JP2008142027A - Stationary net - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stationary net for eliminating huge jellyfish such as Nemopilema nomurai and effectively catching fishes. <P>SOLUTION: In the stationary net installed in a fishing ground through which ocean current flows, a second surrounding net part for storing huge jellyfishes and fishes is provided on the downstream side of a surrounding net part of the stationary net and a fish passage branched from the second surrounding net part and inducing fishes into a box net part or a bag net, etc., is provided and an opening for opening huge jellyfishes stored in the second surrounding part to the outside is provided on the downstream side of the second surrounding net part and Nemopilema nomurai enters the interior of the net together with fishes and induces into the second surrounding net part and fishes are advanced into the body of stationary net and the jellyfishes stored in the second surrounding net part are released to the outside by utilizing difference of swimming characteristics and difference of behavior characteristics between fishes and jellyfishes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a stationary net that prevents a giant jellyfish such as an Echizen jellyfish from entering a box net or a bag net.

  Stationary nets (also called construction nets) are methods of laying nets on the surface of the sea and migrating and catching fish that have strayed into the nets. They have been used as a fishing technique in Japan and are still used today. There is a fishing method. Many ocean currents (for example, the Kuroshio and Oyashio) flow in the waters near Japan, and various types of fish, such as sea bream, sea bream, sea bream, sea bream, sea bream, yellowtail, sea bream, etc. come. This is because plankton, which is the food for small fish, is generated by being transported by the ocean current or gathered near the tide, and contributes greatly to fish production through the food chain.

The type and configuration of the stationary network, the laying method, and the like are disclosed in many documents and homepages (hereinafter abbreviated as HP). For example, it is published in nonpatent literatures 1-4. Here, FIG. 8 shows an example of a standard large stationary network. As shown in FIG. 8, the stationary net 50 includes a fence net 51, a surrounding net 52, a bag net 53, and the like. Inside the surrounding net 52, a space 52a called a playground and a space 52b called a climbing section are provided. In addition, the rope provided on the upper edge of the stationary net 50 is provided with a float, and a fixing rope 54 for fixing the stationary net is further connected to the rope vertically at the floating position. The stationary net 50 is fixed to the end by a fixed weight 55 submerged in the seabed. A fence entrance 56 is provided at a point where the fence 52 and the fence 51 intersect. With the configuration described above, the fish that have traveled on the ocean current are blocked by the fence 51 and guided in the offshore direction along the fence 51. The guided fish enters the cage 52 through the cage entrance 56. Some swim inside the playground 52a and escape to the outside, while the other climbs the climbing net 52b and enters the bag net 53. Since the entrance of the bag net 53 is narrowed and a step is provided, fish that have entered the bag net 53 cannot easily escape to the outside.
Masamura Nomura, The latest fishery technology in general, Naruyamado Shoten, pages 180-196, published in April 2000 Book by Yasuyuki Kaneda, Japanese fishery and fishing methods, Narusendo Shoten, pages 74-85, published in June 2005 Suzuki Marine HP, sea walk 0302, the path that fishermen cannot pass Vol. 10. Surrounding sea environment-9, stationary net-4, structure of stationary net Izumizawa Fisheries HP, stationary net

FIG. 11 shows a stationary network 60 provided with a two-paragraph network that is often used in recent years. In FIG. 11, the same parts as those of FIG. 10 are denoted by the same reference numerals, description thereof is omitted, and different parts are described. In FIG. 9, a box net is provided in a two-stage configuration (first box net 62 and second box net 63) instead of the bag net 53. Further, in FIG. 9, a bag network 64 with a barb called a safe is provided. A climbing net 62 b is provided on the bottom surface of the first box net 62, and a bottom net 63 b is provided on the bottom surface of the second box net 63. With the above configuration, the stationary network 60 has the box networks 62 and 63 connected in cascade and the climbing networks 52b and 62b are arranged in two stages to form two paragraphs. The effect is that the probability that the fish will escape is reduced. Furthermore, there is a feature that the gradient of the climbing network can be reduced. Also, fish that enter the bag net 64 will not escape. In the stationary net 60, the edge of the fence net 51 is provided at the center of the fence net entrance 56.

