Artificial fish bank

Abstract

To provide an artificial fish bank that creates an environment suitable for algae, aquatic plants, and fishes and shellfishes by intentionally creating a naturally occurring flow using a natural water flow (fluctuation or the like) and by supplying fresh water to the surface of the fish bank.SOLUTION: Provided is an artificial fish bank 1 in which a plurality of polygonal prism-shaped reef blocks 5 having a hexagonal or octagonal cross-sectional shape and set to a length of 3 to 10 times a cross-sectional width W are combined, and which includes a parallel reef unit 30 in which a plurality of reef blocks 5 are arranged in parallel on the same plane, with a water gap 6 between adjacent cross-sectional widths W that is 0.3 to 1 times the constant width, or a fish reef unit 2 having any of polygonal atoll units 40 in which multiple reef blocks 5 are arranged in a polygonal ring on the same plane. In the artificial fish reef 1, the fish reef unit 2 is a multistage parallel reef unit 3 in which a plurality of the parallel reef units 30 are stacked in a plurality of stages, and the upper and lower stages are arranged by mutually changing the direction by 90° around the vertical axis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to artificial fish reefs that are sunk into rivers and oceans and serve as breeding and living places, gathering places, hideouts, fishways, and seaweed beds for fish and shellfish, changing the water flow and stirring up nutrients from the bottom, leading to water quality that is rich in nutrients, as well as being able to be used as aquatic structures, part of a dike, wave-dissipating blocks, etc. [Background technology]

[0002] In the past, artificial reefs have been sunk to create undulating seabeds on the bottom of the water to provide feeding and habitat for fish and shellfish and to create beds for algae and aquatic plants in order to encourage the reproduction of fish and shellfish in the waters.

[0003] For example, Patent Document 1 (JP Patent Publication No. 60-251828) shows an algae and fish reef material which consists of several mounting legs which are fixed to a fish reef block which is sunk in the sea, and an umbrella-shaped top plate which is supported by these legs and extends above the block, the top plate being an algae growing bed with water holes, and which provides a preferred living space for fish by the shading effect of the algae breeding on the top plate.

[0004] Patent Document 2 (JP Patent Publication 2013-13357A) discloses a fish reef block formed as a rod-like body of an appropriate length, which is laid horizontally and stacked upwards to form a cubic artificial fish reef, with the structure having a roughly trapezoidal cross section with parallel upper and lower bases, making it easy to form habitats for tiny small fish and fry and habitats for large fish. It is easy to form ideal places for fish to live. Also, by creating habitats for tiny small fish and fry, it is possible to improve the survival rate of fry. This shows a fish reef block and an artificial fish reef that can expand the overall marine resources. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 60-251828 [Patent Document 2] JP 2013-13357 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the algae-fish reef material shown in Patent Document 1, once the algae that grows on the top plate reaches the end of its life and dies, it does not regenerate, and the shading effect is no longer obtained, and there is a concern that its function as a fish reef will be impaired. Artificial fish reefs with reduced functionality require maintenance such as cleaning underwater or being brought ashore for cleaning and then resetting on the bottom of the water, which increases maintenance costs.

[0007] Furthermore, the fish reef block and artificial fish reef shown in Patent Document 2 have a roughly trapezoidal cross section. When the fish reef block is sunk to the bottom of the water, all of the side walls are made of a single plane, making it difficult for seaweed and aquatic plants to settle. Furthermore, a number of fish reef blocks are connected to each other with fixing members and nuts to form a three-dimensional artificial fish reef, but no technology is disclosed for sinking a fish reef block that is not assembled three-dimensionally to the bottom of the water. If a single fish reef block were sunk as is, there was a concern that it would be buried in sediment within a short period of time.

[0008] Furthermore, amino acids are added to the fish reef blocks disclosed in Patent Document 2, giving them the function of attracting fish, shellfish, algae, etc. However, nutrients that attract organisms are not limited to amino acids, and there may be other more effective ingredients.

