JP3335451B2 - Reefs for benthic fish and juveniles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reef for protection and release at the bottom of a water bottom in order to prevent a marine fish such as pheasant grouper and other cultivated seedlings from being damaged by natural enemy fish such as scorpions. It is about.

[0002]

2. Description of the Related Art The size of a released seedling is about 5 cm to 10 cm, taking, for example, a juvenile fish which is a cultivated seedling of pheasant groupers. The release site has been selected as a boulder zone near the shore at a depth of 5 to 10 m, suitable for the ecology of fry. The size of the release is around several thousand to several tens of thousands, and the release time is from September to October. Wintering occurs in the boulder belt, but it does not grow much until spring, and its size does not change.

[0003]

When the water is discharged to one place, the water is temporarily distributed at a high density in a narrow range. For this reason, it has been reported that the natural enemy fish, scorpionfish, etc., already inhabiting the release site cause food damage. Damage continues until early spring when the released seedlings are small. Moreover, the released seedlings have been bred at high density in a narrow net or aquarium until the release, and are not used to the natural environment at all. For this reason, there are many individuals who are unconsciously stopped on a stone when they are released. How to protect seedlings with such properties from natural enemies is a major problem in the pheasant grouper release project.

[0004]

Various methods of protecting pheasant groupers were studied, targeting scorpions, which are the largest natural enemy of pheasant groupers, and which have a great predation ability, which inhabit the release place. First, the differences between pheasant groupers and scorpions are summarized below.

[0005]

[Table 1]

[0006] Further, the ecology of pheasant grouper and scorpionfish at the time of release are examined. First, it has been clarified from the distribution survey etc. that the released pheasant grouper is divided into those that move and disperse rapidly when released and those that stay at the release point for a while. This early dispersal occurs during times when scorpions can be a predator, as the time of release is often in the afternoon due to work. Therefore, individuals that encounter scorpions while dispersing are predated. Also, those that have stayed for a while will be intensively predated if they are found in scorpions. Therefore, in order to protect the pheasant grouper, the following 2
Two methods are considered effective.

The pheasant grouper is dispersed and discharged in a wide range during the period when the scorpion is inactive, and the pheasant grouper is further dispersed before the scorpion becomes active. By this method, the phenomenon of intensive predation could be prevented to some extent. However, since the discharge time is a time zone immediately after dawn, this method is difficult to cope with in reality due to the work. If the pheasant grouper is inactive and you have to release it in the afternoon when scorpions are active, collect pheasant groupers in one place and make a device to prevent scorpion from entering there,
Temporarily protect pheasant groupers. It is necessary to be able to protect from the time of release until midnight when scorpions are inactive, and before dawn when pheasant groupers are able to disperse themselves by themselves. According to this method, pheasant groupers can be safely dispersed in the early morning when scorpions are not active, while preventing intensive feeding damage at the beginning of release.

The following points are required as elements necessary for realizing the above method. (1) It should be possible to prevent the invasion of scorpions that are large enough to prey on the released seedlings. (2) A large amount of pheasant grouper can be temporarily retained on shelter-type reefs. (3) The experimental test equipment for fish reefs for release must be able to be transported and installed manually. This is because after the pheasant leaves the shelter, it will be promptly collected and reused. The inside of the shelter type reef is wide and does not shake even in stormy weather,
Be quiet. The pheasant grouper can easily enter and leave the reef.

