JP6871599B2 - Fishway and fishway formation method - Google Patents

Description

The present invention relates to a fishway and a fishway forming method that are installed in a waterway such as a river and assist the run-up of fish.

Among migratory fish, there are many species that move widely from the sea area to the upper reaches of rivers. In addition, even pure freshwater fish that spend their entire lives in rivers usually live while moving in different water areas. When constructing dams and weirs, fishways are often constructed as a space for fish to move so that the movement of fish is not hindered and the ecosystem is not significantly affected.

As for the fishway, various ideas have been proposed to create an environment in which various fish species can move more easily.
For example, the applicant proposes to install a blocking plate in the fishway to form a region where the water flow is gentle and assist the fish in running up (see Patent Documents 1 and 2).
Further, on the revetment wall provided on the downstream side of the fixed weir, the revetment side edge of the side plate arranged so as to be inclined from the top of the weir toward the downstream riverbed is engaged with the revetment wall, and the waterway side edge of the side plate is connected to the connecting member. A simple fishway device has been proposed in which a plurality of partition walls are provided at intervals in a groove formed by the revetment wall and the side plate while supporting the fishway away from the revetment wall (see Patent Document 3).
Further, the bottom portion becomes a V-shaped groove, and the water channel member having connecting portions at the upstream end and the downstream end are fixed to each other in the V-shaped groove of the water channel member, and a notch is provided at the top. An assembled fishway having a plurality of partition plates and having notches of adjacent partition plates formed at different positions on the left and right in the water flow direction has been proposed (see Patent Document 4).
In addition, in a fishway that has a river bottom consisting of slopes and has two side walls that determine the width of the waterway, a fishway with a groyne uneven part that slows down the flow of water on the side of the side wall on the waterway side is proposed. (See Patent Document 5).
However, although these fishways are expected to have a certain effect on swimming fish such as sweetfish and char, they are too large to assist the run-up of demersal fish, which are more susceptible to the influence of water flow during swimming. There is a problem that the effect cannot be expected.

By the way, the inventor of the present application has taken up sculpin as a representative of demersal fish and the like that are easily affected by the flow of water, observed swimming movements using a waterway model, and reported problems with run-up (non-patent). Reference 1).
That is, for Kajika, (1) a swimming method in which the head is lifted from the bottom, the head jumps diagonally upward forward, and then the bottom is landed in an arc, and (2) a swimming method in which the body is kept horizontal and crawls on the bottom. As a result of selecting the swimming methods (1) and (2) regardless of the flow velocity in the water channel, if the water flow is not sufficiently gentle, the swimming method of (1) above is performed. It was confirmed that when the water flowed up diagonally forward and upward, the balance was lost due to the flow of water received in the abdomen, and the water was pushed back in the downstream direction.
Therefore, it is assumed that the fishway that only relaxes the flow velocity to a certain extent cannot be expected to have the effect of assisting the run-up.

In addition, since the number of fishways required is enormous and there are labor and cost restrictions on construction, it is difficult to take measures for all necessary parts by the conventional method.
Therefore, it can be said that there is a demand for a new type of fishway that can be constructed easily and at low cost and can assist the run-up of fish from a viewpoint different from relaxing the flow velocity.

JP-A-2007-32175 Japanese Unexamined Patent Publication No. 2010-163866 Jikkenhei 6-46036 Gazette Utility Model Registration No. 3117678 Japanese Unexamined Patent Publication No. 2001-348851

KEIKO MURAOKA, SATORU NAKANISHI, YUICHI KAYABA, “BOULDER ARRANGEMENT ON A ROCK RAMP FISHWAY BASED ON THE SWIMMING BEHAVIOR OF FISHES”, Proceeding of 10th International Symposium on Ecohydraulics 2014, 2014.8, “Slide Material”

An object of the present invention is to provide a fishway and a fishway forming method that can solve the above-mentioned problems in the prior art, can be constructed easily and at low cost, and can facilitate the run-up of fish.

As a result of diligent studies by the inventor of the present application in order to solve the above problems, the following findings were obtained.
That is, when a fishway is formed so as to cover the first surface on which the demersal fish or the like is localized with the second surface, the fishway is drawn diagonally upward and forward while lifting the head from the bottom of (1) above. As a result, the swimming method of crawling on the bottom while keeping the body of the above (2) horizontal enables stable run-up.
Further, when demersal fish and the like do not gather in the fishway formed in this way, although the effect cannot be expected, the first surface is inclined from the in-plane direction to the first surface from one end side to the other end side. When the second surface is formed so as to approach each other, the habit of approaching the narrowed part on the other end side of the demersal fish or the like is confirmed, and the swimming method of (1) above is suppressed, and the swimming method of (2) above is adopted. The guiding effect becomes effective.
Further, such an effect can be obtained only by forming the first surface and the second surface, and can be constructed easily and at low cost. In addition, the fishway constructed in this way can also be applied to existing fishway structures such as water flow deceleration members and stair-type fishways, and the construction effort is compared to the case of reconstructing a new fishway. And the cost burden can be reduced.

