JP2022115447A - Aquaculture device of aquatic animal and aquaculture method - Google Patents

Abstract

To provide an aquaculture device that can efficiently remove solid organic matter, etc., reduces sludge formation of the organic matter, etc., and can easily adjust the dissolved oxygen concentration, on farming of aquatic animals using a sand layer.SOLUTION: An aquaculture device (100) of aquatic animals includes: an aquaculture tank (10) for storing aquaculture water (11); a sand layer (12) arranged at the bottom of the aquaculture tank (10); and air bubble feeding means (22) for sending air bubbles along a sand surface of the sand layer (12), and/or toward the sand surface of the sand layer (12). The organic matter moved up with the air bubbles supplied by the air bubble feeding means (22) is removed on the surface layer of the aquaculture water (11).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an aquatic animal farming apparatus and a farming method. In particular, the present invention relates to an aquaculture apparatus and the like suitable for aquaculture using a sand layer, such as shrimp.

A variety of seafood is farmed for mass production, stable supply, and high quality of ingredients. Aquaculture conditions differ depending on the ecology of fish and shellfish, and in general, aquaculture is carried out in accordance with the conditions in which each fish and shellfish naturally inhabits. For example, kuruma prawns are nocturnal and rest in sand layers depending on the time of day. Therefore, when cultivating them, it is necessary to provide a sand layer or the like in the cultivation area. The following documents and the like are disclosed for aquaculture using a sand layer.

Patent Document 1 is characterized in that it has a culture tank and water supply pipes that are arranged at regular intervals in the bottom of the culture tank, and that the water supply pipes are provided with spouts at a constant pitch on the side surface. aquaculture apparatus for aquatic animals.

Patent Document 2 discloses a circular plane-shaped water tank having a sand bed at the bottom and a ring-shaped septic tank for purifying seawater along the peripheral wall, and an upper peripheral edge of a drainage pipe provided at the center of the bottom. and a second circulation mechanism for circulating seawater in the vicinity of the peripheral wall of the circular water tank in the same direction, wherein the drainage pipe and the bottom are open. and seawater supply pipes are connected to the septic tank, respectively.

Patent Literature 3 discloses a prawn culture aquarium characterized by providing a sand layer at the bottom of the aquarium, having a large number of outlets in the sand layer and arranging seawater discharge pipes for continuously supplying fresh seawater. is doing.

JP 2017-085903 A Japanese Patent Application Laid-Open No. 2002-360110 JP-A-61-293325

Kuruma prawn is one of the aquaculture targets using a sand layer. Kuruma prawns are nocturnal and burrow into the sand during the day to rest. At night, they go out on the sand or in the water to feed. For this reason, sand is necessary for culturing kuruma prawns. Kuruma prawn aquaculture technology takes seawater into a large-area aquaculture tank called Ikesu, which has a half or full embankment. In addition, it regulates the dissolved oxygen concentration in photosynthesis of diatoms and aeration by a water wheel. Such conventional traditional prawn farming has the following problems.

(1) Maintenance of dissolved oxygen content. A large amount of water wheel aeration is required to maintain the dissolved oxygen content. In particular, it is necessary to prevent oxygen deficiency due to oxygen consumption, which increases at night when tiger prawns are active. However, with the conventional technology, a large amount of electricity is required for aeration using a large water wheel, and the conventional technology cannot evenly maintain the dissolved oxygen content all the way down to the bottom layer.
(2) Accumulation of solid organic substances and sludge. Solid organic matter such as feces, exuviae, leftover food, and diatoms accumulates in the sand layer, which is the habitat of kuruma prawns. The deposited organic matter is decomposed by bacteria and turned into sludge. Since oxygen is also consumed at this time, if there is an area where oxygen is not supplied, oxygen will be insufficient and an anaerobic environment will be generated, which will hinder the nitrification of highly toxic ammonia. It also generates harmful substances such as hydrogen sulfide. In particular, it becomes difficult to remove solid organic matter and the like mixed in the sand layer.
(3) Difficult to remove from sand layer. In order to remove the solid organic substances and sludge deposited on the sand layer, a great amount of human effort is required to remove the sludge by pulling a net or diving to remove the sludge manually. In addition, it is difficult to manage efficiently because it is mixed with sand layers and visibility is poor, so there are parts that have to rely on the experience and intuition of experts.

In order to prevent the generation of harmful substances due to accumulation of sludge in these sand layers, several aquaculture methods for removing organic matter from sand layers have been proposed as in Patent Documents 1 to 3. These can prevent the stagnation of the organic matter in the sand layer by the structure in which the organic matter is flushed upward by the water flow. Organic matter released into the water is discharged through a filter through a drain port on the bottom of the culture tank. Therefore, it is impossible to prevent the deposition of organic matter on the filter.

Under such circumstances, the present invention provides an aquaculture apparatus and aquaculture method that efficiently removes solid organic matter and the like, reduces sludge formation of the organic matter and the like, and easily adjusts the dissolved oxygen concentration when aquatic animals are cultivated using a sand layer. intended to

Means for Solving the Problems As a result of earnest research in order to solve the above problems, the inventors of the present invention have found that the following inventions meet the above objects, and have completed the present invention. That is, the present invention relates to the following inventions.