[0009] In view of the above circumstances, the present invention aims to provide an artificial fish reef that can serve as a cradle of life, a seaweed bed production site, a hiding place for fish, a fishway, and a source of nutrients for seaweed, aquatic plants, etc. Another objective of the present invention is to provide an artificial fish reef that can utilize the characteristics of water currents in various bodies of water such as the sea, rivers, and lakes to constantly supply fresh water to the surface of the fish reef, and that can intentionally create naturally occurring currents using natural currents (fluctuations, etc.) in the outside world, thereby creating an environment suitable for the habitation and reproduction of seaweed, aquatic plants, and fish and shellfish according to their respective characteristics. [Means for solving the problem]

[0010] In order to solve any of the above problems, the present invention provides an artificial fish reef to be installed underwater, characterized in that it is formed using reef units in which a number of long reef blocks formed with a hexagonal or octagonal cross-section of a constant width are arranged in a parallel or intersecting direction, and a gap for running water is secured between the reef blocks arranged in a line on the same plane. The present invention also provides an artificial fish reef equipped with a fish reef unit having either a parallel reef unit, in which a plurality of polygonal prism-shaped reef blocks, each having a hexagonal or octagonal cross-section of a certain width and a length set to 3 to 10 times the certain width, are combined together, and the plurality of reef blocks are arranged in parallel on the same plane, with a running water gap of 0.3 to 2 times the certain width between adjacent cross-sectional shapes of the certain width, or a polygonal atoll unit, in which a plurality of reef blocks are arranged in a polygonal ring on the same plane.

[0011] The reef block is formed in a polygonal column shape with a hexagonal or octagonal cross section. When the reef block is sunk to the bottom of the water, the side wall on one side of the cross section (polygon) becomes the bottom wall and the side wall on the opposite side of the cross section becomes the top wall. When the water current hits the side wall of the reef block, a downward flow that flows downward and an upward flow that rises are generated, and the downward flow picks up nutrient salts, algae spores, aquatic plant seeds, etc. that have sunk to the bottom of the water, and the upward flow flows smoothly along the top wall, and the stirred up nutrient salts, spores, seeds, etc. are dispersed in the water, changing the water area into a nutrient-rich environment. In particular, the reef block is preferably formed in a regular hexagonal or regular octagonal cross section, and the corners (edges) can also be formed in a rounded shape. However, it is desirable to round the corners to a degree that enables the naturally occurring flows (laminar flow, turbulent flow, Bernoulli effect, Coanda effect, etc.) to be intentionally created and that makes it easier for algae, aquatic plants, etc. to take root.

[0012] The reef block has a polygonal prism shape with a hexagonal or octagonal cross section, and disturbances (eddies) are generated at the edges, so seaweed can easily settle there. This is because living organisms (seaweed, etc.) tend to settle in places where there is water movement and current. Fresh, moving fluids also contain energy (oxygen, nitrogen, carbon dioxide, etc.). Diverse living organisms are likely to develop in places where water is moving. In particular, the trigger for creating a food chain in an ecosystem is the flow from the proliferation of phytoplankton to the proliferation of zooplankton that feeds on the phytoplankton. The reef block plays the role of a cradle of life. For this reason, the cross section of the reef block is hexagonal or octagonal, and preferably hexagonal. If the cross section of the reef block is triangular, the cross section (surface area) is more susceptible to external stresses due to its area ratio and inclination, and there is a possibility that it will be too strongly affected by the energy of the current. In this regard, a hexagon (six sides) in cross section is easier to balance in dispersing disturbances (energy) than a triangle (three sides), and can increase stability when installed. Also, a square (especially a regular square) can cause the sides of the reef blocks to come into close contact with each other when placed side by side, and a pentagon (especially a regular pentagon) can cause a loss of stability when stacked one on top of the other. And a decagon (especially a regular decagon) reduces disturbances (vortexes) at the edges.