The means for solving the above-mentioned problems are as follows. That is,
<1> The first surface formed in the water channel and the entire surface of the first surface located on the water surface side of the water channel with respect to the first surface at a position facing the normal direction of the first surface. Alternatively, with a second surface formed in the water channel so as to cover a part of the first surface and incline toward the in-plane direction of the first surface and approach the first surface from one end side to the other end side. The second surface is composed of an extending portion extending from the other end side itself or the other end side toward the first surface, and the first surface and the other of the second surface. It has a narrow portion that regulates the movement of fish to and from the end side, and at least one of the first surface and the second surface is composed of an artificial structure, and the first surface is composed of an artificial structure. A space extending along the other end side of the second surface as a space defined by the surface, the second surface, and the narrow portion on the opposite surface side of the first surface and the second surface. A fishway provided , wherein an angle formed by the first surface and the second surface itself or an extended surface of the second surface is more than 0 ° and 20 ° or less.
<2> In the <1> where at least a part of the other end side of the second surface itself or the extending portion extending from the other end side toward the first surface is supported by the first surface. The fishway described .
< 3 > The fishway according to any one of <1> to <2> above, wherein the roughness formation is arranged on the opposite surface side of at least one of the first surface and the second surface.
< 4 > The first surface is parallel to the bottom wall, and the other end side of the second surface is arranged on the upstream side of the waterway with respect to one end side of the second surface. The fishway according to any one of <1> to <3 >, wherein the extending direction on the other end side of the surface 2 is a direction inclined with respect to the water flow direction of the water channel.
< 5 > The first surface is parallel to either the inclined surface or the vertical surface whose position on the downstream side is lower than that on the upstream side, and the other end side of the second surface is the second surface. The extending direction of the other end side of the second surface is the flow direction of water on either the inclined surface or the vertical surface so as to be arranged on the water surface side of the water channel with respect to one end side of the water channel. The fishway according to any one of <1> to <3 >, which is considered to be in an inclined direction with respect to the fishway.
< 6 > The fishway according to any one of <1> to <5 >, wherein at least one of the first surface and the second surface is composed of the existing waterway structure itself.
< 7 > The fishway according to any one of <1> to <5 >, which is composed of a flexible resin material in which a first surface, a second surface, and a narrow portion are integrally formed.
< 8 > The fishway according to any one of <1> to <5 >, which is configured as an inner wall of a cylinder.
< 9 > A block-shaped fishway structure that is arranged so as to project from the quay of the waterway in the width direction of the waterway is bored between the upstream side surface and the downstream side surface of the waterway in the fishway structure. The fishway according to any one of <1> to <5 >, which is configured as an inner wall of a through hole.
< 10 > The fishway according to <9 > above, wherein the through hole is formed in a direction inclined with respect to the water flow direction of the water channel.
< 11 > The first surface formed in the water channel and the entire surface of the first surface located on the water surface side of the water channel with respect to the first surface at a position facing the normal direction of the first surface. Alternatively, with a second surface formed in the water channel so as to cover a part of the first surface and to be inclined in the in-plane direction of the first surface and approach the first surface from one end side to the other end side. The second surface is composed of an extending portion extending from the other end side itself or the other end side toward the first surface, and the first surface and the other of the second surface. With a narrow portion that regulates the movement of fish to and from the end side, at least one of the first surface and the second surface is composed of an artificial structure, and the first surface, said. The second surface and the narrow portion extend along the other end side of the second surface as a space defined on the opposite surface side of the first surface and the second surface . It is characterized in that a fish channel having an angle formed by the first surface and the second surface itself or an extended surface of the second surface is more than 0 ° and 20 ° or less is formed in the waterway. How to form a fishway.

According to the present invention, there is provided a fishway and a fishway forming method that can solve the above-mentioned problems in the prior art, can be constructed easily and at low cost, and can facilitate the run-up of fish. Can be done.

It is a perspective view which shows the fishway which concerns on 1st Embodiment. It is a partial cross-sectional view in the width direction of the waterway of the fishway shown in FIG. It is explanatory drawing explaining the fishway which concerns on 2nd Embodiment. It is explanatory drawing explaining the fishway which concerns on 3rd Embodiment. It is explanatory drawing explaining the fishway which concerns on 4th Embodiment. It is explanatory drawing explaining the fishway which concerns on 5th Embodiment. It is explanatory drawing explaining the fishway which concerns on 6th Embodiment. It is explanatory drawing explaining the fishway which concerns on 7th Embodiment. It is a perspective view which shows the fishway which concerns on 8th Embodiment. It is a partial cross-sectional view in the water flow direction of the waterway of the fishway shown in FIG. It is explanatory drawing explaining the fishway which concerns on 9th Embodiment. It is explanatory drawing explaining the fishway which concerns on tenth embodiment. It is explanatory drawing explaining the fishway which concerns on eleventh embodiment. It is a perspective view explaining the fishway which concerns on 12th Embodiment. It is an end view seen from the arrow direction of FIG. It is a figure (1) which shows the modification of the fish path which concerns on 12th Embodiment. It is a figure (2) which shows the modification of the fish path which concerns on 12th Embodiment. It is a figure (3) which shows the modification of the fish path which concerns on 12th Embodiment. It is explanatory drawing explaining the fishway which concerns on 13th Embodiment. It is explanatory drawing explaining the fishway which concerns on 14th Embodiment. It is explanatory drawing explaining the fishway which concerns on 15th Embodiment. It is explanatory drawing explaining the fishway which concerns on 16th Embodiment. It is a top view (top view) which shows the outline of a waterway model. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 23 (a). FIG. 2 is a cross-sectional view taken along the line BB in FIG. 23 (a). It is explanatory drawing which shows the outline of the fishway forming member. It is a figure which shows the cross section of the fish path at the position corresponding to FIG. 23 (c). It is a graph which shows the relationship between the flow velocity and the head lifting rate. It is a graph which shows the relationship between the flow velocity and the number of successful movements (the number of successful run-ups).

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. It should be noted that these embodiments show examples of embodiments of the present invention, and the idea of the present invention is not limited to these embodiments.

First, the fishway according to the first embodiment will be described with reference to FIGS. 1 and 2. Note that FIG. 1 is a perspective view showing a fishway according to the first embodiment, and FIG. 2 is a partial cross-sectional view of the fishway shown in FIG. 1 in the width direction of the waterway.

As shown in FIGS. 1 and 2, the fishway 3 according to the first embodiment is formed of a plate-shaped member and a first surface 1 formed by arranging a plate-shaped member on the bottom wall 4 of the water channel. The first surface 1 is located on the water surface side of the water channel at a position facing the normal direction of the first surface 1 and covers all or a part of the first surface 1 and the first surface 1. It has a second surface 2 formed in the water channel so as to be inclined in the in-plane direction of the water channel and approach the first surface 1 from one end side to the other end side. Reference numeral 5 in the figure indicates a quay.

The size of the first surface 1 is not particularly limited and may be appropriately selected depending on the intended purpose, and may be formed by a bottom wall 4 or the like as described later.
The length of the second surface 2 on the other end side, that is, the length of the fishway 3 in the extending direction is not particularly limited and may be appropriately selected depending on the intended purpose.
There is no particular upper limit to the length of the second surface 2 from the one end side to the other end side, but if it is too short, while lifting the head of a demersal fish or the like localized on the first surface 1. After jumping diagonally forward and upward, the effect of suppressing the swimming method of landing in an arc may be insufficient, and the lower limit is 12 considering the case of targeting fry such as demersal fish. It is preferably 5.5 mm or more, and more preferably 30 mm or more. In other words, the length of the second surface is preferably at least the extent to which the demersal fish and the like are hidden when viewed from above.