<1> A culture tank containing culture water, a sand layer arranged at the bottom of the culture tank, and air bubbles containing oxygen along and/or toward the sandy ground of the sand layer. and an aquatic animal cultivating apparatus for removing organic substances floating on the surface layer of the culture water accompanied by the bubbles supplied by the air bubble supplying means.
<2> The aquaculture apparatus according to <1>, further comprising foreign matter removing means for removing the floating organic matter on the surface layer of the aquaculture water.
<3> The bubble supply means can supply two or more types of bubbles selected from the group consisting of first to third bubbles having different bubble rising speeds,
The first bubbles have a bubble rising speed of 50 mm/sec or less,
The second bubbles have a bubble rising speed of 5 to 500 mm/sec and have a higher bubble rising speed than the first bubbles,
The aquaculture apparatus according to <1> or <2>, wherein the third bubbles have a bubble rising speed of 50 mm/sec or more and have a higher bubble rising speed than the second bubbles.
<4> The aquaculture apparatus according to any one of <1> to <3>, further comprising switching means for switching the air bubbles supplied by the air bubble supply means in accordance with the time period and/or the oxygen concentration of the culture water.
<5> Any one of <1> to <4>, wherein a plurality of the air bubble supply means are arranged, and are arranged so that supply directions are different when the culture tank is viewed from above. aquaculture apparatus according to 1.
<6> The aquaculture apparatus according to any one of <1> to <5>, wherein the aquatic animal is prawn.
<7> A culture tank containing culture water, a sand layer arranged at the bottom of the culture tank, and air bubbles being sent along and/or toward the sandy ground of the sand layer. A method for cultivating aquatic animals using an aquaculture apparatus having a bubble supply means, comprising: a bubble supply step of supplying bubbles by the bubble supply means; Aquaculture method.

According to the aquaculture apparatus and the aquaculture method of the present invention, when aquatic animals are cultivated using a sand layer, solid organic matter can be efficiently removed, sludge formation of the organic matter can be reduced, and the dissolved oxygen concentration can be easily adjusted. can.

1 is a schematic front view of a culture apparatus according to a first embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which planarly viewed the culture apparatus which concerns on 1st embodiment of this invention. 1 is a schematic perspective view of a foreign matter removing means used in the aquaculture apparatus of the present invention; FIG. 1 is a schematic front view of foreign matter removing means used in the aquaculture apparatus of the present invention. FIG. It is the schematic which planarly viewed the foreign material removal means used for the culture apparatus of this invention. Fig. 2 is a schematic front view of a culture apparatus according to a second embodiment of the present invention; FIG. 2 is a schematic front view of a culture apparatus according to a third embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is a flowchart which shows an example of the culture method of this invention. Fig. 2 is a flowchart showing another example of the aquaculture method of the present invention; FIG. 4 is a diagram for explaining control of the aquaculture method of the present invention; It is an image for showing the outline of air bubbles supplied in the present invention.

Embodiments of the present invention will be described in detail below. is not limited to the contents of In this specification, when the expression "~" is used, it is used as an expression including the numerical values before and after it.

[Aquaculture apparatus of the present invention]
The aquaculture apparatus of the present invention comprises an aquaculture tank containing aquaculture water, a sand layer arranged at the bottom of the aquaculture tank, along the sandy ground of the sand layer and/or toward the sandy ground of the sand layer, An air bubble supply means for sending out air bubbles, and removes the organic substances floating on the surface layer of the culture water accompanied by the air bubbles supplied by the air bubble supply means.

[Aquaculture method of the present invention]
The aquaculture method of the present invention includes an aquaculture tank containing aquaculture water, a sand layer arranged at the bottom of the aquaculture tank, along the sandy ground of the sand layer and/or toward the sandy ground of the sand layer, A method for cultivating aquatic animals using an aquaculture apparatus comprising a bubble supply means for sending out bubbles, a bubble supply step for supplying bubbles by the bubble supply means, and a removal for removing organic substances that have floated along with the bubbles. have a process.

According to the aquaculture apparatus and aquaculture method of the present invention, it is possible to efficiently remove solid organic substances and the like, reduce the sludge formation of organic substances and the like, and maintain an appropriate dissolved oxygen concentration when aquatic animals are cultivated using a sand layer. can. In the present application, the aquaculture method of the present invention can also be performed by the aquaculture apparatus of the present invention, and the corresponding configurations in the present application can be used mutually.

The present invention keeps the entire aquaculture tank, including the sand layer and aquaculture seawater, which are the habitats of aquatic animals such as crustaceans, clean at all times while reducing running costs such as labor and electricity costs, thereby improving the quality and production of aquatic animal aquaculture. To provide an aquaculture apparatus capable of improving the quality.

[First embodiment]
FIG. 1 is a schematic front view of a culture apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic plan view of the aquaculture apparatus according to the first embodiment of the present invention. The farming apparatus 100 has a farming tank 10 for containing farming water 11 , a sand layer 12 , and air bubble supply means 22 . It also has foreign matter removing means 30, water supply means 50, and the like.

