JPH0471493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for blocking the 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. This method prevents fish and shellfish from escaping and entering the inside of the cage, but at 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, it is necessary to prevent them from swimming. , 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.

[Problem that the invention seeks to solve]

Therefore, areas where the water is not too deep, where the waves are calm, and where there are few tidal changes are usually selected as areas where fisheries are installed. However, even in areas that meet these conditions, nets may be washed away by typhoons or ships may be lost. The net may be damaged due to contact, and maintenance and upkeep of the net requires a great deal of effort and expense, and there is a problem in that the net cannot reliably block the swimming of fish and shellfish.

In addition, when carrying out large-scale aquaculture such as at marine farms, the total length of the nets used is extremely long, and using nets to block the swimming of fish and shellfish is the best strategy for large-scale aquaculture. It can not be said.

Therefore, the technical problem of this invention is to ensure that swimming of fish and shellfish can be blocked without being affected by ocean conditions such as tide levels and tides, or weather conditions such as typhoons.

[Means for solving problems]

This invention has been made with the above-mentioned points in mind, and provides a method for blocking the swimming of fish and shellfish in seawater, in which the potential gradient is 0.05.
Less than [V/cm], 0.05 [V/cm] or more to 0.1 [V/cm]
This is a method for blocking swimming of fish and shellfish, which is characterized by forming a region in seawater in the order of V/cm, 0.1 [V/cm] or more and 0.2 [V/cm] or less.

[Effect]

In this invention, the potential slope is 0.05 [V/
cm], from 0.05 [V/cm] to 0.1 [V/cm]
A region is formed in seawater in the order of 0.1 [V/cm] or more to 0.2 [V/cm] or less, and fish and shellfish that invade this region are startled by light electrical stimulation if the potential gradient is small. If the potential gradient is large, a reaction such as mild numbness or even paralysis will occur, making it impossible for fish and shellfish to swim through the area, making it possible for fish and shellfish to swim without using nets as in the past. It is not affected by ocean conditions such as tide levels or tides, or weather conditions such as typhoons.
Suitable for large-scale aquaculture such as ocean farms.

〔Example〕

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

First, to explain the principle of this invention, for example, when two electrodes are placed in parallel in seawater and a DC voltage from a DC power source is applied between the two electrodes,
When we investigated the reactions of fish and shellfish swimming between the two electrodes, we found the results shown in Figure 2.
However, this measurement was conducted on "Madai", "Flounder", and "Kuruma Shrimp".

In other words, as shown in Figure 2, when the potential gradient between the two electrodes is almost 0, the target fish shows no reaction, and when the potential gradient becomes about 0.05 [V/cm], it shows a slight electric shock. When the person becomes startled by the stimulus and the potential gradient exceeds 0.05 [V/cm] and becomes around 0.1 [V/cm], a mild numbing reaction occurs, and the potential gradient becomes 0.1 [V/cm].
When it exceeds [V/cm] and reaches about 0.2 [V/cm],
The patient becomes paralyzed, and if the potential gradient increases beyond 0.2 [V/cm], the patient becomes rigid and even fatal.

Therefore, as shown in Figure 1, the first to
The fourth electrodes 1 to 4 are arranged in parallel, and each electrode 1 to 4 is arranged in parallel.
The intervals l ₁ , l ₂ , l ₃ are respectively l ₁ = 200 cm, l ₂ = 150 cm,
l ₃ = 100 cm, for example, with the first electrode 1 as the ground electrode, the potential V ₁ of the second electrode 2, the third
The potential V ₂ of the electrode 3 and the potential V ₃ of the fourth electrode 4 are
V ₁ = 8 [V], V ₂ = 21 [V], V ₃ = 38 [V], respectively.
A DC voltage is applied to each electrode 1 to 4 by the first to third power supplies 5 to 7 so that the potential gradient E ₁ between the first and second electrodes 1 and 2 is less than 0.05 [V/cm]. about
0.03 [V/cm], and the second and third electrodes 2 and 3
The potential gradient E ₂ between is 0.05 [V/cm] or more to 0.1
It is about 0.08 [V/cm] less than [V/cm], and the third
The potential gradient E ₃ between the fourth electrodes 3 and 4 is 0.1 [V/cm]
From the above, a region with a voltage of about 0.16 [V/cm], which is less than 0.2 [V/cm], is formed in seawater.