In the fishway 3, the other end side of the second surface 2 is in contact with the first surface 1 and is formed as a plate-shaped member forming a V shape between the first surface 1 and the second surface 2. , The V-shaped groove formed by the contact between the first surface 1 and the other end side of the second surface 2 moves the demersal fish or the like between the first surface 1 and the second surface 2. It is said to be a narrow part that regulates.
Further, the fishway 3 is a space defined on the opposite surface side of the first surface 1 and the second surface 2 by the first surface 1, the second surface 2, and the narrow portion in the waterway. It extends along the other end side of the surface 2 of 2. In the present embodiment, the formation direction of the other end side of the second surface 2, that is, the direction in which the fishway 3 is extended is the direction opposite to the water flow direction of the water channel (see the arrow in FIG. 1). It is said that.

In the fishway 3 formed in this way, when the demersal fish or the like runs upstream to the upstream side against the flow direction of the water in the waterway, the first surface 1 and the in-plane direction of the first surface 1 The second surface 2 formed in the waterway so as to be inclined and approach the first surface 1 from one end side to the other end side narrows toward the narrow portion (V-shaped groove). Demersal fish such as sculpins gather on the round fishway 3, and the demersal fish and the like are localized on the first surface 1 (see FIG. 2).
After lifting the head of the demersal fish or the like localized on the first surface 1 and jumping forward and diagonally upward, the swimming method of landing in an arc is suppressed, and the demersal fish or the like keeps the body horizontal. By swimming in a swimming method that crawls on the bottom as it is, it is possible to move in the fishway 3 in a stable posture.

The angle θ formed by the first surface 1 and the second surface 2 is not particularly limited, but is preferably more than 0 ° and 40 ° or less. When the temperature exceeds 40 ° on the upper limit side, the head of the demersal fish or the like jumps out diagonally upward and forward, and then the bottom is landed in an arc. The demersal fish or the like is in a stable posture in the fishway 3. May not be able to move. Further, it is particularly preferable that the temperature is 20 ° or less from the viewpoint of strongly suppressing the swimming method in which the head of the demersal fish or the like jumps out diagonally forward and upward and then bottoms out in an arc.
On the lower limit side, if the angle is small, the constituent members become large to secure a space between the first surface 1 and the second surface 2 for the demersal fish and the like to move, which is simpler. Moreover, from the viewpoint of constructing at low cost, it is particularly preferable that the temperature is 5 ° or more.

The first surface 1 and the second surface 2 (and the narrow portion) can be formed of a known artificial material such as a resin material, a steel material, a wood, or a concrete material, and can be constructed easily and at low cost. Can be done.
In the fishway 3, since the second surface 2 is in contact with and supported by the first surface 1, it can be formed in the waterway in a stable state.
Further, when the first surface 1 and the second surface 2 (and the narrow portion) are integrally formed of the flexible resin material, the fishway 3 is formed in a more stable state by following the shape of the water channel. Can be done. Further, when the first surface 1 and the second surface 2 (and the narrow portion) are formed of an elastic resin material (elastomer material), the sluice is crushed when pressed and returns to its original state when the pressing is released. Application to the door stop is also effective.
The fishway 3 solves the swimming problem of the demersal fish such as sculpin, but it can also be applied to fish species such as salmon that run up in the same way. It can also be expected to have an effect on possible shrimp, eel fry, and small fish.

Next, the fishway according to the second embodiment will be described with reference to FIG. Note that FIG. 3 is an explanatory diagram illustrating the fishway according to the second embodiment.
In the fishway 10 according to the second embodiment, the first surface 11 is formed by the bottom wall 4 as an existing waterway structure. The second surface 12 is formed of a plate-shaped member as an artificial structure, and the other end side of the second surface 12 approaching the first surface 11 is embedded in the bottom wall 4 or the quay 5 and supported.
In the fishway 10, since the first surface 11 is formed by using the existing waterway structure, it can be constructed at even lower cost. In the illustrated example, the other end side of the second surface 12 is embedded and supported, but it may be supported by another method.
Since the other matters are the same as those of the fishway according to the first embodiment, the description thereof will be omitted. Further, also in the subsequent embodiments, the description of the matters described in the previous embodiments will be omitted.

Next, the fishway according to the third embodiment will be described with reference to FIG. Note that FIG. 4 is an explanatory diagram illustrating the fishway according to the third embodiment.
The fishway 20 according to the third embodiment is a type of fishway in which the first surface 21 is formed by the bottom wall 4 as an existing waterway structure, similarly to the fishway 10 according to the second embodiment. In the fishway 20 according to the third embodiment, the inclined side surface of the substantially trapezoidal thick-walled member is set as the second surface 22 instead of the plate-shaped member in the fishway 10 according to the second embodiment. It is different from the fishway 10 according to the second embodiment.
Whether to select the plate-shaped member in the fishway according to the second embodiment or the thick-walled member according to the third embodiment depends on the shape and strength of the bottom wall 4 to the quay 5 to be formed. It can be appropriately selected according to the state of.

Next, the fishway according to the fourth embodiment will be described with reference to FIG. Note that FIG. 5 is an explanatory diagram illustrating the fishway according to the fourth embodiment.
In the fishway 30 according to the fourth embodiment, the fishway is formed by the thick member as in the fishway 20 according to the third embodiment. In the fishway 30 according to the fourth embodiment, the fishway 20 according to the third embodiment has the first surface 21 formed by the bottom wall 4 and the second surface 22 formed by the inclined side surface of the thick member. On the other hand, it differs from the fishway 20 according to the third embodiment in that the first surface 31 is formed on the inclined side surface of the thick-walled member and the second surface 32 is formed on the quay 5. As a distinction between the first surface and the second surface, the surface on the side facing the normal direction of one surface and located closer to the water surface of the waterway than the one surface is defined as the second surface. The one surface is defined as the first surface.
Whether to select the fishway 20 according to the third embodiment or the fishway 30 according to the fourth embodiment is appropriately determined according to the shape, strength, and the like of the bottom wall 4 to the quay 5 to be formed. You can choose.

