is, the bottoming promoting base material 6 is arranged in a square shape, in other words, arranged like an m × n matrix, the cord-like member 11 is substantially the same as the frame member 13a. Thus, the cord-like members 11 are arranged in a lattice shape. By arranging the cord-like member 11 in the direction parallel to the sweep body 3 in this way, the distance between the cord-like members 11, 11 corresponding to both ends of the sweep body 3 can be favorably maintained in a long distance range. it can.

  The above bottoming promoting unit A is installed on the ground 2 of the inhabited tidal flat of the clam 1 as shown in FIG. The installation is performed by fixing the fixing member 13 to which the bag body 7 that accommodates the bottoming promoting base material 6 is attached and the support body 11 to which the sweep body 3 is connected to the ground 2. When the support body 11 is fixed to the ground 2, the sweep body 3 is aligned with the bag body 7 and the frame member 13 a so that the sweep body 3 can reciprocate on the surface of the bag body 7. Specifically, for example, after only the support 11 is laid on the ground 2 with the sweep body 3 not attached, the lattices of the support 11 and the frame member 13a overlap the upper surface of the support 11. If the frame member 13a is fixed by an anchor bolt after the frame member 13a is overlapped after being aligned as described above, the support 11 can be fixed to the ground 2 via the fixing member 13. In FIG. 1A, the arrow indicates the direction of tidal current.

  As shown in FIG. 1 (b), in the installed state, the bottoming promoting base material 6 is gathered inside each block 7b of the bag body 7 so as to form unevenness on the entire surface side together with the boundary portion between the blocks 7b and 7b. Placed in. When fine particles such as sand are carried to the bottoming promoting unit A by the tide at high tide, a bottom material that appropriately contains the fine particles and the bottoming promoting base material 6 is formed.

  Further, at the time of tide, as indicated by the two-dot chain arrow in FIG. 1 (b), the sweep body 3 moves so as to sweep the surface of the bag body 7 by the tide, and the fineness on the surface is moved. The larvae of harmful and competing shellfish 4 that have attempted to settle on the surface of the bottoming promoting base 6 exposed in this way, while preventing sedimentation and exposing the bottoming promoting base 6 to the surface layer of the sediment Is also removed by being pushed by the sweep body 3. On the other hand, the larvae of the useful bivalve 1 that settles so as to dive in the fine particles in the gap of the bottoming promoting base material 6 stop in place without being disturbed by the sweep body 3. Further, in the concave portion 14 generated by the arrangement of the bottoming promoting base material 6 described above, a large and small vortex 15 is generated by the tidal current as shown in FIG. 1B, and this is schematically shown by a solid line arrow in FIG. As described above, the flow rate of seawater becomes uneven on the bottoming promotion unit A, and the flow rate gradually changes around the recess 14, so that the bottom of the larvae of the useful bivalve 1 in the region is promoted.

  Thereafter, when the useful bivalve 1 grows to become a normal shellfish, it can be easily collected by removing and opening the bag 7 from the frame member 13a. Since the block 7b is formed in a long length parallel to a specific side of the bag body 7, it does not take much time for sampling as compared with the case where the block body 7 is simply formed in a matrix shape. Moreover, at the time of collection, by using a sieve or the like having a mesh through which the bottoming promotion base material 6 can pass, the bottoming promotion base material 6 and the useful bivalve 1 can be easily sorted. Even if the bottoming promoting base materials 6 and 6 are adhered to each other by a hydration reaction of calcium, they can be easily separated by appropriately shaking the sieve or the like.

  For example, if the bottoming promoting unit A is installed after cultivating a tidal flat using a rake, the mussel 4 already inhabiting the tidal flat can be removed in advance from the installation area. When the inventor thus installed in the spring, in the summer when clams breed relatively well, more clams of larvae of clams 1 than in places where the bottoming promotion unit A in the tidal flat is not installed The bottoming was confirmed, and fewer larvae of otogigi 4 were confirmed.

  It is also possible to promote the growth of the clam 1 by moving the bag 7 near the sea surface where the clam 1 feed is abundant after the bottom of the clam 1 has stabilized. For example, in a seaweed farm where the clam 1 and the farming area approximate, it is possible to hold the clam 1 near the sea surface by utilizing a support post standing in the sea to support the seaweed. In this case, since it is sufficient to collect the bag 7 on the ship, it is possible to make fishing easier when the seawater temperature is low, such as in winter.

DESCRIPTION OF SYMBOLS 1 Useful bivalve 2 Ground 3 Sweep body 4 Harmful / competitive shellfish 5 Cover 6 Bottoming promotion base material 7 Bag body

Claims (7)

  Useful clams such as clams are placed on the surface of the tidal flats, and a string-like sweeping body that reciprocates by the flow of seawater is placed on the ground to regulate the growth of harmful and competing shells on the surface of the tidal flats and breed useful bivalves in the tidal flats. Useful bivalve breeding promotion method to promote.   The method for promoting the reproduction of useful bivalves according to claim 1, wherein both ends of the sweep body are supported so as to be reciprocally movable.   The method for promoting the propagation of useful bivalves according to claim 1 or 2, wherein a plurality of bottoming promoting base materials whose surfaces are covered with a mesh-like covering are arranged on the ground.   The useful bivalve reproduction promoting method according to claim 3, wherein the bottoming promoting base material is pre-packed in a mesh bag and laid on the ground.   The method for promoting the reproduction of useful bivalves according to claim 3 or 4, wherein the sweep body is connected to a mesh-like cover.   A bottoming accelerating unit in which a large number of bottoming promoting base materials are packed in a mesh-like bag body, and the sweep body is movably connected on the surface of the bag body. The bottoming promotion unit according to claim 6, wherein the bag body is partitioned into a plurality of parts.

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