[Aquaculture tank 10]
The culture tank 10 contains culture water 11 . The size of the culture tank 10 is set in consideration of the size of the aquatic animals to be cultured, the culture density, and the like. According to the present invention, the entire aquaculture tank can be efficiently used for aquaculture. A relatively small-scale aquaculture tank having a diameter of about 5 to 20 m can be used in the case of a cylindrical tank. Larger ones may be used.

The shape of the culture tank 10 is not particularly limited as long as it can be cultured, such as a polygonal columnar shape, a columnar shape, or a frustum shape. In order to prevent accumulation in a part of the aquaculture tank 10, a cylinder having a circular outer shape when viewed from above, or a truncated cone shape that facilitates the collection of sand layers on the bottom surface, or the like is used. be able to. The aquaculture tank 10 of the aquaculture apparatus 100 shown in FIG. 1 is cylindrical.

The culture tank 10 can be made of concrete, fiber reinforced plastic (FRP), polypropylene resin, or the like, which has sufficient strength.

[Culture water 11]
Aquaculture water 11 is used according to the aquatic animal to be cultivated. For example, seawater, freshwater, or intermediate brackish water can be used. These may be artificially adjusted or may be taken from rivers or the sea.

[Aquatic animals]
The farming apparatus 100 is for farming aquatic animals. Aquatic animals to be farmed can be edible fish and shellfish that require a sand layer 12 . For example, it can be crustaceans and shellfish. As crustaceans, shrimp and giant clams are ecology with burrowing properties. Examples of shellfish include short-necked clams and tiger bream. Among them, prawns such as prawns such as kuruma prawns, which have an ecology of burrowing and resting in sand and are widely cultivated for food, are preferable.

[Sand layer 12]
The sand layer 12 is a layer of sand arranged on the bottom side of the culture tank 10 . As the sand used for the sand layer 12, sand suitable for the ecology of aquatic animals can be appropriately used. Although sea sand is generally used, it is preferable to use coarse sand with a low density, such as anthracite, so that aquatic animals can easily dive into it and solid organic matter can easily move. The thickness of the sand layer 12 is appropriately adjusted according to the type of aquatic animal.

[Air bubble supply means 22]
The air bubble supply means 22 sends out air bubbles along the sand surface of the sand layer 12 . Alternatively, air bubbles are sent out toward the sandy ground of the sand layer 12 . The air bubble supply means 22 may send out air bubbles in both the direction along the sandy ground and the direction toward the sandy ground. At this time, a plurality of air bubble supply means 22 may be arranged to send air bubbles in both the direction along the sand surface and the direction toward the sand surface, or a single air bubble supply means 22 may supply air bubbles in a plurality of directions. can be sent in both directions.

The air bubble supply means 22 sucks the culture water 11 from the water supply pipe 21 by the circulation pump 23 and supplies air bubbles as water containing air bubbles into the culture tank 10 via the water pipe 20 and the air bubble supply means 22 . As the bubble supplying means 22, one capable of variably controlling the bubble diameter can be used. Water containing air bubbles may be called bubble water.

The aquaculture apparatus or the like of the present invention utilizes the power of air to discharge solid organic matter around the sand layer 12 . For this purpose, bubbly water containing air bubbles is delivered from a bubble supplying means provided on the surface layer or below the sand layer. Due to the foam separation effect of air bubbles, solid organic matter is released upward from the sand layer, and the organic matter is pushed up to the water surface without being retained in the water.

The bubbles supplied by the bubble supply means 22 are bubbles containing oxygen. In supplying such bubbles, the gas used may be, for example, air, high-purity oxygen, or a mixed gas in which the oxygen concentration is adjusted by mixing oxygen with air or other gas. can be done. The oxygen concentration of the gas can be 20-100%.

It is preferable that the bubble supply means 22 can supply two or more types of bubbles having different bubble rising speeds. It is preferable that the bubbles supply two or more kinds of bubbles selected from the group consisting of the following first to third bubbles. The bubble rise rate is assumed to be in seawater at 25°C. According to the Stokes formula, assuming seawater at 25°C, the time it takes for bubbles generated at the bottom of the water of 1 m to reach the water surface is about 10 minutes if the bubble diameter is 50 μm (rising speed: about 1.5 mm/second), about 2.7 minutes (rising speed: about 6.1 mm/second) when the bubble diameter is 100 μm, and about 1.6 seconds when the bubble diameter is 1 mm (rising speed: about 611 mm/second). seconds).

The first bubble has a bubble rising speed of 50 mm/sec or less. The lower limit of the bubble rising speed does not need to be set in particular, and nanobubbles, which are also called ultra-fine bubbles, may be practically 0 mm/sec or theoretically have a negative value. Such first bubbles are useful for improving the concentration of dissolved oxygen, and are actively supplied during periods of active oxygen consumption.

The second bubbles have a bubble rising speed of 5 to 500 mm/sec, and have a higher bubble rising speed than the first bubbles. The second bubbles have a relatively large surface area relative to the volume of the gas, in addition to improving the dissolved oxygen concentration, and are therefore suitable for adsorbing and raising organic matter. For this reason, it is actively supplied during the time period when organic matter is discharged.

