Water quality management system in land-based aquaculture of crustacean and production method of crustacean

Abstract

To provide a technique capable of simplifying control relating to feeding and water change in land-based aquaculture of crustaceans.SOLUTION: A water quality management system in land-based aquaculture of crustaceans, includes an ammonia sensor for detecting an ammonia concentration in rearing water of crustaceans, and a control unit. The control unit decreases an amount of feed to the crustaceans when the detected ammonia concentration is equal to or higher than a predetermined first threshold value as compared with when the detected ammonia concentration is less than the first threshold value, and determines to execute water change of the rearing water when the detected ammonia concentration is equal to or higher than a predetermined second threshold value higher than the first threshold value.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a water quality management system in the terrestrial aquaculture of crustaceans.

Background Art

[0002] Conventionally, terrestrial aquaculture has been carried out for crustaceans such as shrimp and crabs. Generally, in terrestrial aquaculture, water quality management is performed to suppress the deterioration of the health of the organisms to be cultured. For example, in Patent Document 1, the absorbance or volume extinction coefficient of a test water from which suspended substances in the breeding water have been removed is measured, arithmetic processing for obtaining the ammonium ion concentration by a regression formula from the measured value is performed, and when the result of the arithmetic processing exceeds a predetermined upper limit value, a water quality monitoring method for a biological breeding water tank that changes the amount of water to be changed to be below the upper limit value is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the water quality monitoring method described in Patent Document 1, control related to feeding is not considered. For this reason, there is room for improvement from the viewpoint of simplifying control related to feeding and control related to water change. Therefore, in the terrestrial aquaculture of crustaceans, a technique capable of simplifying control related to feeding and control related to water change has been demanded.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, a water quality management system for the land-based aquaculture of crustaceans is provided. This water quality management system includes an ammonia sensor that detects the ammonia concentration in the breeding water of the crustaceans and a control unit. When the detected ammonia concentration is equal to or higher than a predetermined first threshold value, the control unit reduces the feeding amount to the crustaceans compared to the case where it is less than the first threshold value. When the detected ammonia concentration is equal to or higher than a predetermined second threshold value that is greater than the first threshold value, the control unit determines to perform water exchange of the breeding water. This is the characteristic. According to the water quality management system of this aspect, since the feeding amount to the crustaceans and the execution of water exchange of the breeding water are determined using the ammonia concentration, the control related to feeding and the control related to water exchange can be simplified.

[0007] (2) In the water quality management system described in (1) above, when the detected ammonia concentration is equal to or higher than a predetermined third threshold value that is greater than the second threshold value, the control unit may increase the amount of water exchange compared to the case where it is less than the third threshold value. According to the water quality management system of this aspect, the amount of water exchange can be controlled according to the ammonia concentration.

[0008] (3) In the water quality management system described in (1) or (2) above, the crustaceans may be Litopenaeus vannamei. According to the water quality management system of this aspect, in the land-based aquaculture of Litopenaeus vannamei, the control related to feeding and the control related to water exchange can be simplified.

[0009] (4) In the water quality management system described in any one of (1) to (3) above, the ammonia sensor may have a diaphragm electrode. According to the water quality management system of this aspect, since the influence of substances other than ammonia contained in the sample can be reduced, a decrease in detection accuracy can be suppressed.

[0010] (5)According to another aspect of the present disclosure, a method for producing crustaceans in land-based aquaculture is provided. This method for producing crustaceans reduces the feeding amount to the crustaceans when the ammonia concentration in the breeding water of the crustaceans is equal to or higher than a predetermined first threshold value, as compared with the case where it is less than the first threshold value, and determines to perform water exchange of the breeding water when the ammonia concentration in the breeding water is equal to or higher than a predetermined second threshold value that is greater than the first threshold value. According to the method for producing crustaceans in this aspect, since the feeding amount to the crustaceans and the execution of water exchange of the breeding water are determined using the ammonia concentration, the control related to feeding and the control related to water exchange can be simplified.