In order to realize the above three points, several experiments were conducted to develop necessary techniques. About (1) The shelter-type reef must be covered with a mesh that allows pheasant groupers to pass through, but does not allow scorpions to pass through. The mesh of the net is desirably a square with a side of about 2.5 cm. About the above (2) The color that pheasant groupers easily gather is black. It is preferable that pheasant groupers be densely present and adhered so that they can be kept calm.
An artificial seaweed is most suitable as such a material for attachment.
Pheasant groupers have the property of preferring dark places to bright places. Regarding (3) The fish reef for release is relatively light, such as made of aluminum, and the size of one fish reef is preferably about 1 m in both length and width and about 70 cm in height. Further, it is preferable that the weight be within about 30 kg. It is preferable to attach feet of about 15 cm vertically to the four corners of the fish reef bottom for release so that they can be fixed to the sea floor. If a bottom plate is provided at the bottom of the fish reef for release in order to prevent scorpions from entering from the bottom side of the fish reef, it is preferable to make a drain hole in order to reduce the load when picking up. The fish reef for release will have a side plate attached to the surrounding structure. Further, the net of the above (1) is attached to the top, and is used as an entrance to the pheasant grouper. About 16 artificial seaweeds are installed inside the fish reef for release, and around the equipment,
In order to protect the pheasant grouper that has gone outside, it is preferable to attach about 20 artificial seaweeds. The above basic design was performed, a test device was prototyped, and the following verification tests were conducted in a closed manner.

The discharge time was around 2:00 pm, and a boulder zone with a water depth of 5 to 7 m where scorpions and pheasant groupers inhabited was selected as the discharge site. Before release, the prototype was installed on the sea floor. Four prototype devices were installed by two divers in a few hours. The release method was such that pheasant groupers were put into a net and divers were careful that all seeds and seedlings entered the prototype device. Some of them went outside, but the number was dozens per car. Immediately after the release, the pheasant grouper was quietly lying near the bottom inside the device. Judging from the diurnal nature of the pheasant grouper and the state of adhesion to artificial seaweed, it is considered that most of the pheasant grouper will remain in the device until the next morning. Examination of the distribution situation around the device on the day of the release revealed a slight distribution only within a radius of 3 m from the device. A survey at around 11:00 am the day after the release revealed that only tens of dozens of pheasant groupers remained in the device, suggesting that dispersion occurred early in the morning as planned. During the investigation of the distribution situation around the apparatus, many pheasant groupers were observed only within a radius of 5 m, so it can be estimated that the dispersion range at this time was within a radius of about 5 m.

According to the results of the release up to last year, the pheasant grouper immediately after the release had a temporary distribution in a narrow area and intensive feeding damage. In the survey the day after the release, squirrel groupers could be identified only sparsely. In comparison, in the case of the release using the above prototype device, it was possible to almost completely prevent the damage to the fish immediately after the release, and to disperse the pheasant grouper the next morning during the period when the scorpions were inactive. That is the result. From the above results, the effectiveness of the shelter-type prototype device as a fish reef for release was demonstrated.

The released fry is small until the next spring after release.
As a result of experiments, the following points are required as a protective fish reef to prevent scorpion fish damage. (1) They may move due to the winter winds. Therefore,
It is preferable that the shelter-type reef is fixed to a flat seabed under a boulder as much as possible. (2) A bottom plate is unnecessary at a point where the seabed can be along the bottom edge of a shelter-type fish reef, but if there is a gap and there is a risk that natural enemy fish may enter, it is preferable to provide a bottom plate at the bottom. (3) It is preferable that shelter type reefs do not rise even in stormy weather. Further, it is preferable that the structure is such that the seawater in the shelter type fish reef is quiet.

[0013] Juvenile pheasant groupers, represented by benthic fish, can be safely dispersed while being protected from natural enemy fish by being released into the shelter type reef as described above.

According to the present invention, as a fish reef for achieving the purpose of releasing and protecting the juvenile fish, the juvenile fish is provided at least at the top of the bottom-sided and open-topped bottom trapezoidal cylindrical body A. Are arranged, and a net B having a mesh that can pass the natural enemy fish but cannot pass through is arranged. And it shall be installed so that the bottom part of the said cylindrical body A may contact a sea bottom substantially.

A frame 4 is provided on the upper edge of the cylindrical body A having a trapezoidal side surface.
Are attached so that they can be opened and closed, and the net B is attached to the frame 4. A rubber plate is provided on the four lower ends of the cylindrical body A so as to face outward.
It is good to attach 10, 10.