The third bubbles have a bubble rising speed of 50 mm/sec or more, and have a higher bubble rising speed than the second bubbles. There is no particular upper limit for the third air bubbles, but the upper limit may be, for example, 5 m/sec or less, 2 m/sec or less, or 1 m/sec or less. The third air bubble is suitable for adsorbing and rising organic substances, and is also suitable for generating an upward water flow from the bottom side of the culture water 11 to the water surface side and a convection current directed to the outer periphery of the water surface. Along with the rising water flow and the convection toward the outer periphery of the water surface, the air bubbles adsorbing the organic matter are moved to the water surface and moved to the outer periphery of the culture tank 10 . Therefore, after the organic matter is discharged, the organic matter is actively supplied when the foreign matter removal means 30 discharges the organic matter to the outside of the culture tank 10 .

These first to third bubbles are controlled so that they can be switched according to the time of day, the dissolved oxygen concentration measured by a sensor, etc., the activity state of aquatic animals captured by a camera, etc. be able to. The control may be performed by switching the operation conditions of the same air bubble supply means 22, or may be supplied by arranging a plurality of air bubble supply means 22 suitable for each air bubble.

In order to increase the oxygen dissolution effect and maintain the dissolved oxygen amount at an appropriate value by minimizing the fine bubble diameter during the period when the organism actively forages and feeds or molts, It is considered that the value should be at least a value that can maintain the oxygen consumption necessary for the organism to perform feeding and molting activities. As a reference, conventionally, in the case of tiger prawns, the required oxygen consumption is said to be 77 to 135 mL / kg / hour at rest, and about three times that during activity (Reference: Japan Coastal Fisheries Promotion and Development Association (1993). Environmental conditions for aquatic organisms, coastal fishing ground development project facility design guidelines).

In the demonstration experiment of the aquaculture apparatus according to the present invention, DO (Dissolved Oxygen) may change at a relatively low value. Also, tiger prawn activity may be reduced relative to conventional aquaculture. This is because the aquaculture density is high and oxygen consumption is high, so they do not perform unnecessary activities to maintain a balance between activity and oxygen concentration reduction, or they do not need to search for food, so they do not perform unnecessary activities. Conceivable. Even with these tendencies, they grow fast and molt frequently. In other words, it is thought that the need for activities such as searching for food is low, and nutrients are used for growth. Therefore, even if the dissolved oxygen concentration is not maintained at an excessively high level, it is thought that growth can be accelerated by suppressing power consumption and the like and maintaining the amount of oxygen that allows activity.

Bubbles can be generated, for example, by a circulation pump 23 and a bubble generation nozzle. The size of the bubbles is adjusted by controlling the supply amount of these bubble generating nozzles. Therefore, the rising speed of air bubbles in seawater at 25° C. may be grasped in advance, and the set conditions may be regarded as the rising speed of air bubbles during cultivation.

The air bubble rising speed is determined by taking the distance from the air bubble supply means 22 to the surface of the culture water 11 as D, and obtaining an image of the air bubbles generated from the air bubble supply means 22 reaching the water surface of the culture water 11. can be derived by measuring the time T1 for reaching the surface of the culture water 11 and calculating D/(T1-T0). If the bubbles generated by the bubble supply means 22 are too small to be recognized as an image, they can be identified as bubbles having a bubble rising speed of 50 mm/sec or less. If the bubbles generated by the bubble supply means 22 are of a size that can be recognized as an image, 100 points of bubbles generated at time T0 are captured at random, their rising speeds are measured, and the average value is obtained. Thereby, the size of the bubble supplied from the nozzle can be derived.

The air bubble supply means 22 does not have to be operated all the time during cultivation. Intensive operation may be performed during times when aquatic animals are active and dissolved oxygen is likely to decrease, or during times when droppings, leftover food, and husks are produced. Alternatively, a sensor or the like for the concentration of dissolved oxygen, which serves as an indicator of these, may be attached, and control means may be provided for controlling the presence or absence of operation in conjunction with the measured values.

The bubbly water released to the sand layer 12 diffuses along the surface layer of the sand layer 12, adsorbs organic substances near the sand layer 12, pushes them up into the culture water 11, and reaches the surface of the culture water 11. The bubbles that have adsorbed the organic substances that have reached the surface of the culture water 11 float on the surface of the water and are expelled to the outside. When discharging to the outside, it may overflow from the container of the culture tank 10, or a structure for removing it may be provided in the culture tank.

[Organic matter (foreign matter)]
During the farming of aquatic animals, solid organic matter such as droppings, exuviae, leftover food, and diatoms is produced. These may become a source of nutrients for microorganisms, cause unintended metabolism by microorganisms, or accumulate without being decomposed, thereby causing water pollution. Also, in some cases, it is easy to mix with the sand layer, and if it gets into the gaps of the sand layer, it will be difficult for dissolved oxygen to be supplied. be. In the present invention, these solid organic substances and the like are removed by accompanying the bubbles. Note that these solid organic substances are not limited to those that are completely solid, and include those that are viscous, and are sometimes called foreign substances.

[Foreign matter removing means 30]
The foreign matter removing means 30 is arranged such that the water intake is arranged near the surface layer of the culture water 11 in the culture tank 10 . In the aquaculture apparatus 100 , air bubbles entrained with organic matter and the like gather on the surface layer of the aquaculture water 10 , enter the water intake due to water currents and convection, and can be discharged to the outside of the aquaculture tank 10 through the pipe 31 .

