Offshore compound aquaculture facility and construction method thereof

Abstract

To provide a complex culture facility which is safe even in offshore culture susceptible to rough waves and can realize biodiversity by eliminating poor nutrition, and to provide a method for constructing the complex culture facility.SOLUTION: The offshore composite culture facility 10 includes a sink-and-float type fish preserve 20, a sink-and-float type water treatment facility 30 for digesting and decomposing culture residues produced in the sink-and-float type fish preserve 20, and a semi-floating body type reef 40 installed near the sink-and-float type water treatment facility 30 and having a gentle slope.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an offshore integrated aquaculture facility and a method for constructing the same. [Background technology]

[0002] Integrated multi-trophic aquaculture (IMTA) is attracting attention as an aquaculture system of the future. Integrated multi-trophic aquaculture is an aquaculture technique that combines organisms from different trophic levels in the food chain to effectively utilize fish feed and nutrients discharged from aquaculture, creating a balanced system. A common method for cultivating seafood in marine areas is to use underwater cages enclosed by nets or the like. It has been proposed that insoluble organic matter generated in the cages be decomposed into smaller molecules such as phosphorus and nitrogen using a decomposition filter, and then used for the cultivation of seaweed or shellfish. However, if the decomposed nutrients such as phosphorus and nitrogen, and the ammonia contained in urine excreted by fish, dissolve in excess in seawater, harmful plankton will appear in the surrounding sea area, deteriorating the water quality. In order to solve the above problems, for example, Patent Document 1 discloses an integrated fish and shellfish farming device that includes a first fish and shellfish farming cage, a second fish and shellfish farming cage, and an insoluble suspended matter removal device that passes seawater containing insoluble suspended matter such as leftover feed and feces remaining in the first fish and shellfish farming cage through a suspended matter filter to remove the insoluble suspended matter, and returns the seawater after the insoluble suspended matter has been removed to the second fish and shellfish farming cage, and is configured so that the seawater after the insoluble suspended matter has been removed is returned to the first fish and shellfish farming cage via the second fish and shellfish farming cage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-240296 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, the size of the second net cage is limited by the size of the first net cage due to its configuration, which limits the scale of nutrient recycling. Furthermore, since the fish are originally poor in nutrients such as nitrogen and phosphorus, the biological resources that can be cultivated are limited, and there are also issues with promoting biodiversity. Furthermore, offshore aquaculture is subject to the effects of rough waves during stormy weather, which limits the facilities that can be installed. For these reasons, offshore aquaculture faces the problem of difficulty in ensuring the scale of the lower region of the trophic cascade, such as a seaweed bed. On the other hand, in the future, it will also be necessary to operate a sustainable aquaculture facility in a labor-efficient manner that takes the natural environment into consideration. The present invention has been made in consideration of the above circumstances, and aims to provide a comprehensive aquaculture facility and a construction method thereof that is safe even for offshore aquaculture, which is susceptible to the effects of rough waves, and that can eliminate poor nutrition and achieve biodiversity. [Means for solving the problem]