[0013] The parallel reef unit has a water gap between the parallel reef blocks, and each water gap is a flow path along which water flows and is smoothly discharged, so that fresh water is always supplied. The water gap can be 0.3 to 2 times the width of the cross-sectional shape of the reef block, preferably 0.3 to 1 times the width, and particularly preferably 0.4 to 0.6 times the width. Furthermore, each water gap serves as a habitat for fish and shellfish. Seaweed also settles on the edge parts facing each water gap, and then the side walls also function as stable seaweed beds. If the width of the water gap is less than 0.3 times the width of the cross-sectional shape of the reef block, the amount of water flowing in is reduced, and there is a risk that a smooth water flow cannot be obtained. Furthermore, if it exceeds 2 times, there is a risk that the function as a hiding place for fish and shellfish is reduced.

[0014] In the polygonal atoll unit, a number of reef blocks arranged in a polygonal ring form a ring-shaped raised area on the bottom of the water, and when it is affected by currents, wind, waves, tides, etc. from 360° (front, back, up, down, left and right) like the ocean, the water current rises and falls regardless of the direction of the current, stirring the water current inside and outside the polygonal atoll unit and creating nutrient-rich water quality. Also, the inner edge of the polygonal atoll unit serves as a habitat for fish and shellfish.

[0015] The fish reef units may be either parallel reef units or polyhedral atoll units, or may include parallel reef units and / or polyhedral atoll units.

[0016] The present invention can be an artificial fish reef in which a plurality of the parallel reef units are stacked in multiple tiers, with the upper and lower tiers rotated by 90° around a vertical axis relative to each other.

[0017] It is believed that stacking in a three-dimensional grid pattern in two or more layers (three layers, etc.) is effective. Stacking the reef blocks three-dimensionally on the water bottom creates gaps (space) between the top and bottom of the reef blocks. They serve as a habitat for small fish and migratory fish, and also function as a more stable seaweed bed after the seaweed colonies have settled. Considering the efficiency of the settlement area of ​​seaweed, it is better to have a large surface area and not to make it too dense.

[0018] A fish reef unit, consisting of multiple parallel reef units stacked in multiple tiers, generates turbulence and vortexes in the water currents from 360° directions (front, back, up, down, left and right) (i.e., all directions), stirring up nutrients at the bottom of the water into the water and improving water quality. Fresh water always flows inside the parallel reef units stacked in multiple tiers. It provides a habitat for fish and shellfish. When each parallel reef unit in multiple tiers is rotated 90° between each tier, it can be stabilized against water currents, but when stacked by rotating them at an angle other than 90°, it is feared that it will lose stability early due to the influence of water currents and collapse before its lifespan.

[0019] The present invention can also be an artificial fish reef in which the length direction of each reef block of the parallel reef unit is inclined at an angle of 30° to 150° to the direction of the water flow. For example, when installing in a river or other area with a rapid current, the length direction of each reef block can be at a right angle (90°) to the direction of the water flow.

[0020] In rivers, differences in elevation easily generate the energy of unidirectional water currents flowing downstream. In fish reef units, each reef block of a parallel reef unit is arranged at an angle of 30° to 150° to the water flow, creating resistance to the water flow and disrupting it. When arranged perpendicular to the flow direction, the resistance is at its maximum. When in the range of 30° to 150°, it functions similarly to a kerep groyne. It is best to ensure that the length direction of each reef block is not parallel (0°) to the water flow.

[0021] When the length direction of each reef block of the parallel reef unit is tilted at an angle of less than 30 degrees to the direction of the water flow, the water flow passing through the gaps in the flow of water becomes strong, and it becomes unsuitable for fish and shellfish to live. In addition, there is a drawback in that the water flow is not disturbed much. Similarly, when the reef block is tilted at an angle of more than 150 degrees, the water flow passing through the gaps in the flow of water is likely to become strong, and there is a concern that the effect of disturbing the water flow is low.

[0022] The present invention can also be an artificial fish reef in which the fish reef unit is made up of a plurality of parallel reef units, with the longitudinal end walls of each reef block facing each other and connected in multiple rows.