[Water Intake Structure of Foreign Matter Removing Means 30]
FIG. 3 is a schematic perspective view of foreign matter removing means used in the aquaculture apparatus of the present invention. FIG. 3 shows the structure near the water intake. FIG. 3(a) shows a comb tooth 301 provided on the upper part of the water intake. Moreover, FIG.3(b) provides the net|network 302 in the upper part of an intake. By providing these structures, it is possible to prevent non-removable aquatic animals contained in the culture water 11 from being washed away. Foreign matter entrained by air bubbles is discharged from the culture tank 10 through the pipe 31 through the gaps between the comb teeth 301 and the net 302 .

FIG. 4 is a schematic front view of the foreign matter removing means used in the aquaculture apparatus of the present invention. FIG. 4( a ) shows a state where the water intake port of the foreign matter removing means 30 is arranged on the water surface 111 of the culture water 11 . FIG. 4B shows a structure in which the float 303 is arranged near the water intake and the piping is a flexible piping 311 . As a result, even if the water level changes, the water intake port of the foreign matter removing means 30 will be near the water surface 111 of the culture water 11 . The pipe 310 and the flexible pipe 311 are arranged outside the wall 101 of the culture tank so as to serve as an outlet. In addition, by using the flexible pipe 311, it becomes easier to move the foreign matter removing means 30 to the area where the bubble-like unnecessary organic matter adhering to the air bubbles gathers according to the direction of the water flow or the wind, so that the foreign matter removing effect is further enhanced.

FIG. 5 is a schematic plan view of foreign matter removing means used in the aquaculture apparatus of the present invention. The foreign matter removing means 30 shown in FIG. 5 is arranged between the wall 101 and a partition 33 arranged near the wall 101 . The partition 33 is arranged near the surface of the water and can be opened from the middle layer to the bottom layer so that the culture water 11 can circulate. The partition 33 is designed to generate a water flow in the circulation of the culture water 11, and the wall 101 and the partition 33 can be recessed with respect to the traveling direction of the water flow so as to receive the water flow. As a result, the bubbles accompanying the organic substances floating on the water surface are moved by the water flow, gathered in the recessed portion with respect to the water flow, and efficiently discharged from the water intake port of the foreign matter removing means 30 .

In this manner, a swirling flow may be created in the aquaculture tank in order to promote the discharge of air bubbles entrained with organic matter, and the foreign matter removing means may be provided on the peripheral wall of the aquaculture tank. Further, foreign matter removing means may be scattered at the point where the bubble-like organic matter moves depending on the direction of the wind or the like. Alternatively, the water level in the tank may be raised by supplying water from the outside.

[Drain port 40]
The drain port 40 is an opening for draining water arranged at the bottom of the culture tank 10 . The drain port 40 is used, for example, when draining water after culturing. The drainage filter 41 is installed near the water intake of the drainage port 40 so that the sand of the sand layer 12 and aquatic animals do not flow out.

[Water supply means 50]
The water supply means 50 is means for supplying culture water into the culture tank 10 . When the culture water 11 in the culture tank 10 is in good condition, the water supply means 50 is stopped and the culture water 11 in the culture tank 10 can be circulated and used. When the culture water 11 is in a deteriorated state, the water in the culture tank 10 can be improved by supplying water from the outside through the water supply means 50 . Also, the water level can be adjusted by adjusting the amount of water supply so that the bubbles accompanied by organic matter and the like floating on the surface of the water are discharged from the water intake port of the foreign matter removing means 30 .

[Water purification]
In the aquaculture apparatus of the present invention, it is also possible to use aquaculture water to which microorganisms such as bacillus are added after viruses, diatoms, etc. have been removed using a water purification means such as a UV sterilizer. As a result, disease damage can be prevented, water quality can be easily maintained, and transparency increases, making it easier to grasp the state inside the tank.

[Second embodiment]
FIG. 6 is a schematic plan view of the aquaculture apparatus according to the second embodiment of the present invention. A farming device 1001 is a modification of the farming device 100 according to the first embodiment. The aquaculture device 1001 has a plurality of air bubble supply devices 22 arranged therein. In addition, the plurality of air bubble supply devices 22 are arranged so that the supply directions are different when the culture tank is viewed from above. By supplying air bubbles and bubbly water from a plurality of air bubble supply devices 22 in a plurality of different directions, the locations to which the air bubbles are supplied are widened and the water flow is increased. The bubble supply device 22 can be two or more or three or more. If they are arranged excessively, the time and effort involved in preparing the equipment and the power consumed during operation will be excessive, so the number may be 20 or less, 15 or less, or 10 or less.

For example, assuming that the angle toward the center of the culture tank 10 is 0 degrees when viewed from above, the bubble water supply means 22 is oriented 5 to 60 degrees with respect to the angle toward the center of the culture tank 10. can be placed in This angle may be 10-50° or 30-45°.

The aquaculture apparatus 1001 of FIG. 6 has four air bubble supply devices 22 arranged near the wall of the aquaculture tank 10 and near the vertex of an inscribed square of a circle. The bubble supply device 22 is arranged to send out the bubbled water toward the adjacent bubble supply device 22 arranged counterclockwise to each other. This arrangement delivers the bubbly water at an angle of 45° to the angle toward the center of the culture tank 10 .

