Shellfish farming system and shellfish farming method

Abstract

To provide a shellfish aquaculture system and a shellfish aquaculture method by which shellfish such as abalones can be efficiently cultivated at any location.SOLUTION: A shellfish aquaculture system A1 includes a control device 20 that controls a circulation route C1 through which aquaculture water W1 of a shellfish aquaculture water tank 10 is filtered and returned to the aquaculture water tank. The control device 20 detects a calcium ion concentration of the aquaculture water W1 in the aquaculture water tank 10, and supplies sea water, whose calcium ion concentration is increased so that the calcium ion concentration of the aquaculture water W1 can reach a reference value or more, to the aquaculture water tank 10 if the calcium ion concentration is less than the reference value.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In land-based abalone farming, there are two methods: the "run-through method," in which seawater is continuously drawn in and used for farming, and then discharged; and the "closed circulation method" (or "complete circulation method"), in which farming water is purified and circulated for long-term use. Natural seawater or artificial seawater made by dissolving a blend of various salts similar to natural seawater is used as the farming water. There is also a partial circulation method in which seawater is purified as it is used, but is replaced with fresh seawater little by little (for example, Patent Document 1). In the shellfish farming method using the circulation method described in this document, a piping system is used to connect the tank and the filtration tank, and a circulation pump and a water temperature regulator are interposed in the piping system. One end of the piping system is connected to the bottom of the tank as a suction pipe, and the other end is connected to a sprinkler pipe installed in the tank as a return pipe. The filtration tank contains a filter medium containing minerals. The water stored in the tank is circulated between the tank and the filtration tank by a circulation pump.

[0003] Furthermore, a technique for rearing juvenile abalone in seawater with added calcium salts has also been investigated (for example, Non-Patent Document 1). In the technique described in this document, an internal filtration circulation type rearing tank is used, and 1 g / L of calcium chloride is added to the rearing water. The shell width of shells reared with added calcium chloride tended to be greater than that of shells reared without added calcium chloride. This is thought to be because the mantle epithelial cells assimilate calcium chloride, promoting the secretion of calcium carbonate, which causes the shell edges to grow and thicken. It is disclosed that compared to shells without added calcium chloride, shells reared with added calcium chloride have significantly rougher surfaces of the aragonite crystal plates, losing their pearlescent luster, and that deep holes and grooves form in places at the borders around the crystal plates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-119169 A [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, p. 105-109 [Retrieved May 1, 2021], 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] In Patent Document 1, enzyme-treated water treated with a filter medium is used. In this enzyme-treated water, calcium, sodium, potassium, phosphorus, etc. are increased by several ppm. In addition, the calcium ion concentration of natural seawater is 390 to 420 mg / L, which is approximately the same as natural seawater, and the effect of increasing the concentration of the breeding water in general cannot be expected. In addition, in Non-Patent Document 1, 1 g / L of calcium chloride is added, which is not optimized. In particular, abalone are delicate creatures that dislike environmental changes. For this reason, in land-based abalone aquaculture, it is difficult to promote growth unless the water quality is properly adjusted. [Means for solving the problem]

[0007] The shellfish farming system that solves the above problems includes a control device that controls a circulation path that filters the breeding water in a shellfish breeding tank and returns it to the breeding tank. The control device detects the calcium ion concentration of the breeding water in the breeding tank, and if the calcium ion concentration is below a reference value, supplies seawater with an increased calcium ion concentration to the breeding tank so that the calcium ion concentration of the breeding water is equal to or higher than the reference value.

