JPH0442794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric screen generating device for generating an electric screen for blocking swimming of fish and shellfish in seawater when cultivating fish and shellfish.

[Conventional technology]

Generally, when cultivating fish and shellfish, a cage is set up in seawater, and the fish and shellfish are cultured within the cage. Usually, a net is stretched around the seawater to form a cage, and the net is used to extend the fish and shellfish to the outside of the cage. However, in the early stage of aquaculture, farmed fish are still young fish with a body length of several centimeters, and in order to prevent the swimming of these young fish, In this case, it is necessary to use a very fine-mesh net to be placed in seawater.

However, in sea areas where tidal changes can be as large as several meters, the nets are easily damaged, and even if the damage is slight, young fish can easily escape, resulting in the inconvenience of requiring a great deal of effort and expense to maintain and maintain the nets. occurs,
In order to eliminate these inconveniences, conventionally, the sea areas where the fish cages are installed are selected in areas where the water depth is not too deep, the waves are calm, and there are few tidal changes, but even in areas that meet these conditions, typhoons The nets may be washed away due to water pollution, etc., or damaged due to contact with ships, which requires a great deal of effort and expense to maintain and maintain the nets, and the nets cannot reliably block the swimming of fish and shellfish. There is a problem.

In addition, when carrying out large-scale aquaculture such as on marine farms, the total length of the nets used is extremely long, and the labor and expense required to maintain and maintain the nets are correspondingly large. Using nets for isolation is not the best strategy for large-scale aquaculture.

Therefore, the present applicant has proposed an electric screen generator shown in FIG.

That is, as shown in FIG. 5, a plurality of vertically extending rod-shaped conductive electrodes 1a that are longer than the water depth are placed in seawater.
The conductive electrodes 1a are arranged at approximately equal intervals, and the conductive electrodes 1a are electrically connected to each other to form one electrode row 2a.Similarly, a plurality of vertical rod-shaped conductive electrodes 1b, which are longer than the water depth, are placed in seawater as electrodes. The conductive electrodes 1b are arranged at substantially equal intervals with the same pitch as the row 2a, and the conductive electrodes 1b are electrically connected to each other to form the other electrode row 2b,
The electrode row 2b is arranged at a certain distance from the electrode row 2a, and a power source for generating an electric screen (not shown) is used so that, for example, one electrode row 2a has a high potential and the other electrode row 2b has a low potential. , applying, for example, a DC voltage between both electrode rows 2a and 2b,
An electric screen is generated between both electrode rows 2a and 2b.

Fish and shellfish that have entered such an electric screen are electrically stimulated, and when the potential gradient is small, they exhibit a startled state, and as the potential gradient increases, they experience mild numbness, paralysis, and even asphyxia. If the electrode arrays 2a and 2b are arranged so that a specific area is surrounded by the electric screen, the fish will exhibit an electric shock reaction and will be unable to swim through the electric screen. The shellfish are trapped, and the swimming of fish and shellfish is reliably blocked without using nets as in the past, and it is not affected by ocean conditions such as tide level, tide, water depth, or weather conditions such as typhoons. Suitable for large-scale aquaculture such as ocean farms.

However, in this case, the upper ends of each of the conductive electrodes 1a, 1b are exposed above the sea surface, which causes an inconvenience in that navigation of the ship is hindered.

Therefore, as shown in FIG.
To prevent the upper ends of a and 1b from being exposed above the sea surface,
It has been considered to shorten each conductive electrode 1a, 1b, and a voltage is applied by connecting a power source 3 for generating an electric screen to both electrode rows 2a, 2b consisting of such short conductive electrodes 1a, 1b, respectively. Then, a line obtained by connecting equipotential points in an arbitrary vertical cross section perpendicular to both electrode rows 2a and 2b, that is, an equipotential line, becomes a dashed-dotted line in FIG.

That is, as shown in FIG.
The spacing between the equipotential lines is narrow and uniform between a and 2b, whereas the spacing between the equipotential lines gradually widens above and outside of both electrode rows 2a and 2b as you move away from the electrode rows 2a and 2b. , this is both electrode rows 2
This shows that the potential gradient between a and 2b is large and constant, whereas the potential gradient is small and not constant above and outside both electrode rows 2a and 2b, especially above both electrode rows 2a. Near the sea surface, the potential gradient is very small and almost zero.

As a result, for example, the current density distribution at the intermediate position between both conductive electrodes 1a and 1b in FIG. 6 becomes as shown in FIG. Let L' be the water depth of On the upper side, the current density decreases as it approaches the sea surface and becomes 0 near the sea surface, and fish and shellfish can easily move near the sea surface on the upper side of both electrode rows 2a and 2b, where the current density is low, with almost no electrical stimulation. You will be able to pass by swimming.

[Problem that the invention seeks to solve]

Therefore, as shown in FIG.
If electrodes a and 1b are shortened so that their upper ends are not exposed above the sea surface, ships can navigate without any problem even if they are above both electrode rows 2a and 2b. Shellfish can easily swim through the water with almost no electrical stimulation.
Even if such electrode arrays 2a and 2b are arranged to surround a specific range, it is not possible to prevent fish and shellfish from entering and exiting the range, and swimming of fish and shellfish cannot be reliably blocked. The problem is that it cannot be done.

Therefore, the technical object of this invention is to make it possible to reliably block the swimming of fish and shellfish without interfering with the navigation of ships.