Next, the fishway according to the fifth embodiment will be described with reference to FIG. Note that FIG. 6 is an explanatory diagram for explaining the fishway according to the fifth embodiment, and the state of formation of the fishway in the waterway is omitted.
In the fishway 40 according to the fifth embodiment, the first surface 41 and the second surface 41 and the second surface are different from the fishway 3 according to the first embodiment in which the first surface 1 and the second surface 2 form a V shape. It differs from the fishway 3 according to the first embodiment in that the surface 42 has a U-shape in which one plate-shaped member is curved.
That is, in the fishway 40 according to the fifth embodiment, the curved portion extending from the other end side of the second surface 42 toward the first surface 41 is an extending portion, and the extending portion is the first extending portion. A narrow portion is formed between the first surface 41 and the second surface 42 to regulate the movement of demersal fish and the like.

Here, the first face 41 as the distance W ₁ between the other end of the second surface 42 is not particularly limited, even longer, 1.5 withers of such a bottom raw fish of interest The length is preferably twice or less, and specifically, the length is preferably 30 cm or less at the longest in consideration of the body height of a general sculpin. When the length of the interval W ₁ exceeds 30 cm, the tendency of the demersal fish and the like to approach the narrow portion may decrease. In addition, the distance between the first surface 41 and the second surface 42 becomes longer, and the swimming method is to lift the head of the bottom fish or the like, jump out diagonally upward and forward, and then land in an arc. It may not be sufficiently suppressed. The length may be zero as in the fishway 3 according to the first embodiment.
The inclination of the second surface 42 with respect to the first surface 41 when the first surface 41 and the second surface 42 do not form a V-shaped groove as in the fishway 40 according to the fifth embodiment. The angle θ can be set as an angle formed by the first surface 41 and the extended surface of the second surface 42.

Also in the fishway 40 according to the fifth embodiment formed in this way, when the demersal fish or the like moves in the water channel, the first surface 41 and the first surface 41 are inclined in the in-plane direction. Demersal fish and the like gather in the fishway 40 that narrows toward the narrow portion due to the second surface 42 formed in the water channel so as to approach the first surface 41 from one end side to the other end side. , The demersal fish or the like is localized on the first surface 41, and while lifting the head of the demersal fish or the like localized on the first surface 41, it jumps out diagonally forward and upward, and then lands in an arc. The demersal fish and the like can be moved in a stable posture in the fishway 40 by swimming in a swimming method in which the demersal fish and the like crawl on the bottom while keeping their bodies horizontal.

Next, the fishway according to the sixth embodiment will be described with reference to FIG. 7. Note that FIG. 7 is an explanatory diagram for explaining the fishway according to the sixth embodiment, and the state of formation of the fishway in the waterway is omitted.
In the fishway 50 according to the sixth embodiment, the first surface 51 and the second surface 52 are relative to the fishway 3 according to the first embodiment formed only by the first surface 1 and the second surface 2. The fishway 3 is different from the fishway 3 according to the first embodiment in that a surface 53 parallel to the first surface 51 is extended on one end side (open end side) of the second surface 52.
Even when such an extended surface is attached, the same effect as that of the fishway 3 according to the first embodiment can be obtained, and when a certain number of demersal fish and the like move in a group. However, since it is hidden by the extended surface 53, it is difficult for birds and mammals to catch it. That is, the fishway of the present invention is allowed to form an arbitrary attachment member as appropriate according to the purpose as long as the effect of the present invention is not impaired, and at least a part of the fishway of the present invention is viewed as a whole. Those having the characteristics of are included in the present invention.

Next, the fishway according to the seventh embodiment will be described with reference to FIG. Note that FIG. 8 is an explanatory diagram for explaining the fishway according to the seventh embodiment, and the state of formation of the fishway in the waterway is omitted.
In the fishway 60 according to the seventh embodiment, the facing surface side with respect to the fishway 3 according to the first embodiment formed by the first surface 1 and the second surface 2 whose facing surfaces are smooth surfaces. It differs from the fishway 3 according to the first embodiment in that it is formed on the first surface 61 and the second surface 62 on which the protrusion 63 as a roughness forming product is arranged.
By arranging the roughness-forming product, the flow of water in the fishway 60 can be relaxed, and the movement of the demersal fish and the like can be further assisted.
The roughness-forming product is not particularly limited as long as it is a structure that relaxes the flow of water, and can be appropriately selected depending on the intended purpose. In addition to arranging protrusions 63, the facing surface is uneven. It can be formed by forming it as a surface, planting artificial turf, etc. Among them, the artificial turf is preferable from the viewpoint that the flow of water can be relaxed easily and at low cost.
When the roughness-forming product is arranged, the angle θ formed by the first surface 61 and the second surface 62 is not particularly limited, but is preferably more than 0 ° and 45 ° or less, and 5 °. ~ 30 ° is particularly preferable. That is, since the flow of water is relaxed, a particularly preferable range can be set to a wider range as compared with the case where the roughness-forming product is not arranged.

Next, the fishway according to the eighth embodiment will be described with reference to FIGS. 9 and 10. 9 is a perspective view showing the fishway according to the eighth embodiment, and FIG. 10 is a partial cross-sectional view in the water flow direction of the waterway of the fishway shown in FIG.
Here, a case where a fishway is formed in a water channel when a deceleration member for decelerating the flow of water formed of concrete or the like is constructed will be described.
That is, in the water area where dams and weirs are installed, fishway structures are often already constructed for the purpose of assisting the run-up of fish. For example, a block-shaped fishway structure 6 shown in FIGS. 9 and 10 may be constructed so as to project from the quay 5 of the canal in the width direction of the canal. In the fishway structure 6, since the wall surface on the upstream side extends along the width direction of the water channel, the flow of water on the bottom side is blocked by the wall surface, and the entire flow of water can be slowed down.
The fishway of the present invention can synergize the effects of each by utilizing such a fishway structure in the past.
The existing fishway structure can be referred to as an "existing waterway structure" together with the existing quay 5 and bottom wall 4.

The fishway 70 according to the eighth embodiment treats the outer surface of the fishway structure 6 in the same manner as the bottom wall 4 in the fishway according to the first embodiment, and forms a first surface 71 on the outer surface. It is located on the water surface side of the waterway with respect to the first surface 71 at a position facing the normal direction of the surface 71 of 1, and covers the whole or a part on the first surface 71, and is in the surface of the first surface 71. The narrow portion composed of a second surface 72 formed in the waterway so as to be inclined in a direction and approach the first surface 71 from one end side to the other end side, and the second surface 72 itself. Is formed by.
The first surface 71 and the second surface 72 are each formed of a flexible resin material or the like integrally formed with a plate-shaped member, and the fishway 70 follows the shape of the outer surface of the fishway structure 6. Is formed. Further, the fishway 70 is formed from the bottom wall 4 in a direction opposite to the flow of water in the waterway, and extends to a position where the end thereof exceeds the top of the fishway structure 6.