At this time, each electrode 1 to 4 has a diameter of 300 mm.
It is assumed that a plurality of electrode rods made of copper with a diameter of 2 mm are arranged at intervals of 20 cm and are electrically connected in sequence.

For example, by placing the first electrode 1 on the inside and placing each of the electrodes 1 to 4 in seawater so as to surround a predetermined range, fish and shellfish swimming inside the first electrode 1 or a fourth When fish and shellfish swimming outside the electrode 4 enter the region formed by the electrodes 1 to 4 in the order of the potential gradient described above,
Fish and shellfish that have entered the area are electrically stimulated and are therefore unable to swim through the area.
Fish and shellfish will be confined within the range surrounded by the area.

In particular, the potential gradient inside the region is small;
Because the potential gradient is large on the outside, fish and shellfish cultivated within the area surrounded by the above region are less likely to receive strong electrical stimulation, and foreign fish and shellfish are more susceptible to strong electrical stimulation, which makes it difficult for farmed fish and shellfish to receive strong electrical stimulation. Shellfish can be prevented from being damaged by electrical stimulation, and cultured fish and shellfish can be effectively protected.

Therefore, unlike with conventional nets, there is no damage to the nets due to tidal changes or typhoons, and the labor and cost required for net maintenance can be reduced. It is possible to reliably block the swimming of fish and shellfish without being affected by ocean conditions or weather conditions such as typhoons, and it can be applied even in sea areas where there are some tidal changes, making it suitable for large-scale aquaculture such as marine farms. suitable for

In addition, as shown in FIG. 3, six electrodes 8a to 8f are arranged in parallel in seawater, and each electrode 8a to 8f
The potential gradients Ea, Eb, Ec, Ed, and Ee are sequentially less than 0.05 [V/cm], from 0.05 [V/cm] or more to less than 0.1 [V/cm], and from 0.1 [V/cm] or more to 0.2.
[V/cm] or less, from 0.05 [V/cm] or more to 0.1 [V/
cm] and less than 0.05 [V/cm], the potential may be applied to each electrode 8a to 8f.

〔Effect of the invention〕

As described above, according to the method for blocking the swimming of fish and shellfish of the present invention, the potential gradient is less than 0.05 [V/cm],
0.05 [V/cm] or more to less than 0.1 [V/cm], 0.1
By forming a region in seawater consisting of a combination of V/cm or more and 0.2 V/cm or less, it is possible to electrically stimulate fish and shellfish that have invaded the region and prevent them from swimming through the area. This makes it possible to reliably block the swimming of fish and shellfish without being affected by ocean conditions such as tide level, tide, water depth, etc. or weather conditions such as typhoons, as is the case when using nets. It is possible to reduce the labor and costs that were previously required, making it extremely effective for large-scale aquaculture such as on ocean farms, and its effects are extremely large.

[Brief explanation of the drawing]

The drawings show an embodiment of the method for blocking swimming of fish and shellfish of the present invention, and FIGS. 1 and 2 show one embodiment, FIG. 1 is a schematic diagram, and FIG. 2 is a diagram explaining the principle.
FIG. 3 is a schematic configuration diagram of another embodiment. 1-4, 8a-8f... electrode, 5-7... power supply.

Claims (1)

[Claims] 1. A method for blocking the swimming of fish and shellfish in seawater, wherein the potential gradient is 0.05.
Less than [V/cm], 0.05 [V/cm] or more to 0.1 [V/cm]
A method for blocking the swimming of fish and shellfish, characterized by forming an area in seawater with a voltage of less than 0.1 [V/cm] and 0.1 [V/cm] and less than 0.2 [V/cm].