Water quality management system in land-based aquaculture of crustacean, and method for producing crustacean

Abstract

Provided is a technique capable of simplifying the control relating to feeding and the control relating to water changing in land-based aquaculture of a crustacean. This water quality management system in land-based aquaculture of a crustacean is characterized by comprising an ammonia sensor for detecting the ammonia concentration in breeding water for the crustacean and a control unit, wherein: when the detected ammonia concentration is equal to or more than a predetermined first threshold value, the control unit reduces the amount of feeding to the crustacean compared with the case where the detected ammonia concentration is less than the first threshold value; and when the detected ammonia concentration is equal to or more than a predetermined second threshold value that is larger than the first threshold value, the control unit decides the execution of changing of the breeding water.

Description

Water quality control system for land-based crustacean aquaculture and crustacean production method

[0001] The present disclosure relates to a water quality management system for land-based shellfish aquaculture.

[0002] Land-based aquaculture of crustaceans such as shrimp and crabs has been practiced for some time. In land-based aquaculture, water quality is generally controlled to prevent deterioration of the health of the cultured organisms. For example, Patent Document 1 discloses a water quality monitoring method for an organism rearing tank, which measures the absorbance or volume extinction coefficient of sample water from which suspended solids have been removed, performs a calculation process to determine the ammonium ion concentration from the measured values ​​using a regression equation, and, if the result of the calculation process exceeds a predetermined upper limit, changes the amount of water required to bring the concentration below the upper limit.

[0003] Special Publication No. 07-031115

[0004] The water quality monitoring method described in Patent Document 1 does not take into consideration control related to feeding. Therefore, there is room for improvement in terms of simplifying control related to feeding and control related to water exchange. Therefore, there is a need for technology that can simplify control related to feeding and control related to water exchange in land-based crustacean aquaculture.

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

[0006] (1) According to one aspect of the present disclosure, there is provided a water quality management system for land-based crustacean aquaculture. The water quality management system includes an ammonia sensor that detects an ammonia concentration in the rearing water of the crustaceans, and a control unit. When the detected ammonia concentration is equal to or greater than a predetermined first threshold, the control unit reduces the amount of feed to the crustaceans compared to when the ammonia concentration is less than the first threshold, and when the detected ammonia concentration is equal to or greater than a predetermined second threshold that is greater than the first threshold, the control unit determines whether to perform a water change of the rearing water. This form of water quality management system uses the ammonia concentration to determine the amount of feed to the crustaceans and whether to perform a water change of the rearing water, thereby simplifying control over feeding and water change.

[0007] (2) In the water quality control system described in (1) above, the control unit may increase the amount of water exchange when the detected ammonia concentration is equal to or greater than a predetermined third threshold value that is greater than the second threshold value, compared to when the detected ammonia concentration is less than the third threshold value. This type of water quality control system can control the amount of water exchange according to the ammonia concentration.

[0008] (3) In the water quality control system according to (1) or (2), the crustacean may be a whiteleg shrimp. This water quality control system can simplify feeding control and water exchange control in land-based whiteleg shrimp culture.

[0009] (4) In the water quality control system according to any one of (1) to (3), the ammonia sensor may have a diaphragm electrode. This water quality control system can reduce the influence of substances other than ammonia contained in the sample, thereby preventing a decrease in detection accuracy.

[0010] (5) Another aspect of the present disclosure provides a method for producing Crustaceans in land-based aquaculture. This method is characterized in that, when the ammonia concentration in the rearing water for the Crustaceans is equal to or greater than a predetermined first threshold, the amount of feed to the Crustaceans is reduced compared to when the ammonia concentration is below the first threshold, and, when the ammonia concentration in the rearing water is equal to or greater than a predetermined second threshold that is greater than the first threshold, it is determined to perform a water change of the rearing water. This aspect of the method for producing Crustaceans uses the ammonia concentration to determine the amount of feed to the Crustaceans and whether to perform a water change of the rearing water, thereby simplifying control over feeding and water change.