According to the fishway 70 according to the eighth embodiment, in the water area where the flow of water is relaxed by the fishway structure 6, the bottom fish and the like are the fishway structure 6 while receiving movement assistance based on the shape of the fishway 70. It is possible to move from the water area on the downstream side to the water area on the upstream side (see FIG. 10), and the effects of the fishway of the present invention and the existing fishway structure are synergized to assist the run-up of the bottom fish and the like. be able to.

Next, the fishway according to the ninth embodiment will be described with reference to FIG. Note that FIG. 11 is an explanatory diagram illustrating the fishway according to the ninth embodiment.
Similar to the fishway 70 according to the eighth embodiment, the fishway 80 according to the ninth embodiment is a type of fishway in which the first surface 81 is formed by utilizing the fishway structure 6 as an existing waterway structure. Is.
In the fishway 80 according to the ninth embodiment, the eighth embodiment is in that the inclined side surface of the thick-walled member is a second surface 82 instead of the plate-shaped member in the fishway 70 according to the eighth embodiment. It is different from the fishway 70 according to the above.
Whether to select the fishway 70 according to the eighth embodiment or the fishway 80 according to the ninth embodiment depends on the shape and strength of the outer surface of the quay 5 or the fishway structure 6 to be formed. It can be appropriately selected accordingly.

Next, the fishway according to the tenth embodiment will be described with reference to FIG. Note that FIG. 12 is an explanatory diagram illustrating the fishway according to the tenth embodiment.
Here, a case will be described in which the fishway of the present invention is formed in the fishway structure 16 in which the peak portion 17 having a lowered top portion is formed instead of the fishway structure 6. That is, some of the existing fishway structures, such as the fishway structure 16, have a peak portion 17 for allowing the fish to run up.
Also in this case, similarly to the fishway forming method for the fishway structure 6, the first surface 91 is formed on the outer surface of the fishway structure 16, and the first surface 91 is opposed to the first surface 91 in the normal direction. The first surface is located on the water surface side of the waterway and covers all or part of the first surface 91, and is inclined from the in-plane direction of the first surface 91 from one end side to the other end side. The fishway 90 according to the tenth embodiment can be formed by the second surface 92 formed in the waterway so as to approach the 91 and the narrow portion formed by the second surface 92 itself. it can.

The direction of forming the fishway 90 on the vertical surface of the fishway structure 16 from the bottom wall 4 to the top is the direction opposite to the flow of water from the bottom wall 4 as in the fishway 70 according to the eighth embodiment (similar to the fishway 70 according to the eighth embodiment). It may be formed vertically above), but here, as shown in the figure, a case where it is formed so as to be inclined with respect to the water flow direction will be described.
In this case, the fishway 90 is formed so that the other end side of the second surface 92 is arranged on the bottom wall 4 side of the water channel with respect to the one end side of the second surface 92, that is, on the one end side. A method of directing a certain open end side toward the water surface side, and as shown in the figure, the other end side of the second surface 92 is arranged on the "water surface side" of the water channel with respect to the one end side of the second surface 92. There are two conceivable methods of forming the fishway 90, that is, directing the open end side toward the bottom wall 4.
However, according to the former method, once the fishway 90 is directly entered from above the vertical direction, and then the fishway 90 is strongly affected by the flow of water that goes out of the fishway 90 through the second surface 92, and the demersal fish and the like in the fishway 90 are caught in the fishway 90. It may be difficult to stay inside.
On the other hand, in the latter method, the flow of water is blocked on the surface of the second surface 92 opposite to the surface facing the first surface 91, so that the flow of water received by the demersal fish and the like in the fishway. Is relaxed, and demersal fish and the like can be more stably localized in the fishway 90 than the former.
Therefore, according to the latter method, when the first surface 91 is a surface parallel to the vertical surface, the other end side of the second surface 92 is the one end side (open end side) of the second surface 92. The extension direction of the other end side of the second surface 92 may be a direction inclined with respect to the flow direction of water on the vertical surface so that the second surface 92 is arranged on the water surface side of the water channel. preferable.

Next, the fishway according to the eleventh embodiment will be described with reference to FIG. Note that FIG. 13 is an explanatory diagram illustrating the fishway according to the eleventh embodiment.
Here, a case where the fishway of the present invention is formed in the fishway structure 26 in which the surface on the downstream side slopes in a mountain shape from the top to the bottom will be described.
Also in this case, similarly to the fishway forming method for the fishway structures 6 and 16, the first surface is formed on the outer surface of the fishway structures 6 and 16, and the first surface is formed at a position facing the normal direction of the first surface. The fishway is located on the water surface side of the water channel with respect to the first surface and covers all or a part of the first surface, and is inclined from the in-plane direction of the first surface from one end side to the other end side. The fishway according to the eleventh embodiment can be formed by the second surface formed in the waterway so as to approach the first surface and the narrow portion formed by the second surface. it can.

As a method of forming a fishway on the inclined surface of the fishway structure 26 from the bottom wall 4 to the top 27, the fishway forming method in the fishway 90 according to the tenth embodiment, that is, the other end side of the second surface is the first. Examples thereof include a method of forming a fishway following the method of forming a fishway so as to be arranged on the “water surface side” of the water channel with respect to the one end side of the surface 2.
The fishway structure 16 and the fishway structure 26 differ in whether the surface of the fishway structure from the bottom wall 4 to the top is a vertical surface or an inclined surface, but the other end of the second surface. Placing the side on the "water surface side" of the waterway with respect to the one end side of the second surface contributes to stable localization of demersal fish in the fishway. It is common in that it does.

Here, further, the fishway 100 formed by the first surface 101 and the second surface 102, the fishway 110 formed by the first surface 111 and the second surface 112, and the first surface 121 and the second surface An example of a fishway configuration formed by being divided into three parts of a fishway 120 formed by a surface 122 of the above is illustrated (see FIG. 13).
That is, the fishway does not necessarily have to be integrally formed, and can be appropriately divided and formed according to the structure of the fishway structure. The fishways 100, 110, and 120 each have the characteristics of the fishway of the present invention, but if any one of the fishways has the characteristics of the fishway of the present invention, it is included in the present invention, and the other fishways have different configurations. It doesn't matter if it is a fishway.