[0005] The inventors discovered that by setting up sink-and-float fish pens offshore for aquaculture, setting up a sink-and-float water treatment facility at a location away from the sink-and-float fish pens to digest and decompose the aquaculture waste generated from the sink-and-float fish pens, and providing nutrients such as nitrogen and phosphorus discharged from the sink-and-float water treatment facility to a semi-floating artificial reef with a gently sloping surface set up around the sink-and-float water treatment facility, a seaweed bed will form on the gently sloping surface, thereby solving the above-mentioned problems and leading to the present disclosure. That is, the present disclosure is as follows. [1] This disclosure relates to an offshore integrated aquaculture facility comprising a sink-and-float fish pen, a sink-and-float water treatment facility for digesting and decomposing aquaculture waste generated in the sink-and-float fish pen, and a semi-floating reef with a gently sloping surface installed near the sink-and-float water treatment facility. [2] The offshore integrated aquaculture facility described in [1] above, wherein the floating-type fish cage comprises at least a rearing fish cage, an impermeable area at the bottom of the rearing fish cage for collecting aquaculture waste, a transport tube connecting the impermeable area to the sink-and-reach water treatment facility, and a pump for generating a flow that causes the aquaculture waste collected in the impermeable area to flow into the sink-and-reach water treatment facility via the transport tube. [3] The offshore integrated aquaculture facility described in [1], wherein the sinking and floating water treatment facility comprises a buoyant float, a biological filtration pool containing biological carriers, and an aeration device that supplies air to the biological carriers. [4] The offshore integrated aquaculture facility according to [1], which has an electric power control vessel as an auxiliary facility. [5] A method for constructing an offshore integrated aquaculture facility, comprising the steps of: installing a sink-and-float fish pen offshore; installing a sink-and-float water treatment facility spaced apart from the sink-and-float fish pen to digest and decompose aquaculture waste generated in the sink-and-float fish pen; and installing a semi-floating reef with a gently sloping surface near the sink-and-float water treatment facility. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a comprehensive aquaculture facility and a construction method thereof that is safe even for offshore aquaculture, which is susceptible to the effects of rough waves, and that can eliminate poor nutrition and realize biodiversity. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic plan view of the offshore integrated aquaculture facility of this embodiment. [Figure 2] FIG. 1 is a schematic side view of the offshore integrated aquaculture facility of this embodiment. [Figure 3] FIG. 1 is a schematic side view of the offshore integrated aquaculture facility of this embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view showing the configuration of a biological treatment device. [Figure 5] 2 is a cross-sectional view taken along the line XX in FIG. 1. [Figure 6] 1 is a schematic cross-sectional view of a portion of a reef. [Figure 7] FIG. 1 illustrates a power control vessel. [Figure 8] This is a schematic plan view of a number of offshore integrated aquaculture facilities. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0009] [Offshore aquaculture complex] As shown in Figure 1, the offshore aquaculture complex 10 of this embodiment comprises a sink-and-float fish pen 20, a sink-and-float water treatment facility 30 that digests and decomposes aquaculture waste generated in the sink-and-float fish pen 20, and a semi-floating reef 40 with a gently sloping surface that is installed near the sink-and-float water treatment facility 30. In this specification, the term "gentle inclined surface" refers to a surface having an inclination such that when the vertical length is 1, the horizontal length is 1.5 or more. The offshore aquaculture complex 10 of the present invention digests and decomposes aquaculture waste generated in the sink-and-float cages 20 into low molecular weight compounds such as nitrogen and phosphorus, and inorganic salts, in the sink-and-float water treatment facility 30, and provides the waste to a semi-floating reef 40 with a gently sloping surface arranged around the sink-and-float water treatment facility 30. With this configuration, nutrients are provided from the sink-and-float water treatment facility 30 to the semi-floating reef 40. As sunlight shines onto the gently sloping surface, a seaweed bed A can be formed by transplanting seaweed or the like, or over time. As a result, the problem of oligotrophy, which has been an issue in offshore aquaculture, can be solved, and the lower stages of the trophic cascade can be harvested on a large scale, thereby increasing biodiversity. Each component will be described in detail below.

[0010] <Floating fish tank> As shown in Figure 2, the sink-and-float type fish cage 20 includes at least a rearing cage 22, an impermeable area 23 for collecting aquaculture residues provided at the bottom of the rearing cage 22, a catch basin 26, a transport tube 28 connecting the impermeable area 23 to the sink-and-float type water treatment facility 30, and a pump 27 for generating a flow that causes the aquaculture residues collected in the impermeable area 23 to flow into the sink-and-float type water treatment facility 30 via the transport tube 28.

[0011] The upper end of the rearing cage 22 is supported by a first float 21. The first float 21 is connected to a second float 24 by a rope 25. The second float 24 is TLP moored to the seabed by a rope 29 so as to be fixed at a predetermined position in the sea.

[0012] When the waves are calm, the buoyancy of the rearing cage 22 is increased by pumping air into the first float 21, causing the rearing cage 22 to rise to the sea surface S. On the other hand, when the weather is rough, the buoyancy is reduced by releasing the air from the first float 21, causing the rearing cage 22 to sink to a position deeper than the second float 24, as shown in Figure 3. The rearing cage 22 can be caused to sink by stopping the power supply. Known floats used in offshore fishing can be used as the first float 21 and the second float 24. For example, floats made of foamed polypropylene or the like can be used.