[0023] The end walls of each reef block in the longitudinal direction are connected facing each other, and the fish reef units arranged in multiple rows form a fishway. It can mainly play a protective role on both sides of the river (bank). It can also be used as a habitat for slender, anadromous migratory fish such as eels. Fish habitats are created at the bottom of each flowing water gap. It also functions to slow down the flow speed in rapids. Gaps of the same gap size as the flowing water gap and oriented perpendicular to the flowing water gap can be provided between the front and rear end walls of each reef block. The meridian flowing water gap in the water flow direction and the latitudinal flowing water gap in the direction perpendicular to the water flow can be connected to each other in a net-like manner.

[0024] Fish reef units primarily focus on three-dimensional gaps. Ideally, they should be natural rock formations (biotope landscapes) that exist in the upstream areas of rivers in the natural world. These should be shorelines and lush grass areas that are ideal habitats for fish. Even in rapids, areas with gentle currents where fish can rest are essential. To meet these conditions, it is desirable for the reef blocks to have a regular hexagon or octagonal cross-section.

[0025] The present invention can also be used to create an artificial fish reef in which the fish reef unit is a multi-tiered atoll unit formed by stacking multiple polygonal atoll units in multiple tiers, one above the other, with each apex angle of one of the upper or lower polygonal atoll units positioned at a position equivalent to 1 / 2 the length of each reef block of the other polygonal atoll unit, either above or below.

[0026] There are various possible shapes for stacking in the ocean, but the point is to secure space. The aim is to create a synergistic effect between the role of the stacks as a habitat for migratory fish and the growth of seaweed. However, light is important for seaweed clusters, so the balance between water depth and vegetation must also be considered, with stacks being placed in shallow waters in oceans with low visibility and deep waters in oceans with high visibility.

[0027] Multi-tiered atoll units rise higher from the bottom of the water, and have a greater impact on water currents. They can become habitats and gathering places for larger fish and shellfish. In a structure in which multiple polygonal atoll units are stacked one on top of the other, the most stable structure is one in which the apex angles of either the upper or lower polygonal atoll units are positioned at a position equivalent to 1 / 2 the length of each reef block of either the upper or lower polygonal atoll units. Structures in which the apex angles of either the upper or lower polygonal atoll units are positioned at a position other than 1 / 2 the length of each reef block of either the upper or lower polygonal atoll units are prone to losing stability and collapsing.

[0028] The present invention can be an artificial fish reef in which the fish reef unit is made up of a plurality of large and small multi-tiered atoll units each using a different number of reef blocks, with the larger multi-tiered atoll units surrounding the outer periphery of the smaller multi-tiered atoll units.

[0029] The purpose of the system is to create an appropriate gap to secure countless spaces of various sizes, and random spaces when stacked. Combining small and large multi-atoll units makes the structure more complex, and can generate more complex water currents. Fish and shellfish habitats are also formed between the small and large multi-atoll units.

[0030] In the present invention, the reef block is made of a mixture of inorganic and organic matter, and the inorganic matter can be cement sand, stones, etc., and the organic matter can be aged humus, etc. The organic matter promotes the establishment of seaweed and aquatic plants, etc., and the artificial fish reef promotes the deterioration of the reef block over time so that the seaweed and aquatic plants will collapse and return to sand as the lifespan of the seaweed and aquatic plants expires.

[0031] The organic matter functions as a nutrient (supplement) for cultivating the sea. As it ages (deteriorates), it creates a state in which it returns to sand (reduction). Although it is a structure, it does not need to be very strong, so it is best to use something (mainly sand) that will return to the sea or rivers after a useful life of about 5 to 8 years, which is in line with the algae cycle. It is known that the growth of seaweed, aquatic plants, etc. in the natural world is related to organisms of living organisms (such as matured humus) and ions.

[0032] The structure that accelerates the deterioration of the reef blocks over time and collapses as the seaweed and aquatic plants die out can be a structure to which organic matter such as mature humus has been added, as mentioned above, or a structure to which granular or powdery material that is more susceptible to deterioration over time than concrete has been added.