[0011] Note that the present disclosure can be implemented in various forms, for example, in the forms of a crustacean aquaculture system, a control method for a crustacean aquaculture system, a crustacean aquaculture apparatus, a crustacean aquaculture method, and the like.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0013] A. First Embodiment: A-1. System Configuration: FIG. 1 is a block diagram showing a schematic configuration of a water quality management system 100 in the land-based aquaculture of crustaceans as one embodiment of the present disclosure. The water quality management system 100 is a system for managing the water quality of the breeding water in the water tank 210 for breeding crustaceans in the land-based aquaculture of crustaceans. In FIG. 1, for convenience of explanation, the configuration of the aquaculture system 200 including the water quality management system 100 is shown by a broken line. The crustaceans to be cultured are not particularly limited, and examples include shrimps and crabs, which may be freshwater crustaceans or marine crustaceans. The crustaceans to be cultured are preferably swimming shrimps, more preferably swimming shrimps, and even more preferably marine swimming edible shrimps. The marine swimming edible shrimps are not particularly limited, and examples include Litopenaeus vannamei, Penaeus chinesis, Penaeus stylirostris, Penaeus merguiensis, Penaeus indicus, etc. The marine swimming edible shrimps are particularly preferably Litopenaeus vannamei. It should be noted that the crustaceans to be cultured may be immature individuals such as juvenile shrimps and juvenile crabs, or mature individuals.

[0014] The aquaculture system 200 includes a water tank 210, a feeding unit 220, a water changing unit 230, and a water quality management system 100.

[0015] The water tank 210 is configured to be able to store breeding water therein and breed the crustaceans to be cultured. The breeding water is not particularly limited and is selected according to the crustaceans to be cultured. The breeding water is not particularly limited, and examples include fresh water such as pure water and well water, and water containing salts such as brackish water, seawater, and artificial seawater. The salt concentration in the water containing salts is not particularly limited, and for example, it may be managed so that the salt concentration is 1% to 10% by mass, or it may be managed so that the salt concentration is 1% to 2% by mass.

[0016] The feeding unit 220 supplies feed for the crustaceans to be cultured into the water tank 210. The feeding unit 220 includes a feeding reception unit 222 that receives an instruction for feeding, and a supply unit 224 that supplies feed into the water tank 210. The supply unit 224 is configured to include, for example, a weighing unit (not shown) that weighs the feed, a feeding unit (not shown) that feeds the feed into the water tank 210, and the like.

[0017] The water changing unit 230 changes the breeding water in the water tank 210. The water changing unit 230 includes a water changing reception unit 232 that receives an instruction for water changing, a drainage unit 234 that drains the breeding water from the water tank 210, and a water supply unit 236 that supplies the breeding water into the water tank 210. The drainage unit 234 is configured to include, for example, a pump (not shown) provided in the water tank 210, a drain pipe (not shown) connected to the water tank 210, a valve, and the like. The water supply unit 236 is configured to include, for example, a water supply pipe (not shown) capable of supplying the breeding water into the water tank 210, a valve, and the like.

[0018] The water quality management system 100 includes an ammonia sensor 10 and a control unit 20.