[0011] The present disclosure can be realized in various forms, for example, a crustacean farming system, a crustacean farming system control method, a crustacean farming device, a crustacean farming method, etc.

[0012] Fig. 1 is a block diagram showing a schematic configuration of a water quality management system for land-based crustacean aquaculture. Fig. 2 is a flowchart showing an example of control related to feeding. Fig. 3 is a flowchart showing an example of control related to water exchange. Fig. 4 is a flowchart showing an example of control related to feed amounts and decisions on performing water exchange. Fig. 5 is a flowchart showing an example of control related to water exchange in a second embodiment. Fig. 6 is a flowchart showing an example of control related to feed amounts and water exchange amounts in a second embodiment. Fig. 7 is an explanatory diagram showing an example of information related to threshold values.

[0013] A. First Embodiment: A-1. System Configuration: FIG. 1 is a block diagram showing the schematic configuration of a water quality management system 100 for land-based crustacean aquaculture according to one embodiment of the present disclosure. The water quality management system 100 is a system for managing the water quality of rearing water in aquariums 210 in which crustaceans are cultivated in land-based crustacean aquaculture. For ease of explanation, FIG. 1 shows the configuration of an aquaculture system 200 including the water quality management system 100 with dashed lines. Crustaceans to be cultivated are not particularly limited, but examples include shrimp and crabs, and may be freshwater crustaceans or saltwater crustaceans. The crustaceans to be cultivated are preferably pelagic shrimp, more preferably pelagic shrimp, and even more preferably saltwater pelagic edible shrimp. The saltwater-swimming edible shrimp is not particularly limited, but examples thereof include white-leg shrimp (Litopenaeus vannamei), Korean shrimp (Penaeus chinesis), blue shrimp (Penaeus stylirostris), banana shrimp (Penaeus merguiensis), and Indian shrimp (Penaeus indicus). As the saltwater-swimming edible shrimp, white-leg shrimp is particularly preferred. The crustaceans to be cultured may be immature individuals such as juvenile shrimp or juvenile crab, or may be mature individuals.

[0014] The aquaculture system 200 comprises an aquarium 210, a feeding section 220, a water changing section 230, and a water quality control system 100.

[0015] The aquarium 210 is configured to store rearing water therein and is used to rear the crustaceans to be cultured. The rearing water is not particularly limited and is selected depending on the crustaceans to be cultured. The rearing water is not particularly limited, but examples thereof include fresh water such as fresh water and well water, and water containing salt such as brackish water, seawater, and artificial seawater. The salt concentration of the salty water is not particularly limited, but may be controlled to be, for example, 1% to 10% by mass, or 1% to 2% by mass.

[0016] The feeding unit 220 supplies feed for the crustaceans to be cultivated into the aquarium 210. The feeding unit 220 includes a feeding reception unit 222 that receives feeding instructions, and a supply unit 224 that supplies feed into the aquarium 210. The supply unit 224 is configured to include, for example, a weighing unit (not shown) that weighs the feed, an injection unit (not shown) that injects the feed into the aquarium 210, and the like.