[0033] Reef blocks containing mature humus as organic matter dissolve the components of the mature humus into the water, promoting the growth of seaweed and aquatic plants, and the organic matter accelerates the deterioration of the reef blocks over time. When the seaweed and aquatic plants reach the end of their lifespan, the reef blocks collapse and become sand on the bottom of the water. No maintenance such as cleaning or repairs is required. After use, the blocks collapse, making it easy to install new ones. It shall be so.

[0034] In the present invention, the fish reef unit can be placed horizontally on a frame installed on the bottom of the water. The frame can be composed of a beam that supports the reef blocks that constitute the reef unit in a horizontal state and a support that supports the beam upright from the bottom of the water. Furthermore, the frame can be a structure integrated with four supports and four beams that are horizontally installed below the upper ends of each of the four supports by a distance equivalent to the length of one side of the cross-sectional shape of the reef block.

[0035] In the ocean, the ocean is in a constant state of disturbance due to the influence of 360° vertical and 360° horizontal (front, back, up, down, left and right) currents, wind, waves, tide levels, etc. When underwater, they are placed on a pedestal (the frame mentioned above). Spaces (gaps) are left and they are not arranged too closely together. The reason for leaving gaps is to ensure a constant supply of fresh water to the surface. Also, it is preferable to intentionally create a naturally occurring flow (laminar flow, turbulent flow, Bernoulli, Coanda effect, etc.) that utilizes the natural flow of the outside world (fluctuations, etc.).

[0036] The reef blocks are polygonal pillars with hexagonal or octagonal cross sections turned on their side. When water flows along the length of the top wall, an upward current is generated where the frame is in contact with the ground, which causes spores that have accumulated on the bottom of the water to rise and promotes the establishment of algae on the reef blocks. This makes it easier for seaweed to settle and continues to supply nutrients even after they have grown.

[0037] The frame supports the parallel reef units in water and allows water to flow above and below the parallel reef units. Sunlight reaches the top of the parallel reef units, making it easier for algae and aquatic plants to take root. The bottom of the parallel reef units, where algae and aquatic plants have taken root and the sunlight is blocked, becomes a habitat for fish and shellfish. The frame can be made of the same material as the reef blocks and configured to deteriorate with age and collapse at the same time that the algae and aquatic plants die. The frame can carry the parallel reef units in a horizontal state on two opposing beams among the four beams. The frame can also have four beams that are horizontally placed between the four supports, each lower than 1 / 2 of the dimension between the top and bottom ends. The frame can carry the parallel reef units in a horizontal state on two opposing beams among the four beams and two opposing beams among the four beams. Effect of the Invention

[0038] The artificial fish reef of the present invention can intentionally create a naturally occurring flow by utilizing the natural flow (such as fluctuations) of the outside world, making it easier for algae and aquatic plants to settle. The gaps between the reef blocks where the flowing water can flow can become habitats for fish and shellfish. It can have the excellent effect of stirring up the water flow and stirring up nutrients, spores, seeds, etc. that sink to the bottom of the water, improving the surrounding water quality. [Brief description of the drawings]

