JPH0472492B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fish reef block used for creating spawning grounds for molluscs such as squid (hereinafter also simply referred to as squid).

(Prior Art and Problems to be Solved by the Invention) In general, squid and the like have the habit of laying eggs in large numbers on the underside of boulders on the ocean floor, and on the ceilings of rock ledges and rock crevices. Particularly, the place where a large amount of eggs are laid is the hollow part of the ceiling surface of a relatively narrow space with an opening height of about 20 to 50 cm. In addition, it is desirable that the environment is clear and has good tidal flow.

However, there are few natural reef zones suitable for spawning squid and other species that meet these conditions. Furthermore, conventional fish reef blocks of this type have not sufficiently taken into consideration the habits of the above-mentioned squid and the like.

Based on these backgrounds, the present invention provides a fish reef block that is suitable for creating spawning grounds and has good stability when installed on the seabed, taking into account the habits of squid and the like.

(Means and effects for solving the problems) The fish reef block of the present invention employs the following configuration based on the above intention. That is, the present invention provides a fish reef block in which a recess with a depth of at least 5 cm or more is formed on the lower surface of a flat top plate, and a plurality of legs are provided radially around the center of the flat top plate. A space corresponding to 10 to 30% of the area of the flat top plate is provided in the center of at least one of the stacked fish reef blocks, excluding the top tier. This fish reef block is characterized in that it is provided with a through hole, and the flat top plate of the uppermost fish reef block is not provided with such a through hole.

One of the features of the fish reef block of the present invention is that a recess with a depth of at least 5 cm is formed on the lower surface of the flat top plate.

The depth of this depression was determined by the present inventor through various studies on the habits and body lengths of squid, etc., and squid etc. prefer to select spawning sites in depressions with a depth of less than 5 cm. There is no such tendency, and selectivity as a spawning ground is only observed when the depth is 5 cm or more, and even more so when the depth is 7 cm or more. In addition, it is desirable that the shape of the recess is such that the side wall surface of the recess is an inclined surface.In particular, the cross-sectional shape of the recess cut along a plane in the depth direction of the recess is triangular, trapezoidal, or semicircular. It is preferable to have an inclined side surface shape such as a shape. Furthermore, the size of the opening of the recess also has an effect, and when the length of the base of the triangular, trapezoidal or semicircular cross-sectional shape of the recess is 5 cm or more, preferably 0 cm or more, squid, etc. The selectivity of this species as a spawning ground is remarkable.

In addition, the fish reef block of the present invention requires a plurality of legs to be provided on the lower surface of the flat top plate, and preferably, a plurality of legs are provided radially around the center of the flat top plate. is provided. Providing a plurality of legs not only improves the positional stability of the fish reef block, but also allows each leg to be made thinner, reducing the area on the lower surface of the flat top plate where a recess can be provided. It is possible to secure as much as possible. In addition, by providing a plurality of legs radially around the center of the flat top plate, a passageway for water to flow out or inflow radially on the lower surface of the flat top plate can be obtained.
This is useful for creating a clear environment with good water flow that squid and the like like.

FIG. 1 is a partially cutaway perspective view showing a typical embodiment of a unit reef block constituting the stacked reef block of the present invention.

Fig. 2 is a detailed view of the fish reef block shown in Fig. 1. Fig. A is a front view, Fig. B is a plan view, Fig. C is a bottom view, and Figs.
They are a sectional view of A and a sectional view of B to B.

A recessed portion 2 is formed on the lower surface of the flat top plate 1, and leg portions 13 are provided radially around the center of the flat top plate 1.

The shape of the flat top plate 1 is not particularly limited, but in order to allow for a certain degree of variation and to form a spawning place with uniform conditions throughout, a regular polygonal flat top plate is preferable, particularly a regular hexagonal shape. A flat top is preferred. In the case of a regular polygonal flat top plate such as a regular hexagonal shape, there is an advantage that there is no directionality when installing the fish reef block on the seabed, it is easy to sink, and it can respond to all kinds of tidal currents even after installation.