[0016]

The fish reef of the present invention is installed so that the bottom of the cylindrical body A is almost in contact with the sea bottom, as shown in FIGS. Then, the young fish is released into the cylindrical body A. Since the circumference of the cylindrical body A is surrounded and at least the top is covered with the net B, the released larvae are protected by the cylindrical body A and ensure that they are eaten by natural enemy fish. Can be prevented. Since the inside of the tubular body A is relatively wide and the periphery of the tubular body A is surrounded, the inside of the fish reef does not move even in stormy weather, is quiet, and is advantageous for the inhabitation of juvenile fish.
The juvenile fish can easily enter and exit through the mesh of the net B.

[0017]

[0018] Then, the upper edge of the cylindrical body A side trapezoidal mounting the frame 4 to be freely opened and closed, is attached to the network element B to the frame body 4. Therefore, this part can be opened and closed freely, which is convenient for releasing juveniles into the reef. Further, when the frame 4 is closed, the juvenile fish released into the reef can be protected from natural enemy fish.

When rubber plates 10 and 10 are attached to the outer periphery of the lower end of the cylindrical body A, when the fish reef is installed on the seabed, the rubber plates 10 and 10 allow the installation surface with the seabed to be smooth. can do.

[0020]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a plan view of the entire fish reef before the artificial seaweed C is attached, and FIG. 2 is a front view thereof. As shown in FIG. 2, the reef according to the present invention basically allows a baby fish to pass through at least a top portion of a bottom-sided, trapezoidal tubular body A having an open bottom portion and an open bottom portion. Is an arrangement of a mesh body B having a mesh that cannot pass therethrough.

The cylinder A is preferably made of a relatively light material such as aluminum. The reason why it is better to keep the cylinder A relatively light is that after a short period of use, the fish reef is promptly collected and reused.
This is to make installation possible. Cylindrical body A shown in the embodiment
Are 4 arranged on a diagonal line of a square as shown in FIG.
The column 1 is surrounded by four covers 2 so as to form an integrated cylinder.

The top of the cylindrical body A is open as shown in FIG. 3, and the juvenile fish can pass through the open portion,
The natural enemy fish arranges the net body B having a mesh that cannot pass.
In the embodiment, as shown in FIGS. 1 and 2, hinges 3, 3 attached near the upper edges of the two left and right covers 2, 2 divide the left and right frames into an open top portion of the cylindrical body A. 4,4
Are arranged so as to be openable and closable, and the mesh body B is attached to the back side of both frames 4. When one or both of the left and right frames 4, 4 are opened, the top of the cylindrical body A is opened.

At four corners of the cylindrical body A, as shown in FIG. 2, vertical legs 5 are attached downward. When the fish reef is installed on the sea bottom as shown in FIGS. 4 and 5, the four legs 5 and 5 are inserted deeply into the bottom of the sea bottom and used to fix the fish reef.

As shown in FIG. 2, one bottom plate 6 is horizontally arranged at the lower open portion of the cylindrical body A shown in the embodiment, and a bottom plate reinforcing member 7 is formed on the back side thereof in a square shape. They are arranged diagonally. The bottom plate 6 has an appropriate number of holes 6a for draining water as shown in FIG.

As shown in FIG. 1, a flat U-shaped weight guide 8 is attached to the upper surface of the bottom plate 6 so as to be located on the center line thereof. Weights 9 are respectively inserted as shown in FIG. The weight 9 is useful for preventing the fish reef installed on the sea floor from moving due to wind waves.

As shown in FIGS. 1 and 2, a rubber plate is provided around the four lower ends of the cylindrical body A shown in the embodiment.
10, 10 are attached. The rubber plate 10 is used for smoothing the installation surface between the fish reef and the sea bottom when the fish reef is set on the sea bottom. The rubber plate shown in the embodiment
The tip of 10 has a saw-tooth shape as shown by 10a in FIG. 1, and the space between each saw-tooth 10a is cut as shown by 10b in FIG.