[0039] [Figure 1] (a) A perspective view of the artificial reef with parallel reef units placed on the frame. (b) Three-view of the frame. [Diagram 2] (a) Photograph of an artificial reef with one tier of parallel reef units (fish reef units) placed on a frame. (b) Photograph of an artificial reef with two tiers of parallel reef units (fish reef units) placed on a frame. [Diagram 3] (a) A photograph of a fish reef unit with two layers of parallel reef units. (b) A photograph of a fish reef unit with three layers of parallel reef units. (c) A photograph of a fish reef unit with three layers of densely packed reef blocks. [Figure 4] (a) A photograph of a four-tiered small multi-tier atoll unit. (b) A photograph of a two-tiered large multi-tier atoll unit. (c) A photograph of an artificial reef made up of a combination of large and small multi-tier atoll units. [Diagram 5] (a) Photograph of an artificial reef consisting of parallel reef units inclined toward the river flow direction F. (b) Photograph of an artificial reef consisting of parallel reef units sunk into the water bottom that has a slope (uplift) in some parts. [Figure 6] (a) Photograph of an undesirable artificial reef 8. (b) Photograph of an undesirable artificial reef 8. (c) Photograph of an undesirable artificial reef 8. (d) Photograph of an undesirable artificial reef 8. [Figure 7] (a) Photograph of an undesirable artificial reef 8. (b) Photograph of an undesirable artificial reef 8. [Figure 8] (a) A regular hexagonal cross-section of a reef block. (b) A regular octagonal cross-section of a reef block. (c) An equilateral triangular cross-section of an undesirable reef block. (d) A square cross-section of an undesirable reef block. (e) A regular pentagonal cross-section of an undesirable reef block. (f) A regular heptagonal cross-section of an undesirable reef block. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The artificial fish reef according to this embodiment will be specifically described below with reference to the drawings. In particular, this embodiment can be installed in various bodies of water, such as mountain streams, rivers flowing through plains, drains and irrigation channels, lakes, swamps, and the sea. This artificial fish reef can be sunk by a small number of people or using a small-scale crane or the like. However, the artificial fish reef of the present invention is not limited to the following embodiment, and can be large or small.

[0041] As shown in Figures 1 and 2, in the artificial reef 1 of this embodiment, a fish reef unit 2 having parallel reef units can be placed horizontally on a frame 7 installed on the bottom of the water. Each reef block 5 of the fish reef unit 2 can be mounted in a position arranged on the same horizontal plane.

[0042] As shown in Figures 1 and 2(a), the fish reef unit 2 can be a parallel reef unit 30 in which a number of reef blocks 5 are arranged in parallel on the same plane, and a water flow gap 6 of 0.3 to 2 times the constant width W is provided between adjacent cross-sectional shapes of the constant width W.

[0043] As shown in Figures 1 and 8(a) and (b), the reef block 5 may be a polygonal prism having a regular hexagonal or regular octagonal cross section with a constant width W and a length L set to 3 to 10 times the constant width W. For example, the reef block 5 may be a regular hexagonal cross section, with the constant width W being 100 to 300 mm, preferably 200 mm, and the length L being 300 to 2,000 mm, preferably 1,000 mm.

[0044] The reef block 5 is a mixture of inorganic and organic matter, and may include cement and sand as inorganic matter, and mature humus as organic matter.

[0045] The cement paste used to make the reef block 5 is preferably mixed so that the mixing ratio of the sand and organic matter to the cement is greater than the mixing ratio of aggregate to cement in normal concrete. If the reef block contains more aggregate than normal, it can accelerate deterioration over time so that it will disintegrate along with the lifespan of seaweed and aquatic plants (in 5 to 8 years) when submerged in water.

[0046] The cement paste used to make the reef blocks 5 can be mixed with a higher ratio of water to cement than that of regular concrete. By containing more water than usual, the reef blocks can be accelerated to deteriorate over time after manufacture so that they will disintegrate along with the lifespan of seaweed and aquatic plants (in 5 to 8 years).

[0047] As shown in Figure 8(b), the reef block 5 may have a regular octagonal cross section. In the case of such a regular octagonal shape, the side surface has flat portions extending in the vertical direction, which become resistant to the water current and are easily affected by the water current.

[0048] As shown in Figures 8(c) and (d), reef blocks 9 whose cross-sectional shape is an equilateral triangle or square (rectangle) have flat side walls 90 and few edges, making it difficult for seaweed and aquatic plants to take root. As shown in Figures 8(e) and (f), reef blocks 9 whose cross-sectional shape is a regular pentagon or regular heptagon have an apex angle 92 on the top wall 91, making them unstable when stacked. Furthermore, if the cross-sectional shape is a polygon exceeding a regular octagon, the area of ​​the bottom wall 93 becomes narrow, making stable installation difficult.