[0008] The shellfish farming method that solves the above problem is a circulating shellfish farming method in which the breeding water in a breeding tank is filtered and returned to the breeding tank, and when replacing part of the stored water with new seawater, seawater that has been increased in calcium ion concentration to 450 to 650 mg / L is supplied. Effect of the Invention

[0009] According to the present invention, shellfish such as abalone can be efficiently cultured regardless of the culture location. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of a shellfish farming system according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of a hardware configuration according to the embodiment. [Diagram 3] FIG. 4 is an explanatory diagram of a processing procedure according to the embodiment. [Figure 4] FIG. 2 is an explanatory diagram of shell length corresponding to the number of days elapsed in the growth of abalone in an embodiment. [Diagram 5] Photograph of abalone in an embodiment. [Figure 6] Photograph of abalone in an embodiment. [Figure 7] FIG. 2 is an explanatory diagram of shell length corresponding to the number of days elapsed in the growth of abalone in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, one embodiment of a shellfish farming system and a shellfish farming method will be described with reference to Figures 1 to 7. In this embodiment, Ezo abalone is farmed on land by feeding them artificial feed pellets.

[0012] As shown in FIG. 1, a circulating shellfish farming system A1 includes a breeding tank 10, a control device 20, and a circulation path C1. The breeding tank 10 is an aquarium for breeding (land-based culturing) abalone, and is equipped with an aeration / water flow mixing device 11 and a shelter 12. Breeding water W1 is stored in the breeding tank 10. In this embodiment, seawater in the breeding tank 10 is referred to as breeding water W1.

[0013] The aeration / water current agitation device 11 stabilizes the water quality of the breeding water W1 in the breeding aquarium 10 by aeration and agitation through water current. The shelter 12 is provided with an enclosure that provides shade to accommodate the shady nature 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 supplies seawater with an adjusted calcium ion concentration to the breeding tank 10. The seawater supplied to the breeding tank 10 is agitated throughout the tank by an aeration / water current agitation device 11. The control device 20 manages the circulation of the breeding water W1 (seawater) through the circulation path C1.

[0015] (Hardware configuration example) FIG. 2 shows an example of the hardware configuration of an information processing device H10 that functions as the control device 20.

[0016] 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 H 15. Note that this hardware configuration is an example, and the information processing device H10 may include other hardware.

[0017] 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 a 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.

[0018] The processor H15 controls each process in the control device 20 using the programs and data stored in the storage device H14. Examples of the processor H15 include a CPU and an MPU. The processor H15 expands a program stored in a ROM or the like into a RAM and executes various processes corresponding to various processes. For example, when an application program of the control device 20 is started, the processor H15 operates a process that executes each process. The processor H15 is not limited to a processor that performs software processing for all the processes it executes. For example, the processor H15 may include a dedicated hardware circuit (for example, an application specific integrated circuit: ASIC) that performs hardware processing for at least a part of the processes it executes.

[0019] (Functions of shellfish farming systems) In this embodiment, the control device 20 shown in Fig. 1 is connected to a sensor 30, valves V1 to V3, and a pump P1. The control device 20 adjusts the calcium ion concentration of seawater circulated through a circulation path C1 based on the result of measurement by the sensor 30. In this embodiment, seawater to which artificial seawater powder 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 controlled to 450 to 650 mg / L, and the pH is controlled to 7.8 to 8.2.

[0020] 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.

[0021] The calcium chloride supplying device 31 supplies calcium chloride as a calcium agent to the buffer tank 32. In this case, an appropriate amount of calcium chloride material is supplied according to the calcium ion concentration of the breeding water W1 in the breeding aquarium tank 10. As the calcium chloride material, calcium chloride powder of a quality suitable for use as a food additive is used.

[0022] 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 supplied from the breeding aquarium 10, natural seawater or artificial seawater is supplied to this buffer tank 32 as necessary.

[0023] 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, a voltage is applied to electrode plates arranged inside the pipe to partially oxidize the organic matter and promote microbial decomposition.

[0024] The solid matter removal device 34 is a cylindrical filter cloth (drum filter) that physically removes solid waste such as residual food and droppings. This solid matter removal device 34 detects clogging of the filter cloth according to the amount of filtration, and backwashes the cloth as necessary to restore the filter performance.

[0025] The solid matter 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.

[0026] The denitrification unit 35 is a device that performs nitrate treatment, in which microorganisms convert nitrate into nitrogen, rendering it harmless. Specifically, it oxidizes the strong ammonia derived from waste and converts it into nitrate. Here, ammonia-oxidizing bacteria grow using oxygen and ammonia as their energy source. Furthermore, when oxygen runs out, denitrifying bacteria obtain energy from nitrate (nitrate respiration) and break down organic matter. The nitrogen atoms in the nitrate become nitrogen molecules, which are released into the air.