[0019] The ammonia sensor 10 detects the ammonia concentration in the breeding water of crustaceans. The ammonia concentration is used as an indicator of the degree of contamination of the breeding water. The higher the ammonia concentration, the more contaminated the breeding water tends to be. The ammonia sensor 10 of the present embodiment measures and detects the ammonia concentration of the breeding water by collecting and treating the breeding water in the water tank 210. The ammonia sensor 10 includes a water sampling unit 12, a treatment unit 14, and a communication unit 16. The water sampling unit 12 has a pump (not shown) and collects the breeding water in the water tank 210. The treatment unit 14 has a diaphragm electrode 15. In the treatment unit 14, by adding a reagent such as a base to the collected breeding water, ammonia contained in the sample is gasified and passed through a diaphragm (not shown). In the diaphragm electrode 15, the ammonia gas that has passed through the diaphragm dissolves in the internal liquid near the detection unit, and its concentration is measured. In the diaphragm electrode 15, only the ammonia contained in the sample is gasified and reaches the electrode, so the influence of substances other than ammonia contained in the sample can be reduced, and as a result, a decrease in detection accuracy can be suppressed. More specifically, for example, when seawater is used as the breeding water and the measurement sample contains a large amount of sodium chloride or other contaminants, false detection by unintended substances can be prevented. Note that the treatment unit 14 may have an automatic measurement function and an automatic calibration function. The communication unit 16 is configured to be able to communicate with the communication unit 26 of the control unit 20 wirelessly or by wire. The communication unit 16 receives a detection instruction for the ammonia concentration from the control unit 20 and outputs the detection result of the ammonia concentration to the control unit 20.

[0020] The control unit 20 is a computer including a CPU (Central Processing Unit) 22, a storage unit 24, and a communication unit 26, and can perform various operations, controls, and information processing. The CPU 22 controls various operations in the water quality management system 100 by executing a program pre-stored in the storage unit 24. Also, the control unit 20 of the present embodiment controls the overall operation of the aquaculture system 200, but the overall operation of the aquaculture system 200 may be further controlled by a higher-level device.

[0021] The control unit 20 sends a detection instruction for ammonia concentration to the ammonia sensor 10 via the communication unit 26 and acquires the detection result of the ammonia concentration. The control unit 20 (CPU 22) controls the execution of the feeding amount and water change according to the ammonia concentration detected by the ammonia sensor 10, as will be described later. The communication unit 26 is configured to be able to communicate with the communication unit 16 of the ammonia sensor 10, the feeding unit 220, the water change unit 230, etc. by wireless or wired means. The storage unit 24 includes a memory such as a ROM or a RAM, for example. The storage unit 24 stores the ammonia concentration acquired by the communication unit 26. Also, the storage unit 24 stores information such as the detection schedule of the ammonia concentration, the feeding schedule, the water change schedule, the feeding amount, the water change amount, and the threshold values described later.

[0022] The detection schedule of the ammonia concentration in the breeding water may be set as appropriate. As the detection schedule, it is preferably set to constantly monitor the ammonia concentration. However, for example, it may be set to detect at regular intervals of 30 minutes to 12 hours, preferably 30 minutes to 6 hours, more preferably 30 minutes to 2 hours, etc. Also, as the detection schedule, for example, it may be set to detect at regular timings such as 0 minutes per hour, and may be set according to the number of times, for example, 2 to 24 times per day, preferably 4 to 24 times, more preferably 12 to 24 times.

[0023] The feeding schedule to the water tank 210 may be set as appropriate. As the feeding schedule, for example, it may be set to feed at regular intervals of 1 hour to 12 hours, preferably 1 hour to 3 hours, etc., or at regular timings such as 0 minutes per hour, and may be set according to the number of times, for example, 2 to 24 times per day, preferably 8 to 24 times. The feeding amount may be set as appropriate and may be set according to, for example, the capacity of the water tank 210, the amount of breeding water, the number of crustaceans in the water tank 210, etc. The feeding amount is adjusted by the control described later.

[0024] The water change schedule of the breeding water may be set as appropriate. As the water change schedule, for example, it may be set to change water at regular intervals such as every 6 hours to 1 week, preferably every 12 hours to 4 days, or it may be set so that water change is scheduled at regular timings such as 9 o'clock every day or 7 o'clock on Monday every week. It may also be set according to the number of times such as 1 to 14 times per week, preferably 2 to 7 times per week. The amount of water change may be set as appropriate, and for example, it may be set according to the capacity of the water tank 210, the amount of breeding water, the number of crustaceans in the water tank 210, etc. The amount of water change may be set to a predetermined water amount value with respect to the amount of breeding water in the water tank 210, but it is preferably set at a predetermined ratio such as 5% to 50%, preferably 10% to 30%.

[0025] A-2. Control of the water quality management system: Figures 2 to 4 are flowcharts showing an example of the control of the water quality management system 100. Figure 2 is a flowchart showing an example of the control related to feeding. Figure 3 is a flowchart showing an example of the control related to water change. Figure 4 is a flowchart showing an example of the control related to the determination of the feeding amount and the execution of water change. The controls shown in Figures 2 to 4 are executed in parallel.

[0026] As shown in FIG. 2, in the control regarding feeding, the control unit 20 specifies whether it is the feeding timing (step S110). Whether it is the feeding timing is specified based on the feeding schedule. When it is specified that it is not the feeding timing (step S110: NO), step S110 is repeated. On the other hand, when it is specified that it is the feeding timing (step S110: YES), the control unit 20 specifies whether an instruction to decrease the feeding amount has been input (step S120). When it is specified that an instruction to decrease the feeding amount has not been input (step S120: NO), the process proceeds to step S140. On the other hand, when it is specified that an instruction to decrease the feeding amount has been input (step S120: YES), the control unit 20 sets the feeding amount to be decreased (step S130). The control unit 20 outputs an instruction to feed with the set feeding amount to the feeding unit 220 (step S140). When the decrease setting of the feeding amount is not performed, the preset feeding amount is used. The feeding unit 220 executes feeding with the set feeding amount (step S150). After the completion of step S150, the process returns to step S110.

[0027] As shown in FIG. 3, in the control regarding water change, the control unit 20 specifies whether it is the water change timing (step S210). Whether it is the water change timing is specified based on the water change schedule. When it is specified that it is not the water change timing (step S210: NO), step S210 is repeated. On the other hand, when it is specified that it is the water change timing (step S210: YES), the control unit 20 specifies whether there is a decision to execute water change (step S220). When it is specified that there is no decision to execute water change (step S220: NO), it returns to step S210 and waits until the next water change timing. On the other hand, when it is specified that there is a decision to execute water change (step S220: YES), the control unit 20 outputs an instruction to change water to the water change unit 230 with the set water change amount (step S230). The water change unit 230 executes water change with the set water change amount (step S240). After the completion of step S240, it returns to step S210 and waits until the next water change timing. According to the control shown in FIG. 3, when there is an instruction to execute water change, water change is performed at the preset water change timing. On the other hand, when there is no instruction to execute water change, water change at the preset water change timing is not performed.

[0028] As shown in FIG. 4, in the control regarding the feeding amount and the decision to execute water change, the control unit 20 specifies whether it is the detection timing of the ammonia concentration based on the detection schedule of the ammonia concentration (step S310). When it is specified that it is not the detection timing of the ammonia concentration (step S310: NO), step S310 is repeated. On the other hand, when it is specified that it is the detection timing of the ammonia concentration (step S310: YES), the control unit 20 sends a detection instruction of the ammonia concentration to the ammonia sensor 10 (step S320). The ammonia sensor 10 measures and detects the ammonia concentration of the breeding water in the water tank 210 (step S330). The control unit 20 acquires the ammonia concentration detected by the ammonia sensor 10 (step S340).

[0029] The control unit 20 determines whether the detected ammonia concentration is equal to or higher than a predetermined first threshold (step S350). The first threshold is stored in the storage unit 24 of the control unit 20. The first threshold is set to an arbitrary value such as 1.5 ppm or more and less than 3 ppm, for example. When it is determined that the detected ammonia concentration is not equal to or higher than the first threshold (step S350: NO), that is, when the ammonia concentration is less than the first threshold, the process returns to step S310.

[0030] When it is determined that the detected ammonia concentration is equal to or higher than the first threshold (step S350: YES), the control unit 20 outputs an instruction to decrease the feeding amount to the crustaceans as compared with the case where it is less than the first threshold (step S360). In the present embodiment, the control unit 20 decreases the feeding amount at one feeding timing after step S360. According to the feeding schedule, feeding is performed with the decreased feeding amount at the feeding after step S360. More specifically, in the control regarding feeding shown in FIG. 2, since it is determined that an instruction to decrease the feeding amount is input (step S120: YES), the feeding amount is decreased (step S130), and then, after an instruction to feed is output with the set feeding amount (step S140), feeding is executed with the set feeding amount (step S150). The amount of feed to be decreased is not particularly limited, but may be decreased by 10% to 50%, for example, as compared with the preset normal feeding amount.

[0031] For example, when the first threshold is set to 2 ppm, when the ammonia concentration of the breeding water is less than 2 ppm, feeding is performed with the preset normal feeding amount at the next feeding timing. On the other hand, when the ammonia concentration of the breeding water is 2 ppm or more, feeding is performed with a feeding amount decreased from the preset normal feeding amount at the next feeding timing.

[0032] The control unit 20 determines whether the detected ammonia concentration is equal to or higher than a predetermined second threshold value (step S370). The second threshold value is a value larger than the first threshold value and is stored in the storage unit 24 of the control unit 20. The second threshold value is set to an arbitrary value, for example, equal to or higher than 3 ppm and less than 5 ppm. When it is determined that the detected ammonia concentration is not equal to or higher than the second threshold value (step S370: NO), that is, when the ammonia concentration is equal to or higher than the first threshold value and less than the second threshold value, the process returns to step S310.

[0033] When it is determined that the detected ammonia concentration is equal to or higher than the second threshold value (step S370: YES), it is determined to perform a water change of the breeding water (step S380). In this case, in the control regarding the water change shown in FIG. 3, since it is determined that there is a decision to perform a water change (step S220: YES), an instruction for water change is output (step S230), and then the water change is performed (step S240).

[0034] For example, when the second threshold value is set to 4 ppm, if the ammonia concentration of the breeding water is less than 4 ppm, the execution of the water change of the breeding water will not be determined. Therefore, the water change at the next scheduled water change timing will be skipped and no water change will be performed. On the other hand, if the ammonia concentration of the breeding water is 4 ppm or higher, since the execution of the water change of the breeding water is determined, the water change at the next water change timing will be performed.

[0035] After completion of step S380, the process returns to step S310. In the detection schedule of the ammonia concentration, when it is set to constantly monitor the ammonia concentration, in the control shown in FIG. 4, steps S310 to S330 are omitted and the flowchart starts from step S340.

[0036] According to the water quality management system 100 of the first embodiment described above, when the detected ammonia concentration is equal to or higher than the first threshold value, the feeding amount to the crustaceans is decreased as compared with the case where it is less than the first threshold value, and when the detected ammonia concentration is equal to or higher than the second threshold value which is larger than the first threshold value, it is determined to perform water change of the breeding water. For this reason, since the feeding amount to the crustaceans and the execution of water change of the breeding water are determined using the ammonia concentration, the control related to feeding and the control related to water change can be simplified. Therefore, since two types of controls, feeding and water change, can be performed using the detection result by one type of sensor, complication of the system configuration can be suppressed.

[0037] Further, according to the water quality management system 100 of the present embodiment, when the detected ammonia concentration is equal to or higher than the first threshold value, the feeding amount to the crustaceans is decreased as compared with the case where it is less than the first threshold value. Therefore, it is possible to suppress deterioration of water quality due to an excessive feeding amount. As a result, it is possible to suppress deterioration of the health state of the crustaceans due to deterioration of water quality, and as a result, it is possible to suppress mortality and thus suppress a decrease in the yield of aquaculture.

