Shellfish farming methods

Abstract

To provide a shellfish breeding method allowing a user to efficiently cultivate shellfish such as abalone regardless of a cultivation location.SOLUTION: A shellfish breeding method comprises: using a shellfish cultivation system A1 including a control device 20 that controls a circulation path C1 for filtering breeding water W1 of a breeding water tank 10 for abalone a1, which is the shellfish, and returning the water to the breeding water tank 10; measuring breeding conditions of the shellfish in the breeding water tank 10; and according to the breeding conditions, immersing a calcium supply material with a controlled sustained-release property in the breeding water W1 to breed the abalone a1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a shellfish farming method for cultivating shellfish such as abalone. [Background technology]

[0002] Land-based abalone farming can be performed using either the "flowing system," in which seawater is continuously drawn in and used for rearing, then discharged, or the "closed circulation system" (or "complete circulation system"), in which the rearing water is purified and circulated for long-term use. The rearing water can be natural seawater or artificial seawater made by dissolving a blend of various salts similar to natural seawater. There is also a partial circulation system, in which seawater is purified and used while gradually replacing it with fresh seawater (see, for example, Patent Document 1). The shellfish rearing method using the circulation system described in this document connects the aquarium and the filtration tank with a piping system, which includes a circulation pump and a water temperature regulator. One end of the piping system is connected to the bottom of the aquarium as a suction pipe, and the other end is connected to a sprinkler pipe installed in the aquarium as a return pipe. The filtration tank contains mineral-containing filter media. A circulation pump circulates the water stored in the aquarium between the filtration tank and the water tank.

[0003] Furthermore, techniques for rearing juvenile abalone in seawater supplemented with calcium salts have also been investigated (e.g., Non-Patent Document 1). The technique described in this document involves using an internal filtration and circulation type rearing tank, and adding 1 g / L of calcium chloride to the rearing water. Shell widths of oysters reared with calcium chloride supplementation tended to be larger than those reared without supplementation. This is thought to be due to the mantle epithelial cells assimilating calcium chloride, promoting the secretion of calcium carbonate, and causing the shell margins to grow and thicken. It has been disclosed that, compared to oysters reared without supplementation, oysters reared with calcium chloride supplementation exhibit significantly rougher surfaces of the aragonite crystal plates, losing their pearly luster, and developing deep holes and grooves at the borders around the crystal plates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-119169 [Non-patent literature]

[0005] [Non-Patent Document 1] Hideyo Sakai, "Shell changes in juvenile abalone reared in seawater containing calcium salts", [online], March 25, 1975, Fisheries and Fisheries Science, Vol. 22, No. 3-4, pp. 105-109 [Retrieved January 23, 2022], Internet <URL:https: / / www.jstage.jst.go.jp / article / aquaculturesci1953 / 22 / 3-4 / 22_3-4_105 / _pdf / -char / ja> Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 uses enzyme-treated water treated with a filter medium. This enzyme-treated water exhibits an increase of several ppm in calcium, sodium, potassium, phosphorus, and other elements. Furthermore, the calcium ion concentration in natural seawater is 390 to 420 mg / L, which is comparable to that of natural seawater, and therefore no significant increase in the concentration of the overall rearing water can be expected. Furthermore, Non-Patent Document 1 adds 1 g / L of calcium chloride, which is not optimized. Abalone, in particular, are delicate creatures that dislike environmental changes. Therefore, in land-based abalone aquaculture, promoting growth is difficult unless the water quality is properly adjusted. [Means for solving the problem]

[0007] The shellfish farming method that solves the above problem uses a shellfish farming system equipped with a control device that controls a circulation path that filters the breeding water in the shellfish breeding tank and returns it to the breeding tank. The breeding conditions of the shellfish in the breeding tank are measured, and a calcium supply material with controlled sustained release properties is immersed in the breeding water according to the breeding conditions, and the shellfish are raised. [Effects of the Invention]