Next, the fishway according to the twelfth embodiment will be described with reference to FIGS. 14 and 15. 14 is a perspective view for explaining the fishway according to the twelfth embodiment, and FIG. 15 is an end view taken from the direction of the arrow in FIG. In addition, all drawings omit the status of formation of fish canals in waterways.
The fishway 130 according to the twelfth embodiment shows an example configured as an inner wall of a triangular cylinder. That is, when the surface 131 is the first surface, the fishway 130 with the surface 132 as the second surface is shown.
As described above, the fishway of the present invention can also be configured as an inner wall of a tubular body.

A modified example of the fishway 130 according to the twelfth embodiment configured as the inner wall of the cylinder will be further described.
First, a first modification is shown in FIG. Note that FIG. 16 is a diagram (1) showing a modified example of the fish path according to the twelfth embodiment.
The fishway of the present invention has two movement paths by combining the fishway 130A and the fishway 130B, which are configured in the same manner as the fishway 130, in a square tubular shape like the fishway 140 according to the first modification. It may be a fishway.

A second modification is shown in FIG. Note that FIG. 17 is a diagram (2) showing a modified example of the fish path according to the twelfth embodiment.
The fishway of the present invention may be a fishway having four movement paths by connecting the fishway 140A and the fishway 140B, which are configured in the same manner as the fishway 140, like the fishway 150 according to the second modification. ..

Further, the cylinder does not necessarily have to be a triangular cylinder, and as shown in FIG. 18, a cylinder having an inner wall hollowed out in a triangular cylinder shape as a fishway 160 having a first surface 161 and a second surface 162. It may be a body. Note that FIG. 18 is a diagram (3) showing a modified example of the fish path according to the twelfth embodiment.

Next, the fishway according to the thirteenth embodiment will be described with reference to FIG. Note that FIG. 19 is an explanatory diagram illustrating the fishway according to the thirteenth embodiment.
The fishway of the present invention has an upstream side surface and a downstream side surface of the waterway in the fishway structure 6 as shown in the drawing, with respect to the block-shaped fishway structure 6 which is arranged so as to project from the quay 5 in the width direction of the waterway. It may be configured as an inner wall of a through hole formed between and.
That is, the fishway of the present invention can also form the inner wall of the through hole as a fishway 170 having a first surface 171 and a second surface 172.
The direction of the through hole is not particularly limited and may be parallel to the water flow direction of the water channel as shown in the figure. However, from the viewpoint of relaxing the water flow in the fishway, the water in the water channel may be formed. It is preferable that the direction is inclined in the horizontal direction with respect to the flow direction.

Next, the fishway according to the fourteenth embodiment will be described with reference to FIG. Note that FIG. 20 is an explanatory diagram illustrating the fishway according to the fourteenth embodiment.
Here, a method of forming a fishway in a fishway structure 7 known as a stepped fishway in a water area where a dam, a weir, or the like is installed will be described.
In the fishway structure 7, there is a head on the water surface from the upstream side to the downstream side, and in a water area where the water flow is fast, a landing as a resting place for the fish going up and a vertical surface as a step are alternately arranged. Will be done.
The fishway of the present invention can synergize the effects of each by utilizing such a fishway structure in the past.

That is, by forming fishways 3a to 3d in each of the landing and the step, a fishway that assists the run-up is provided while providing a resting place for demersal fish and the like.
Here, in the fishways 3a and 3c in which the first surface is formed with the landing as the bottom wall and the surface parallel to the bottom wall, unlike the fishway 3 according to the first embodiment, the water area where the water flow is faster. That is, the second end side of the second surface is arranged on the "upstream side" of the water channel with respect to the one end side of the second surface. It is preferable that the extending direction of the other end side of the surface, that is, the extending direction of the fishways 3a and 3c is a direction inclined with respect to the water flow direction of the water channel.
Rather than forming the other end side of the second surface so as to be arranged on the "downstream side" of the waterway with respect to the one end side of the second surface, the other end side of the second surface is If the water is formed so as to be arranged on the "upstream side" of the waterway with respect to the one end side of the second surface, the water is on the side opposite to the surface of the second surface facing the first surface. Therefore, the flow of water received by the demersal fish and the like in the fishway is relaxed, and the demersal fish and the like can be localized more stably in the fishway.
Further, in the fishways 3b and 3d in which the first surface is formed by the vertical surface forming the step, it is related to the tenth embodiment in consideration of being formed in a water area where the flow of water is fast. The method of forming a fishway in the fishway 90, that is, the other of the second surface so that the other end side of the second surface is arranged on the "water surface side" of the water channel with respect to the one end side of the second surface. It is preferable that the extending direction on the end side is a direction inclined with respect to the flow direction of water on the vertical surface.

Next, the fishway according to the fifteenth embodiment will be described with reference to FIG. Note that FIG. 21 is an explanatory diagram illustrating the fishway according to the fifteenth embodiment.
The fishway 180 according to the fifteenth embodiment has a second surface formed by a first surface 11 formed by the bottom wall 4 and a second surface 12 formed by an artificial structure of the plate-shaped member. With respect to the fishway 10 according to the embodiment, the position of embedding the plate-shaped member in the quay 5 is changed, and a part of the quay 5 is formed from the other end side of the second surface 182 to the first surface. As the extending portion extending toward 181, the first surface 181 formed by the bottom wall 4, the second surface 182 formed by the artificial structure of the plate-shaped member, and the quay 5 are used. It is different from the fishway 10 according to the second embodiment in that it is formed by the extending portion formed by the fishway.
The distance W ₁ between the other end portion of the first surface 181 of the second surface 182 defining the fishway 180, as described for fish ladder 40 according to the fifth embodiment, even longer, The length is preferably 1.5 times or less the body height of the target demersal fish or the like, and specifically, the length is 30 cm or less at the longest in consideration of the body height of a general sculpin. Is preferable.
Even in such a fishway 180, the effect of assisting the movement of the demersal fish and the like can be expected.