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

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

[0019] The ammonia sensor 10 detects the ammonia concentration in the rearing water of crustaceans. The ammonia concentration is used as an indicator of the degree of contamination of the rearing water. A higher ammonia concentration indicates that the rearing water is more polluted. The ammonia sensor 10 of this embodiment measures and detects the ammonia concentration of the rearing water by sampling and processing the rearing water in the aquarium 210. The ammonia sensor 10 includes a water sampling unit 12, a processing unit 14, and a communication unit 16. The water sampling unit 12 has a pump (not shown) and samples the rearing water in the aquarium 210. The processing unit 14 has a diaphragm-type electrode 15. The processing unit 14 adds a reagent such as a base to the sampled rearing water, thereby gasifying the ammonia contained in the sample and causing it to pass through a diaphragm (not shown). In the diaphragm-type electrode 15, the ammonia gas that passes through the diaphragm dissolves in the internal liquid near the detection unit, and its concentration is measured. With the diaphragm-type electrode 15, only the ammonia contained in the sample is gasified and reaches the electrode, thereby reducing the influence of substances other than ammonia contained in the sample and suppressing a decrease in detection accuracy. More specifically, when the measurement sample contains a large amount of sodium chloride or other impurities, such as when seawater is used as breeding water, erroneous detection due to unintended substances can be prevented. The processing 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 via a 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 equipped with a CPU (Central Processing Unit) 22, a storage unit 24, and a communication unit 26, and is capable of performing various calculations, controls, and information processing. The CPU 22 controls various operations in the water quality control system 100 by executing programs pre-stored in the storage unit 24. Furthermore, although the control unit 20 of this embodiment controls the overall operation of the aquaculture system 200, the overall operation of the aquaculture system 200 may also be controlled by a higher-level device.

[0021] The control unit 20 sends an instruction to detect the ammonia concentration to the ammonia sensor 10 via the communication unit 26, and also acquires the detection result of the ammonia concentration. The control unit 20 (CPU 22) controls the feed amount and the execution of water changes according to the ammonia concentration detected by the ammonia sensor 10, as described below. 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., wirelessly or via a wire. The memory unit 24 is configured to include memory such as ROM and RAM. The memory unit 24 stores the ammonia concentration acquired by the communication unit 26. The memory unit 24 also stores information regarding the ammonia concentration detection schedule, feeding schedule, water change schedule, feed amount, water change amount, threshold values ​​(described below), etc.

[0022] The detection schedule for the ammonia concentration of the rearing water may be set as appropriate. The detection schedule is preferably set so that the ammonia concentration is constantly monitored, but may also be set so that detection occurs at regular intervals, such as every 30 minutes to 12 hours, preferably every 30 minutes to 6 hours, and more preferably every 30 minutes to 2 hours. The detection schedule may also be set so that detection occurs periodically, such as at the top of the hour, or may be set so that detection occurs 2 to 24 times per day, preferably 4 to 24 times per day, and more preferably 12 to 24 times per day.

[0023] The feeding schedule for the aquarium 210 may be set as appropriate. The feeding schedule may be set, for example, so that the fish are fed at regular intervals, such as every 1 to 12 hours, preferably every 1 to 3 hours, or at regular intervals, such as at the top of the hour, or may be set two to 24 times per day, preferably eight to 24 times per day. The amount of food to be fed may be set as appropriate, and may be set, for example, depending on the capacity of the aquarium 210, the amount of breeding water, the number of crustaceans in the aquarium 210, etc. The amount of food to be fed is adjusted by a control process described below.

[0024] The water change schedule for the rearing water may be set as appropriate. The water change schedule may be set, for example, so that water changes are scheduled at regular intervals, such as every 6 hours to 1 week, preferably every 12 hours to 4 days, or at regular times, such as 9:00 a.m. every day or 7:00 a.m. every Monday, or may be set to a frequency of 1 to 14 times per week, preferably 2 to 7 times per week. The amount of water change may be set as appropriate, for example, depending on the capacity of the aquarium 210, the amount of rearing water, the number of crustaceans in the aquarium 210, etc. The amount of water change may be set to a predetermined volume value relative to the amount of rearing water in the aquarium 210, for example, or preferably set to 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 control of the water quality management system 100. Figure 2 is a flowchart showing an example of control related to feeding. Figure 3 is a flowchart showing an example of control related to water changes. Figure 4 is a flowchart showing an example of control related to feed amounts and decisions on whether to perform water changes. The controls shown in Figures 2 to 4 are executed in parallel.