[Third embodiment]
FIG. 7 is a schematic front view of a culture apparatus according to a third embodiment of the present invention. A farming device 1002 is a modification of the farming device 100 according to the first embodiment. The aquaculture apparatus 1002 has a filter 13 arranged at the bottom of the aquaculture tank 10 . The filter 13 is a mesh filter from which the sand of the sand layer 12 does not easily leak, and by providing the sand layer 12 on the filter 13, the lower part of the filter 13 has a double-bottomed structure without sand.

A plurality of air bubble supply devices 221 for supplying air bubble water in the direction toward the sand layer 12 are arranged in the lower layer of the filter 13 . With such a structure, the solid organic matter mixed in the sand layer 12 can be prevented from clogging and can be removed together with the air bubbles. This is particularly effective in preventing clogging in the vicinity of the sand layer 12, preventing anaerobic treatment from occurring, and preventing sludge formation.

[Farming method]
FIG. 8 is a flow diagram showing an example of the aquaculture method of the present invention. In the method for cultivating aquatic animals using the culturing apparatus, step S1, which is an air bubble supplying step of supplying air bubbles by the air bubble supplying means, is first performed during culturing. In addition, step S2, which is a removal process for removing the organic matter that has floated along with the air bubbles, is performed. These are carried out continuously until the cultivation is completed. Step S3 is performed to determine whether or not the cultivation is completed, and when the cultivation is completed, the supply of air bubbles and the like are terminated. Steps S1 and S2 are repeated until the cultivation is completed. Note that the step S1 of supplying air bubbles may not always be performed, and may be adjusted depending on the time zone and the conditions in the water tank.

FIG. 9 is a flowchart showing another example of the aquaculture method of the present invention. In this flow, first, step S11 of supplying first air bubbles is performed in order to improve the dissolved oxygen in the culture water during culture. It is determined in step S21 whether a predetermined time has passed. When the predetermined time has passed, step S31 of supplying a third bubble is performed. Further, even if the determination in step S21 is before the predetermined time has elapsed, it is determined in step S22 whether the activity of the aquatic animal has subsided and the oxygen consumption has decreased. If the oxygen consumption has decreased, step S31 of supplying a third bubble is performed. If the predetermined time has not elapsed and oxygen consumption is active, the first air bubbles are supplied until the predetermined time has elapsed. Note that step S22 may be omitted if time zone management is sufficient. Alternatively, step S21 may be omitted and switching may be performed in step S22.

As described above, the step S31 of supplying the third air bubbles is performed when the organic substances are to be actively removed depending on the time of day or the like. Next, step S41 is performed to remove the foreign matter accompanied by the third air bubble. It is determined in step S51 whether or not a predetermined time has passed, and the third air bubbles are supplied until the predetermined time has passed. After step S51 has been performed for a predetermined period of time, step S61 is performed to determine whether the aquaculture has been completed. If not, the process returns to step S11. When the aquaculture in the aquaculture device is completed, it ends.

FIG. 10 is a diagram for explaining control of the aquaculture method of the present invention. Here, the setting assuming that the first bubble, the second bubble, and the third bubble are respectively supplied will be described. When nocturnal aquatic animals such as tiger prawns are reared, it is believed that they start feeding at night, excrete and molt due to digestion after feeding, and rest during the day.

In accordance with this ecology, from 18:00 in the evening to 24:00 (0:00) in the middle of the night, active oxygen consumption is assumed, so the first bubbles with a small diameter are supplied. Next, from 0:00 to 6:00 when feeding and the like are expected to settle down and excretion and molting are assumed, the second air bubbles having a slightly larger diameter are supplied by adsorbing organic matters and the like to rise. Next, during the daytime from 6:00 to 18:00, when the tiger prawns are resting and oxygen consumption is considered to be low, a third bubble with a large bubble diameter is supplied to remove organic matter and the like. Kuruma prawn farming takes several months from juvenile prawns to reach shipping size.

For this reason, it is possible to have switching means for switching the air bubbles supplied by the air bubble supply means according to the time zone and/or the oxygen concentration of the culture water.

FIG. 11 is an image for showing an outline of bubbles to be supplied in the present invention. The aquaculture tank that supplies these air bubbles contains prawn excrement and peeled skin.

The left side of FIG. 11 shows a state in which micro-sized bubbles corresponding to the first bubbles are supplied. Such bubbles hardly rise. The center of FIG. 11 shows a state in which micro-sized bubbles corresponding to the second bubbles are supplied. Such bubbles rise slowly, and since the surface area of the bubbles is large, they accompany the organic substances so as to positively adsorb them. The right side of FIG. 11 shows a state in which small-sized bubbles corresponding to the third bubble are supplied. With such bubbles, the rising speed of the organic matter also increases, and strong water convection is generated on the surface of the water.

A large electricity bill is required for water change using a pump to remove organic matter and the like from the entire embankment, which is conventional technology. However, the effect of contaminant removal is not sufficient. In addition, after the completion of aquaculture, it is necessary to completely drain the breeding seawater and dig up the sand layer using heavy machinery for purification before the next seedlings are added. In addition, unless a large amount of sand is replaced on a regular basis, it is not possible to maintain the bottom sediment suitable for aquaculture, so the cost is also a factor that puts pressure on management.