[0008] According to the present invention, shellfish such as abalone can be efficiently cultivated regardless of the cultivation location. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of a shellfish farming system according to an embodiment. [Figure 2] FIG. 3 is an explanatory diagram of a holder according to the embodiment. [Figure 3] FIG. 2 is an explanatory diagram of a hardware configuration according to an embodiment. [Figure 4] FIG. 2 is an explanatory diagram of a processing procedure according to an embodiment. [Figure 5] 1A to 1D are explanatory diagrams illustrating the relationship between rearing conditions and ease of dissolution in an embodiment, where (a) is the flow rate, (b) is the amount reared, (c) is the water exchange rate, and (d) is the pH. [Figure 6] FIG. 2 is an explanatory diagram of a processing procedure according to an embodiment. [Figure 7] FIG. 2 is an explanatory diagram of a processing procedure according to an embodiment. [Figure 8] FIG. 10 is an explanatory diagram of a holder according to another example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of a shellfish farming method will be described with reference to Figures 1 to 7. In this embodiment, a sustained-release calcium substance (calcium supply material) is added to perform land-based farming of Ezo abalone.

[0011] 1, a circulation-type shellfish farming system A1 includes breeding tanks 10, a control device 20, and a circulation path C1. In this embodiment, a plurality of breeding tanks 10 are connected to one circulation path C1.

[0012] The breeding tank 10 is an aquarium for breeding (land-based farming) abalone a1, and is equipped with an aeration / water current stirring device 11 and a shelter 12. Breeding water W1 is stored in the breeding tank 10. In this embodiment, seawater to which a sustained-release calcium substance has been added is used, and the salinity of the seawater is adjusted to 30 to 31‰. Furthermore, the calcium ion concentration of the seawater is adjusted to 450 to 650 mg / L, and the pH is adjusted to 7.8 to 8.2. In this embodiment, the seawater in the breeding tank 10 is referred to as breeding water W1.

[0013] The aeration and water flow agitation device 11 and the shelter 12 are installed in the breeding tank 10. This aeration / water current agitation device 11 stabilizes the water quality of the breeding water W1 through aeration and agitation by water current. The shelter 12 is an enclosure that provides shade to suit the shade-loving habits of shellfish.

[0014] A portion of the breeding water W1 in the breeding tank 10 is supplied to the circulation path C1. The circulation path C1 returns the filtered seawater to the breeding tank 10. The seawater supplied to the breeding tank 10 is agitated throughout the breeding tank 10 by an aeration and water flow agitation device 11.

[0015] Furthermore, in this embodiment, the holder 15 is suspended from the upstream edge of the breeding aquarium 10. 2, holder 15 is a cylindrical member having an opening 150 on its lower surface (bottom surface). Support material 151 is provided in opening 150. A wire is used as support material 151, bridging the ends of opening 150 on the lower surface.

[0016] A block of gypsum pillar 500 (gypsum dihydrate) made of calcium sulfate as a sustained-release calcium substance is inserted into the holder 15 as a calcium supply material. The support material 151 holds the gypsum pillar 500 through the opening 150 to prevent it from falling out. The outer diameter of the gypsum pillar 500 is approximately the same as the inner diameter of the holder 15. The gypsum pillar 500 slides on the inner surface of the holder 15 and is supported by the support material 151.

[0017] The lower end of this holder 15 is immersed in the breeding water W1. As a result, the plaster pillar 500 is exposed to the breeding water W1 over the opening area (a fixed area) at the opening 150. As a result, calcium sulfate dissolves into the breeding water W1.

[0018] When the gypsum pillar 500 slides inside the holder 15 and the remaining amount becomes small, a new gypsum pillar 500 is added through the opening at the top of the holder 15. The control device 20 manages the circulation of the breeding water W1 (seawater) through the circulation path C1.

[0019] (Example of hardware configuration) FIG. 3 shows an example of the hardware configuration of an information processing device H10 that functions as the control device 20.

[0020] The information processing device H10 includes a communication device H11, an input device H12, a display device H13, a storage device H14, and a processor H15. Note that this hardware configuration is an example, and the information processing device H10 may include other hardware.

[0021] The communication device H11 is an interface that establishes a communication path with other devices and transmits and receives data, such as a network interface or a wireless interface. The input device H12 is a device that accepts input from an administrator or the like, such as a mouse or a keyboard. The display device H13 is a display or touch panel that displays various information. The storage device H14 is a storage device that stores data and various programs for executing various functions of the control device 20. Examples of the storage device H14 include a ROM, a RAM, a hard disk, etc.