[0026] As shown in FIG. 2 , in the feeding control, the control unit 20 determines whether it is time to feed the animal (step S110). Whether it is time to feed the animal is determined based on the feeding schedule. If it is determined that it is not time to feed the animal (step S110: NO), step S110 is repeated. On the other hand, if it is determined that it is time to feed the animal (step S110: YES), the control unit 20 determines whether an instruction to reduce the amount of feed has been input (step S120). If it is determined that an instruction to reduce the amount of feed has not been input (step S120: NO), the process proceeds to step S140. On the other hand, if it is determined that an instruction to reduce the amount of feed has been input (step S120: YES), the control unit 20 sets the amount of feed to be reduced (step S130). The control unit 20 outputs an instruction to the feeding unit 220 to feed the set amount of feed (step S140). If a feed amount reduction setting has not been made, a preset amount of feed is used. The feeding unit 220 feeds the set amount of food (step S150). After step S150 is completed, the process returns to step S110.

[0027] As shown in FIG. 3 , in the control of water change, the control unit 20 determines whether it is time for water change (step S210). Whether it is time for water change is determined based on the water change schedule. If it is determined that it is not time for water change (step S210: NO), step S210 is repeated. On the other hand, if it is determined that it is time for water change (step S210: YES), the control unit 20 determines whether a decision to perform water change has been made (step S220). If it is determined that a decision to perform water change has not been made (step S220: NO), the control unit 20 returns to step S210 and waits until the next water change timing. On the other hand, if it is determined that a decision to perform water change has been made (step S220: YES), the control unit 20 outputs a command to the water change unit 230 to perform water change at the set water change volume (step S230). The water change unit 230 performs water change at the set water change volume (step S240). After completing step S240, the control unit 20 returns to step S210 and waits until the next water change timing. 3, when an instruction to perform water change is given, water change is performed at a preset timing. On the other hand, when an instruction to perform water change is not given, water change is not performed at the preset timing.

[0028] As shown in FIG. 4 , in controlling the feed amount and water change execution decisions, the control unit 20 determines whether it is time to detect the ammonia concentration based on the ammonia concentration detection schedule (step S310). If it is determined that it is not time to detect the ammonia concentration (step S310: NO), step S310 is repeated. On the other hand, if it is determined that it is time to detect the ammonia concentration (step S310: YES), the control unit 20 sends an instruction to the ammonia sensor 10 to detect the ammonia concentration (step S320). The ammonia sensor 10 measures and detects the ammonia concentration of the rearing water in the aquarium 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 greater than a predetermined first threshold (step S350). The first threshold is stored in the memory unit 24 of the control unit 20. The first threshold is set to an arbitrary value, for example, equal to or greater than 1.5 ppm and less than 3 ppm. If the detected ammonia concentration is determined to be less than the first threshold (step S350: NO), that is, if the ammonia concentration is less than the first threshold, the process returns to step S310.

[0030] If the detected ammonia concentration is determined to be equal to or greater than the first threshold (step S350: YES), the control unit 20 outputs an instruction to reduce the amount of feed to the crustaceans compared to when the ammonia concentration is less than the first threshold (step S360). In this embodiment, the control unit 20 reduces the feed amount in the feeding session performed after step S360. In accordance with the feeding schedule, the reduced feed amount is fed in the feeding session performed after step S360. More specifically, in the feeding control shown in FIG. 2, since it is determined that an instruction to reduce the feed amount has been input (step S120: YES), the feed amount is reduced (step S130). After that, a feeding instruction is output (step S140), and feeding is performed at the set feed amount (step S150). The amount of feed to be reduced is not particularly limited, but may be reduced by 10% to 50% compared to a preset normal feed amount, for example.

[0031] For example, if the first threshold is set to 2 ppm and the ammonia concentration in the rearing water is less than 2 ppm, the fish will be fed at the next feeding timing at a preset normal feed amount, whereas if the ammonia concentration in the rearing water is 2 ppm or higher, the fish will be fed at the next feeding timing at a feed amount that is reduced from the preset normal feed amount.