A plurality of recesses 2 are formed radially around the center of the flat top plate 1, and a cross section of the recess 2 is cut along a plane passing through the center of the flat top plate 1 and perpendicular to the flat top 1. The shape is trapezoidal. By arranging the recesses 2 radially in this way,
It is possible to ensure non-directionality and to efficiently form spawning grounds within a certain area. As mentioned above, the depth and width of the recess 2 are as follows.
The depth must be 5 cm or more, and the length of the base of the trapezoid whose frontage is the cross-sectional shape of the depression (indicated by symbol l in Figure 2 E) is 5 cm or more, preferably 10 cm or more. It is hoped that

Therefore, for example, a structure in which a large number of shallow grooves are simply provided on the lower surface of the flat top plate 1 so that laid eggs can easily adhere thereto does not fall within the category of recesses referred to in the present invention. Doesn't belong.

Further, on the lower surface of the flat top plate 1, a plurality of legs 3 are provided radially around the center of the flat top plate. The leg portions 3 are provided radially as follows.
When the flat top plate 1 has a regular polygonal shape as shown in FIG. 1, it is preferable to provide legs at diagonal positions of the regular polygon in order to ensure uniformity of water passage.

When creating a spawning ground for squid, etc. using these fish reef blocks, one or more of the fish reef blocks described above may be installed in close proximity, but the most preferred embodiment is This is an embodiment in which fish reef blocks are stacked in multiple stages. When such an embodiment is adopted, by appropriately adjusting the length of the legs of each reef block to be stacked so that the distance between the flat top plates of adjacent reef blocks is preferably 20 to 50 cm, squid, etc. It is possible to efficiently construct the ceiling surface of a relatively narrow space with an opening height of about 20 to 50 cm, which is preferred as a spawning ground by the spider. FIG. 3 shows a perspective view of a four-tier stack. The details of the topmost reef block are shown in FIG. 2, the second and third tiers are shown in FIG. 4, and the bottommost reef block is shown in FIG. 5. However, as can be understood from FIG. 5, the lowest fish reef block does not have a recessed portion of a predetermined depth formed on the lower surface of the flat top plate, and the fish reef block alone is not as good as the fish reef block of the present invention. It does not belong to this category. In this way, when these reef blocks are stacked and used, it is not necessarily necessary that all of the stacked reef blocks have the characteristics of the above-mentioned reef blocks, and other types of reef blocks may be used as appropriate. It can be used for some of them. In the embodiment shown in Fig. 3, a fish reef block with a bone structure is used as the bottom fish reef block, as shown in detail in Fig. 5, which improves the passage of water and prevents sand and mud from accumulating and adhering. This makes it easier to obtain a clear place with good water flow that is preferred by squid and the like, and also prevents the scour phenomenon and improves positional stability, which is a particular problem when used in stacks. In FIG. 5, Figure A is a front view, Figure B is a plan view, Figure C is a bottom view, and Figures D and E are sectional views taken along lines A to A and B to B in Figure B, respectively.

In addition, as shown in FIG. 4, the second and third tier fish reef blocks have a through hole 5 in the center of the flat top plate 1 with a width corresponding to 10 to 30% of the area of the flat top plate 1. is provided. In FIG. 4, Figure A is a front view, Figure B is a plan view, Figure C is a bottom view, and Figures D and E are sectional views taken along lines A to A and B to B in Figure B, respectively.

In this manner, by providing the through hole 5 in the center of the flat top plate of the middle fish reef block, among the fish reef blocks except for the top one, the passage of water can be made even better. The through hole 5 is 10 to 30% of the area of the flat top plate 1.
It is preferable that the area is equivalent to . If it is less than 10%, it may not always be possible to obtain sufficient water permeation, and if it exceeds 30%, there will be less adhesion surface for spawning and it will be difficult to obtain a ceiling surface with a stable atmosphere suitable for spawning.

On the other hand, it is preferable not to provide a through hole in the topmost reef block in order to keep the interior of the stacked reef blocks appropriately dark and create an environment suitable for spawning. In this way, a through hole with a width corresponding to 10 to 30% of the area of the flat top plate is provided in the center of the flat top plate of at least one of the stacked fish reef blocks, excluding the topmost one. One of the major features is that the flat top plate of the topmost fish reef block is not provided with such a through hole 5.