[0049] As shown in Fig. 8(a), the reef block 5 has a hexagonal column shape with a regular hexagonal cross section, and has side apex angles 52a on both side walls 52. The top wall 53 and the bottom wall 54 can be installed horizontally. The areas of the top wall 53 and the bottom wall 54 can be set larger.

[0050] As shown in Fig. 8(b), the reef block 5 has a regular octagonal cross section and has four side apex angles 52a on both side walls 52. The top wall 53 and the bottom wall 54 can be installed horizontally.

[0051] As shown in Figures 2(b) and 3(a) and (b), the fish reef unit 2 can be a multi-tiered parallel reef unit 3 in which a plurality of the parallel reef units 30 are stacked in multiple tiers, with the upper and lower tiers rotated by 90 degrees around the vertical axis. For example, it can be two tiers, one above the other, as shown in Figure 3(a), or three tiers, one above the other, as shown in Figure 3(b). Also, as shown in Figure 3(c), a unit that does not have a water flow gap 6 between each reef block 5 is not very effective because water does not flow.

[0052] The underframe 7 according to this embodiment has a depth D7 that is 55% to 90% (550 to 900 mm) of the length L of the reef block 5, and can be set to, for example, 750 mm. The width W7 is 90% to 160% (900 to 1600 mm) of the length L of the reef block 5, and can be set to, for example, 1500 mm.

[0053] The frame 7 has four pillars 70 with a length L (1,000 mm) corresponding to the reef block 5, erected at each of the rectangular corners. Four crosspieces 71 are horizontally connected between the middle parts of each of the four pillars 70, slightly lower than half the dimension between the upper and lower ends. Four beams 72 are horizontally connected between the upper ends of each of the four pillars 70 and a position below the length S (100 mm) of one side of the cross-sectional shape of the reef block 5. The framework of each of the pillars 70, crosspieces 71 and beams 72 may be a rectangular column with a square cross section with one side of 100 mm. The frame 7 may be made of the same material as the reef block 5. However, the size of the frame may be changed as desired depending on the installation location and purpose.

[0054] The parallel reef unit 30 shown in Figures 1 and 2(a) can itself be the artificial reef 1. The multi-stage parallel reef unit 3 (fish reef unit 2) shown in Figures 2(b) and 3(a) and (b) can itself be the artificial reef 1.

[0055] The fish reef unit 2 may have a polygonal atoll unit 40 in which a plurality of reef blocks 5 are arranged in a polygonal ring shape on the same plane. The polygonal atoll unit 40 may itself become an artificial fish reef 1. The fish reef unit 2 may be a multi-tiered atoll unit 4 in which a plurality of the polygonal atoll units 40 are stacked up and down in multiple tiers, with each apex angle 401 of one of the upper or lower polygonal atoll units 40 being positioned at a position equivalent to 1 / 2 the length L of each reef block 5 of the other polygonal atoll unit 40. The multi-tiered atoll unit 4 may itself become an artificial fish reef 1.

[0056] As shown in Figure 4(a), the multi-tiered atoll unit 4 can be configured with three polygonal atoll units 40 stacked one above the other, with three reef blocks 5 arranged to form a triangular shape in plan view. Also, as shown in Figure 4(b), the multi-tiered atoll unit 4 can be configured with two polygonal atoll units 40 stacked one above the other, with six reef blocks 5 arranged to form a hexagon in plan view.

[0057] As shown in Figure 4(c), the fish reef unit 2 can be arranged with multiple large and small multi-tiered atoll units 4 using different numbers of reef blocks 5, with the larger multi-tiered atoll units 4 surrounding the outer periphery of the smaller multi-tiered atoll units 4. The small multi-tiered atoll units 4 can be two-tiered, one above the other, of polygonal atoll units 40, with three reef blocks 5 arranged to form a triangular shape in plan. The large multi-tiered atoll unit 4 can be two-tiered, one above the other, of polygonal atoll units 40, with six reef blocks 5 arranged to form a hexagon in plan.

