JP4085167B2 - Larvae collection and river return device - Google Patents

Description

  In the present invention, when larvae of several days after hatching, for example, larvae such as larvae or swordfish are taken into the intake of a river and enter the intake channel, the larvae are recovered without being damaged and returned to the river again. It relates to the device.

  Ayu is a major fishery resource in rivers and is a typical fish in Japan. Ayu lays eggs in the river and hatches from an egg with a diameter of about 1 mm. Ayu, which is about 6 mm long, goes down the river, heads to the sea, grows to some extent in the sea, and then returns to the river. Ayu is also grown.

However, if there is a water intake or irrigation channel in the middle of the river, the baby ayu with weak swimming ability can be taken into this water intake by the river flow and enter the water intake channel and head to the sea. Disappear. Therefore, when a water intake is provided in the river where the sweetfish lives, it is necessary to take measures to prevent the baby sweetfish from being taken into the water intake. As a countermeasure, for relatively large fish with swimming ability, the method of returning the fish that approached the intake side to the opposite side with an electric screen etc. has been adopted. Such a method was not applicable, and no effective measures were taken to prevent the pupa ayu from being taken into the water intake. For this reason, baby sweetfish, etc. taken into the water intake and entering the water intake channel are guided to the surface water section by light, and the baby sweetfish guided to this surface water section are taken together with water from the opening at the water surface position of the intake device. There has been proposed a method of taking in and feeding it into a fish tank, pumping the pupa sweetfish together with water with a pumping device, returning it to the return channel, and returning it to the river from the return channel (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-6123

  In the method described in Patent Document 1, puppy sweetfish and the like are guided to the surface water part by light. However, in the case of a puppy sweetfish having a weak swimming ability, all the puppy sweetfish are not always guided to the surface water part, and the water surface. It was not always taken in from the opening at the position, and there was a certain limit in the recovery rate of sweetfish. Moreover, since all the water continuously taken in from the intake device has to be stored in the fish tank, there is also a problem that the capacity of the fish tank has to be increased.

  This invention is made | formed in view of such a situation, and utilizes the repelling reaction with respect to the mesh part (mesh part) of a larva and the inclination effect of a mesh, without using the guidance means by a larval light, a fish collection tank, etc. It is an object of the present invention to provide a larval fish recovery / river return device that enables high recovery to the river and return of survival.

First, the fish collection function of the present invention will be described.
FIG. 1 illustrates the fish collecting function of the present invention. The upper diagram (a) uses a mesh with a length of 0.5 mm, and reduces the relative speed between running water and the mesh portion. When the baby sweetfish approaches a mesh part with running water, the state which does not pass a mesh part by the repelling reaction of a baby sweetfish is shown. The baby sweetfish has a swimming speed of about 1 to 2 cm / s and a rushing speed of about 6 cm / s. Therefore, the relative speed between the flowing water and the mesh portion is made small, for example, 10 cm / s or less so that it can be efficiently used. You can collect fish. Further, when approaching obliquely as shown in FIG. 1A, the mesh portion becomes more difficult to pass due to the finer mesh projection size.
However, as shown in the lower figure (b), when the 0.5 mm mesh is fixed orthogonally to the flow and the baby sweetfish approaches perpendicularly with running water, the baby sweetfish almost passes.
FIG. 2 shows the experimental results of the recovery rate of baby sweetfish when a 0.5 mm mesh is installed perpendicular to the running water. It can be seen that only over 20% can be recovered at 10 cm / s or less. Therefore, the fish collection function can be improved by reducing the relative speed between the flowing water and the mesh portion and by positioning the mesh portion obliquely with respect to the flowing water.

Next, the characteristics of ensuring the survival rate of the present invention will be described.
When catching puppy ayu with a fixed net, the puppy ayu is more likely to attach to the net and die. Decreasing the relative speed between the net and the flowing water reduces the death and injury rate and improves the survival return rate.
Therefore, in order to improve the survival return rate of the collected pupa sweetfish, the relative speed between the flowing water and the mesh part is reduced, and the puppy sweetfish is guided to the fish collecting part without contacting the mesh part by the repelling reaction of the puppy sweetfish It is necessary to do so.
FIG. 3 shows the relationship between the relative speed and the survival rate of baby sweetfish. In the figure, for example, the indication “0.5 mm pressure resistance time 5 seconds” means a case where a 0.5 mm mesh is used and a baby sweetfish is placed in flowing water having a certain relative velocity for 5 seconds. .
From this figure, it can be seen that the survival rate within a relative speed of 10 cm / s is 90% or more.