[0032] The control unit 20 determines whether the detected ammonia concentration is equal to or greater than a predetermined second threshold (step S370). The second threshold is a value greater than the first threshold and is stored in the memory unit 24 of the control unit 20. The second threshold is set to an arbitrary value, for example, equal to or greater than 3 ppm and less than 5 ppm. If the detected ammonia concentration is determined to be less than or equal to the second threshold (step S370: NO), that is, if the ammonia concentration is equal to or greater than the first threshold and less than the second threshold, the process returns to step S310.

[0033] If the detected ammonia concentration is determined to be equal to or greater than the second threshold (step S370: YES), a decision is made to perform a water change (step S380). In this case, since the water change control shown in FIG. 3 determines that a water change is to be performed (step S220: YES), a water change instruction is output (step S230), and then the water change is performed (step S240).

[0034] For example, if the second threshold is set to 4 ppm and the ammonia concentration in the rearing water is less than 4 ppm, the decision to change the rearing water will not be made. As a result, the water change at the next scheduled water change timing will be skipped and will not be performed. In contrast, if the ammonia concentration in the rearing water is 4 ppm or higher, the decision to change the rearing water will be made, and the water change will be performed at the next scheduled water change timing.

[0035] After step S380 is completed, the process returns to step S310. If the ammonia concentration detection schedule is set to constantly monitor the ammonia concentration, steps S310 to S330 are omitted from the control shown in Figure 4, and the flowchart starts from step S340.

[0036] According to the water quality control system 100 of the first embodiment described above, when the detected ammonia concentration is equal to or greater than a first threshold, the amount of food to be fed to the crustaceans is reduced compared to when the ammonia concentration is less than the first threshold, and when the detected ammonia concentration is equal to or greater than a second threshold that is greater than the first threshold, a decision is made to perform a water change of the rearing water. Therefore, since the ammonia concentration is used to determine the amount of food to be fed to the crustaceans and whether to perform a water change of the rearing water, the control of feeding and the control of water change can be simplified. Therefore, since the detection results from a single type of sensor can be used to perform two types of control, feeding and water change, the system configuration can be kept from becoming complicated.

[0037] Furthermore, according to the water quality control system 100 of this embodiment, when the detected ammonia concentration is equal to or greater than the first threshold, the amount of feed given to the crustaceans is reduced compared to when the ammonia concentration is less than the first threshold, thereby preventing deterioration of water quality due to excessive feeding. As a result, deterioration of the health of the crustaceans due to deterioration of water quality can be prevented, and death can be prevented, which in turn prevents a decrease in the farming yield.

[0038] Furthermore, according to the water quality management system 100 of this embodiment, since the control related to feeding and the control related to water changes can be automated, it is possible to suppress variations in the quality of feeding and water changes, and as a result, it is possible to suppress instability in the quality of the crustaceans being cultivated. Furthermore, since the control related to feeding and the control related to water changes can be automated, feeding and water changes can be carried out even when workers are not present, such as at night. Furthermore, since the control related to feeding and the control related to water changes can be automated, it is possible to suppress forgetting to carry out feeding or water changes, and as a result, it is possible to suppress deterioration in the health of the crustaceans and their deaths.

[0039] B. Second Embodiment: FIG. 5 is a flowchart showing an example of water exchange control in the second embodiment. FIG. 6 is a flowchart showing an example of feed and water exchange control in the second embodiment. The water quality management system 100 of the second embodiment, compared to the first embodiment, further performs control to adjust the water exchange rate. 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; therefore, the same components are designated by the same reference numerals and detailed descriptions thereof are omitted. Also in the second embodiment, the feed control shown in FIG. 2 and the water exchange control shown in FIG. 5 are executed in parallel with the feed and water exchange control 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 therefore 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 therefore detailed descriptions thereof are omitted.