[0013] The rearing cages 22 are cages surrounded by netting, and fish such as tuna, sea bream, horse mackerel, and mackerel are cultivated in separate rearing cages 22. The shape of the rearing cages 22 may be cylindrical, elliptical cylindrical, cubic, or the like, but a cylindrical shape is preferred for its strength and stability. Diameter d of the first float 21 20 (See FIG. 1) is preferably about 50 m or less in terms of strength, ease of management, etc. Depth D of the net part of the breeding cage 22 20 (See FIG. 2) is preferably within 35 m, and more preferably within 30 m. Side L of second float 24 20 is preferably 60 m or less, and more preferably 50 m or less.

[0014] The impermeable area 23 provided at the bottom of the rearing cage 22 is preferably in an inverted cone shape to facilitate collection of insoluble organic matter such as leftover feed and feces generated during aquaculture, as shown in Figure 2. The impermeable area 23 is preferably made of a resin sheet such as soft vinyl chloride or polypropylene. A catch basin 26 and a pump 27 are provided below the impermeable area 23. The aquaculture waste collected in the impermeable area 23 is deposited in the catch basin 26 and sent to a transport tube 28 by the pump 27.

[0015] The sink-float cage 20 may be provided with an automatic feeding system for feeding.

[0016] <Sink-float water treatment facility> The sink-float water treatment facility 30 has the function of digesting and decomposing the aquaculture waste generated in the sink-float fish cage 20. The planar shape of the sink-and-float water treatment facility 30 of this embodiment is circular, as shown in Figure 1. There are no particular limitations on the planar shape of the sink-and-float water treatment facility 30, and examples include circular, elliptical, and polygonal shapes. From the viewpoint of being able to efficiently arrange the semi-floating reef 40 around the sink-and-float water treatment facility 30, a circular or polygonal shape is preferable.

[0017] As shown in Figure 4, the sink-and-float water treatment facility 30 comprises a biological filtration pool 31, an aeration device (not shown) that supplies air to the biological carriers, and a float 32 provided around the aeration device. The biological filtration pool 31 houses biological carriers 33 inside. Aquaculture waste collected in the sink-and-float fish pen 20 is pushed out by a pump 27 and discharged into the biological filtration pool 31 through a transport tube 28. In the biological filtration pool 31, the biological carriers 33, to which air is supplied by aeration, decompose the aquaculture waste into low-molecular-weight compounds containing nitrogen, phosphorus, etc., and inorganic salts. The low-molecular-weight compounds and inorganic salts are released from the biological filtration pool 31 into the surrounding seawater by the pressure of the pump 27. The biological carrier 33 is a carrier with a large specific surface area on which microorganisms have been acclimatized. It is desirable to use a fluidized bed type carrier that is less likely to clog, that is, a floating carrier held in place by a net or the like, but sinking carriers with sufficient gaps can also be used. Amphipods, lugworms, etc. that feed on the residue are periodically scattered in the biological filtration pool 31 to promote the breakdown of the residue into smaller molecules and to serve as food for the growth of surrounding fish and other organisms.

[0018] As shown in Figure 2, the submersible water treatment facility 30 is connected by a rope 34 to a float 41 on a nearby reef 42. When the waves are calm, the submersible water treatment facility 30 increases its buoyancy by pumping air into the float 32 (see Figure 4), causing it to rise to the surface of the sea. On the other hand, in rough weather, the buoyancy is reduced by releasing the air from the float 32, causing the submersible water treatment facility 30 to sink to a position deeper than the float 41 on the semi-floating reef 40, as shown in Figure 3. The facility can be lowered by cutting off the power supply. As the float 32, a known float used in offshore fishing can be used.

[0019] <Semi-floating reef> The semi-floating reef 40 is installed near the submersible water treatment facility 30 and has a gently sloping surface. Specifically, the semi-floating reef 40 has a float 41 and a reef 42 formed on the float 41. The outer wall 42a of the reef 42 forms a gently sloping surface. The semi-floating reef 40 is moored to the seabed by a TLP with a rope 46. Here, the above-mentioned "nearby" preferably means that the semi-floating reef 40 and the submersible water treatment facility 30 are separated at a distance that avoids collision between the submersible water treatment facility 30 and the semi-floating reef 40 and that allows nutrients from the submersible water treatment facility 30 to be sufficiently provided to the semi-floating reef 40. For example, the distance is preferably between 5 m and 50 m. The buoyancy of the floats 41 of the semi-floating reef 40 is adjusted so that the floats 41 remain at a predetermined position in the sea. Any conventional floats used in floating facilities can be used as the floats 41. For example, floats made of steel, lightweight concrete, etc. can be used.

[0020] The planar shape of the float 41 in this embodiment is hexagonal, as shown in Fig. 1. The planar shape of the float 41 is not particularly limited, and examples thereof include a circle, an ellipse, and a polygon. From the viewpoint of efficiently arranging the float 41 around the sink-and-float water treatment facility 30 and taking in nutrients, a rectangular or polygonal shape is preferable. The size of each float 41 is 4 x 10 2 m2 Over 1.6 x 10 3 m 2 Preferably, it is 5 x 10 or less. 2 m 2 3x10 or more 3 m 2 It is more preferable that the length in one direction is equal to or less than L 40 It is preferable that the length is between 20 m and 60 m.

[0021] As shown in Fig. 5, the reef 42 has an outer wall 42a that is a gently sloping surface. The gently sloping surface may be the entire outer wall 42a of the reef 42, or may be a stepped gently sloping surface with a horizontal surface midway along the gently sloping surface.

[0022] The reef 42 has a shape with a recess 43 near the center of the hexagon. The reef 42 is made of a permeable wall that allows for good water permeability. The method of forming such a permeable wall will be described in detail later, but as shown in Figure 6, it can be formed by stacking blocks 44, each made of a gabion filled with porous concrete artificial rock, on the float 41 so that the outer wall 42a forms a gently sloping surface. It is preferable to further layer porous concrete connected artificial rocks 45 on the surface of the block 44. The thickness T1 of the base of the reef 42 is preferably between 2m and 4m, from the viewpoints of ensuring strength and allowing for good water permeability.

[0023] The void ratio of the porous concrete is preferably 20% or more and 30% or less, and the gabion volume ratio is preferably 60% or more and 80% or less. By using such materials and configuring the reef 42, there are appropriate gaps between the blocks 44 made of porous concrete, so that the reef 42 can be used as a water-permeable wall.

[0024] In the offshore aquaculture complex 10, the pumps 27 of the sink-and-float cages 20 pump aquaculture waste toward the sink-and-float water treatment facility 30, causing seawater to flow from the sink-and-float water treatment facility 30 toward the surrounding semi-floating reef 40. Seawater containing low-molecular-weight compounds and inorganic salts discharged from the sink-and-float water treatment facility 30 is discharged onto the semi-floating reef 40 and provided to the recess 43 and the gently sloping surface of the outer wall 42a.

[0025] It is sufficient to have at least one semi-floating reef 40 for each sink-and-float water treatment facility 30, but from the perspective of efficient nutrient utilization, it is preferable to place multiple semi-floating reefs 40 around one sink-and-float water treatment facility 30, as in this embodiment.

[0026] (weed bed) As described above, the float 41 of the semi-floating reef 40 is located at a depth of D 40 is within a range of approximately 20 m, preferably within 15 m, and the outer wall 42a of the reef 42 is a gently sloping surface, allowing sunlight to penetrate the outer wall 42a. Therefore, by transplanting seaweed, seaweed, etc. onto the gently sloping surface, or over time, a seaweed bed A is formed. In particular, in this embodiment, six semi-floating reefs 40 are arranged around one submerged water treatment facility 30, allowing a wide seaweed bed A to be formed. Furthermore, the shape of the reef 42 has a recess 43 in the center, which has the advantage that low-molecular-weight compounds and inorganic salts tend to stagnate inside the recess 43 and further tend to seep out onto the gently sloping surface of the outer wall 42a due to the permeability of the reef 42. In this way, the aquaculture facility of this embodiment can provide a large-scale seaweed bed A because it is possible to establish a seaweed bed A over a wide area of ​​the outer wall 42a of the reef 42. Seaweed Bed A provides a habitat for a variety of organisms, including fish, sea urchins, abalone, sea cucumbers, and bottom fish, and can also provide a spawning site and nursery for young fish and fry. Its hollow shape is also advantageous in terms of increasing the habitat for these fish and shellfish.