Further, as shown in FIG. 4, a downwardly inclined groove 6 extending from the periphery of the top plate to the through hole 5 is provided on the upper surface of the flat top plate 1. This inclined groove 6 is useful for preventing sand and mud from accumulating on the upper surface of the flat top plate 1. The sand and mud deposited around the inclined groove 6 are washed by seawater and enter the inclined groove, and together with the sand and mud deposited in the inclined groove, they move toward the through hole 5 and fall. Further, on the upper surface of the flat top plate 1, there is provided a concave leg fixing recess 7 into which the leg tips of the fish reef blocks to be stacked on the upper tier are fitted, and furthermore, the center part of the leg fixing recess 7 is provided with a flat surface. A connecting hole 4 is bored through the top plate 1. When stacking fish reef blocks, fit the tip of the leg of the upper fish reef block into the leg fixing recess of the lower fish reef block, stack them one after another, and then insert the length from the top fish reef block to the bottom fish reef block into the connecting hole 4. By inserting a connecting rod such as a reinforcing bar, the reef blocks can be easily connected and fixed. Of course, it is also possible to insert a connecting rod in advance into the connecting hole of the lowest reef block and stack the reef blocks one after another via the connecting rod.

The material of the fish reef block of the present invention is usually concrete, but in addition to this, it has a certain degree of corrosion resistance against the environment of the submerged site, and has good moldability, mechanical strength, positional stability, ease of maintenance, and Materials with good quality are selected as appropriate after comprehensive evaluation including cost aspects.
For example, if the reef blocks are stacked in several tiers, one of the preferred embodiments is to mold the bottom tier of reef blocks with regular concrete and the upper tier of reef blocks with foamed light concrete from the standpoint of positional stability. be.

Moreover, it can also be colored as appropriate using, for example, a pigment. When colored black, the shading effect is large, and it is also preferable to color appropriately to obtain the appropriate brightness as a spawning ground.

(Effects of the Invention) By employing the above configuration, the fish reef block of the present invention has the following excellent effects as a fish reef block as partially described.

First, since the lower surface of the flat top plate has a predetermined depression, a place suitable for the shape of the spawning ground that squid and the like prefer as a habit can be obtained. In particular, by stacking them in several stages, it is possible to efficiently create an open space that squid and the like prefer.

Furthermore, by arranging the plurality of legs preferably in a radial manner, a uniform drainage passage can be obtained in all directions and good positional stability can be obtained. especially,
By stacking the reef blocks in several tiers and providing a through hole in the flat top plate of the middle tier,
The tidal flow is extremely good, making it easy to obtain a clear environment that squid and other animals prefer as spawning grounds.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a typical aspect of a unit reef block constituting the stacked reef block of the present invention, and FIG. 2 is a detailed view of the reef block shown in FIG. 1. In addition, FIG. 3 is a perspective view showing an example of a mode in which the stacks are stacked in several stages, and FIGS.
This is a detailed view of the third and bottom fish reef block. In addition, in Fig. 2, Fig. 4, and Fig. 5,
In each case, Figure A is a front view, Figure B is a plan view, Figure C is a bottom view, and Figures D and E are sectional views from A to A and B to B in Figure B, respectively. 1 is a flat top plate, 2 is a recessed portion, 3 is a leg portion, 4 is a connecting hole, 5 is a through hole, 6 is an inclined groove, and 7 is a leg fixing recess.

Claims (1)

[Claims] 1 At least 5cm deep on the bottom side of the flat top plate.
A plurality of reef blocks each having the above-mentioned recesses formed therein and having legs arranged radially around the center of the flat top plate are stacked in multiple stages, and the topmost stage of the stacked reef blocks is excluded. A through hole with a width equivalent to 10 to 30% of the area of the flat top plate is provided in the center of at least one flat top plate of at least one of the fish reef blocks, and a hole is provided in the flat top plate of the topmost fish reef block. A fish reef block characterized by not having such a through hole.