[0058] As shown in FIG. 5(a), the fish reef unit 2 can be an artificial fish reef 1 in which a plurality of parallel reef units 30 are provided, and the end walls 50 of each reef block 5 are arranged facing each other in a row. The parallel reef units 30 can be arranged with the adjacent reef blocks 5 offset in the length direction. The fish reef unit 2 can be an artificial fish reef 1 in which the length direction of each reef block 5 of the parallel reef units 30 is inclined by 30° to 150° with respect to the water flow direction F. A gap of the same size as the flowing water gap 60 can be provided between the front and rear end walls 50 of each reef block 5. A flow path can be formed by the meridian flowing water gap 6 along the water flow direction and the latitudinal flowing water gap 60 in the direction crossing the water flow (only the arrangement position is shown in FIG. 5(b) because no gap is provided). For example, as shown by an upside-down metal container in the photograph of Figure 5(b), the parallel reef units 30 of the artificial reef 1 can be placed on a convex topography such as rocks on the bottom of the water, and can be submerged in a state where part or all of the unit is inclined to follow the topography.

[0059] As shown in Figure 6(a), it is possible to make an artificial fish reef 8 by stacking multiple reef blocks 5 in a roughly triangular prism shape, but considering the efficiency of the area for seaweed to attach and the habitat of fish and shellfish, it is better to increase the surface area and not make the blocks too dense. The less effective artificial fish reefs 8 shown in Figures 6(b), (c), and (d) and Figures 7(a) and (b) all have no gaps for running water (6) and the reef blocks 5 are too densely packed together. These are examples of reefs that quickly become buried in sand or do not function well as resistors (water current disruptors). [Industrial Applicability]

[0060] The artificial fish reef of the present invention can be used not only for constructing artificial fish reefs in the sea or rivers, but also for groynes, bed hardening, wave dissipation, erosion control, vegetated bank protection, fishway, etc. [Explanation of symbols]

[0061] 1 Artificial reef 2. Fish Reef Unit 3. Multi-stage parallel reef unit 30 Parallel Reef Unit 4. Multi-Atoll Unit 40 Polycyclic Atoll Unit 401 Vertical angle 5 Reef Blocks 50 End wall 51 Same multilayer film 52 Side wall 52a Same side apex angle 53 Same ceiling wall 54 Bottom wall W Same constant width L Length of reef block 5 S: Length of one side of the cross section 6. Water gap F. River flow direction α Incline angle 7 Frame D7 Same depth W7 Same width 70 Same pillar 71 Same 72 Same beam 8. Ineffective artificial reefs 9 Inactive Reef Blocks 90 Side wall 91 Same ceiling wall 92 Vertical angle

Claims

1. An artificial reef installed underwater, comprising: A plurality of long reef blocks formed into a hexagonal or octagonal cross section of a certain width are arranged in parallel or intersecting directions, This artificial fishing reef is characterized in that it is formed using reef units in which gaps for running water are secured between the reef blocks arranged side by side on the same plane.

2. An artificial fish reef as described in claim 1, wherein the fish reef unit is arranged in multiple rows, with the longitudinal direction of each reef block arranged in a line at an angle of 30° to 150° to the direction of the water flow, and the longitudinal end walls of each reef block are connected facing each other.

3. The artificial fish reef of claim 1, wherein the fish reef unit is a polygonal atoll unit consisting of a plurality of small blocks arranged in a polygonal ring on the same plane, and a plurality of the polygonal atoll units are stacked one on top of the other in multiple tiers, with each apex angle of one of the upper or lower polygonal atoll units being positioned at a position equivalent to 1 / 2 the length of each reef block of the other polygonal atoll unit.

4. The reef unit is further provided with a frame installed on the bottom of the water, the reef unit being placed on the frame in a horizontal manner, An artificial fish reef described in any one of 1 to 3, wherein the frame comprises beams that support the reef blocks that constitute the reef unit in a horizontal position and pillars that support the beams upright from the bottom of the water.

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