In addition, with conventional farming techniques, it is difficult to ascertain the habitat of the prawns being farmed, resulting in wasted feeding and a tendency to lower farming yields. In addition, if excessive serving is performed, the bottom sediment environment of the ikesu will gradually deteriorate, and areas where prawns can live will be further invaded, and cannibalism may occur due to the inability to maintain an appropriate density.

In addition, in the conventional technology, the period during which aquaculture is possible differs depending on the region, and the period is limited. This is because a large amount of seawater is required for large ikesu, and the only way to maintain an appropriate temperature for prawns to grow is to replace the seawater, which inevitably depends on the temperature of the surrounding seawater. In recent years, due to the effects of global warming, the temperature of seawater has been on the rise, making it more difficult to maintain an appropriate water temperature for prawns to grow.

In addition, it is difficult for the conventional technology to grasp the inventory amount in the IKES. Due to the large ikesu and the environment where diatoms spring up, it is not possible to ascertain the number of prawns living in the ikesu. In addition, in order to maintain the amount of dissolved oxygen in the ikesu seawater, aeration with multiple large water turbines is required, which incurs a high electricity bill. This is also influenced by the fact that oxygen supply by photosynthesis of diatoms and environmental regulation by diatoms were thought to be necessary. However, when diatoms proliferate, diatoms do not undergo photosynthesis at night and consume oxygen at the same time as nocturnal prawns. Moreover, it is thought that it also becomes the cause which visibility falls.

As described above, the conventional technology requires a great deal of human labor and cost to maintain the sediment in the pond in a suitable environment. From the viewpoint of maintaining an aerobic environment, it is necessary to supply oxygen to the sand layer to prevent it from turning into sludge. In addition, from the viewpoint of removal of contaminants, since contaminants are in the sand layer, it is necessary to manually remove them by netting or diving from a ship.

In addition, the conventional technology also has the following problems. Food wastage occurred. Kuruma prawns cannot live in areas where the aquaculture environment has deteriorated, but since it is not possible to see the areas where the environment has deteriorated from the surface of the water, if feeding is done in those areas as well, they will not be eaten and will accumulate as leftover food, resulting in increased feed costs. A vicious cycle is created in which waste is generated and accumulated leftover food is further turned into sludge.

Farming yield does not increase. The deterioration of the aquaculture environment, such as the generation of sludge due to organic matter, narrows the area where prawns can live.

The aquaculture apparatus and aquaculture method according to the present invention can solve these problems of the conventional technology, and can improve productivity, improve the quality of aquaculture, and contribute to an improvement in yield.

According to the present invention, the entire aquaculture environment can be kept clean. In addition, a wide area in which aquatic animals can live can be maintained.

Moreover, according to the present invention, the supplied air bubbles also have the effect of increasing dissolved oxygen in water. The sand layer can always be maintained in an aerobic environment by releasing air bubbles from around the sand layer. Even if organic matter is trapped in the sand layer, it can be prevented from becoming sludge and generating harmful substances due to an anaerobic environment due to oxygen deficiency. As a result, the culture density can be made uniform throughout the culture tank. In addition, the rate of food intake relative to the amount of feed is increased, the growth can be uniformed, and it can contribute to production with a low mortality rate and high aquaculture density.

Moreover, according to the present invention, it is not necessary to spring diatoms to maintain the amount of dissolved oxygen. Therefore, since there is no need to introduce foreign diatoms, the diatoms can be reared in purified seawater from which viruses, fungi, etc. have been removed by a UV sterilizer or the like. As a result, deterioration in yield due to pathogen infection to aquatic animals can also be prevented. In this way, it is possible to contribute to productivity improvement and running cost reduction.

Further, according to the present invention, since there are few parts of the sand layer where organic matter accumulates and becomes anaerobic, there are few parts that turn into sludge. Therefore, feeding to areas where prawns cannot live can be avoided, and wasteful feeding can be reduced. In addition, since it is difficult to turn into sludge, it is not necessary to apply manual labor to remove the sludge.

Moreover, in the present invention, the bubble supply means does not have to be operated all the time. The effect can be realized by intensive operation during the period when the activities of aquatic animals are active and dissolved oxygen is feared to decrease, and during the period when excrement, leftover food, and husks are generated.

Therefore, there is no power that needs to be operated all the time, and the pump driven by an AC power supply can be used to periodically change the water and discharge the accumulated nutrient salts and the like. Also, during normal aquaculture, the air bubble supply means, which can be used with a power of about several hundred watts, can be driven when necessary. These can be operated using power stored by solar panels or late-night power in the storage battery, and the electricity bill can be greatly reduced.

In addition, according to the present invention, since the sand layer does not become sludge, etc., the burden of sand layer restoration work between aquaculture is reduced, so the switching period can be shortened and the next aquaculture can be started. can be increased to increase production.

Moreover, according to the present invention, since the entire culture tank can be used efficiently, it is suitable for miniaturization of the culture tank. By reducing the size of the culture tank, it is possible to install equipment that provides lighting and light shielding, or to place it indoors, making it easier to control light control. As a result, the brightness can be adjusted to match the ecology of the aquatic animals so that they can be considered to be active. In addition, by blocking light during the daytime, it is possible to suppress the generation of a large amount of algae, especially in the summer. In addition, by shielding the water during the day, it is possible to suppress the increase in water temperature due to direct sunlight.