Based on these features of collecting fish and ensuring the survival rate, the larval fish recovery / river return device of the present invention is used to recover the larvae that have returned to the river without damaging the larvae that entered the river intake. In the return device, a bucket that moves from the water to the upper surface of the water with a certain angle and relative speed difference with respect to the flow of the flowing water in the intake channel is provided, and the bucket has a mesh part that can pass water and a position behind the mesh part. It has a fish collection part that accommodates larvae and water, and is characterized by collecting fish by utilizing a repelling reaction to the mesh part of the larvae and a fine mesh projection size due to the inclination of the mesh part.
The larval fish recovery / river return device of the present invention is characterized in that the moving speed of the bucket is set so that the speed component in the flowing direction of the flowing water is 0.3 to 10 cm / s greater than the flowing water speed.
In addition, the larval fish recovery / river return device of the present invention is an angle calculated by the cover rate with respect to the flow of running water with respect to the flow angle of the bucket moving from underwater to the upper surface of the water (in the experiment, 10 ° to 40 °). It is characterized by setting upward.
Moreover, the larval fish recovery / river return device of the present invention is characterized in that a plurality of buckets are mounted at predetermined intervals on a transmission member of an endless rotation mechanism installed in a water channel.
In addition, the larval fish recovery / river return device according to the present invention is characterized in that a plurality of buckets are mounted at predetermined intervals on a transmission member of a dust removal mechanism including an endless rotation mechanism.
In addition, the larval fish recovery / river return device of the present invention has a bucket with a flat mesh portion and a side section that is substantially triangular and has the same width as the mesh portion, and is watertight by an upper surface plate, a lower surface plate, both side plates, and a bottom plate. It is characterized by comprising a formed fish collection part.
In addition, the larval fish recovery / river return device of the present invention is provided with the upper surface plate of the fish collection part continuously on the flat mesh part, and the bottom plate of the endless rotation mechanism is arranged so that the opening of the fish collection part faces the moving direction. It is characterized by being fixed to a transmission member.
In addition, the larval fish recovery / river return device of the present invention is characterized in that the flat mesh portion is made of stainless steel having a mesh with a length of one piece (about 0.5 mm or more) through which the larvae pass. .
In addition, the larval fish recovery / river return device of the present invention gradually tilts the bucket that has been moved from the water to the surface of the water, so that the larvae in the fish collection unit together with the water is placed in a return waterway that is higher than the river water level. It is characterized by having returned.
In addition, the larval fish recovery / river return device of the present invention is set such that the cover size for filtering the flowing water by the mesh portion is the optimal recovery condition, the bucket size, the installation interval, the angle with the flowing water and the relative speed. It is characterized by achieving a high recovery rate and survival return rate.

The present invention has the following excellent effects.
(1) By using the repelling reaction to the mesh part, larvae such as pupa that are very easily damaged and very difficult to survive and recover can be recovered and returned to the river without damage. .
(2) A high recovery rate and survival return rate can be achieved by reducing the relative speed between the flowing water and the mesh portion and by positioning the mesh portion obliquely with respect to the flowing water.
(3) By setting the bucket size, the installation interval, the angle with the running water and the relative speed difference so that the covering ratio that the mesh section filters the running water is the optimum collecting condition, more than 70% of the intrusion amount can be collected. More than 90% of the collected items can be returned to life.
(4) In existing intake channels, rivers can be collected without damaging larvae such as larvae without installing a new device just by attaching the bucket of the present invention to the transmission member of the dust remover already installed. Can be returned to.
(5) By realizing a means for achieving a high recovery rate and survival return rate of larvae, it is possible to smoothly promote a business such as a water supply business or a water transfer business using a river.

  The best mode for carrying out the larval fish recovery / river return device according to the present invention will be described below with reference to the drawings based on the embodiments.