Next, the fishway according to the 16th embodiment will be described with reference to FIG. 22. Note that FIG. 22 is an explanatory diagram for explaining the fishway according to the sixteenth embodiment, and the state of formation of the fishway in the waterway is omitted.
In the fishway 190 according to the sixteenth embodiment, the first surface 191 formed of one plate-shaped member and the other plate-shaped member are bent so as to be recessed toward the first surface 191. The movement path of the demersal fish and the like formed by the second surfaces 192a and b is formed by the first surface 191 and the second surface 192a, and the first surface 192 and the second surface 192b. Two are formed by the one formed by and. At the bent position, the other plate-like member is supported on the first surface 191 via columns 193 arranged at appropriate intervals. The first surface 191 between the adjacent columns 193 and the other end of the second surfaces 192a and 192b at the position where the other plate-shaped member is bent are open as shown in the drawing. You may.
The first surface 191 when the open, second surface 192a, as the interval W ₂ between the other end of the b includes a first surface 41 the other end of the second surface 42 A fifth embodiment 40 (see FIG. 6) in which the space is closed, and a fifteenth embodiment 180 (FIG. 21) in which the space between the first surface 181 and the other end of the second surface 182 is closed. Unlike distance W ₁ in the reference), for restricting the movement of such a bottom raw fish in spacing W _2, it must be the bottom withers less in length, such as raw fish of interest, specifically, general Considering the height of the sculpin, the length must be 20 cm or less at the longest.

(Comparison example)
In order to examine the movement of sculpins under running water, the waterway models shown in FIGS. 23 (a) to 23 (c) were prepared. 23 (a) is a plan view showing an outline of the waterway model, FIG. 23 (b) is a sectional view taken along line AA in FIG. 23 (a), and FIG. 23 (c) is a view. 23 (a) is a sectional view taken along line BB.

As shown in FIGS. 23 (a) to 23 (c), the water channel model 200 is configured by using a square tubular flow path 201 formed of a transparent acrylic member as a main material, and the flow path 201 has one end (upstream end). ) To the other end (downstream end) is 1,900 mm, and the inner diameter is 200 mm in width and 100 mm in height. The length of the observation unit 202 located on the body of the flow path 201 in the water flow direction is 1,300 mm.

In the water channel model 200, water is introduced from the upstream end of the flow path 201 and drained at the downstream end. At this time, water is allowed to flow under the condition that the inside of the flow path 201 is filled with running water. The water temperature of the water used is set to 17 ° C.
For the waterway model 200 in this state, the sculpin is thrown into the flow path 201 from the fish input pipe 203 connected to the downstream side of the flow path 201, and the behavior of the sculpin is observed.
The sculpins used were freshwater sculpins caught in the Azusa River, which flows through Matsumoto City, Nagano Prefecture, and 1 to 6 sculpins were used in one observation.
The method of observing the sculpin is to observe the video recorded by four high-speed video cameras (50 fps) installed around the flow path 201.
Further, the flow velocity of water in the flow path 201 is measured by using an electromagnetic current meter installed in the flow path 201 through the fish input pipe 203.
Under the above conditions, a fishway (waterway model) according to the comparative example was formed, and the behavior of the sculpin was observed.

(Example 1)
In the fishway (waterway model) according to the comparative example, the fishway forming member 210 (thickness 5 mm) shown in FIG. 24A is placed in contact with the plate material forming the one side plate and the top plate of the flow path 201 at the position of the observation unit 202. The fishway according to Example 1 was formed in the same manner as the fishway according to the comparative example except that the fishway 220 shown in FIG. 24B was formed by arranging the fishways.
Note that FIG. 24A is an explanatory view showing an outline of the fishway forming member, and FIG. 24B is a diagram showing a cross section of the fishway at a position corresponding to FIG. 23C.
Here, in the fishway according to the first embodiment, the angle θ formed by the bottom plate forming the flow path 201 and the swash plate forming the fishway forming member 210 is set to 40 °. In addition, the swash plate is formed of a brown acrylic member in order to darken the inside of the fishway. Further, the space diagonally above the left in FIG. 24B is a closed space in which water is not introduced.

As for the flow velocity in the flow path 220, the movement of tapioca when tapioca as a tracer is flown from the upstream end to the downstream end in the flow path is observed by a high-speed video camera (50 fps) installed on the bottom surface side of the flow path 220. However, it was determined by the moving speed of this tapioca.
Other than this, the behavior of the sculpin was observed using the fishway according to Example 1 in the same manner as the observation method in the fishway according to the comparative example.

(Example 2)
The fishway according to the second embodiment was formed in the same manner as the fishway according to the first embodiment except that the angle θ formed by the bottom plate and the swash plate forming the flow path was changed from 40 ° to 25 °. Behavioral observation was performed.

(Example 3)
The fishway according to the third embodiment was formed in the same manner as the fishway according to the first embodiment except that the angle θ formed by the bottom plate and the swash plate forming the flow path was changed from 40 ° to 20 °. Behavioral observation was performed.

(Example 4)
The fishway according to the fourth embodiment was formed in the same manner as the fishway according to the first embodiment except that the angle θ formed by the bottom plate and the swash plate forming the flow path was changed from 40 ° to 15 °. Behavioral observation was performed.

(Example 5)
The fishway according to the fifth embodiment was formed in the same manner as the fishway according to the first embodiment except that the angle θ formed by the bottom plate and the swash plate forming the flow path was changed from 40 ° to 10 °. Behavioral observation was performed.

Next, the behavior observation results of the sculpin performed using the fishways according to Comparative Examples and Examples 1 to 5 will be described.
First, for sculpin, there are (1) a swimming method in which the head is lifted from the bottom, the head jumps diagonally upward, and then the sculpin lands in an arc, and (2) a swimming method in which the body is kept horizontal and crawls on the bottom. It has been confirmed that swimming is performed by the two methods of (1), and the swimming method of (1) tends to be pushed back in the downstream direction.
Therefore, in the behavior observation, the behavior of lifting the head of the sculpin was observed. The observation results are shown in FIG. Note that FIG. 25 is a graph showing the relationship between the flow velocity and the head lifting rate.
Here, the "head lifting rate" indicates the matters defined below.
Head lifting rate = Number of cases in which the head was lifted at the start of the action when either run-up or flow-down action was taken / Total number of the observed actions In addition, even if the action was taken, the following In the case of, it is excluded from the number of cases.
-When the sculpin is driven from the fish input pipe 203 toward the observation unit 202, the section of the observation unit 202 is moved to the upstream at once without landing.-In Examples 1 to 5, the swash plate rises. When taking action at the corner between the side plate on the opposite side of the side plate and the bottom plate ・ When taking action in a place where multiple sculpins overlap and are localized ・ After turning the body toward the downstream side , If it flows down

