JPH05306508A - Block for fish-gathering place - Google Patents

Abstract

PURPOSE:To make surroundings suitable for the growth and activity of aquatic organisms such as fishes and shellfishes by feeding oxygen and nutrition through a waterway, by a method wherein a floor slab, a longitudinal wall stood on the floor slab, and holding and enclosing walls having escaping ways on some places of them, arc provided. CONSTITUTION:A horizontal floor slab 2 is provided, a longitudinal wall 3 and a holding wall 5 are respectively located at the rear and front peripheral parts thereof, an enclosing wall 7 is located in the front and rear direction thereof at the middle of the left peripheral part thereof, and they are integrally stood thereon, and thus the title block 1 is formed. In this case, reinforcing steel bars are buried in concrete, and escaping ways 8 each are formed between the one end of the enclosing wall 7 and the longitudinal wall 3 and between the other end thereof and the holding wall 5. When a revetment provided with a fish-gathering place is constructed, coarse gravel is laid on the surface of the lower part of a slope at a waterway and blinding concrete is placed thereon. A plurality of the blocks 1 are placed on the surface of the blinding concrete, directing the rear of the longitudinal wall 3 toward the slope. After that, gravel, the coarse gravel, cobble and the like are laid on the floor slab 2, and thus a first step is formed, following which a second step and a third step are formed in the same manner, at positions where the blocks are progressively shifted rearward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block used for revetment of waterways such as rivers and artificial canals, head works, and fishways.
In particular, the present invention relates to a fish nest block suitable for inhabiting aquatic organisms such as fish, shellfish, and crabs.

[0002]

2. Description of the Related Art The following is known as a conventional revetment or heading construction using a fish nest block. (1) As described in Japanese Utility Model Publication No. 1-90821, a square box-shaped fish nest block having an internal space surrounded by a wall with an opening is used, and this fish nest block is used as a slope of a waterway. A seawall with fish nests that is simply piled up along the line and the fronts of these fish nest blocks are arranged flush with each other like a wall.

(2) As described in Japanese Utility Model Laid-Open No. 59-69226, a slanted plate along the slope of a waterway, a vertical wall erected at the rear end thereof, and horizontally from the upper end of the vertical wall to the front. Use a fish nest block consisting of protruding horizontal walls and the space between them so that the rear end of the slope plate of this fish nest block abuts the front end of the slope plate of the next fish nest block. A seawall with a fish nest in which the horizontal walls are arranged in a staircase pattern by arranging them on the slope of the waterway.

(3) As described in Japanese Utility Model Laid-Open No. 3-79325, a flat rectangular base portion, a rear vertical wall and a front vertical wall erected at a rear edge portion and a front edge portion, and an upper end of the rear vertical wall. A fish nest block consisting of a horizontal wall and a fish nest block, which are buried in a waterway at a distance from each other.

[0005]

However, the conventional fish nest has the following problems. First, in the seawall with fish nest in (1) above, the fish nest is formed inside the nest of the fish nest block, the shape is quite different from the natural depression, and the water inside does not circulate so much, so it is aquatic. It was difficult to say that it was the optimal environment for living creatures. In addition, since there is little direct sunlight on this fish nest, the water temperature does not rise easily, and there is a problem that aquatic plants such as aquatic plants and algae, which are preferable for aquatic organisms, do not grow well.

Further, in the above-mentioned (2) revetment with a fish nest, the fish nest is formed in the space between the slant board of the fish nest block and the vertical wall and the horizontal wall, and especially the upper surface of the slant board is inclined. Therefore, there is a problem in that it is impossible to lay gravel, stones or boulders suitable for habitation of fish on the upper surface. In addition, there is a problem that this fish nest block must be manufactured each time by adjusting the inclination angle to the slope different for each waterway.

Further, in the fish depression of the above (3), since the fish nest is formed in a trough shape by the base portion of the fish nest block, the left vertical wall and the right vertical wall, The problem in 2) fish nests is improved. However, since there is no escape route for aquatic organisms in this fish nest block, there is a problem that the aquatic organisms are trapped in the fish nest when the water flow rate of the river is significantly reduced.

Therefore, the object of the present invention is to form a fish nest close to nature suitable for habitat of aquatic organisms such as fish, shellfish and crabs by using it for revetment of waterways, head works, fishways, etc. At the same time, it is to provide a novel fish nest block that allows aquatic organisms to escape from the fish nest when the water flow in the waterway is significantly reduced.