The above-mentioned stationary net is a fishing method that captures fish that migrate around the ocean current, and can capture a large amount of fish with relatively little effort, and is one of the powerful fishing methods that can be applied to various fish. Met. However, as shown in Fig. 10, in recent years, Echizen jellyfish have been generated on the coasts of China and South Korea, and while growing, they ride northward on the Sea of Japan (Tsushima Warm Current) and come to the coast of the Sea of Japan. Has come to occur frequently. Jellyfish that have come to the coast of the Sea of Japan have also entered fixed nets, which are particularly damaging to fixed net fisheries. Large Echizen jellyfish has an umbrella diameter of 1m or more and weighs 200kg. Therefore, the fishing net is damaged by the netting of Echizen jellyfish. Damage such as damage (decrease in commercial value) has occurred (see Non-Patent Documents 5 and 6).
About Shimane Fisheries Experiment Station HP, Echizen Jellyfish Edited by Toru Yasuda, UHO Jellyfish at Sea, pages 116-120, Hoshiseisha Koseikaku

An effective means of preventing the entry of Echizen jellyfish into the stationary net has not yet been developed. The proposed method is disclosed in Non-Patent Document 7. FIG. 11 shows this method, FIG. 11 (A) shows a conventional stationary network, and FIG. 11 (B) shows the proposed method. As is clear from the comparison of these figures, the proposed method enlarges the mesh of the fence net and reduces the quantity of the Echizen jellyfish passing through the mesh and entering the body net (such as a net). However, Echizen jellyfish range from small to large as described above. There is a danger of passing small fish and medium fish when passing to a large echidna jellyfish, and there is a risk that the catch will be almost zero, which is a big problem in practice.
Ocean Center HP, fixed net fishery 5th, 1-2 Echizen jellyfish measures

  The present invention has been made under such circumstances, and it is an object of the present invention to provide a stationary net that effectively captures fish by eliminating giant jellyfish such as Echizen jellyfish by a relatively simple improvement.

The present invention employs the following configuration in order to solve the above problems. That is,
According to the first aspect of the present invention, in the stationary net installed in the fishing ground where the ocean current flows, the second enclosure is provided on the downstream side of the enclosure of the stationary net to store a giant jellyfish and fish. A fishway that branches off from the net and guides the fish to the box net or bag net is provided, and an opening is provided downstream of the second net to open the giant jellyfish accumulated in the second net. It is characterized by that.
In the present invention, Echizen jellyfish and the like (hereinafter, simply referred to as jellyfish) are introduced together with the fish and guided to the second enclosure, and the difference in the swimming characteristics between the fish and the jellyfish (for example, fish has a swimming ability compared to the jellyfish Is very large) and differences in behavioral characteristics (for example, depending on the presence or absence of vision), fish enter the main body of the stationary net (box net, bag net, etc.) and release the jellyfish accumulated in the second enclosure. It is characterized by doing.

The invention described in claim 2 is characterized in that, in the invention described in claim 1, the fishway has a fishway that branches from the branching point and has a predetermined distance or more in the upstream direction against the ocean current.
The invention described in claim 3 is characterized in that, in the invention described in claim 2, the predetermined distance is a distance that allows fish to pass easily but makes giant jellyfish difficult to pass.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the opening is provided in a rear wall network at the most downstream side of the second encircling mesh part, and is opened when the giant jellyfish is opened. It is characterized by providing an opening / closing means that closes when catching fish.
According to a fifth aspect of the present invention, in the invention of the fourth aspect, the opening / closing means is configured such that the opposite side rotates in the horizontal direction with one side as an axis, and can be opened / closed in a double door. It is characterized by being.
In the above two inventions (Claims 4 and 5), an open / close means (such as a screen door) for opening a giant jellyfish is provided to release the jellyfish accumulated in the second surrounding net part to the outside, and the stationary net is damaged by a large amount of jellyfish Or it is characterized by preventing it from functioning.

According to a sixth aspect of the present invention, in the first to third aspects of the invention, the opening has been lifted by cutting away a part of the uppermost sea surface side of the second encircling mesh portion. It is characterized by being configured to open a giant jellyfish.
The present invention is characterized by utilizing the property that Echizen jellyfish floats to the surface of the sea surface before sunset.

