JPH0365734B2 - - 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. .

By the way, in sea areas where tidal changes can be as large as several meters, 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 this inconvenience, the sea area where the fish tank is usually placed is not too deep, the waves are calm, and there are few tidal changes.However, even in sea areas that meet these conditions, typhoon The nets may be washed away due to water damage, 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.

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. 6, the present applicant arranged two electrode rows 1a and 1b, each consisting of a plurality of rod-shaped electrodes, at a certain distance apart, in seawater, and 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.

Further, as shown in FIG. 7, a light blocking screen 3 is formed by continuously irradiating seawater with band-shaped or fan-shaped light from a light source, and the aquaculture area is surrounded by this light blocking screen 3. The applicant has also proposed blocking the swimming of farmed fish and foreign enemy fish by using the threatening effect of

[Problem that the invention seeks to solve]

However, in the case of blocking swimming by the electric screen 2 shown in Fig. 6, if the electric field strength of the electric screen 2 is too high, the fish that have entered the electric screen 2 will be paralyzed by the electric stimulation and will take sufficient repellent behavior. If the electric field strength of the electric screen 2 is too low, the fish that enter the electric screen 2 will not be able to take sufficient repellent action. However, there is a problem that it easily passes through the electric screen 2.

Therefore, the electric field strength of the electric screen 2 is set to a level that slightly paralyzes the fish body, and the electrode row 1
It is conceivable to intermittent the electric screen 2 by intermittent energization to a and 1b, but in this case, as shown in FIG. However, due to the avoidance behavior of the electrical stimulation, the number of fish that pass through the electric screen 2 immediately drops to 0, and then the electricity is stopped, and after a certain amount of time has passed after the electricity is stopped, the number of fish that pass through the electric screen 2 decreases to 0. If the energization period is too long, the number of fish will increase rapidly.
If the number of paralyzed fish increases, resulting in damage to the fish body, and if the energization period is too long, the fish may escape from the aquaculture area during the energization period. difficult.

On the other hand, in the case of blocking swimming by the light blocking screen 3 shown in FIG. 7, a sufficient intimidating effect is obtained at the beginning of the light irradiation, and as shown in FIG. 9, the number of fish passing through the light blocking screen 3 is zero. However, as time passes, the fish become accustomed to the light-blocking screen 3, and the threatening effect fades, as shown in Figure 9.
There is a problem in that the number of fish passing through the light blocking screen 3 increases rapidly, making it impossible to reliably block the swimming of fish.

Further, if the electric screen 2 and the light shielding screen 3 are formed continuously, there is a problem that power consumption increases and it is not economical.

Therefore, the technical object of this invention is to make it possible to reliably block the swimming of fish and to reduce power consumption.

[Means for solving problems]

The present invention has been made with the above-mentioned points in mind, and includes a method for blocking fish swimming in seawater, which includes forming an electric screen and a light blocking screen with a predetermined electric field strength in seawater; A method for blocking swimming of fish, characterized in that either the electric screen or the light blocking screen is turned on and off.

[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.

At this time, even if either the electric screen or the light-blocking screen is turned on and off, the swimming of the fish is blocked due to the intimidating effect of the light-blocking screen, the electrical stimulation by the electric screen, and the learning effect of the fish, as described above. Therefore, power consumption can be reduced.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 to 5 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 rising diagonally to the right in Fig. 2, and parallel to the electric screen ES is formed diagonally upward to the left in the figure. A light blocking screen LS is formed as indicated by diagonal lines.

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 looking at the light blocking screen LS, and the number of fish that approach both screens ES and LS will decrease. At the same time, the swimming of fish is reliably blocked.
Damage to the fish body due to electrical stimulation will be significantly reduced.

At this time, if only the electric screen ES is interrupted by intermittent energization of the power supply, as shown in Figure 3, some fish try to pass through both screens ES and LS at the beginning of the electric screen ES generation period T'. However, the number of fish that pass through both screens ES and LS soon becomes almost zero, and during the period when the electric screen ES is stopped, the light blocking screen is used as described above.
Due to the threatening effect of LS and the learning effect of fish, the number of fish that try to pass through both screens ES and LS remains small, and when the electric screen ES occurs again, the same phenomenon will be repeated, and as time passes, this phenomenon will increase. The phenomenon becomes noticeable and eventually the number of fish passing through both screens ES and LS becomes zero.