[0027] (Water quality monitoring device) The offshore aquaculture complex 10 of this embodiment may be provided with a water quality monitoring device installed around the reef 42 of the semi-floating reef 40 to measure the concentration of nutrients in the water. By installing the water quality monitoring device, the concentration of nutrients provided by the submerged water treatment facility 30 can be measured. The water quality monitoring device may include, for example, an inlet for seawater, a measuring unit that measures predetermined ion concentrations, such as ammonium ions, nitrate ions, phosphate ions, and total organic carbon (TOC), and a transmitting unit that transmits the results to a management unit on land.

[0028] The measured nutrient concentrations can be used to confirm that the water treatment in the offshore aquaculture complex 10 is proceeding smoothly. By monitoring the water quality around the semi-floating reef 40, aquaculture waste can be efficiently decomposed and supplied to the surrounding sea area as nutrients, eliminating oligotrophy and providing a seaweed bed fishing reef rich in biological resources.

[0029] <Power Control Ship> The offshore aquaculture complex 10 of this embodiment preferably has an electric power control vessel 50 as an auxiliary facility, as shown in Fig. 1. As shown in Fig. 7, the electric power control vessel 50 includes a hull 51, and on the hull 51, an auxiliary power solar panel 52, a small wind power generator 53, an electric control storage battery air blower 54, and a backup storage battery 55. Electric power is supplied from the power control vessel 50 to the sink-and-float fish cage 20 and the sink-and-float water treatment facility 30. When the waves are calm, power is supplied near the offshore integrated aquaculture facility 10, but when the weather is rough, the power supply is stopped and the vessel retreats into the bay. At this time, the sink-and-float fish cage 20 and the sink-and-float water treatment facility 30, for which the power supply has been stopped, cannot maintain buoyancy and therefore sink by the length of the ropes 25 and 34, respectively, as shown in Figure 3. In this way, the force of rough surface seawater can be avoided. Furthermore, the electricity for the offshore integrated aquaculture facility 10 is provided by natural energy sources such as solar panels and wind power generation, which makes it possible to achieve labor savings.

[0030] The offshore aquaculture facility 10 of this embodiment, having the above-described configuration, produces nutrients in the oligotrophic offshore aquaculture area and realizes the cyclical use of the nutrients. In addition, the gently sloping reef 42 allows sunlight to enter, making it possible to establish a lower stage of a trophic cascade like the seaweed bed A. Seaweed Bed A will contribute to the maintenance of biodiversity by providing a fishing ground for sea urchins, abalone, sea cucumbers, and bottom fish, as well as a diverse fishing ground for raising eggs, fry, and young fish, and for aquaculture such as seed production. Furthermore, by establishing a large-scale seaweed bed A, photosynthesis of seaweed and seagrass will become more active, and oxygen essential for the survival of living organisms can also be supplied.

[0031] In the above embodiment, the case where there is one offshore integrated fishing ground facility 10 has been described, but as shown in Figure 8, it is also possible to arrange a plurality of sink-floating cages 20 in two rows, and provide a sink-floating water treatment facility 30 along the sink-floating cages 20, and six semi-floating reefs 40 around the sink-floating water treatment facility 30. One sink-floating cage 20 corresponds to one sink-floating water treatment facility 30 and six semi-floating reefs 40. By adopting such a configuration, it is possible to obtain a more diverse range of fishery resources while ensuring a large scale in the lower region of the trophic cascade.

[0032] [How to build an offshore aquaculture complex] The construction method for the offshore integrated aquaculture facility 10 of this embodiment includes the steps of installing a sink-floating cage 20 offshore, installing a sink-floating water treatment facility 30 spaced apart from the sink-floating cage 20 to digest and decompose aquaculture waste generated in the sink-floating cage 20, and installing a semi-floating reef 40 with a gently sloping surface near the sink-floating water treatment facility 30.