[0038] Further, according to the water quality management system 100 of the present embodiment, since the control related to feeding and the control related to water change can be automated, it is possible to suppress variations in the quality of the work of feeding and water change. As a result, it is possible to suppress destabilization of the quality of the crustaceans to be cultured. In addition, since the control related to feeding and the control related to water change can be automated, feeding and water change can be performed even when there is no operator at night or the like. Further, since the control related to feeding and the control related to water change can be automated, it is possible to suppress forgetting to perform feeding and water change, and as a result, it is possible to suppress deterioration of the health state of the crustaceans and mortality.

[0039] B. Second Embodiment: FIG. 5 is a flowchart showing an example of control related to water replacement in the second embodiment. FIG. 6 is a flowchart showing an example of control related to the feeding amount and the water replacement amount in the second embodiment. In the water quality management system 100 of the second embodiment, compared with the first embodiment, control for adjusting the water replacement amount is further performed. Since the system configuration of the water quality management system 100 of the second embodiment is the same as that of the water quality management system 100 of the first embodiment, the same components are denoted by the same reference numerals, and detailed descriptions thereof are omitted. Also in the second embodiment, the control related to feeding shown in FIG. 2 and the control related to water replacement shown in FIG. 5 are executed in parallel with the control related to the feeding amount and the water replacement amount shown in FIG. 6. In the flowchart of FIG. 5, steps S210 to S220 are the same as those in the flowchart of the first embodiment shown in FIG. 4, and thus detailed descriptions thereof are omitted. In the flowchart of FIG. 6, steps S310 to S380 are the same as those in the flowchart of the first embodiment shown in FIG. 4, and thus detailed descriptions thereof are omitted.

[0040] In the control related to water replacement shown in FIG. 5, when it is determined that there is a decision to execute water replacement (step S220: YES), the control unit 20 determines whether an instruction to increase the water replacement amount has been input (step S222). When it is determined that an instruction to increase the water replacement amount has not been input (step S222: NO), the process proceeds to step S230. On the other hand, when it is determined that an instruction to increase the water replacement amount has been input (step S222: YES), the control unit 20 sets an increase in the water replacement amount (step S224). The control unit 20 outputs an instruction to replace water to the water replacement unit 230 with the set water replacement amount (step S230). When the increase setting of the water replacement amount is not performed, a preset water replacement amount is used. The water replacement unit 230 executes water replacement with the set water replacement amount (step S240). After completion of step S240, the process returns to step S210 and waits until the next water replacement timing.

[0041] In the control regarding the feeding amount and the water replacement amount shown in FIG. 6, when the detected ammonia concentration is specified to be equal to or higher than a second threshold value (step S370: YES), the control unit 20 determines to execute water replacement of the breeding water (step S380). The control unit 20 specifies whether or not the detected ammonia concentration is equal to or higher than a predetermined third threshold value (step S390). The third threshold value is a value larger than the second threshold value and is stored in the storage unit 24 of the control unit 20. The third threshold value is set to an arbitrary value such as, for example, 5 ppm or more and less than 10 ppm. When the detected ammonia concentration is specified not to be equal to or higher than the third threshold value (step S390: NO), that is, when the ammonia concentration is equal to or higher than the second threshold value and less than the third threshold value, the process returns to step S310.

[0042] On the other hand, when the detected ammonia concentration is specified to be equal to or higher than the third threshold value (step S390: YES), an instruction to increase the water replacement amount is output as compared with the case where it is less than the third threshold value (step S400). After completion of step S400, the process returns to step S310.

[0043] In step S400, the control unit 20 of the present embodiment increases the water replacement amount at one time of the water replacement timing performed after step S400. According to the water replacement schedule, in the water replacement performed after step S400, the water replacement is performed with the increased water replacement amount. More specifically, in the control regarding the water replacement shown in FIG. 5, since it is specified that an instruction to increase the water replacement amount is input (step S222: YES), the water replacement amount is increased and set (step S224). Then, after an instruction to replace water is output with the set water replacement amount (step S230), the water replacement is executed with the set water replacement amount (step S240). The amount of water to be increased is not particularly limited, but may be increased by, for example, 10% to 50% as compared with the preset normal water replacement amount. Therefore, when the value of the detected ammonia concentration is equal to or higher than the third threshold value, more breeding water is replaced as compared with the case where it is less than the third threshold value.