Therefore, even if the electric field strength of the electric screen ES is lowered to the extent that it slightly paralyzes, and even if the stop period of the electric screen ES is made longer than in the case where only the electric screen shown in FIG. 6 is formed, The swimming of the fish is reliably blocked, damage to the fish body due to electrical stimulation is reduced, and power consumption can be reduced by intermittent operation of the electric screen ES.

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 source for electric screen generation connected to the rows 4a and 4b; 6 a support such as a buoy floating on the sea surface outside the electrode row 4b; 7
is a light source supported by the support 6, and 1 in the figure
A fan-shaped light as shown by the dotted chain arrow is irradiated into the seawater to form a light-blocking screen LS in parallel with the electric screen ES.

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
The aquaculture area is formed by both screens ES and LS with the light-blocking screen LS inside, and the electric screen ES is formed by intermittent energization of the power source 5.
If this is done intermittently, the fish bodies of the cultured fish will not be damaged in the culture area for the reasons mentioned above.
To be able to cut off the swimming of cultured fish, to be able to reliably prevent the escape of cultured fish from outside the culture area, and at the same time to be able to surely prevent the invasion of foreign enemy fish into the culture area, and to reduce power consumption by intermittent power supply 5. I can do it.

Comparing the relationship between the elapsed time and the number of paralyzed fish, and the relationship between power consumption and passage rate in the case of a combined type of both screens ES and LS, and the relationship between power consumption and passage rate with the case of only the electric screen ES, it is found that 4
As shown in FIG. 5 and FIG.

In other words, Figure 4 shows the relationship between the elapsed time after the formation of the electric screen ES and the number of fish paralyzed by electrical stimulation. As shown by the dashed line in the figure, the value is very high at the beginning of screen formation, but both screens ES and LS
In the case of the complex type, as shown by the solid line in the figure,
Only a small number of fish were paralyzed, indicating that the treatment had the effect of suppressing damage to the fish body.

In addition, Figure 5 shows the relationship between power consumption and the ratio of the number of fish that pass through both screens ES and LS to the total number of farmed fish, and in the case of only the electric screen ES shown by the dashed-dotted line in the figure. In contrast, in the case of the composite type shown by the solid line in the same figure, the power supply 5 can be turned on and off to provide a period when the electric screen ES is stopped.
Not only can power consumption be significantly reduced, but the passage rate of fish passing through both screens ES and LS can also be significantly lowered, making the above-mentioned combined type highly economical.
It is also clear that there is a swimming blocking effect.

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.

In addition, the light source 7 can be intermittent to create a light blocking screen.
The present invention can be implemented in the same way even if the LS is intermittent.

Furthermore, it goes without saying that both screens ES and LS may be formed partially overlappingly or completely overlappingly.

〔Effect of the invention〕

As described above, according to the method for blocking swimming of fish of the present invention, even if the electric field strength of the electric screen is lowered to a level that slightly paralyzes, the stop period of the electric screen when the electric screen is intermittent can be reduced compared to the conventional method. Even if it is longer than when only an electric screen is formed, it is possible to reliably block the swimming of fish, and it is possible to significantly reduce damage to the fish body caused by electrical stimulation. It becomes possible to reduce power consumption by intermittent screen display, and the effect is extremely significant.

[Brief explanation of drawings]

1 to 5 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 FIGS. 2 and 3 are A diagram explaining the principle; Figure 4 is a relationship diagram between the elapsed time from the start of screen formation and the number of fish paralyzed by electrical stimulation; Figure 5 is a relationship diagram between power consumption and the passage rate of fish passing through the screen; Figures 6 and 7 are schematic diagrams of conventional fish swimming blocking methods, respectively, and Figures 8 and 9 show the elapsed time from the start of screen formation and the number of fish passing through the screen in the cases of Figures 6 and 7, respectively. This is a relationship diagram. ES...Electric screen, LS...Light blocking screen.

Claims (1)

[Claims] 1. A method for blocking the swimming of fish in seawater, which involves forming an electric screen and a light blocking screen with a predetermined electric field strength in the seawater, and intermitting either the electric screen or the light blocking screen. A method for blocking swimming of fish, characterized by: