JPH0365733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for blocking fish from swimming in seawater when culturing fish.

[Conventional technology]

Conventionally, when cultivating fish, a cage is set up in seawater, and the fish are cultured within the cage.Usually, a net is stretched around the seawater to form a cage, and the net is used to transport the fish to the outside of the cage. This prevents fish from escaping and from entering the inside of the cage.
At the early stage of aquaculture, farmed fish are still young fish with a body length of several centimeters, and in order to block the swimming of these young fish, it is necessary to use a very fine mesh net placed in the seawater. .

However, in sea areas where tidal changes can be several meters, nets are easily damaged, and even if the damage is slight, young fish can easily escape, requiring a great deal of effort and expense to maintain and maintain the nets. In order to eliminate this inconvenience, a sea area where the water is not too deep, where the waves are calm, and where there is little tidal change is usually selected as the sea area where the fish tank is placed. However, the nets may be washed away by typhoons or damaged due to contact with ships, and the maintenance and upkeep of the nets still requires a great deal of effort and expense, and the nets do not reliably block the swimming of fish. I can't.

In addition, when carrying out large-scale aquaculture such as at ocean 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, blocking the swimming of fish. Using nets is not the best strategy for large-scale aquaculture.

Therefore, as shown in FIG. 4, the present applicant arranged two electrode rows 1a and 1b, each consisting of, for example, a plurality of rod-shaped electrodes, in seawater at a certain distance apart, and created a gap between the two electrode rows 1a and 1b. A voltage is continuously applied to form an electric screen 2 between both electrode rows 1a and 1b, the aquaculture area is surrounded by this electric screen 2, and swimming of cultured fish and predator fish is blocked by electrical stimulation of the electric screen 2. I am proposing that.

In addition, as shown in FIG. 5, a light-blocking screen 3 is formed by continuously irradiating seawater with band-shaped or fan-shaped light, and the aquaculture area is surrounded by this light-blocking screen 3, and the light-blocking screen 3 is used as a threat. The applicant has also proposed blocking the swimming of farmed fish and foreign enemy fish depending on the effect.

[Problem that the invention seeks to solve]

However, in the case of blocking swimming by the electric screen 2 shown in Fig. 4, if the electric field strength of the electric screen 2 is too high, the fish that have invaded the electric screen 2 will be paralyzed by the electrical stop stimulation and may not take sufficient repellent behavior. If the electric field strength of the electric screen 2 is too low, the fish that invade the electric screen 2 will be able to take sufficient repellent action. On the other hand, there is a problem that it easily passes through the electric screen 2.

On the other hand, in the case of blocking swimming by the light blocking screen 3 shown in Fig. 5, a sufficient intimidating effect can be obtained at the beginning of the light irradiation, but as time passes, the threatening effect becomes less effective as the fish become accustomed to the light blocking screen 3. There is a problem in that it fades and cannot reliably block fish from swimming.

Therefore, the technical problem of this invention is to ensure that swimming of fish can be blocked.

[Means for solving problems]

This invention has been made with the above points in mind, and includes a method for blocking fish swimming in seawater, which includes forming an electric screen with a predetermined electric field strength and a light blocking screen in seawater. This is a method for blocking the swimming of fish.

[Effect]

Therefore, according to the present invention, when both screens are initially formed, fish do not approach both screens due to the intimidating effect of the light blocking screen, and even when the intimidating effect fades, the electrical stimulation of the electric screen prevents fish from approaching both screens. Swimming will be blocked, and eventually, due to the learning effect of the fish, the fish will avoid both screens just by seeing the light from the light blocking screen, and the number of fish approaching both screens will decrease, ensuring that the swimming of the fish will be blocked. At the same time, damage to the fish body caused by electrical stimulation is significantly reduced compared to conventional methods.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 to 3 showing one embodiment thereof.

First, to explain the principle of this invention, an electric screen ES is formed in seawater as shown by the diagonal line going diagonally upward to the right in Fig. Form a light blocking screen LS. However, at this time, both screens ES and LS are formed by superimposing them.

At the beginning of the formation of both screens ES and LS,
Due to the threatening effect of the light blocking screen LS, fish do not approach both screens ES and LS, but as the threatening effect of the light blocking screen LS fades, fish begin to approach both screens ES and LS.
Furthermore, a large number of fish begin to invade both screens ES and LS, but these invading fish receive electrical stimulation from the electric screen ES and invade both screens.
They will no longer be able to pass through ES and LS, and eventually, due to the fish's learning effect, they will avoid both screens ES and LS just by seeing the light from the light blocking screen LS, and the number of fish that approach both screens ES and LS will also decrease. At the same time, the swimming of the fish is reliably blocked, and at the same time, the damage to the fish body caused by electrical stimulation is greatly reduced.
This phenomenon is noticeable when LS overlaps, and a similar phenomenon is seen when both screens ES and LS partially overlap or are parallel.