[0009]

In order to achieve the above object, a fish nest block of the present invention comprises a bottom plate, a vertical wall extending in the left-right direction which is erected at a rear edge of the bottom plate, and the vertical wall. And a support wall projecting forward from the upper end of the above (claim 1). Further, another fish nest block of the present invention comprises a plurality of stages of bottom plates arranged at intervals in the vertical direction and a vertical wall connecting the rear edge portions of the bottom plates (claim 2). ..

In each of the fish nest blocks, a receiving wall extending in the left-right direction may be provided upright at the front edge of the bottom plate, and an escape route for aquatic organisms may be formed in a part of the receiving wall (claim). 3). Further, a blocking wall extending in the front-rear direction may be provided upright on the left edge, the right edge or the middle of the bottom plate, and an escape route for aquatic organisms may be formed on a part of the blocking wall (claim 4). .. The receiving wall or the blocking wall may be formed integrally with the bottom plate, or may be formed separately from the bottom plate and attached to the bottom plate (claim 5).

Further, it is preferable that at least a part of the surface is provided with irregularities (claim 6), and the following means can be exemplified. A plurality of convex portions or concave portions are integrally formed on the upper surface of the bottom plate. Mount multiple protrusions on the top surface of the bottom plate. The bottom plate, the receiving wall or the blocking wall, or the attachment to them is formed of water-permeable concrete having irregularities (claim 7). Since a part of the bottom plate, the receiving wall, the blocking wall, and the like are less loaded than the vertical wall and the supporting wall, there is no problem in strength even if they are made of water-permeable concrete. When the bottom board is made of water-permeable concrete, carbon, synthetic resin,
It is preferable to use a reinforcing bar that does not rust, such as stainless steel.

[0012]

The fish nest blocks according to the first aspect of the present invention can be stacked to construct a seawall, a drop construction, or can be arranged in a line to construct a fishway. When stacking, the bottom plate of the upper fish nest block can be placed and supported on the upper surfaces of the vertical wall and the support wall of the lower fish nest block. And
By changing the relative positions of the upper and lower fish nest blocks in the front-rear direction, it is possible to cope with revetments with different slopes and head drop construction.
Further, the fish nest block according to claim 2 can construct a revetment, a drop construction, etc. simply by arranging the fish nest blocks in a row.

Furthermore, the fish nest block according to the first or second aspect of the present invention forms a near-native fish nest suitable for inhabiting aquatic organisms such as fish, shellfish, and crabs for the following reasons. First, a shallow fish nest with a shallow depression is formed on the upper surface of the bottom plate. On the upper surface of the bottom plate, any one of gravel, cobblestone, and cobblestone (in this order, the size increases) may be laid singly or in a uniform height or in an uneven shape. In the sense of changing the fish nest, it is preferable to lay it in a concavo-convex shape by combining gravel, cobblestone, or cobblestone.

Further, since direct sunlight is appropriately applied to the fish nest from above the front edge of the bottom plate, the water temperature is appropriately increased, and an environment favorable for growth of aquatic plants such as aquatic plants and algae is formed. In addition, since the shade is appropriately formed below the support wall, it creates a good environment for resting aquatic organisms. Moreover, the fish nest has a very good water circulation, thus forming an environment rich in oxygen and nutrients.

Furthermore, in the fish nest block according to claim 1 or 2, since there is no barrier at the front edge of the bottom plate for the passage of aquatic organisms, when the water flow in the waterway is significantly reduced, It can easily pass over the front edge and escape from the fish nest.

According to the fish nest block of the third aspect, the receiving wall prevents the gravel, the crushed stones, or the cobblestones laid on the bottom plate from spilling forward, thereby stabilizing the environment of the fish nest. Moreover, since an escape route for aquatic organisms is formed in a part of the receiving wall, the aquatic organisms can escape from the fish nest through this escape route when the water flow rate of the canal decreases significantly.

According to the fish nest block of the fourth aspect, the blocking wall prevents lateral movement of the gravel, cobblestone, or cobblestone laid on the bottom plate, so that the environment of the fish nest is stabilized. Moreover, because an escape route for aquatic organisms was formed in a part of the blocking wall, when the water flow in the canal decreased significantly,
Aquatic organisms can escape from fish nests through this escape path.