The fish reef shown in the embodiment has such a structure. This fish reef is installed, for example, on a boulder belt S on the sea floor as shown in FIGS. 4 and 5. They may be installed on mud on the sea floor or on sandy ground. The method of using the fish reef shown in the embodiment will be described by taking as an example the case where the fish reef is installed on the boulder belt S on the seabed. The fish reef is positioned almost in contact with the boulder zone S on the seabed, and the fish reef is fixed. Then, a juvenile fish (eg, pheasant grouper) is released into the cylindrical body A.

Since the periphery of the cylindrical body A is surrounded by the cover 2 and at least the top is covered with the net B, the released juvenile fish (Phyllotta) is protected by the cylindrical body A. , It can be reliably prevented from being eaten by natural enemy fish (magpies). The inside of the cylinder A is relatively wide,
In addition, since the periphery of the cylindrical body A is surrounded, even in stormy weather, the inside of the fish reef does not fluctuate, and it is quiet, which is advantageous for the habitat of juvenile fish (Phaselotta). Juvenile fish (pheasant grouper) can easily enter and exit through the mesh of the net B.

The reef is formed by the four legs 5 and 5 inserted into the boulder belt S and the weight of the weight 9 disposed on the bottom plate 6 even though the cylinder A is relatively light. It is stably fixed on the top, and movement by wind waves is prevented.

At the bottom of the cylindrical body A, a bottom body, for example, a bottom plate 6
By providing the fin, it is possible to completely prevent natural enemy fish from entering from the bottom side of the reef. If the location of the fish reef is not the boulder zone S, for example, on mud on the seabed or on sand, a net body may be attached to the bottom of the cylindrical body A instead of the bottom plate 6. When the location of the reef is on the boulder zone S, there is a danger that the natural enemy fish (Kasago) will enter between the boulders and the natural enemy fish (Kasago) will enter from the bottom side of the cylinder A. This is because when the installation location is on mud on the sea floor or on sandy ground, natural enemy fish (scorpions) do not penetrate therethrough, and the net is sufficient.

As shown in the embodiment, if a hole 6a for draining water (see FIG. 3) is opened in the bottom plate 6, water collected in the cylinder A when the fish reef is picked up can be removed from the hole 6a for draining water. It can be discharged naturally and the load at the time of picking up can be reduced.

Further, as shown in the embodiment, when the frame 4 is attached to the upper edge of the cylindrical body A having a trapezoidal side surface so as to be openable and closable, and the net B is attached to the frame 4, Because the part can be opened and closed freely, it is convenient for releasing juveniles into the reef. Further, if the frame 4 is closed, the juvenile fish released into the reef can be protected from natural enemy fish. In addition, as shown in the embodiment, when the frame body 4 is of a double-opening type, it is extremely advantageous in releasing the juvenile fish (pheasant grouper) and other aspects.

On the other hand, in the embodiment, artificial seaweed C is attached inside and outside the fish reef as shown in FIG. When artificial seaweed C is attached inside and outside the reef in this way, the juvenile fish (pheasant grouper)
You can hide inside. And, in the reef, the artificial seaweed C in the reef has a juvenile fish (Kijihata)
Can exist densely and still be calm. Further, outside the fish reef, the artificial seaweed C outside the fish reef can protect the juvenile fish (Phaselotta) which has gone outside. The reef and artificial seaweed C are preferably black. The reason is that the color that pheasant grouper easily gathers is black, and the pheasant grouper can exist densely and still be calm.

In the embodiment, as shown in FIG. 1 and FIG. 2, a plurality of mounting rods 11, 11 are arranged at equal intervals on the open top portion of the cylindrical body A so as to extend back and forth. Stick 1
Artificial seaweed C inside the fish reef can be attached to 1 and 11. As shown in FIG. 3, flanges 12 and 12 are fixed to an open portion which is an upper edge of the cylindrical body A, and mounting holes 12a and 12a are formed in the flanges 12 and 12, respectively.
The artificial seaweed C can be positioned outside the fish reef by attaching the artificial seaweed C to each of the a and 12a and extending them both to the outside of the fish reef.