[0022] The processor H15 controls each process in the control device 20 using programs and data stored in the storage device H14. Examples of the processor H15 include a CPU and an MPU. The processor H15 loads programs stored in a ROM or the like into a RAM and executes various processes corresponding to the various processes. For example, when an application program of the control device 20 is started, the processor H15 runs a process that executes each process. The processor H15 is not limited to a processor that performs software processing for all of the processes it executes. For example, the processor H15 may be equipped with a dedicated hardware circuit (e.g., an application specific integrated circuit: ASIC) that performs hardware processing for at least some of the processes it executes.

[0023] (Functions of shellfish farming systems) In this embodiment, the control device 20 shown in FIG. 1 controls the sensor 30, the valves V1 to V3, and the pump P1.

[0024] The sensor 30 measures the calcium ion concentration of the breeding water W1 in the breeding aquarium 10. The valve V1 is a control valve that controls the supply and stop of the breeding water W1 of the breeding aquarium 10 to the buffer tank 32.

[0025] The buffer tank 32 is a water storage tank that accumulates seawater to be supplied to the breeding aquarium 10. In addition to the breeding water W1 supplied from the breeding aquarium 10, natural seawater or artificial seawater is supplied to this buffer tank 32 as needed.

[0026] The valve V2 is a control valve that controls the supply and stop of seawater from the buffer tank 32 to the electrolysis device 33. The electrolysis device 33 partially oxidizes the pigments (hard-to-decompose organic matter) to make them easier to remove. Specifically, by applying a voltage to electrode plates arranged inside the pipe, the organic matter is partially oxidized and microbial decomposition is promoted.

[0027] The solid matter removal device 34 is a cylindrical filter cloth (drum filter) that physically removes solid waste such as leftover food and droppings. This solid matter removal device 34 detects clogging of the filter cloth depending on the filtration volume and backwashes the filter as necessary to restore its performance.

[0028] The solids removal device 34 is connected to a denitrification device 35 via a valve V3. The valve V3 is a control valve that controls the supply and stop of seawater from the solid matter removal device 34 to the denitrification device 35.

[0029] The denitrification unit 35 is a device that periodically performs nitrate treatment, in which microorganisms (ammonia-oxidizing bacteria and denitrifying bacteria) convert nitrate into nitrogen, rendering it harmless. Specifically, ammonia-oxidizing bacteria grow using oxygen and ammonia as their energy source, oxidizing the strong ammonia derived from waste and converting it into nitrate. Furthermore, when oxygen runs out, denitrifying bacteria obtain oxidizing power from nitrate (nitrate respiration) and decompose organic matter. The nitrogen atoms in the nitrate become nitrogen molecules, which are released into the air.

[0030] The downstream of the denitrification device 35 is connected to a biological filtration tank 36. The denitrification device 35 periodically performs nitrate treatment. To this end, a valve V3 is opened and closed, thereby controlling the start and stop of the supply of seawater from the solid removal device 34. A bypass pipe is provided from the solid removal device 34 to the biological filtration tank 36.

[0031] The biological filtration tank 36 performs ammonia treatment, in which microorganisms attached to the filter media convert harmful ammonia into less toxic nitrate, and soluble organic matter decomposition treatment, in which organic matter is decomposed. Here, coral is used as the porous mineral-containing filter media. The minerals in this case include iron, calcium, magnesium, sulfur, potassium, titanium, phosphorus, cobalt, aluminum, sodium, manganese, strontium, barium, tin, zinc, vanadium, polonium, nickel, and copper.

[0032] A cooler 37 is connected to the biological filtration tank 36 via a pump P1. The pump P1 circulates the seawater through the circulation path C1. The pump P1 may circulate the seawater constantly or periodically.

[0033] The cooler 37 adjusts the temperature of the seawater supplied to the breeding tank 10. In this embodiment, the water temperature is set to 15°C, thereby maintaining the growth rate of the abalone a1 and suppressing the proliferation of bacteria. The temperature-adjusted seawater is then returned to the breeding tank 10.

[0034] (Breeding treatment) This rearing treatment includes an initial treatment, a concentration confirmation treatment, and a sustained release confirmation treatment.

[0035] (Initial processing) The initial processing will be described with reference to FIG. First, the breeding conditions are measured (step S11). The breeding conditions include the flow rate of the breeding tank 10, the amount of abalone a1 being bred, the water exchange rate, and pH. Specifically, the water flow rate of the breeding tank 10 is measured using a current meter. The amount of abalone a1 being bred is measured based on the number of abalone a1 in the breeding tank 10 and their size (shell length). The greater the number of abalone a1 and the larger their size, the greater the amount of abalone a1 being bred. The water exchange rate is the rate at which the breeding water W1 in the breeding tank 10 is replaced per unit time. This water exchange rate is calculated by multiplying the capacity of the breeding tank 10 by the amount of water measured by the water meter on the circulation path C1. The pH is the hydrogen ion concentration of the breeding water W1 in the breeding tank 10. This pH is measured using a pH meter.