Next, FIG. 1 showing the specific configuration of this embodiment will be explained.

In the figure, 4a and 4b are two electrode rows formed by electrically connecting a plurality of rod-shaped electrodes that are longer than the depth of the water and arranged at approximately equal intervals in the vertical direction, and 5 is a row of both electrodes. A power supply connected to the rows 4a and 4b and applying voltage between both electrode rows 4a and 4b to form an electric screen ES; 6 is a power supply connected to both electrode rows 4a and 4b;
7 is a light source supported by the support 6, which irradiates the seawater with fan-shaped light as shown by the dashed-dotted line arrow in the same figure. , superimposed on the electric screen ES to form a light blocking screen LS.

At this time, a plurality of light sources 7 for generating the light blocking screen LS are installed at regular intervals, and each light source 7 is
The light blocking screen LS is formed by sequentially overlapping a part of the irradiated light, and both screens ES, LS
By forming both screens ES and LS to surround the aquaculture area, based on the principle described above, the swimming of the aquaculture fish can be blocked without damaging the bodies of the aquaculture fish in the aquaculture area, and the aquaculture outside the aquaculture area can be prevented. It is possible to reliably prevent fish from escaping, and at the same time, it is possible to reliably prevent foreign fish from entering the aquaculture area.

Then, we investigated the swimming blocking effect in the case of such a combination of both screens ES and LS by using an electric screen.
A comparison between the case of only ES and the case of only light blocking screen LS is shown in FIG. 3.

That is, in Fig. 3, the horizontal axis is time, and the vertical axis is distance from one end of screens ES and LS, and now the distance to the other end of both screens ES and LS, that is, both screens ES, The width of both LS is D, and the longest distance that a swimming fish can reach from one end of the screens ES and LS to the other after starting to drive the power source 4 and light source 6 to form the screens ES and LS. shows how it changes over time, and in the case of only electric screen ES, it will change as shown by the dashed line in the figure, and before reaching the other end of electric screen ES. , becomes paralyzed by the electrical stimulation of the electric screen ES, becomes unable to swim, and sinks to the sea floor, so the reach distance is close to D. If only the light blocking screen LS is used, as shown by the two-dot chain line in the figure. When the light-blocking screen LS is first formed, the light has a threatening effect, so the reach distance is 0, but as time passes, the threatening effect fades due to habituation, and the light gradually invades the light-blocking screen LS. ,
Furthermore, it will begin to pass through, and the distance it can reach will increase rapidly.

On the other hand, in the case of a combined type of both screens ES and LS, as shown by the solid line in Figure 3, as explained in the principle above, initially the fish were attracted to both screens due to the threatening effect of the light blocking screen LS. Screen ES, LS
The fish do not penetrate into the interior and the reach distance begins to increase slightly, but due to the electrical stimulation of the electric screen ES and the fish's learning action, the fish return to both screens.
It no longer intrudes into ES and LS, and the reach distance becomes 0.

Note that the apparatus for forming the electric screen ES and the light shielding screen LS is not limited to the one consisting of the electrode arrays 4a, 4b, the power source 5, the support body 6, and the light source 7 as shown in FIG.

Moreover, even if both screens ES and LS are formed partially overlappingly or in parallel, the present invention can be implemented in the same manner.

〔Effect of the invention〕

As described above, according to the method for blocking swimming of fish of the present invention, since an electric screen and a light blocking screen are formed in seawater, it is possible to prevent damage to the fish body due to paralysis caused by electrical stimulation. It is now possible to reliably prevent fish from swimming, and the effect is extremely large.

[Brief explanation of drawings]

1 to 3 show an embodiment of the method for blocking the swimming of fish according to the present invention, FIG. 1 is a schematic diagram of an apparatus for forming an electric and light blocking screen according to the present invention, and FIG. 2 is a diagram illustrating the principle. FIG. 3 is a diagram showing the relationship between the elapsed time from the start of screen formation and the swimming distance of fish, and FIGS. 4 and 5 are schematic diagrams of conventional fish swimming blocking methods, respectively. ES...Electric screen, LS...Light blocking screen.

Claims (1)

[Claims] 1. A fish swimming blocking method for blocking fish swimming in seawater, which comprises forming an electric screen with a predetermined electric field strength and a light blocking screen in seawater.