As shown in FIG. 5, only one fish reef may be installed on the seabed, but usually several fish reefs are arranged on the seabed. Then, larvae (pheasant groupers) are released into each reef. When several fish reefs are arranged side by side on the seabed, as shown in FIG. 4, the rubber plates 10, 10 attached outward from the four lower ends of the cylindrical body A are positioned so as to overlap each other, Several boulders on it
It is good to put S '.

In the illustrated example, the case where the present fish reef is set on the boulder zone S on the sea floor is illustrated. However, the boulders are removed only at the portion where the present fish reef is to be set, and the present fish reef is set at a place that is one step lower. It may be.

Although not shown, if a buoy called a feeding buoy is floated above the location where the fish reef is installed, and an automatic feeding device mounted on the buoy feeds the food toward the fish reef installed on the seabed, It is very convenient because it can feed the young fish automatically. Feeding the juveniles while emitting sound, which is called acoustic feeding, can prevent the dispersal of the juveniles and allow them to grow while protecting the juveniles on the shelter type reef. It is very convenient for the juvenile fish release business.

In the embodiment, the case where the present reef is used for the release of juvenile fish, particularly for the release of pheasant grouper represented by benthic fish is described. Of course, you can. Also,
Of course, this reef can be used for the release, protection and wintering of juveniles other than pheasant groupers.

In the other drawings, reference numeral 13 denotes a cylinder A
This is a suspension ring attached to the outside of the four corners of the sea, and is used when the fish reef is taken from the seabed.

[0041]

According to the present invention, when the reef according to the first aspect is installed on the seabed, the released juvenile fish can be dispersed while being safely protected, and it can be surely prevented from being eaten by natural enemy fish. There is an effect that can be. In particular, opening the frame 4
Can open the top of the cylindrical body A.
It is extremely convenient to release fry into the reef,
Once the frame 4 is closed, the child released into the reef
This has the effect of reliably protecting fish from natural enemy fish.
You.

[0042]

[0043]

According to the fishing reef of the second aspect, when this fishing reef is installed on the seabed, there is an effect that the installation surface with the seabed can be made smooth.

[0045]

[Brief description of the drawings]

FIG. 1 is a plan view of an entire fish reef showing one embodiment of the present invention,
This shows a state before the artificial seaweed is attached.

FIG. 2 is a front view of the fish reef shown in FIG. 1, with a portion cut away and showing a state in which a right frame of two frames on the left and right sides is being opened.

FIG. 3 is a plan view showing a case where a frame at the top of a cylinder which is a part of a fish reef and a net attached to the frame are removed.

FIG. 4 is a front view showing only the vicinity of an adjacent portion when fish reefs are arranged side by side on the sea floor.

FIG. 5 is a front view showing a state where artificial seaweed is attached to the inside and outside of the fish reef when the fish reef is installed on the seabed, and is partially cut away.

[Explanation of symbols]

A─ cylindrical body, B─ net, C─ artificial seaweed, 4─ frame, 6─ bottom plate, 10─ rubber plate.

Continuation of the front page (56) References JP-A-5-219857 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A01K 61/00

Claims (2)

(57) [Claims] 1. A net B having a mesh that allows passage of a juvenile fish but cannot pass a natural enemy fish is disposed at least on the top of a tubular body A having a trapezoidal side with a bottom and a top that is open and whose bottom is open. And, in a reef for juvenile fish and juvenile fish which is installed so that the bottom of the cylindrical body A is almost in contact with the seabed,
A frame 4 is attached to the upper edge of the cylinder A so as to be openable and closable.
4. A reef for juvenile fish and juvenile fish , wherein the net B is attached to 4 . 2. The outer periphery of the lower end of the cylindrical body A is
2. A reef for benthic fish and juvenile fish according to claim 1, wherein the slabs are attached .