[0027] The downstream of the denitrification device 35 is connected to a biological filtration tank 36. The denitrification device 35 periodically performs nitrate treatment. For this purpose, the supply and stop of seawater from the solid removal device 34 is controlled by opening and closing a valve V3, and a bypass pipe is provided from the solid removal device 34 to the biological filtration tank 36.

[0028] The biological filtration tank 36 performs ammonia treatment, in which microorganisms attached to the filter media convert harmful ammonia into less toxic nitric acid, 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.

[0029] 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.

[0030] The cooler 37 adjusts the temperature of 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 and suppressing the proliferation of bacteria. The temperature-regulated seawater is then returned to the breeding tank 10.

[0031] (Breeding treatment) Next, the breeding process will be described with reference to Fig. 3. This process is executed periodically at predetermined time intervals.

[0032] First, the control device 20 executes a process of detecting a calcium ion concentration (step S101). 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.

[0033] Next, the control device 20 executes a process of determining whether or not the detected calcium ion concentration is outside the reference value range (step S102). Specifically, the control device 20 compares the detected calcium ion concentration with the reference value. In this embodiment, the reference range is set to 450 to 650 mg / L.

[0034] When it is determined that the concentration is outside the reference value range (YES in step S102), the control device 20 executes a calcium chloride addition process (step S103). Specifically, the control device 20 calculates the calcium chloride deficiency concentration based on the difference between the calcium ion concentration detected by the sensor 30 and the reference value range. Then, the control device 20 calculates the required amount of calcium chloride by multiplying the calcium ion deficiency concentration by the total volume of the breeding aquarium 10. Note that, when the volume of seawater in the circulation path C1 is large, this may be included in the total volume. Next, the control device 20 instructs the calcium chloride supply device 31 to supply the required amount to the buffer tank 32. Then, the pump P1 is driven to supply the seawater in the buffer tank 32 to the breeding aquarium 10 via the circulation path C1. In this case, the seawater supplied to the breeding aquarium 10 is stirred by the aeration / water flow stirring device 11, and the calcium ion concentration is improved overall.

[0035] On the other hand, if it is determined that the calcium chloride is within the reference value range ("NO" in step S102), the control device 20 skips the calcium chloride addition process (step S103). Then, when the breeding period (for example, 100 days) has elapsed, the breeding process is terminated.

[0036] 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, the circulation shellfish farming method can reduce the effects of climate change and achieve stable farming without affecting the marine environment.

[0037] (2) In this embodiment, the calcium ion concentration of the breeding water W1 in the breeding aquarium 10 is set to a reference range of 450 to 650 mg / L. Figure 4 is a graph that examines the growth of shell length for three cases, cases 1 to 3. In each case, different juvenile oysters were reared under the same growth conditions. Up until 90 days had passed, a calcium ion concentration close to that of natural seawater (380-420 mg / L) was used. After 90 days, the calcium ion concentration was changed to 480-520 mg / L. It can be seen that the growth rate increases after 90 days, when the calcium ion concentration was increased. The following von Bertalanffy approximation was used for the evaluation.

[0038] Shell length L=α·(1-exp(-kt)) Here, α is the growth limit multiplier (= expected maximum shell length), k is the growth multiplier (growth rate per hour), and t is the number of days reared. The growth multiplier k of the initial growth curve up to 90 days is "0.019", whereas after calcium addition it is "0.041", indicating that growth has been promoted.

[0039] Figures 5 and 6 are photographs of grown abalone shells. Region a1 is the region of the juvenile abalone. Region a2 is the region grown in seawater, and region a3 is the region grown with the addition of calcium chloride. Even in region a3, where the growth rate is higher, the shell quality is roughly the same as region a2 in natural seawater.