Moreover, according to the present invention, the need for oxygen supply by diatoms or the like is low. Therefore, by supplying UV-sterilized seawater into the culture tank, it is possible to suppress the generation of diatoms. As a result, it is possible to prevent a sudden drop in dissolved oxygen at night when nocturnal prawns are active.

In addition, visibility in the tank is improved by downsizing and not generating diatoms. This makes it easier to capture the activity status of aquatic animals with a camera, and it is also possible to visually grasp the number of prawns living in the ikesu. Thus, the aquaculture apparatus and the like of the present invention can greatly reduce power consumption, labor, and the like. In addition, it is possible to visualize inventory, which was difficult to grasp in the past, and improve yield and density, which can be expected to improve profitability.

[Test example]
Test examples are described below. In addition, the present invention is not limited to the following test examples unless the gist thereof is changed.

[Aquaculture equipment]
Water tank: Cultivation was carried out using a rectangular parallelepiped tank having a short side of 1 m, a long side of 2 m, and a water depth of about 1 m when viewed from above. Sand was placed over the entire bottom of the tank to provide a sand layer.
Air bubble supply means: Air bubbles with an average rising speed of about 5 to 10 mm/sec and a diameter of about 100 μm were supplied by adjusting the amount of air bubbles taken in by the air bubble nozzle.
The air bubble supply means had a discharge port placed on the sand layer, and the discharge direction was slanted downward at an angle of about 5 degrees with respect to the horizontal direction toward the sand layer.
By supplying such bubbles, the bubbles gradually rise toward the surface of the water, entraining the organic substances. In addition, the organic substance which floated was removed using the net near the surface of the water.
・Aquaculture target: Kuruma shrimp was cultivated. The culture density was 40 fish/m ² , which is higher than the general culture density, and the number of days was increased.

As a result of cultivating for 2 months while replacing 1/3 of the water once a week, there was almost no death, and the number of confirmed deaths was 1 fish. In addition, it was confirmed that the kuruma prawns molted frequently and grew large during the cultivation period. Also, prawn activity was low during this culture. It is thought that this is because there is no need to compete for food and the environment can be fully utilized, so the actual occupation area of each individual is large and the environment is less stressful. In addition, the highly toxic ammonia concentration did not increase in the culture water during the cultivation. On the other hand, since the nitric acid concentration increased to a certain extent, it is thought that the oxygen concentration was maintained at a certain level and nitrification progressed. In addition, nitric acid could be controlled by replacing the water with a sufficiently non-toxic one.

INDUSTRIAL APPLICABILITY The present invention can be used for farming prawns and the like, and is industrially useful.

Reference Signs List 10 aquaculture tank 100, 1001, 1002 aquaculture apparatus 101 wall 11 aquaculture water 111 water surface 12 sand layer 13 filter 20 water pipe 21 water supply pipe 22, 221 air bubble supply means 23 circulation pump 30 foreign matter removal means 301 comb tooth 302 net 303 float 31, 310 Pipe 311 Flexible pipe 40 Drainage port 41 Drainage filter 50 Water supply means

Claims (7)

an aquaculture tank containing aquaculture water;
a sand layer placed on the bottom of the culture tank;
air bubble supply means for delivering air bubbles containing oxygen along and/or toward the sandy ground of the sand layer;
An apparatus for cultivating aquatic animals, which removes organic substances floating on the surface layer of the culture water accompanied by air bubbles supplied by the air bubble supply means. 2. The aquaculture apparatus according to claim 1, further comprising foreign matter removing means for removing the floating organic matter on the surface layer of the aquaculture water. The air bubble supply means is
It is capable of supplying two or more types of bubbles selected from the group consisting of first to third bubbles having different bubble rising speeds,
The first bubbles have a bubble rising speed of 50 mm/sec or less,
The second bubbles have a bubble rising speed of 5 to 500 mm/sec and have a higher bubble rising speed than the first bubbles,
3. The aquaculture apparatus according to claim 1 or 2, wherein the third bubbles have a bubble rising speed of 50 mm/sec or more and have a higher bubble rising speed than the second bubbles. 4. The aquaculture apparatus according to any one of claims 1 to 3, further comprising switching means for switching the air bubbles supplied by said air bubble supply means in accordance with the time period and/or the oxygen concentration of the culture water. A plurality of the air bubble supply means are arranged,
5. The aquaculture apparatus according to any one of claims 1 to 4, wherein the aquaculture tank is arranged such that supply directions thereof are different when viewed from above. The aquaculture apparatus according to any one of claims 1 to 5, wherein the aquatic animal is prawn. An aquaculture tank containing aquaculture water, a sand layer arranged at the bottom of the aquaculture tank, and air bubble supply means for sending air bubbles along and/or toward the sandy ground of the sand layer. and an aquatic animal farming method using a farming apparatus having
a bubble supply step of supplying bubbles by the bubble supply means;
A method for cultivating aquatic animals, comprising a removing step of removing organic matter that has floated along with the air bubbles.

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