Further, according to the fish nest block of the fifth aspect, since the receiving wall or the blocking wall is formed separately from the bottom plate, the receiving wall or the blocking wall is formed when the fish nest block is formed. The shape is simplified to the extent that there is not, and the design and demolding of the mold are facilitated.

According to the fish nest block of the sixth aspect, since at least a part of the surface of the fish nest block is made uneven, the surface area of the fish nest is increased and the natural riverbed condition is approached. Therefore, a fish nest close to nature suitable for habitation of aquatic organisms is formed without laying gravel, cobblestone, or cobblestone or reducing the laying amount. Further, when walking in a waterway, it is difficult to slip on the upper surface of the bottom plate, so that a slip accident can be prevented. Further, according to the fish nest block of claim 7, since the bottom plate, the receiving wall or the blocking wall or the attachment to them is formed of uneven water-permeable concrete, its porosity prevents oxygen and nutrition. Supply is improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A fish nest block according to a first embodiment of the present invention will be described below with reference to FIGS. This fish nest block 1 is molded into a shape as shown in FIG. 1 with concrete in which reinforcing reinforcing bars are embedded, and the thickness of each part is 200 mm. It should be noted that the dimensions of the respective parts listed below are examples, and can be appropriately changed.

This fish nest block 1 is provided with a horizontal bottom plate 2 formed in the shape of a rectangular plate, and its length in the left-right direction is 1980.
mm, the width in the front-back direction is 2000 mm. A vertical wall 3 extending in the left-right direction is integrally erected on the rear edge of the bottom plate 2,
The height from the bottom surface of the bottom plate is 1000 mm. Vertical wall 3
A support wall 4 horizontally projecting forward is integrally formed at the upper end of the, and the projecting width from the rear surface of the vertical wall is 1000 mm.

A receiving wall 5 extending in the left-right direction is integrally provided upright on the front edge of the bottom plate 2. The length in the left-right direction is 1830 mm, which is shorter than that of the bottom plate 2, and the height from the top face of the bottom plate is 3.
It is 00 mm. Therefore, an escape path 6 in the front-rear direction is formed on the right side of the receiving wall 5 at this front edge portion, and the opening width thereof is 150 mm.

A blocking wall 7 extending in the front-rear direction is integrally provided upright in the middle of the left edge of the bottom plate 2. The width in the front-rear direction is 1100 mm, which is shorter than that of the bottom plate 2, and the height from the top surface of the bottom plate is 2. It is 150 mm. Therefore, a left-right escape path 8 is formed between both ends of the blocking wall 7 and the vertical wall 3 and the receiving wall 5 at the left edge portion, and the opening width thereof is 250 mm.

Grooves are formed on the front surface 9 of the support wall 4 and the front surface 10 of the receiving wall 5 at intervals of 100 mm in the vertical and horizontal directions to form an uneven surface in a lattice pattern. This uneven surface contributes to improving the natural feeling of the landscape and fish nests. Further, the bottom plate 2 and the support wall 4 are formed with connection holes 11 for passing bolts that connect the fish nest blocks 1 when the fish nest blocks 1 are stacked vertically.

By using the fish nest block 1 of this embodiment, a seawall with a fish nest as shown in FIG. 2 can be constructed. In other words, 1 stones on the lower surface of the slope 15 of the waterway
6 is laid, and waste concrete 17 is cast on the cobblestone 16. On the upper surface of this waste concrete 17, a plurality of fish nest blocks 1 are placed and lined up with the rear surface of the vertical wall 3 facing the slope 15, and on the upper surface of the bottom plate 2 there are gravel, stones or boulders (hereinafter, stones). Etc. 18) are singly or combined and are laid at a uniform height or in a concavo-convex shape to form the first stage. At the position shifted rearward from the first stage, the second stage is similarly formed and the third stage is further formed.

Further, by using the fish nest block 1 of this embodiment, it is possible to construct a head structure with a fish nest as shown in FIG. That is, a stepped concrete base 14 is cast on the step of the riverbed 13 so as to extend in the transverse direction of the river. A plurality of fish nest blocks 1 are placed and lined up on the upper surface of each step of the concrete base 14 with the rear surface of the vertical wall 3 facing the upstream side, and the stones 18 and the like are laid on the upper surface of the bottom plate 2. As a result, the first stage, the second stage and the third stage are formed.