FIG. 4 is an overall perspective view seen from a slightly front side for explaining the situation where the larval fish recovery / river return device according to the present invention is installed in the intake channel provided in the river.
In FIG. 4, the river indicated by reference numeral 1 is upstream on the left side and downstream on the right side. The river 1 is provided with an intake channel 2, and a larval fish recovery / river return device is provided across the entire width of the intake channel 2. 3 is installed. A plurality of larval fish recovery / river return devices 3 are installed in parallel according to the width of the intake channel, but may be one if the width of the intake channel is narrow.
Of the larvae that live in the river 1, most of the larvae taken together with running water as indicated by the arrows in the intake channel 2 were recovered by the larval fish recovery / river return device 3 and transported from underwater to the upper surface of the water. After that, it is discharged together with water into the return water channel 4 laid under the larval fish recovery / river return device 3 and returned to the river via the return water channel 4 connected to the river downstream from the intake port of the intake channel 2. Is done.

FIG. 5 is a view for explaining an embodiment of the larval fish recovery / river return device 3 according to the present invention, and shows a side view of the intake channel 2 and the larval fish recovery / river return device 3 installed in the intake channel 2. It is the whole schematic seen from.
The left side of FIG. 5 is the upstream side (river side) of the intake channel 2, and water flows at a velocity V from the left side to the right side.
The larval fish recovery / river return device 3 includes a rotating wheel 5 provided near the bottom of the intake channel 2, a rotating wheel 6 with a motor provided above the water surface, idlers 7 and 8 provided therebetween, The endless rotating mechanism is formed by the endless annular transmission member 9 applied to the rotating wheels 5 and 6 and the idlers 7 and 8. A plurality of buckets 10 are mounted on the transmission member 9 at predetermined intervals. The transmission member 9 is rotationally driven in the direction of running water, that is, clockwise by the motor-driven rotating wheel 6. The conductive member 9 has a predetermined width that can be attached to the bucket 10, has a strength capable of holding the bucket 10 and moving at a constant speed, and can be reversed along the outer periphery of the rotary wheels 5 and 6. For example, it is comprised from well-known things, such as a chain.
The rotating wheel 5 and the rotating wheel 6 are installed so that the angle of the conductive member 9 from the rotating wheel 5 toward the rotating wheel 6, that is, the angle of the moving direction of the bucket 10 is upward by an angle θ with respect to the flow of running water. The angle θ is set to an angle calculated based on the cover ratio, but it is desirable to set the angle θ within a range of 10 ° to 40 ° based on the experimental results. Moreover, the moving speed of the bucket 10 is set so that the speed component in the flowing direction of the flowing water is 0.3 to 10 cm / s larger than the flowing water speed.
As the transmission member 9 is driven, the bucket 10 that is inverted at the portion of the rotating wheel 5 captures larvae that live in the water, for example, larvae, and transports them above the water surface when moving from above the water surface. As the conductive member 9 in the motor-driven rotating wheel 6 is reversed, the opening is gradually reversed downward so that the larvae in the bucket 10 are discharged together with water toward the return water channel 4 laid down below. It has become.
The return water channel 4 is laid higher than the water level of the river, and is a relatively short water channel connected to the river at a position downstream of the river intake.
The bucket 10 can be used as a larval fish recovery / river return device according to the present invention by attaching the bucket 10 to a transmission member of a dust removal mechanism including an existing endless rotation mechanism installed in a water channel.
The bucket 10 is preferably moved by the endless rotation mechanism as described above, but is not limited thereto, and other known means may be employed.

FIG. 6 shows the bucket 10, and FIG. 6 (a) is a perspective view showing a state in which two rows of buckets are arranged in parallel and four of them are arranged in the moving direction, and FIG. 6 (b) is a side view of the bucket. FIG.
As shown in FIG. 2B, the bucket 10 has a flat mesh portion 11, a side cross-section that is substantially triangular and has the same width as the mesh portion 11, and includes an upper surface plate 12, a lower surface plate 13, and both side plates 15. And the fish collection part 16 formed watertightly by the baseplate 14 is comprised.
The upper surface plate 12 of the fish collection portion 16 is provided continuously with the flat mesh portion 11, and the lower surface plate 13 is attached to the transmission member 9 of the endless rotation mechanism so that the opening 17 of the fish collection portion 16 faces the moving direction of the bucket. It is mounted so as to be substantially parallel. The flat mesh portion 11 is made of stainless steel having a mesh whose length is about 0.5 mm. The mesh size is not limited to 0.5 mm and may be larger.
Of the larvae 18 approaching the bucket 10 from above, the larvae that have approached the mesh part 11 exhibit a repellent reaction in the vicinity of the mesh part 11 and are directed in the direction of the fish collection part 16 as indicated by a broken line in FIG. It is converted and stored in the fish collection unit 16 together with running water. At this time, since the larvae 18 approach the slanting direction with respect to the mesh part 11, the mesh projection size is made finer by an amount corresponding to the inclination, and the larvae cannot pass through the mesh part 11, so that the fish collection effect is further increased. Will be enhanced.