[0036] Next, the solubility of the plaster pillar is evaluated (step S12). Specifically, the solubility required for the plaster pillar is evaluated based on the breeding conditions using the solubility table T1. The solubility table T1 records the solubility (sustained release) required for the plaster pillar based on the breeding conditions.

[0037] As shown in Figure 5, the solubility of the gypsum pillars is adjusted depending on the rearing conditions. For example, as shown in Figure 5(a), the faster the flow rate, the more easily the sustained-release calcium substance dissolves, making the gypsum pillars less soluble. Also, as shown in Figure 5(b), when the rearing quantity of abalone a1 is high, the sustained-release calcium substance is consumed in large amounts, making the gypsum pillars more soluble. Also, as shown in Figure 5(c), the higher the water exchange rate, the more easily the sustained-release calcium substance dissolves, making the gypsum pillars less soluble. Also, as shown in Figure 5(d), when the pH is low, the sustained-release calcium substance dissolves easily, making the gypsum pillars less soluble.

[0038] Then, the moisture content of the plaster pillar is determined based on the solubility (step S13). Specifically, the solubility table T1 is used to calculate the statistical value of the identified graded evaluation. The moisture content is determined corresponding to this statistical value. In this case, moisture content determination information is used to determine the moisture content based on the statistical value of the graded evaluation of the solubility of the plaster pillar. Here, the higher the evaluation result of the solubility required for the plaster pillar, the higher the moisture content. In other words, by comprehensively evaluating the solubility required for the plaster pillar, the moisture content appropriate to the breeding conditions is determined.

[0039] Next, a gypsum pillar with an adjusted moisture content is produced (step S14). Specifically, the amount of water added to the calcium sulfate powder is adjusted to produce the gypsum pillar 500 so that the moisture content is determined using the solubility table T1.

[0040] The gypsum pillar is then supplied to the aquarium (step S15). Specifically, the manufactured gypsum pillar 500 is loaded into the holder 15. This holder 15 is hung from the upstream edge of the breeding aquarium 10 so that the opening 150 on the bottom surface is immersed in the breeding water W1. The supply position of the calcium agent may be any location that allows calcium ions to be easily distributed throughout the breeding water W1, and is not limited to the upstream side of the breeding aquarium 10.

[0041] (Concentration confirmation process) Next, the concentration confirmation process will be described with reference to Fig. 6. This process is executed periodically at predetermined time intervals during the rearing of the abalone a1.

[0042] First, the control device 20 executes a process of detecting the calcium ion concentration (step S21). Specifically, the control device 20 uses the sensor 30 to detect the calcium ion concentration of the breeding water W1 in the breeding aquarium 10.

[0043] Next, the control device 20 executes a process of determining whether the concentration is appropriate (step S22). Specifically, the control device 20 compares the detected calcium ion concentration with a reference value. In this embodiment, the reference range is 450 to 650 mg / L.

[0044] If it is determined that the calcium ion concentration is within the reference value range (YES in step S22), the control device 20 waits until the next timing to execute the calcium ion concentration detection process (step S21).

[0045] On the other hand, if it is determined that the calcium ion concentration is outside the reference value range ("NO" in step S22), the control device 20 executes a warning process (step S23). Specifically, the control device 20 outputs a warning message to the display device H13. This warning message includes information about the calcium ion concentration detected by the sensor 30. In this case, the administrator performs a sustained release confirmation process, which will be described later. Then, the control device 20 waits until the timing to execute the next calcium ion concentration detection process (step S21).

[0046] (Slow-release confirmed treatment) The sustained release confirmation process will be described with reference to Fig. 7. This process is executed periodically at predetermined time intervals when a warning message is output in the concentration confirmation process described above or when the abalone a1 is being raised.

[0047] First, similarly to step S11, the rearing conditions are measured again (step S31). Next, it is determined whether the rearing conditions have changed (step S32). Specifically, the rearing conditions measured in the initial process are compared with the current rearing conditions. If the required solubility has changed in the stage evaluation of the solubility table T1, it is determined that the rearing conditions have changed.