In the revetment or head drop construction, the fish nest blocks 1 in the second and third stages are sufficiently stabilized by their own weight.
However, if bolts (not shown) are connected to the connecting holes 11 of the upper base 2 and the lower support wall 4 to connect them, the displacement of the fish nest blocks 1 can be more reliably prevented.
Moreover, when riverbed scouring, ground subsidence, etc. occur, the fish nest blocks 1 can be connected in a flexible structure. Also, as shown in FIG. It is preferable that anchor rebars 19 fixed to the fish nest block 1 and protruding rearward are embedded in the concrete base 14 to prevent the fish nest block 1 from being displaced due to earth pressure and running water pressure.

The fish nest block 1 in the upper stage may be stacked directly above the fish nest block 1 in the lower stage, or may be stacked in a staggered manner. In either case, the bolts can be connected. Further, by changing the relative position of the upper and lower fish nest blocks 1 in the front-rear direction, the slope of the revetment or head drop can be easily changed.

Since the fish nest block of this embodiment is constructed as described above, it has the following actions and effects. (1) Due to the following reasons, it is possible to form near-native fish nests suitable for aquatic organisms such as fish, shellfish, and crabs over a wide area. On the upper surface of the bottom plate 2 of the fish nest block 1, a shallow and wide depression surrounded by the vertical wall 3, the receiving wall 5 and the blocking wall 7 is formed, and this depression forms a fish nest close to nature. Further, since this fish nest is formed for each fish nest block 1 in each stage, the total area thereof is extremely large.

Since the upper surface of the bottom plate 2 is horizontal, as described above, it is possible to lay the stone 18 or the like at a uniform height or in an uneven shape. The crushed stones 18 and the like are held on the upper surface of the bottom plate 2 because the receiving wall 5 prevents them from spilling forward and the blocking wall 7 prevents them from moving in the left-right direction. The cobblestones 18 thus retained form a favorable environment for activities of aquatic organisms, spawning, and the like.

Direct sunlight is appropriately applied to the fish nest between the upper end of the receiving wall 5 and the front end of the support wall 4, so that the water temperature is appropriately increased, and an environment suitable for growth of aquatic plants such as aquatic plants and algae is provided. To form. Since the shade is appropriately formed below the support wall 4, an environment good for resting aquatic organisms is formed. Since the fish nest is a shallow depression along the water stream, the water circulation is very good, forming an environment rich in oxygen and nutrients.

(2) Since the escape passages 6 in the front-rear direction are formed between the adjacent receiving walls 5, and the escape passages 8 in the left-right direction are formed on both sides of the blocking wall 7, the flow rate of the river Abundantly diminishes, aquatic life escapes from its nest 6,
8 to escape to a lower fish nest or waterway.

Next, in the fish nest block 1 of the second embodiment shown in FIG. 4, the receiving wall and the blocking wall are omitted, or
The receiving wall 5 and the blocking wall 7 are formed separately from the bottom plate 2,
It differs from the first embodiment in that it is attached to the bottom plate 2 with bolts 12. When the receiving wall and the like are omitted, aquatic organisms can easily pass through the upper part of the front edge of the bottom plate 2 and easily escape when the water is reduced as described above. Further, when the receiving wall 5 and the like are formed separately, when the fish nest block 1 is formed, the shape is simplified by the fact that the bottom plate 2 does not have the receiving wall 5 and the blocking wall 7, and Easy to design and demold.

Next, in the fish nest block 1 of the third embodiment shown in FIG. 5, square rod-shaped projections 21 are fitted in a plurality of vertically and horizontally mounted mounting grooves 20 formed on the upper surface of the bottom plate 2. Therefore, it is different from the first embodiment in that the bottom plate 2 is provided with irregularities. According to the present embodiment, the surface area of fish nests increases and approaches the state of a natural river bed, so that it is close to nature suitable for habitation of aquatic organisms even without laying stones or reducing the laying amount. A fish nest is formed. Further, when walking in a waterway, it is difficult to slip on the upper surface of the bottom plate, so that a slip accident can be prevented. When rubble stones and the like are laid, the protruding projections 21 extending in the front-rear direction act as blocking walls.