[0044] For example, when the third threshold is set to 6 ppm, if the ammonia concentration in the breeding water is less than 6 ppm, water change is performed at the next water change timing with the preset normal water change volume. On the other hand, if the ammonia concentration in the breeding water is 6 ppm or more, water change is performed at the next water change timing with a water change volume increased from the preset normal water change volume.

[0045] FIG. 7 is an explanatory diagram showing an example of information regarding the threshold value. In FIG. 7, the first threshold value, the second threshold value, and the third threshold value are respectively shown. In the example shown in FIG. 7, as the third threshold value, three-stage values are exemplified. Thus, in the mode where a plurality of stages of threshold values are used as the third threshold value, the larger the detected ammonia concentration value, the more the water change amount is increased and the more replacement of the breeding water is performed. In the flowchart in the case of using the threshold values shown in FIG. 7, for the detected ammonia concentration, when it is equal to or higher than the third threshold value a, it may be further specified whether it is equal to or higher than the third threshold value b, and when it is equal to or higher than the third threshold value b, it may be further specified whether it is equal to or higher than the third threshold value c. In the example shown in FIG. 7, when the ammonia concentration is equal to or higher than the third threshold value a and less than the third threshold value b, the water change volume is increased by 10% compared to normal, when it is equal to or higher than the third threshold value b and less than the third threshold value c, the water change volume is increased by 20% compared to normal, and when it is equal to or higher than the third threshold value c, the water change volume is increased by 30% compared to normal.

[0046] According to the water quality management system 100 of the second embodiment described above, when the detected ammonia concentration is equal to or greater than a predetermined third threshold greater than the second threshold, the amount of water change is increased as compared with the case where it is less than the third threshold. For this reason, the amount of water change can be further adjusted using the ammonia concentration, so that the control related to water change can be simplified. Therefore, it is possible to perform the control of the feeding amount, the execution control of water change, and the control of the amount of water change using the detection result of one type of sensor, so that it is possible to suppress the complication of the system configuration. Further, according to the water quality management system 100 of the second embodiment, it is possible to suppress the deterioration of water quality due to insufficient amount of water change. As a result, it is possible to suppress the deterioration of the health state of crustaceans due to the deterioration of water quality, so that it is possible to suppress the death and as a result, suppress the decrease in the yield of aquaculture.

[0047] C. Other Embodiments According to another aspect of the present disclosure, a method for producing crustaceans in land-based aquaculture is provided. In this method for producing crustaceans, when the ammonia concentration in the breeding water of crustaceans is equal to or greater than a predetermined first threshold, the feeding amount to the crustaceans is decreased as compared with the case where it is less than the first threshold, and when the ammonia concentration in the breeding water is equal to or greater than a predetermined second threshold greater than the first threshold, the execution of water change of the breeding water is determined. According to this method for producing crustaceans, since the feeding amount to the crustaceans and the execution of water change of the breeding water are determined using the ammonia concentration, the control related to feeding and the control related to water change can be simplified. In the method for producing crustaceans as well, similar to the second embodiment described above, when the detected ammonia concentration is equal to or greater than a predetermined third threshold greater than the second threshold, the amount of water change may be increased as compared with the case where it is less than the third threshold.

[0048] D. Modification Examples: The configurations of the water quality management system 100 and the aquaculture system 200 in the above-described embodiments are merely examples and can be variously modified. For example, the aquaculture system 200 may be configured to include a plurality of water tanks 210. In this configuration, the control unit 20 may be configured to be able to identify each water tank 210 in order to manage the water quality of the plurality of water tanks 210.