[0040] In Figure 7, up until 30 days had passed, a calcium ion concentration close to that of natural seawater (380-420 mg / L) was used. After 30 days, calcium ion concentrations were changed to no addition (380-420 mg / L), 650 mg / L, 880 mg / L, and 1100 mg / L. At a calcium ion concentration of 650 mg / L, growth was faster than with no addition, but at higher calcium ion concentrations the growth rate slowed down.

[0041] That is, the calcium content of the mineral components is higher in the breeding water in the breeding tank 10 than in seawater. As a result, while the mineral components other than calcium have a composition ratio similar to that of seawater, it is possible to achieve a higher composition ratio than seawater by focusing on calcium, which is the main component of shells and is particularly essential for growth. As a result, it is possible to increase the growth rate of the shellfish themselves, including the growth of the shells. In particular, by steadily adding an appropriate amount of calcium salt that is easily soluble, such as sodium chloride, it is possible to achieve a calcium ion concentration suitable for promoting the growth of abalone.

[0042] (3) In this embodiment, the control device 20 executes a calcium ion concentration detection process (step S101) and a process of determining whether or not the calcium ion concentration is outside the reference value range (step S102). If the control device 20 determines that the calcium ion concentration is outside the reference value range (YES in step S102), the control device 20 executes a process of adding calcium chloride (step S103). This makes it possible to maintain an appropriate calcium ion concentration.

[0043] (4) In this embodiment, calcium chloride is supplied in the buffer tank 32. Unlike a case in which calcium chloride is directly supplied to the breeding aquarium 10, it is possible to suppress concentration variations in the calcium ion concentration.

[0044] (5) 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 enables the water quality of the circulating rearing water to be purified and the minerals contained in the filter media to be supplied.

[0045] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction. In the above embodiment, the abalone farming is controlled using the control device 20. Here, calcium chloride may be added manually while checking the calcium ion concentration.

[0046] In the above embodiment, the rearing process is executed periodically at a predetermined time interval. This time interval may be changed depending on the rearing status of the abalone (for example, the number of reared abalone) and the growth status. In the above embodiment, the circulation path C1 includes the electrolysis device 33, the solid matter removal device 34, the denitrification device 35, and the biological filtration tank 36. The configuration for water purification is not limited to these.

[0047] In the above embodiment, the shellfish farming system A1 is applied to the farming of abalone. However, the shellfish farming system A1 is not limited to abalone and may be applied to any shellfish that consumes calcium to grow.

[0048] In the above embodiment, calcium chloride is used as the calcium agent, but the present invention is not limited to this as long as calcium can be supplied. [Explanation of symbols]

[0049] A1...shellfish farming system, C1...circulation path, P1...pump, V1~V3: valves, W1...breeding water, 10...breeding tank, 11...aeration and water flow mixing device, 12...shelter, 20...control device, 31...calcium chloride supply 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 system comprising a control device for filtering water in a shellfish breeding tank and controlling a circulation path for returning the water to the shellfish breeding tank, The control device, Detecting a calcium ion concentration in the breeding water of the breeding tank; A shellfish farming system characterized in that, if the calcium ion concentration is below a standard value, seawater with an increased calcium ion concentration is supplied to the breeding tank so that the calcium ion concentration of the breeding water is equal to or greater than the standard value.

2. The circulation path includes a buffer tank, The control device, Calculating the calcium ion concentration deficiency; 2. The shellfish farming system according to claim 1, wherein a calcium agent that compensates for the deficiency concentration is supplied to the buffer tank according to the deficiency concentration and the volume of the breeding water.

3. In the breeding tank, abalone is cultivated as a shellfish, The shellfish farming system according to claim 1 or 2, characterized in that the control device supplies seawater in which the calcium ion concentration of the breeding water has been increased to 480 to 650 mg / L.

4. A shellfish farming method for cultivating abalone in a circulation system in which water in a breeding tank is filtered and returned to the breeding tank, comprising: A shellfish farming method, characterized in that when replacing a portion of the breeding water with new seawater, seawater having a calcium ion concentration of 480 to 650 mg / L is supplied to the breeding water.

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