[Means for solving problems]

This invention has been made with the above-mentioned points in mind.
an electrode row, a second electrode row that is electrically connected to each other and is made up of a plurality of conductive electrodes arranged at a certain distance from the first electrode row and arranged at approximately equal intervals; and a voltage between the two electrode rows. and a power source for electric screen generation that applies a voltage, and each of the conductive electrodes of the first and second electrode rows is inclined toward the second and first electrode rows, respectively. It is a device.

[Effect]

Therefore, in the present invention, a voltage is applied by a power source for generating an electric screen between a first electrode row disposed under the sea and a second electrode row located a certain distance from the first electrode row, An electric screen is formed between both electrode rows, and the electric screen blocks swimming of fish and shellfish.

At this time, the conductive electrodes of the first and second electrode rows are inclined toward the second and first electrode rows, respectively, and the upper ends of the conductive electrodes are arranged in the sea without being exposed above the sea surface. , the electric potential gradient and current density of the electric screen near the sea surface above both electrode arrays will not become zero, preventing interference with ship navigation and at the same time blocking the swimming of fish and shellfish. become.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 to 4 showing one embodiment thereof.

In FIGS. 1 and 2, 4a is a first electrode row consisting of a plurality of conductive electrodes 5a arranged at approximately equal intervals in the sea and electrically connected to each other, and 4b is a first electrode row. A second electrode row is provided at a certain distance from 4a, and is composed of a plurality of conductive electrodes 5b arranged at approximately equal intervals and electrically connected to each other, and is electrically connected to both electrode rows 4a, 4.
The conductive electrodes 5a and 5b of b are the second and first conductive electrodes, respectively.
The electrode rows 4b, 4a are provided in an inclined manner, and a DC voltage is applied between the two electrode rows 4a, 4b by a power source 6 for generating an electric screen, for example, with the first electrode row 4a as a ground electrode, and the electrode rows 4a, An electrical screen is formed between 4b.

The equipotential line in any vertical cross section perpendicular to both electrode rows 4a, 4b becomes like the dashed-dotted line in FIG. The potential gradient between the electrode arrays 4a and 4b gradually increases from the lower end toward the upper end, and is maximum between the upper ends of both electrode arrays 4a and 4b, and the potential gradient above both electrode arrays 4a and 4b is equal to the sea level. The potential gradient gradually decreases as it approaches , but the potential gradient never reaches 0 near the sea surface.

Therefore, both conductive electrodes 5a and 5b in FIG.
The distribution of current density at the intermediate position is as shown in Figure 3. As in the case of Figure 6, if the water depth to the seabed is L and the water depth to the top of the conductive electrodes 5a and 5b is L'. , the current density is maximum at water depth L', and from water depth L' to L, the current density gradually decreases as the water depth increases,
Similarly, between water depths 0 and L', the current density gradually decreases as the water depth becomes shallower, but the current density does not become 0 even near the sea surface.

When both the electrode rows 4a and 4b are arranged so as to surround a specific range with the electric screen, when the voltage applied between the two electrode rows 4a and 4b is changed, the electric screen passes through the electric screen from within the range. The number of fish and shellfish to be collected is as shown by the solid line in FIG.
The number of fish and shellfish passing through is 0 even if the applied voltage between
On the other hand, if a voltage higher than a predetermined value is applied between both electrode rows 4a and 4b, the number of fish and shellfish passing through the screen becomes 0, and no fish and shellfish can pass through the electric screen at all. It is possible to prevent the current from easily passing through a nearby region with low current density, and the upper end of each conductive electrode 5a, 5b is not exposed above the sea surface, and at the same time, it is possible to prevent the navigation of the ship from being hindered. It can reliably block the swimming of fish and shellfish.

Note that the conductive electrodes 5a and 5b are not limited to the rod-shaped ones described above.

Furthermore, it goes without saying that an AC voltage or a pulse voltage may be applied between the electrode arrays 4a and 4b using a power source for generating an electric screen.

〔Effect of the invention〕

As described above, according to the electric screen generator of the present invention, the first and second electrode rows 4a, 4 are placed underwater.
b, and each conductive electrode 5 of both electrode rows 4a, 4b
a, 5b are the second and first electrode rows 4b, 4a, respectively.
Because the conductive electrodes 5a, 5b are tilted to the side, the upper ends of each conductive electrode 5a, 5b are not exposed above the sea surface, which prevents the navigation of ships from being hindered. It is possible to prevent the potential gradient and current density near the sea surface of the electric screen from becoming zero, and it is possible to reliably block the swimming of fish and shellfish, which is extremely effective.

[Brief explanation of drawings]

1 to 4 show one embodiment of the electric screen generator of the present invention, FIG. 1 is a perspective view,
Figure 2 is a schematic configuration diagram, Figure 3 is a diagram of the relationship between current density and water depth when an electric screen is generated, Figure 4 is a diagram of the relationship between applied voltage and the number of fish and shellfish passing through, and Figures 5 and 6. 7 are a perspective view and a schematic configuration diagram of an electric screen generator compared with this invention, respectively.
The figure is a diagram showing the relationship between current density and water depth when an electric screen is generated in the apparatus of FIG. 6. 4a, 4b...electrode row, 5a, 5b...conductive electrode, 6...power source.

Claims (1)

[Claims] 1. A first electrode row consisting of a plurality of conductive electrodes arranged at approximately equal intervals underwater and electrically connected to each other, and a plurality of conductive electrodes arranged at approximately equal intervals and provided at a certain distance from the first electrode row. a second electrode row made up of conductive electrodes electrically connected to each other; and a power source for generating an electric screen that applies a voltage between both the electrode rows; An electric screen generating device characterized in that the conductive electrodes are inclined toward the second and first electrode rows.