JPH0458838A - Artificial fishing ground - Google Patents

Abstract

PURPOSE:To generate complicate turbulent flow, to promote the proliferation of plankton, etc., and to improve the fishattracting effect by providing particularly shaped fishing banks having hemispherical dome-shaped top part and arranging short fishing banks around a tall fishing bank. CONSTITUTION:Each fishing bank used in the present artificial ground has a top part formed in nearly the form of a hemispherical dome and has through holes in the bank. A fishing bank 2 having a height corresponding to 1/10 of the water depth of the installing sea area is placed at the center and fishing banks 3 having a height corresponding to < 1/10 of the water depth are arranged around the central fishing bank to form satellite banks. Tidal current colliding with individual fishing banks generates a turbulent flow, which is amplified by the cooperative action of the arranged tall bank 2 and short banks 3 to form a complicate turbulent flow over the whole sea-bottom of the installing area. Flow of sea water is generated over a wide area by this action to promote the proliferation of plankton, etc., and improve the fish-attracting effect.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention relates to an artificial fishing ground that is highly effective at attracting fish.

<Conventional technology and its problems> In general, a fishing ground (pronounced ``rgiyojiyo 1'', different from ``rgiyoba'', hereinafter the same) is a certain area of water where a large number of aquatic organisms of a certain type live. During a certain period of time, there may be a fairly large number of shoals that can be caught using an appropriate method, and the catch will be sufficient to compensate for the cost and effort. If available, it refers to the water area of Mo. All fish and other aquatic organisms live in their own suitable environments, so they naturally flock together, but their range is quite wide, and in order to form a particularly dense community and create a good fishing ground, they must hunt for food and spawning 2
There are two motives. Animals search for food, so if there is a large amount of food in a given body of water, many flocks will flock to it, and this phenomenon occurs as follows. In other words, various elements are dissolved as compounds in both seawater and terrestrial water, but nitrogen, phosphorus, and silicic acid tend to be insufficient for microscopic floating algae (phytoplankton) to proliferate. However, breeding often occurs. This component is called nutrient salt, and is an important factor that influences the reproduction of phytoplankton.

Dead animals and plants sink to the ocean floor, decomposing and producing large amounts of nutrients. However, since plants assimilate carbon dioxide through sunlight, they cannot reproduce unless they are on the surface of the ocean where sunlight can penetrate, and the nutrients in the deep ocean floor cannot be used as they are.

Therefore, the nutrients on the sea floor are best utilized and phytoplankton can breed in shallow areas, or in places where vertical mixing of water occurs and the nutrients on the sea floor can rise to the surface. Such places include inner bays, shallow coastal areas, continental shelves, islands, reefs, rapids, and tidal boundaries where cold and warm currents meet, where ocean currents blow up from below or create whirlpools to disturb the water. This causes the supply of nutrients to the surface layer. When phytoplankton breeds well in such areas, zooplankton that feed on these plankton breed, and fish and other species that feed on these plankton gather, creating good fishing grounds. This is also the reason why fishing grounds can be predicted to some extent based on topography and ocean current conditions. Fish and other species then flock to the spawning grounds, and along the way, the spawning grounds become good fishing grounds. This phenomenon occurs when large schools of salmon and trout swim up to rivers to spawn, and when herring flock to shallow coastal areas where algae grow and spawn.

Therefore, in order to increase the yield of seafood and seaweed, some artificial activities are added to fishing grounds to improve fishing grounds.

Its aim is the same as that of proliferation, but it is an expression with a broader concept than that. In other words, breeding is a concept that focuses only on the target organisms, while fishing ground improvement is based on the idea that in order to increase the catch, it is important to first improve the environment to make it a better place for fish and shellfish to live. ing.