[0049] Also, for example, the aquaculture system 200 may further include a user interface unit for communicating with the user of the aquaculture system 200. The user interface unit may include, for example, an input unit configured by a touch panel, buttons, a microphone, etc., and an output unit configured by a touch panel, a display, a speaker, etc. In this configuration, in step S140 shown in FIG. 2, the control unit 20 may output a feeding instruction to the user interface unit instead of the feeding unit 220, and the user may perform an operation for feeding. Also, in step S230 shown in FIG. 3, the control unit 20 may output a water change instruction to the user interface unit instead of the water change unit 230, and the user may perform an operation for water change.

[0050] Also, for example, the water quality management system 100 may include other sensors in addition to the ammonia sensor 10, and the water quality of the breeding water may be managed using the detection results of sensors other than the ammonia sensor 10. The other sensors are not particularly limited, and examples include a nitrate sensor, a turbidity sensor, a dissolved oxygen sensor, a temperature sensor, a pH sensor, a conductivity sensor, a salinity sensor, an image sensor, etc.

[0051] Also, in the water quality management system 100 of the above embodiment, a single-stage value was used for the first threshold, but a multi-stage threshold may be used as in the third threshold shown in FIG. 7. In an aspect where a multi-stage threshold is used as the first threshold, the amount of feeding may be decreased as the detected ammonia concentration value is larger. For example, in a flowchart in the case where a three-stage threshold (first threshold a < first threshold b < first threshold c) is set as the first threshold, for the detected ammonia concentration, when it is equal to or greater than the first threshold a, it is further specified whether it is equal to or greater than the first threshold b, and when it is equal to or greater than the first threshold b, it may be further specified whether it is equal to or greater than the first threshold c. According to such an aspect, since the feeding amount is set to decrease as the detected ammonia concentration value is larger, deterioration of the water quality of the breeding water can be more suppressed.

[0052] The present invention is not limited to the above-described embodiments, and can be realized in various configurations without departing from the gist thereof. For example, the technical features in the embodiments and examples corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above problems or to achieve some or all of the above effects. Also, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

Description of Reference Numerals

[0053] 10…Ammonia sensor, 12…Water sampling unit, 14…Processing unit, 15…Membrane electrode, 16…Communication unit, 20…Control unit, 22…CPU, 24…Storage unit, 26…Communication unit, 100…Water quality management system, 200…Aquaculture system, 210…Water tank, 220…Feeding unit, 222…Feeding reception unit, 224…Supply unit, 230…Water change unit, 232…Water change reception unit, 234…Drainage unit, 236…Water supply unit

Claims

1. A water quality management system for the land-based aquaculture of crustaceans, comprising: an ammonia sensor for detecting the ammonia concentration in the breeding water of the crustaceans; a control unit; wherein the control unit when the detected ammonia concentration is equal to or higher than a predetermined first threshold value, reduces the feeding amount to the crustaceans as compared with the case when it is lower than the first threshold value; when the detected ammonia concentration is equal to or higher than a predetermined second threshold value that is greater than the first threshold value, determines to perform water exchange of the breeding water. A water quality management system, characterized by the above.

2. In the water quality management system according to Claim 1, the control unit when the detected ammonia concentration is equal to or higher than a predetermined third threshold value that is greater than the second threshold value, increases the amount of water exchange as compared with the case when it is lower than the third threshold value. A water quality management system, characterized by the above.

3. In the water quality management system according to Claim 1 or Claim 2, the crustacean is Litopenaeus vannamei. A water quality management system, characterized by the above.

4. In the water quality management system according to Claim 1 or Claim 2, the ammonia sensor has a diaphragm electrode. A water quality management system, characterized by the above.

5. A method for producing crustaceans in land-based aquaculture, comprising: when the ammonia concentration in the breeding water of the crustaceans is equal to or higher than a predetermined first threshold value, reducing the feeding amount to the crustaceans as compared with the case when it is lower than the first threshold value; when the ammonia concentration in the breeding water is equal to or higher than a predetermined second threshold value that is greater than the first threshold value, determining to perform water exchange of the breeding water. A method for producing crustaceans, characterized by the above.

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