FIG. 7 is a diagram for explaining the coverage in the collection of larvae by the bucket 10 described above.
In FIG. 7, the height of the bucket is H _B , the bucket interval is L _B , the flow velocity of running water is V, the bucket moving speed is V _B , and the bucket moving angle is θ. The bucket moving speed V _B is set slightly larger than the flowing water flow velocity V.
Now, if the relative velocity between the velocity V of the running water and the velocity component in the direction of running of the bucket is Vr,
The relative velocity Vr = V _B cos θ−V, and the bucket motion on the relative velocity has an upward angle θr larger than θ with respect to the direction of running water as indicated by an arrow 19.
And, since it is expressed by the coverage ratio = collection part / bucket passing interval, calculating this,
Recovery part = H _B cos (θr−θ)
Bucket feed intervals _{= L B sin (θr-θ} )
Because
Cover ratio = recovered portion / bucket passage interval = H _B cos (θr−θ) / L _B sin (θr−θ) = H _B / L _B / tan (θr−θ).
As is clear from this equation and FIG. 7, by reducing the gap between one recovery portion and the next recovery portion, the coverage rate can be increased and the recovery rate of larvae can be increased.
FIG. 7 shows a case where the cover ratio <1 and FIG. 8 shows a case where the cover ratio> 1.

FIG. 9 is an explanatory diagram for selecting an experiment case for obtaining a recovery experiment result.
The recovery theory can be represented by a dimensionless graph as shown in FIG. 9A, where bucket height HB / bucket passage interval LB × bucket speed VB / flowing water flow velocity V = constant (coverage). Since the purpose of the experiment is to see the correlation between the coverage rate and the feedback rate, a case that can confirm the purpose was selected in this graph and the experiment was conducted. The case where this experiment was conducted is as plotted in FIG. Moreover, the conditions in which the experiment was performed are shown in FIG.

FIG. 10 is a scatter diagram of the coverage rate and the return rate created based on the data obtained using the larval fish recovery / river return device according to the present invention. The correlation coefficient was 0.73, and there was a correlation between the coverage rate and the feedback rate, and the recovery theory could be verified.
Moreover, the feedback rate was able to ensure about 70% as the coefficient 0.69 of the formula y = 0.69x.

FIG. 11 shows the experimental results of measuring the survival rate of baby sweetfish.
As a result of conducting experiments with the upstream flow velocity and bucket rotation speed set to 11 types as shown in the figure, the survival rate immediately after returning the returned solid in terms of the number of returned pupa sweetfish was 86% or more in all cases The average of these values was as high as 95.7%.

FIG. 12 shows the results of examining the subsequent survival rate of the returned sweetfish.
The survival rate after 17 hours in the experimental group was 83.1%, and the target group was 85.1%.
In FIG. 12, the “experiment group” is the experiment in which the puppy collected and returned in the bucket is housed and observed in the beaker, and the “target group” is the puppy of the same puppy that is used for the collection experiment. This is an experiment in which a beaker was housed and observed.
Thus, it can be seen that the subsequent survival rate of the puppy sweetfish returned by the larval fish recovery / river return device according to the present invention is almost the same as the survival rate of the puppy sweetfish in the normal growth state.

  As described above, according to the larval fish recovery / river return device according to the present invention, for example, 70% of the larvae that have been taken into (or entrapped in) the intake channel can be recovered and returned. Ninety percent of the collected and returned pups survived.