The invention according to claim 7 is the invention according to claims 1 to 6, wherein the bubble generating device is arranged close to or coincident with the opening, the giant jellyfish is allowed to pass through the opening, and the fish passes therethrough. It is characterized by making it difficult.
According to the present invention, fish have eyes, and some fish react sensitively to bubbles and take avoidance actions. Since Echizen jellyfish does not have eyes, it utilizes the property that it moves to the outside through the opening of the second surrounding net part by riding on the tide without reacting to the bubbles.

  The invention according to claim 8 is characterized in that, in the invention according to any one of claims 1 to 7, the enclosure of the stationary net is combined with the second enclosure. .

  According to the present invention, the jellyfish together with the fish are reticulated together and guided to the second surrounding net part, and the fish is placed in the stationary net body (box) using the difference in swimming characteristics and behavioral characteristics between the fish and jellyfish. The jellyfish accumulated in the second surrounding net part are discharged to the outside. In addition, since the jellyfish do not enter the stationary net body, there is almost no chance of contact between the fish and the jellyfish, and the fish body can be captured without being damaged. Furthermore, since the jellyfish accumulated in the second surrounding net part are appropriately discharged to the outside, an effect that an accident such as breakage of the stationary net can be prevented can be obtained.

  An embodiment of the present invention (an example of a stationary network estimated to be the best) will be described with reference to FIGS. FIG. 1 is an overall schematic diagram of a stationary network 10 according to an embodiment. Here, the method of laying the stationary network 10 is the same as that of the prior art (for example, see Non-Patent Documents 1 and 2), and the description thereof is omitted. In FIG. 1, the fence 11 is stretched almost perpendicular to the flow direction of the ocean current (or tidal current). One end portion 11 a of the fence net 11 is installed to enter an entrance portion (also referred to as a bag mouth or an end mouth) 12 a of the surrounding net 12. The surrounding net 12 is composed of a space 12b and a space 12c. The space 12b is called a playground and has no bottom net. On the other hand, the space 12c is provided with a flat bottom net or a climbing net with a gentle slope. The second enclosure 14 is connected to the downstream of the space 12c, and a flat bottom (or climbing net) that is continuous with the bottom of the space 12c is installed at the bottom of the second enclosure 14.

  An opening 15 for discharging the accumulated jellyfish to the outside is provided on the downstream side of the second enclosure 14. The opening 15 will be described later. A guide net (or fishway) 16 is provided on the side wall on the offshore side of the second net 14 to guide the fish to the box net (or also called a drop net) 17. The guide net 16 is configured in a U-shape, and is directed a predetermined distance upstream from the connection end with the second surrounding net 14 and then downstream. This predetermined distance (L) is a distance that allows fish to swim easily, and is preferably a distance that cannot easily reach the jellyfish. A climbing net or a horizontal bottom net is provided at the bottom of the guide net 16. A second box net 18 is provided downstream of the box net 17 to prevent the fish that entered the double drop net from escaping. The bottom of the box net 17 is a climbing net, and the bottom of the second box net 18 is a horizontal bottom net.

FIG. 2 is a front view of the opening 15 provided in the downstream wall net of the second surrounding net 14 and the openable / closable screen door 20 provided in the opening 15. FIG. 2 shows an embodiment in which the screen door 20 is opened and closed in the horizontal direction. The screen door 20 includes a frame body 21 to be attached to the opening 15 of the second enclosure 14 and a screen door body 22 that is rotatably supported by the frame body 21. A mounting piece 23 having a small hole for mounting is fixed outside the frame body 21, and a support member 24 that rotatably supports the screen door body 22 and a hydraulic drive device 25 that drives the screen door body 22 to open and close are framed. It is fixed to the body 21. An attachment piece 27 provided with a small hole for attaching a net is also fixed to the screen door main body 22.