Therefore, there are a wide variety of means and methods for improving fishing grounds, depending on the purpose, ranging from small-scale projects that can be done using only human labor to large-scale projects that use modern construction machinery. In ancient times, a method of cutting out mountain rocks and dumping them into the ocean floor in large numbers of 40 to 50 cm cubes and stacking them in a two-dimensional or three-dimensional structure, and a method of sinking abandoned ships were also used. Recently, instead of natural rocks, concrete structures molded into various shapes have been increasingly used.These concrete structures are so-called artificial fish reefs, and it is true that these fish reefs The shape of the reef has a significant influence on the eddy current effect, feeding effect, and shading effect, which have been shown to be reasons for fish gathering. Regarding the relationship between fish reefs when they are individually sunk to the seabed, that is, how to arrange fish reefs with limited volume (displacement volume) on the seabed to maximize the fish attracting effect mentioned above. has never been considered.There are facts that have been slightly considered (for example, "Artificial Fish Reef" by Yasuo Oshima, published by the Japan Fisheries Resources Conservation Association, December 23, 1960). issue)
However, this only clarifies the number of fish reefs in a certain area, but it does not include the size (height) of the fish reefs used for this purpose, or the arrangement of fish reefs of different sizes. There is no clear cut as to whether it will be enforced or not. In particular, when creating fishing grounds, basically, in that case, some kind of protrusion is placed on the seabed, and this protrusion itself creates a whirlpool phenomenon in the current, and this whirlpool collects nutrients that feed on plankton. The theory is that this attracts plankton, which in turn attracts fish that feed on this plankton. Therefore, the efficiency of fish collection depends on how efficiently these nutrient salts or plankton can be collected.In this case, the vortex effect must be maximized, and of course, they must be of the same size (height). Eddy currents are generated even when fish reefs are arranged in this way, but larger and stronger (amplified) eddy currents are generated when there are fish reefs of various sizes, as seen in natural reefs. However, according to the inventor's experiments, regarding the difference in size of fish reefs, large fish reefs
It has been found that the eddy current effect is enhanced by having a depth of at least one-tenth of the water depth of the sea area in which it is installed, and by placing smaller ones around larger ones as if they were satellites.

Means for Solving the Problems> Therefore, the artificial fishing ground according to the present invention has been developed based on the above-mentioned viewpoint. Among the fish reef bodies that have been constructed, we will focus on those whose height is one-tenth of the water depth of the installation area.
In addition, fish reef bodies with a height less than one-tenth of the water depth of the installation area are installed around them as if they were satellites, to avoid overlapping shadows between fish reefs and to exert the shading effect without waste. By creating unevenness regularly and over as wide a range as possible to ensure a vortex effect against currents from all directions, this also promotes the proliferation of plankton and the like and increases the feeding effect. It is designed to have the maximum fish-attracting effect with the minimum volume of the reef.

Embodiments Next, embodiments of the artificial reef according to the present invention will be described based on the drawings. 1 is a seabed, 2 is a tall fish reef, and 3 is a short fish reef. Both of these fish reefs 2 and 3 have a substantially hemispherical dome-shaped top and are formed with a hole penetrating the inside, and the tall fish reef 2 has a height that corresponds to the water depth of the sea area where it is installed. The height of the short fish reef 3 shall be less than one-tenth of the water depth of the installation sea area. Therefore, the specific dimensions of these tall fish reefs 2 and short fish reefs 3 will be determined by the water depth distance of the sea area where they are installed. Moreover, regarding the arrangement of these tall fish reefs 2 and short fish reefs 3, the former is placed in the center and the latter are placed around it like satellites. In addition, regarding the distance between these reefs 2.3, it is preferable to make them extremely close or far apart in consideration of the shading effect (according to the inventor's experiments, the height of the tall fish reef 2 is approximately It turns out that keeping a distance of 1 minute is preferable.

<Effects of the Invention> As described above, according to the artificial reef according to the present invention, the top of the reef is formed into a substantially hemispherical dome shape, and a hole is drilled through the inside of the reef body. Centered on the main body of the fish reef, which has a height of
Since the main body of the fish reef, which has a height of less than 1/2, is installed around it as if it were a satellite, the tidal current collides with each individual reef, creating a whirlpool, and an array of tall and low reefs. together amplify the eddy current, creating a complex eddy current on the entire seabed where fish reefs are arranged, a seawater flow area is generated over a wide area, promoting the proliferation of plankton, etc., and combined with the shading effect and feeding effect, it has a fish attracting effect. This has the effect of increasing the

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of an artificial fishing ground according to the present invention. 1... Seabed 2... Tall reef 3... Short reef

Claims (1)

[Claims] The reef body has a roughly hemispherical dome-shaped top and a hole drilled through the inside, and the reef body has a height that is 1/10 of the water depth in the installation area. Surrounding it is a fish reef body with a height less than one-tenth,
This artificial fishing ground is characterized by being set up like a satellite.