JPS62275635A - Method for blocking migration of fish - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for blocking the swimming of fish in seawater when culturing fish.

[Conventional technology]

Generally, when cultivating fish, cages are set up in seawater.
Fish are cultivated in these cages, and the cages are usually formed by stringing nets around the seawater, and the nets prevent fish from escaping to the outside of the cage and preventing fish from entering inside the cage. However, in the early stage of aquaculture, the farmed fish are still young fish with a body length of 7, and in order to block the swimming of these young fish, very fine mesh nets must be placed in the seawater. It is necessary to use

[Problem that the invention seeks to solve]

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. In order to eliminate this inconvenience, 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. However, the nets may be washed away by typhoons or damaged due to contact with ships, and maintenance and maintenance of the nets requires a great deal of effort and expense, and the nets do not reliably block the swimming of fish. The problem is that it is not possible.

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. The use of nets is not the best strategy for large-scale aquaculture.

Therefore, in this invention, we have developed a technology that can reliably block the swimming of fish, without using conventional nets, and without being affected by sea conditions such as tide level and tides, or weather conditions such as typhoons. This will be a major issue.

[Means for solving problems]

This invention was made with the above points in mind,
A method for blocking the swimming of fish in seawater, which is characterized in that a light blocking screen is formed in the seawater and the light blocking screen is intermittent.

[For production]

Therefore, in this invention, a light blocking screen is formed in seawater, and the light blocking screen is intermittent at a predetermined period, and the intermittent emission of light has a threatening effect on fish. The screen will block fish from swimming.

〔Example〕

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

In FIGS. 1 and 2, (1) is a plurality of linear light generating means installed in parallel on the seabed and projecting linear light;
As shown in the figure, a directional light source (2) such as a laser, a lindrical lens (3) that spreads the beam from the light source (2) in one direction only, and a linear lens (3). It consists of a polygon mirror (4) formed by attaching a mirror to the circumferential surface of a regular octagonal prism that is rotatable around a rotation axis parallel to the longitudinal direction of the linear beam. ) and a mirror (4) are housed in the housing (5), and linear light is projected from the light projection window of the housing (5).

At this time, due to the rotation of the mirror (4) in the direction of the solid line arrow in FIG. 2, the lens (3) reflected by the mirror (4)
) rotates in the direction of the dashed arrow in the figure, and the linear light from the linear light generating means (1) is swept in one direction at a period based on the rotation period of the mirror (4). become.

(6) is a long reflecting plate arranged on the seabed, and the linear light from each linear light generating means (1) is reflected from the seabed to the sea surface by the reflecting plate (6), and the linear light is By sweeping, a light blocking screen (7) as shown in FIG. 3 is formed in the seawater.

Then, as described above, when the linear lights from each generating means (1) are swept in synchronization with the same period and a light blocking screen (7) that emits light intermittently is formed in the seawater, the screen (
Due to the threatening effect of the intermittent light emission of 7), as shown in Figure 4, the screen (7) is attacked from both sides of the screen (7).
Fish swimming towards (F), (F) is the screen (7)
The swimmer turns back before reaching the screen (7), and is unable to swim through the screen (7), and is blocked from swimming.

Therefore, by arranging the generating means (1) and the reflecting plate (6) so as to surround a specific area with a light blocking screen (7), escape of fish from inside the specific area to outside the area is prevented. At the same time, fish are prevented from entering the specific area from outside the specific area, and fish can be cultivated within the specific area.

At this time, in order to investigate the threatening effect of intermittent light emission on fish, we measured the relationship between the sweeping speed of the linear light from the generating means (1) and the swimming blocking rate of the fish by the screen (7). As shown in Figure 5, when the sweep speed is within a certain range, the swimming interception rate of fish is approximately 100.
%, and if the sweep speed is too slow, the period of intermittent light becomes long and the threatening effect becomes low, and the blocking rate decreases. If the sweep speed is too fast, the period of intermittent light becomes short and the light becomes continuous light. As the distance approaches, the threat effect becomes lower and the blocking rate decreases.

Note that the device for forming and intermittent light blocking screen is not limited to the one described above.

〔Effect of the invention〕

As described above, according to the method for blocking fish swimming of the present invention, there is no need to use nets as in the past, and fish swimming is not affected by sea conditions such as tide levels and tides, or weather conditions such as typhoons. can be reliably blocked, and the effect is great.

[Brief explanation of drawings]

The drawings show one embodiment of the method for blocking swimming of fish according to the present invention, and FIG. 1 is a perspective view, FIG. 2 is a partial perspective view, and FIGS. 3 and 4 are perspective views for explaining the operation. and a cross-sectional view, and FIG. 5 is a diagram showing the relationship between the sweeping speed of linear light and the swimming blocking rate of fish. (1)... Linear light generating means, (7)... Light blocking screen.

Claims (1)

[Claims] (1) A method for blocking fish swimming in seawater, the method comprising forming a light blocking screen in seawater and intermittent use of the light blocking screen.