3 and 4 are explanatory views of the hydraulic drive device 25. FIG. FIG. 3A shows a front view, and FIG. 3B shows a cross-sectional view taken along the line XX. FIG. 4 shows a longitudinal sectional view. As shown in FIG. 3B, the hydraulic drive device 25 is fixed to the cylindrical tube wall 28, two fixed plates 29 fixed to the inside of the tube wall 28, and the rotary shaft portion 22a. The rotary hydraulic cylinder includes a rotary plate 30 that swings between 29 and 29 and ports 31 and 32 that supply and discharge pressure oil. The cylindrical wall 28 is provided with stoppers 34 and 35 for limiting the rotation angle of the rotary plate 30. In addition, a thrust bearing 33 is provided on the rotating shaft portion 22a. The ports 31 and 32 are connected via a connector 35 to a hydraulic pump mounted on a fishing boat (not shown). When pressurized oil is supplied in the direction of the arrow shown in FIG. 4, the screen door body 22 rotates counterclockwise, the opening 15 opens, and jellyfish can be released. When pressure oil is supplied in the direction opposite to the arrow in the figure, it rotates in the clockwise direction. Thereby, the opening 15 can be closed again. The hydraulic ports of the two rotary hydraulic cylinders 25, 25 shown in FIG. 2 are connected by a pipe (not shown) and operate in synchronization.

  The screen door 20 is not limited to the one described above, and may be, for example, a double door screen that opens in both directions from the center. Further, the rotary hydraulic cylinder 25 is connected to a screen door with one end of the rope, and is connected to a winch or a fishing boat mounted on a fishing boat or the like to be pulled and opened. You may have done.

  The embodiment described above functions as follows. That is, as shown in FIG. 1, fish and jellyfish riding on the ocean current change their course by hitting the fence net 11 and are guided along the fence net 11 in the offshore direction. The inside enters from the net entrance 12a. Part of the fish and jellyfish that have entered further pass through the bottom net 12 c and enter the second surrounding net 14. Fishes that have entered the second enclosure 14 are migrating, and some of them further swim upstream through the portion of the guide net 16 and fall into the box nets (falling nets) 17 and 18. The fish that entered the box net 18 cannot stay out of the box, so they stay there. On the other hand, the jellyfish that has entered the second enclosure 14 remains within the second enclosure 14 because its swimming ability is small. The fish that have fallen into the box nets (falling nets) 17 and 18 are lifted at an appropriate time (for example, every morning) to catch the fish inside. Moreover, the jellyfish staying inside the second surrounding net 14 opens the opening 15 and discharges the jellyfish downstream. The opening time of the opening 15 does not need to coincide with the time of catching the fish, but it is preferable that a large amount of jellyfish be released before accumulating inside the second enclosure 14.

The opening 15 is not limited to the embodiment described above, and may be configured as shown in FIG. 5 or FIG. The method shown in FIG. 5 is a method in which the upper side portion 38 of the rear mesh of the second surrounding net 14 is cut out and always opened. This method utilizes the floating properties of moon jellyfish. In other words, these jellyfish float in the middle layer around 7m during the day, and many (50% or more) of jellyfish float on the surface layer near 2m before sunset, and again around 7m after sunset. It returns to the middle layer, and has the property of staying at a low level of 12 to 13 m from night (around 19 o'clock) to morning (around 5 o'clock) (see Non-Patent Document 8). Echizen jellyfish have common properties similar to moon jellyfish, so Echizen jellyfish is considered to have similar properties. Therefore, the surfaced jellyfish flow out of the second enclosure 14 by the ocean current. The depth of the opening 38 from the sea surface is preferably about 3 m. This method is excellent in that the opening / closing operation of the screen door 22 described above is unnecessary. However, it can be applied to catching fish (flounder, etc.) that migrate in the middle and lower layers, but it cannot be applied to fish (such as yellowtail, coral, horse mackerel, sea bream) that migrate around the surface layer.
Edited by Toru Yasuda, UHO Jellyfish at Sea, pages 63-73

Another difference between fish and jellyfish is that fish has eyes, can distinguish between light and darkness and color, and jellyfish do not have eyes (see Non-Patent Document 9). Therefore, the advancing direction of the fish can be changed by the bubble curtain (see Patent Document 1), but the jellyfish only floats by the bubble curtain. From the above, as shown in FIG. 6, the opening 15 is provided on the upper side of the rear net 14 and the bubble generating tube 41 is disposed on the bottom of the opening 15 so that the bubble generating device 40 is placed on the sea surface. Provided. The bubble generator 40 may have a configuration in which, for example, a compressor 40b and a driving battery are provided in a sealed floating box 40a. Further, the depth of the opening 39 from the sea surface is the depth at which the jellyfish floats, and the depth at which light from the sea surface reaches is preferably about 15 m. With the above configuration, the fish that have entered the second enclosure 14 remain in the second enclosure 14, and part of the fish enters the box nets 17 and 18 through the guide mesh 16. On the other hand, the jellyfish that has entered the second enclosure 14 exits from the opening 39 toward the downstream.
Masamura Nomura, The latest fishery technology in general, Naruyamado Shoten, pages 108-112, published in April 2000 Published Patent Publication, Japanese Patent Laid-Open No. 5-95746, Method for Inducing Fish School for Stationary Net Using Bubble Screen and Device