As shown in FIG. 25, the fishway of the comparative example (the plot indicated by “none” in the figure) and the fishway of Examples 1 to 5 (the plot indicated by “40 ° to 10 °” in the figure) , The fishways of Examples 1 to 5 tend to have a lower head lifting rate.
In particular, in Examples 3 to 5 in which the angle θ formed by the bottom plate and the swash plate forming the flow path 201 is 20 ° or less, the head lifting rate is more remarkable than in Examples 1 and 2 in which the θ exceeds 20 °. It is low.
Regarding the seven plots related to the fishway in the comparative example, the head lifting rate is 0 in the two plots, but since the flow velocity is high near the localization limit, the localization is prioritized and the head is lifted, which is the beginning of movement. It seems that he did not take action.
That is, the behavior observation using the fishway of the comparative example is performed multiple times by adjusting the flow velocity, but when the flow velocity becomes 0.432 m / s or more, it cannot be localized in the flow path and is flowed down. It seems that localization was prioritized near this localization limit.

Here, it is also noted that the fishways of Examples 1 to 5 can be localized in the flow path beyond the localization limit of the flow velocity of 0.432 m / s. This is done by moving to the water area near the rising side of the swash plate (see FIG. 24B) that constitutes the fishway forming member 210, where the flow velocity is slower than the water area where the flow velocity was measured using tapioca. It seems that it was able to be localized within.

Next, the observation result regarding the run-up of the sculpin is shown in FIG. Note that FIG. 26 is a graph showing the relationship between the flow velocity and the number of successful movements (number of successful run-ups).
Here, the "number of successful moves" indicates the items defined below.
Number of successful moves = (Number of successful sculpins) / {(Experimental time h in each case) · (Number of sculpins thrown in at the same time in the same case)}
In addition, "movement success" corresponds to the case where the vehicle moves in the upstream direction at once, and the case where the vehicle moves in small steps continuously and moves in the upstream direction. It was decided not to count as "successful movement" if the movement distance stays within approximately 1 cm, not to mention the case of being swept down, even if the movement is in the upstream direction. Further, when the sculpin is driven from the fish input pipe 203 toward the observation unit 202, even if the section of the observation unit 202 is moved to the upstream at once without landing, it is not counted as "successful movement".

As shown in FIG. 26, in the fishway according to Examples 1 to 5, after localization in the flow path exceeding the localization limit of the flow velocity of 0.432 m / s, the sculpin further moves in the upstream direction (runs up). Can be done. It is shown that the flow velocity in the range indicated by the arrow in FIG. 26 cannot move (further, localize itself) without the fishway forming member 210 used for forming the fishway according to Examples 1 to 5. ing.

1,11,21,31,41,51,61,71,81,91,101,111,121,131,161,171,181,191 ... First surface 2,12,22,32, 42, 52, 62, 72, 82, 92, 102, 112, 122, 132, 162, 172, 182, 192a, 192b ... Second surface 3,3a to 3d, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 ... Fishway 4 ... Bottom wall 5 ... Quay 6,7,16, 26 ... Fishway structure

Claims (11)

The first surface formed in the waterway and
It is located on the water surface side of the water channel with respect to the first surface at a position facing the normal direction of the first surface, covers all or a part of the first surface, and is in the plane of the first surface. A second surface formed in the water channel so as to be inclined in a direction and approach the first surface from one end side to the other end side.
It is composed of the other end side itself of the second surface or an extending portion extending from the other end side toward the first surface, and the first surface and the other end of the second surface. Has a narrow part, which regulates the movement of fish to and from the side,
At least one of the first surface and the second surface is made of an artificial structure, and the first surface, the second surface, and the narrow portion together with the first surface. A space defined on the side facing the second surface is extended along the other end side of the second surface .
A fishway characterized in that the angle formed by the first surface and the second surface itself or an extended surface of the second surface is more than 0 ° and 20 ° or less. The fishway according to claim 1, wherein at least a part of the other end side of the second surface itself or an extending portion extending from the other end side toward the first surface is supported by the first surface. The fishway according to any one of claims 1 to 2, wherein the roughness-forming product is arranged on the opposite surface side of at least one of the first surface and the second surface. The second surface is arranged so that the first surface is parallel to the bottom wall and the other end side of the second surface is arranged on the upstream side of the waterway with respect to one end side of the second surface. The fishway according to any one of claims 1 to 3, wherein the extending direction on the other end side of the waterway is inclined with respect to the water flow direction of the waterway. The first surface is parallel to either the inclined surface or the vertical surface whose position on the downstream side is lower than that on the upstream side, and the other end side of the second surface is one end side of the second surface. The extending direction of the other end side of the second surface is relative to the water flow direction on either the inclined surface or the vertical surface so as to be arranged on the water surface side of the water channel. The fishway according to any one of claims 1 to 3, which is considered to be an inclined direction. The fishway according to any one of claims 1 to 5, wherein at least one of the first surface and the second surface is composed of the existing waterway structure itself. The fishway according to any one of claims 1 to 5, wherein the first surface, the second surface, and the narrow portion are integrally formed of a flexible resin material. The fishway according to any one of claims 1 to 5, which is configured as an inner wall of a cylinder. A through hole formed between the upstream side surface and the downstream side surface of the waterway in the fishway structure with respect to the block-shaped fishway structure arranged so as to project from the quay of the waterway in the width direction of the waterway. The fishway according to any one of claims 1 to 5, which is configured as an inner wall of the fishway. The fishway according to claim 9, wherein the through hole is formed in a direction inclined with respect to the flow direction of water in the water channel. The first surface formed in the water channel and the first surface are located on the water surface side of the water channel at a position facing the normal direction of the first surface and are located on the water surface side of the water channel, and all or part of the first surface. A second surface formed in the water channel so as to be inclined from the in-plane direction of the first surface and approach the first surface from one end side to the other end side, and the first surface. It is composed of the other end side itself of the second surface or an extending portion extending from the other end side toward the first surface, and the first surface and the other end side of the second surface. With a narrow portion that regulates the movement of fish between, at least one of the first surface and the second surface is composed of an artificial structure, and the first surface and the second surface are The first surface and the narrow portion extend along the other end side of the second surface as a space defined on the opposite surface side of the first surface and the second surface. The formation of a fish channel in the waterway, wherein the angle formed by the surface of the second surface itself or the surface obtained by extending the second surface is more than 0 ° and 20 ° or less. Method.

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