Next, in the fish nest block 1 of the fourth embodiment shown in FIG. 6, the concavo-convex plate 25 and the receiving wall 5 are formed separately from the bottom plate 2 by water-permeable concrete having irregularities. The point that the bottom plate 2 is indirectly roughened by forming a large number of quadrangular truncated pyramid-shaped convex portions 22 and concave portions 26 on the concave and convex plate 25. This is different from the one embodiment. The upper surface of the bottom plate 2 and the lower surface of the support wall 4 are tapered for easy demolding at the time of manufacturing. This embodiment has the same effects as those of the second and third embodiments, and the supply of oxygen and nutrients is improved due to the porosity of the water-permeable concrete.

Next, in the fish nest block 1 of the fifth embodiment shown in FIG. 7, the receiving wall 5 which is not heavily loaded is made of water-permeable concrete having irregularities, and the other parts are made of normal concrete. At the same time, it is different from the first embodiment in that the receiving wall 5 and the bottom plate 2 are made uneven by integrally forming a plurality of vertical and horizontal projections 23 on the upper surface of the bottom plate 2. This example has the same effects as the third example, and the supply of oxygen and nutrients is improved due to the porosity of the water-permeable concrete.

Next, in the fish nest block 1 of the sixth embodiment shown in FIG. 8, the receiving wall 5 and the two blocking walls 7 are formed separately from the bottom plate 2 by uneven water-permeable concrete. , The bottom plate 2
It is different from the first embodiment in that it is attached with bolts 12 and that the receiving wall 5 and the blocking wall 7 are provided with tunnel-shaped through holes 27 through which aquatic life can pass. This embodiment has the same effects as the fourth embodiment.

Next, in the fish nest block 1 of the seventh embodiment shown in FIG. 9, the upper half of the vertical wall 3 and the support wall 4 are formed separately from the lower half of the vertical wall 3 to form a vertical structure. Bolts 12 on the bottom half of wall 3
The two fixing walls 7 are integrally formed in the middle of the bottom plate 2 and the point fixed by the above, and the supporting projections 24 protruding from the central portions of both the closing walls 7 and the front edge of the supporting wall 4 come into contact with each other. Thus, the point that the weight of the support wall 4 is supported auxiliary is different from the first embodiment. This embodiment has the same effects as those of the second and third embodiments.

Next, the fish nest block 31 of the eighth embodiment shown in FIG. 10 will be described. This fish nest block 31 is formed by integrally forming three nests of fish nest blocks, and is provided with a three-tiered bottom plate 2 and an uppermost top plate 32, which are vertically arranged at a pitch of 1000 mm. Length is 200
The width in the front-rear direction is 0 mm and 1000 mm. The rear edges of the bottom plate 2 are connected by a tall vertical wall 3 formed integrally therewith. A receiving wall 5 extending in the left-right direction is integrally provided upright at the front edge of the bottom plate 2, and a front-rear escape path 6 is formed on the left and right sides thereof.

A support wall 33 for connecting and supporting the bottom plates 2 (or the bottom plate 2 and the top plate 32) is integrally provided upright at the center of the fish nest block 1 in the left-right direction, and the center of the middle of the support wall 33 is provided. A through hole 34 for aquatic life is formed therethrough. The support wall 33 may be omitted, or may be provided at one or both of the right end and the left end of the fish nest block 31, as shown by the chain line in the figure. A passage groove 36 is provided on the left side end surface of the bottom plate 2 of the second and third stages from the bottom so that aquatic organisms can move between the stages, and a fitting that fits the passage groove 36 shallowly on the right end face of the bottom plate 2. A mating protrusion 37 is provided. The number of steps of the bottom plate 2 can be changed appropriately.

By using the fish nest block 31 of the present embodiment, a seawall with a fish nest as shown in FIG. 11 can be constructed. That is, the concrete base 35 is placed on the lower upper surface of the slope 15 of the waterway, and the concrete base 3
The fish nest blocks 31 are placed and lined up on the upper surface of 5 in an inclined state. Crushed stones 18 and the like are laid on the upper surface of each bottom plate 2, but in this construction method, since the bottom plate 2 is inclined and the cobblestones 18 are biased toward the rear part, the upper surface of the bottom plate 2 is the same as in the third to sixth embodiments. It is preferable to make the uneven surface not to rely only on the stone 18 or the like. In addition, even if the receiving wall 5 is omitted, the stone 18 etc.
No spillage to the front of This embodiment has substantially the same operation and effect as the first embodiment except that the steps are not displaced in the front-rear direction and the left-right direction.