[0033] The sink-and-breed fish pen 20 is installed, for example, in a bay, with a rearing fish pen 22, an impermeable area 23, a catch basin 26, and a pump 27 attached, and connected to a first float 21 and a second float 24. Then, these are towed to a predetermined location outside the bay and moored to the TLP with a mooring rope 29.

[0034] The sink-and-float water treatment facility 30 is completed by attaching a biological filtration pool 31 to a float 32 and then placing a biological carrier 33 in the biological filtration pool 31 in the sea.

[0035] The semi-floating reef 40 is constructed by constructing a float 41 on land or near a quay. Next, an L-shaped reinforced concrete retaining wall is constructed at the planned construction location of the reef 42 on the float 41, and then porous concrete artificial rock gabion blocks 44 are piled up. Furthermore, porous concrete connected artificial rocks 45 are piled up on the surface to complete the reef 42.

[0036] Next, the submersible water treatment facility 30 and the semi-floating reef 40 are connected by a rope 34. The submersible water treatment facility 30 and the semi-floating reef 40 are preferably spaced at least 5 m apart to avoid collision. The floating water treatment facility 30 and the semi-floating reef 40 are towed to a predetermined location outside the bay and moored to the TLP with mooring ropes 46.

[0037] Next, the sink-floating cage 20 and the sink-floating water treatment facility 30 are connected by a transport tube 28, and various equipment is installed. The length of the transport tube 28 is preferably 50 m or more and 100 m or less. Finally, the fry and young fish of the fish to be cultivated are released into the breeding cage 22 and the cultivation begins.

[0038] In the embodiment of the construction method described above, the order of the steps of installing the sink-floating fish cage 20, installing the sink-floating water treatment facility 30, and installing the semi-floating reef 40 is an example and can be changed as appropriate. [Explanation of symbols]

[0039] 10. Offshore Aquaculture Complex 20 Floating fish tank 21 First Float 22 Breeding Tank 23 Impermeable area 24 Second Float 25, 29 Rope 26 Drainage pit 27 Pump 28 Transport Tube 30. Sink-and-float water treatment facility 31 Biological filtration pool 32 Float 33 Biocarriers 34 Rope 40 Semi-floating reef 41 Float 42 Reef 42a (reef) outer wall 43 Recess 44 blocks 45 Porous concrete interlocking imitation rock 46 Rope 50 Power Control Ship 51 Hull 52 Auxiliary power solar panel 53 Small wind power generator for power supply 54 Electrically controlled battery air blower 55 Backup battery

Claims

1. A floating fish tank and a sink-float water treatment facility for digesting and decomposing aquaculture residues generated in the sink-float fish cage; A semi-floating reef having a gently sloping surface, installed near the sink-and-float water treatment facility; An offshore aquaculture complex facility equipped with:

2. 2. The offshore integrated aquaculture facility according to claim 1, wherein the sink-and-rearrangement fish cage comprises at least a rearing fish cage, an impermeable area at the bottom of the rearing fish cage for collecting the aquaculture residue, a transport tube connecting the impermeable area to the sink-and-rearrangement water treatment facility, and a pump for generating a flow that causes the aquaculture residue collected in the impermeable area to flow into the sink-and-rearrangement water treatment facility through the transport tube.

3. The offshore integrated aquaculture facility according to claim 1, wherein the floating water treatment facility comprises a buoyant float, a biological filtration pool containing biological carriers, and an aeration device that supplies air to the biological carriers.

4. The offshore aquaculture facility according to claim 1, wherein the offshore aquaculture facility has a power control vessel as an auxiliary facility.

5. installing a sink-and-float fish pen offshore; a step of installing a sink-float water treatment facility spaced apart from the sink-float cage to digest and decompose aquaculture waste generated in the sink-float cage; Installing a semi-floating reef with a gently sloping surface near the sink-and-float water treatment facility; A method for constructing an offshore integrated aquaculture facility having the above features.

Images