[0048] If it is determined that the rearing conditions have not changed ("NO" in step S32), the plaster pillars are filled as necessary (step S33). On the other hand, if it is determined that the rearing conditions have changed (YES in step S32), the process returns to the initial process, and the processes after the evaluation of the solubility of the plaster pillar (step S12) are performed. Then, the plaster pillar 500 in the holder 15 is replaced.

[0049] According to this embodiment, the following effects can be obtained. (1) In this embodiment, the shellfish farming system A1 includes a breeding tank 10 and a circulation path C1. This allows shellfish to be farmed anywhere. Compared to marine aquaculture, which involves farming in the ocean, the circulation-type shellfish farming method can mitigate the effects of climate change, allowing for stable farming without impacting the marine environment.

[0050] (2) In this embodiment, the calcium ion concentration of the breeding water W1 in the breeding aquarium 10 is set to a standard range of 450 to 650 mg / L. Experiments have confirmed that using this calcium ion concentration increases the growth rate. Furthermore, even when the growth rate increases, the shell quality remains nearly equivalent to that of breeding in natural seawater. On the other hand, in experiments with even higher calcium ion concentrations, the growth rate slows. That is, the calcium content of the mineral components is increased in the breeding water in the breeding aquarium 10 compared to seawater. Therefore, while achieving a composition ratio similar to that of seawater for mineral components other than calcium, it is possible to achieve a higher composition ratio than seawater, focusing on calcium, the main component of shells and particularly essential for growth. As a result, it is possible to increase the growth rate of shellfish themselves, including shell growth.

[0051] (3) In this embodiment, the circulation path C1 includes an electrolysis device 33, a solid matter removal device 34, a denitrification device 35, and a biological filtration tank 36. This allows the water quality of the circulating rearing water W1 to be purified and the minerals contained in the filter media to be supplied.

[0052] (4) In this embodiment, the rearing conditions are measured (step S11), the solubility of the gypsum pillar is evaluated (step S12), and the moisture content of the gypsum pillar is determined based on the solubility (step S13). This allows calcium to be supplied to the rearing water W1 over a long period of time by taking advantage of the sustained release properties. The amount of calcium required varies depending on the rearing conditions, but by adjusting the moisture content, an appropriate calcium concentration can be maintained depending on the rearing conditions.

[0053] (5) In this embodiment, the plaster pillar 500 is inserted into the holder 15 having an opening 150 on the bottom surface. The plaster pillar 500 is immersed in the rearing water W1 at the opening 150. Therefore, since the plaster pillar 500 is immersed with the opening area of ​​the opening 150, the dissolution rate can be maintained constant.

[0054] (6) In this embodiment, the control device 20 executes a process of detecting the calcium ion concentration (step S21) and a process of determining whether the concentration is appropriate (step S22). If the control device 20 determines that the concentration is inappropriate ("NO" in step S22), the control device 20 executes a process of issuing a warning (step S23). This allows the calcium ion concentration to be maintained at an appropriate level.

[0055] (7) In this embodiment, a sustained release confirmation process is performed. The rearing conditions may change depending on the growth of the shellfish, and the plaster pillar can be recreated as needed to accommodate these changes.

[0056] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility. In the above embodiment, the rearing conditions used are the flow rate of the rearing tank 10, the number of abalone a1 reared, the water exchange rate, and pH. The rearing conditions are not limited to these, and some of these or other factors may be added as long as they affect the calcium supply.

[0057] In the above embodiment, the concentration confirmation process is performed using the control device 20. However, the calcium ion concentration may be confirmed manually. Furthermore, in the above embodiment, the rearing conditions are remeasured manually, but this may also be done by the control device 20. In this case, a flow meter and a pH meter are permanently installed in the rearing aquarium 10. Furthermore, a water level meter for the rearing water W1 flowing through the circulation path C1 is permanently installed. A camera for photographing the interior of the rearing aquarium 10 is also permanently installed. The control device 20 then obtains the measured water flow velocity and the pH of the rearing water W1 in the rearing aquarium 10 from the flow meter, pH meter, and water level meter. The control device 20 also obtains the circulating water volume from the water level meter. The control device 20 then divides the volume of the rearing water W1 in the rearing aquarium 10 by the circulating water volume to calculate the water exchange rate.