Next, in the fish nest block 41 of the ninth embodiment shown in FIG. 12, the point where the vertical wall 3 is inclined and the receiving wall 5 are formed separately from the bottom plate 2, and the bottom plate 2 is bolted. 12 is different from the eighth embodiment in that it is attached by means of 12, the support wall 33 is omitted, and an uneven member 38 made of water-permeable concrete is attached by means of bolts 12 on the upper surface of the bottom plate 2.
According to the present embodiment, since the vertical wall 3 corresponds to the slope of the slope, the bottom plate 2 is kept substantially horizontal, and it is easy to lay stones and the like.

The present invention is not limited to the configuration of the above-described embodiment, and can be embodied by appropriately changing it without departing from the spirit of the invention.

[0044]

EFFECTS OF THE INVENTION Since the fish nest block according to claims 1 to 4 of the present invention is constructed as described above, it can be used for revetment of waterways, head works, fishways, etc. It is possible to form a fish nest close to nature suitable for the aquatic life of, and when the water flow in the waterway decreases significantly,
It has an excellent effect that aquatic life can escape from the fish nest.

According to the fish nest block of the fifth aspect, the design and demolding of the mold can be facilitated when molding the fish nest block.

According to the fish nest block of the sixth aspect, a fish nest close to nature suitable for aquatic life can be obtained without laying gravel, chestnut or cobblestone or reducing the laying amount. As well as being formed, it is possible to prevent slipping accidents when walking in a waterway. Furthermore, according to the fish nest block of claim 7, the porosity of the water-permeable concrete improves the supply of oxygen and nutrients.

[Brief description of drawings]

FIG. 1 is a perspective view of a fish nest block according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a seawall with a fish nest constructed by the fish nest block.

FIG. 3 is a cross-sectional view of a drop structure with a fish nest constructed by the fish nest block.

FIG. 4 is a perspective view of a fish nest block of a second embodiment.

FIG. 5 is a perspective view of a fish nest block according to a third embodiment.

FIG. 6 is a perspective view of a fish nest block according to a fourth embodiment.

FIG. 7 is a perspective view of a fish nest block according to a fifth embodiment.

FIG. 8 is a perspective view of a fish nest block according to a sixth embodiment.

FIG. 9 is a perspective view of a fish nest block of a seventh embodiment.

FIG. 10 is a perspective view of a fish nest block of an eighth embodiment.

FIG. 11 is a cross-sectional view of a seawall with a fish nest constructed by the fish nest block.

FIG. 12 is a perspective view of a fish nest block of a ninth embodiment.

[Explanation of symbols]

1 Fish nest block 2 Bottom plate 3 Vertical wall 4 Support wall 5 Retaining wall 6 Escape path 7 Blocking wall 8 Escape path 20 Mounting groove 21 Convex projection 22 Convex section 23 Convex section 24 Supporting projection 25 Uneven plate 26 Recessed section 31 Fish nest block 38 Concavo-convex member 41 Fish nest block

Claims (7)

[Claims] 1. A fish nest block comprising a bottom plate, a vertical wall erected on a rear edge portion of the bottom plate, and a support wall protruding forward from an upper end of the vertical wall. 2. A fish nest block comprising a plurality of bottom plates vertically arranged at intervals and a vertical wall connecting rear edges of the bottom plates. 3. The fish nest block according to claim 1, wherein a receiving wall extending in the left-right direction is provided upright on the front edge of the bottom plate, and an escape path for aquatic organisms is formed in a part of the receiving wall. 4. A blocking wall extending in the front-rear direction is provided upright on the left edge, right edge or midway of the bottom plate, and an escape path for aquatic organisms is formed in a part of the blocking wall. The fish nest block described in 2. 5. The fish nest block according to claim 3 or 4, wherein the receiving wall or the blocking wall is formed separately from the bottom plate and is attached to the bottom plate. 6. The fish nest block according to claim 1 or 2, wherein at least a part of the surface thereof has irregularities. 7. The fish nest block according to claim 6, wherein the bottom plate, the receiving wall or the blocking wall, or an attachment to these is made of water-permeable concrete having irregularities.