It is the schematic explaining the fish collection function of this invention. It is a figure which shows the experimental result of the recovery rate of a pupa sweetfish when a 0.5 mm mesh is installed perpendicularly to flowing water. It is the figure which showed the relationship between relative velocity and the survival rate of a sweetfish. It is the whole perspective view seen from the front and slightly diagonal explaining the condition which installed the larval fish recovery and river return device concerning the present invention in the intake channel provided in the river. BRIEF DESCRIPTION OF THE DRAWINGS It is for demonstrating one Embodiment of the larval fish recovery and river return apparatus which concerns on this invention, and is the whole schematic view which looked at the apparatus installed in the intake channel and the intake channel from the side. BRIEF DESCRIPTION OF THE DRAWINGS The bucket which concerns on embodiment of this invention is shown, FIG. (A) is a perspective view of the state which provided two buckets in parallel and arranged these 4 units | sets in the moving direction, (b) is a bucket. FIG. It is a figure explaining the coverage in collection | recovery of the larva by the bucket which concerns on embodiment of this invention. It is a figure for demonstrating the case where cover rate> 1. It is explanatory drawing for selecting the experiment case for obtaining a collection experiment result. It is a scatter diagram of the coverage and return rate created based on the data obtained using the larval fish recovery and river return device according to the present invention. It is a figure which shows the experimental result of the survival rate measurement of a puppy sweetfish. It is a figure which shows the result of having investigated the subsequent survival rate of the returned sweetfish.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 River 2 Intake channel 3 Larvae collection / River return device 4 Return channel 5 Rotating wheel 6 Motorized rotating wheel 7 Idler 8 Idler 9 Endless annular transmission member 10 Bucket 11 Flat plate mesh portion 12 Top plate 13 Bottom plate 14 Bottom plate 15 Side plate 16 Fish collection part 17 Opening 18 Larval fish approaching bucket 19 Bucket movement on relative speed

Claims (10)

In the larval fish recovery and river return device, which recovers the larvae that entered the river intake channel without damaging them and returns them to the river, it moves from the water upward to the water surface with a certain angle and relative speed difference with respect to the flow of the flowing water in the intake channel. A bucket portion that has a mesh portion through which water can pass and a fish collection portion that can store larvae and water at a rear position of the mesh portion, and the bucket moving speed is determined between the velocity component in the flowing direction of the flowing water and the flowing water. A larval fish recovery / river return device characterized in that the relative speed is set to be 0.3 to 10 cm / s and the mesh part is positioned obliquely with respect to running water .   The larval fish recovery / river return device according to claim 1, wherein the moving speed of the bucket is set so that the speed component in the flowing direction of the flowing water is 0.3 to 10 cm / s larger than the flowing water speed.   The larval fish recovery / river return device according to claim 1 or 2, wherein an angle of movement of the bucket moving from underwater to the upper surface of the water in water is set by an angle obtained from a coverage of the flowing water based on a coverage rate.   The larval fish recovery / river return device according to any one of claims 1 to 3, wherein a plurality of buckets are mounted at predetermined intervals on a transmission member of an endless rotation mechanism installed in a water channel.   The larval fish recovery / river return device according to any one of claims 1 to 4, wherein a plurality of buckets are mounted at predetermined intervals on a transmission member of a dust removal mechanism including an endless rotation mechanism.   The bucket is composed of a flat mesh portion and a fish collection portion having a substantially triangular side section and the same width as the mesh portion and formed watertight by an upper surface plate, a lower surface plate, both side plates and a bottom plate. The larval fish recovery / river return device according to any one of claims 1 to 5.   The upper surface plate of the fish collection part is continuously provided on the flat mesh part, and the lower surface plate is fixed to the transmission member of the endless rotation mechanism so that the opening of the fish collection part faces the moving direction. The larval fish collection and river return device described.   The larval fish recovery / river return device according to claim 6 or 7, wherein the flat mesh portion is made of stainless steel having a mesh length of about 0.5 mm or more through which the larvae pass.   The bucket moved from the water to the surface of the water is gradually tilted downward so that the larvae in the fish collection unit are returned together with water to a return channel provided at a position higher than the river water level. The larval fish collection / river return device according to claim 8. High recovery rate and survival return rate are achieved by setting the bucket size, installation interval, angle with running water, and relative speed so that the coverage rate by which the mesh section filters the running water is the optimal collection condition. The larval fish recovery / river return device according to any one of claims 1 to 9.

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