[0058] The control device 20 also acquires photographed images of the inside of the breeding tank 10 from the camera. Next, the control device 20 identifies the number and size of the abalone a1 in the breeding tank 10 by image recognition of the photographed images, and calculates the breeding quantity. The control device 20 then uses this information to check for changes in the breeding conditions.

[0059] In the above embodiment, the concentration confirmation process and sustained release confirmation process are performed periodically (at predetermined time intervals). This time interval may be changed depending on the rearing status (e.g., number of reared abalone) and growth status of the abalone a1.

[0060] In the above embodiment, the circulation path C1 includes an electrolysis device 33, a solid matter removal device 34, a denitrification device 35, and a biological filtration tank 36. The configuration for water purification is not limited to these.

[0061] In the above embodiment, the shellfish farming system A1 is applied to the farming of abalone a1. However, the shellfish farming system A1 is not limited to abalone a1 as long as it is a shellfish that consumes calcium to grow. In the above embodiment, calcium sulfate is used as the sustained-release calcium substance, but the present invention is not limited to this as long as calcium can be supplied. For example, calcium hydroxide, calcium carbonate, etc. can be used. Calcium hydroxide has high solubility, but since it alkalizes the solution, pH adjustment is required. Calcium carbonate has low solubility, so it can be used as an adjuster for highly soluble calcium substances.

[0062] In the above embodiment, the support material 151 is configured as a wire bridging the ends of the opening 150 on the underside, but this configuration is not limiting as long as it can keep the opening area immersed in the breeding water constant and prevent the plaster column 500 from falling off. For example, protrusions may be provided around the opening 150 as long as they do not affect the opening area.

[0063] In the above embodiment, the moisture content of the gypsum pillar is determined based on the ease of dissolution (step S13). The method for adjusting the calcium supply amount is not limited to adjusting the moisture content. For example, instead of or in addition to the moisture content, calcium hydroxide (second calcium agent) may be dispersed in calcium sulfate (first calcium agent) to adjust the moisture content.

[0064] As shown in Fig. 8, calcium hydroxide agent 510 is uniformly embedded in a gypsum pillar 500. The amount of calcium supplied is adjusted by the amount of embedded calcium hydroxide agent 510. In this case, the calcium concentration and pH may be adjusted using first and second calcium agents. [Explanation of symbols]

[0065] A1...shellfish farming system, C1...circulation path, P1...pump, valve...V1 to V3, W1...breeding water, 10...breeding tank, 11...aeration and water flow mixing device, 12...shelter, 15...holder, 150...opening, 151...support part, 500...gypsum pillar, 510...calcium hydroxide agent, 20...control device, 32...buffer tank, 33...electrolysis device, 34...solids removal device, 35...denitrification device, 36...biological filtration tank, 37...cooler.

Claims

1. A shellfish farming method using a shellfish farming system equipped with a circulation path that filters breeding water in a shellfish breeding tank and returns it to the breeding tank, Measure the breeding conditions of the shellfish in the breeding tank; A shellfish rearing method, characterized in that a calcium supply material whose slow-release properties have been adjusted according to the rearing conditions is immersed in the rearing water and the shellfish are reared.

2. 2. The shellfish rearing method according to claim 1, wherein the calcium supply material is gypsum whose moisture content is adjusted according to the rearing conditions.

3. The shellfish rearing method described in claim 2, characterized in that the calcium supply material is a mixture of gypsum as a first calcium agent and a second calcium agent in an amount according to the rearing conditions dispersed therein.

4. A shellfish rearing method described in any one of claims 1 to 3, characterized in that the rearing conditions include at least one of the following elements: the water flow rate in the rearing tank, the amount of shellfish being reared, the water exchange rate of the rearing tank, and the pH of the rearing water.

5. A shellfish rearing method described in any one of claims 1 to 4, characterized in that the calcium supply material is made up of a block, and a certain area of ​​the block is immersed in the rearing water.

6. The columnar calcium supply material is held in a holder having an opening on the bottom surface, 6. A shellfish rearing method as described in claim 5, wherein the calcium supply material is immersed in the rearing water at the opening.

7. In the breeding tank, abalone is cultivated as the shellfish, A shellfish rearing method described in any one of claims 1 to 6, characterized in that the control device that controls the circulation path supplies seawater in which the calcium ion concentration of the rearing water has been increased to 450 to 650 mg / L.

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