  FIG. 7 shows an embodiment 45 in which the second enclosure 14 is also used as a part (lower part) 12c of the enclosure 12 in the stationary network 10 of the embodiment described above. If this embodiment is used, it can be implemented with only a slight change from the conventional stationary net. However, since the second net 14 and the net entrance 12a are close to each other, the fish that have entered the net escape. There is a disadvantage that the probability increases.

As described above, according to the stationary net of this embodiment, even when a fish and a jellyfish migrate together on the ocean current, there is an effect that only the fish can be captured by separating the jellyfish. In addition, if the jellyfish are appropriately discharged before a large amount of jellyfish accumulates in the second enclosure, it is possible to prevent damage of the stationary net.

  Although the embodiment of the present invention has been described in detail with reference to the drawings, the technical scope of the present invention is not limited to this. For example, because the fish whose path is blocked by the fence has the property of turning in the deep direction on the offshore side, in the above embodiment the surrounding net is provided on the offshore side, but not limited to this, it may also be provided on the land side It belongs to the technical scope of the present invention. The same applies to the laying position of the box net or the like. In the above embodiment, the case of a double drop network has been described. However, the technical scope of the present invention is not limited to this, and the present invention is also applicable to other types of stationary networks and medium-sized or small-sized stationary networks having different sizes.

An embodiment which carried out the present invention is shown. The front view of the screen door provided in the opening part of this embodiment is shown. (A), (B) shows the whole view and plane sectional view of a rotary hydraulic cylinder which opens and closes a screen door. 1 shows a longitudinal sectional view of a rotary hydraulic cylinder. Another example of the opening of this embodiment is shown. Another example of the opening of this embodiment will be described. Another example of a modification of this embodiment is shown. The structural example of the conventional stationary network is shown. The example of the stationary network which employ | adopted the conventional double dropping net is shown. This shows the ocean currents that Echizen jellyfish come and go. A conventional stationary net that prevents entry of Echizen jellyfish is shown.

Explanation of symbols

10, 45 Stationary net 11 Hedge net 12 Enclosure 12a Entrance 14 Second enclosure 15 Opening 16 Guide net (fishway)
17, 18 Box network 20 Screen door 21 Screen door frame 22 Screen door body
25 Hydraulic drive device 40 Bubble generator 41 Bubble generator tube

Claims (8)

In the stationary net installed in the fishing ground where the ocean current is flowing, a second enclosure part for storing giant jellyfish and fish is provided downstream of the enclosure part of the stationary net, and the branching from the second enclosure part is a box for fish. A stationary net provided with a fishway that leads to a net or a bag net, and provided with an opening on the downstream side of the second net to open a giant jellyfish accumulated in the second net. 2. The stationary net according to claim 1, wherein the fishway has a fishway that is branched from the branch point and has a predetermined distance or more toward an upstream direction against the ocean current. The fixed net according to claim 2, wherein the predetermined distance is a distance that allows fish to pass through easily but makes it difficult for giant jellyfish to pass through. 2. The opening is provided in a rear wall net at the most downstream side of the second encircling net, and is provided with opening / closing means that opens when opening a giant jellyfish and closes when catching fish. The stationary net according to claim 3. 5. The stationary net according to claim 4, wherein the opening / closing means is configured such that the opposite side rotates in a horizontal direction with one side as an axis, and can be opened / closed in a double door. The opening is configured so as to open a giant jellyfish that has floated by cutting off a part of the uppermost sea surface side of the second encircling net. The described stationary net. The stationary net according to claim 1, wherein a bubble generating device is arranged close to or coincident with the opening, a giant jellyfish is allowed to pass through the opening, and fish is difficult to pass through. The stationary net according to claim 1, wherein the stationary net is configured to serve as the second net part.

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