[0040] In the water change control shown in FIG. 5, if it is determined that a decision has been made to perform water change (step S220: YES), the control unit 20 determines whether an instruction to increase the water change volume has been input (step S222). If it is determined that an instruction to increase the water change volume has not been input (step S222: NO), the process proceeds to step S230. On the other hand, if it is determined that an instruction to increase the water change volume has been input (step S222: YES), the control unit 20 increases the water change volume (step S224). The control unit 20 outputs an instruction to the water change unit 230 to perform water change at the set water change volume (step S230). If an increase in the water change volume has not been set, a preset water change volume is used. The water change unit 230 performs water change at the set water change volume (step S240). After completing step S240, the process returns to step S210 and waits for the next water change timing.

[0041] In the control of the feed amount and water change amount shown in FIG. 6 , if the detected ammonia concentration is determined to be equal to or greater than the second threshold (step S370: YES), the control unit 20 determines whether to perform a water change of the rearing water (step S380). The control unit 20 determines whether the detected ammonia concentration is equal to or greater than a predetermined third threshold (step S390). The third threshold is a value greater than the second threshold and is stored in the memory unit 24 of the control unit 20. The third threshold is set to an arbitrary value, such as 5 ppm or greater and less than 10 ppm. If the detected ammonia concentration is determined not to be equal to or greater than the third threshold (step S390: NO), i.e., if the ammonia concentration is equal to or greater than the second threshold and less than the third threshold, the process returns to step S310.

[0042] On the other hand, if the detected ammonia concentration is determined to be equal to or greater than the third threshold (step S390: YES), an instruction to increase the water exchange rate is output (step S400) compared to when the ammonia concentration is less than the third threshold. After completion of step S400, the process returns to step S310.

[0043] In step S400, the control unit 20 of this embodiment increases the water change volume for the next water change performed after step S400. In accordance with the water change schedule, the water change performed after step S400 is performed at the increased water change volume. More specifically, in the water change control shown in FIG. 5 , since it is determined that an instruction to increase the water change volume has been input (step S222: YES), the water change volume is increased (step S224). After that, a water change instruction for the set water change volume is output (step S230), and the water change is performed at the set water change volume (step S240). The increased water change volume is not particularly limited, but may be, for example, 10% to 50% higher than the preset normal water change volume. Therefore, when the detected ammonia concentration is equal to or greater than the third threshold, a larger amount of water is changed than when the detected ammonia concentration is below the third threshold.

[0044] For example, if the third threshold is set to 6 ppm, and the ammonia concentration of the rearing water is less than 6 ppm, the next water change will be performed at a preset normal water change rate, whereas if the ammonia concentration of the rearing water is 6 ppm or higher, the next water change will be performed at a rate greater than the preset normal water change rate.

[0045] FIG. 7 is an explanatory diagram showing an example of information related to thresholds. FIG. 7 shows a first threshold, a second threshold, and a third threshold. In the example shown in FIG. 7, three levels of values ​​are exemplified as the third threshold. In this manner, in an embodiment in which multiple levels of thresholds are used as the third threshold, the greater the detected ammonia concentration, the greater the amount of water change, resulting in a greater amount of water change. In the flowchart using the thresholds shown in FIG. 7, when the detected ammonia concentration is equal to or greater than the third threshold a, it may be further determined whether it is equal to or greater than the third threshold b. When the ammonia concentration is equal to or greater than the third threshold b, it may be further determined whether it is equal to or greater than the third threshold c. In the example shown in FIG. 7, when the ammonia concentration is equal to or greater than the third threshold a but less than the third threshold b, the amount of water change is increased by 10% compared to normal. When the ammonia concentration is equal to or greater than the third threshold b but less than the third threshold c, the amount of water change is increased by 20% compared to normal. When the ammonia concentration is equal to or greater than the third threshold c, the amount of water change 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, which is greater than the second threshold, the amount of water exchange is increased compared to when the detected ammonia concentration is less than the third threshold. Therefore, the amount of water exchange can be further adjusted using the ammonia concentration, simplifying water exchange control. Therefore, since the detection results from a single type of sensor can be used to control the feed amount, the execution of water exchange, and the amount of water exchange, the system configuration can be kept from becoming too complicated. Furthermore, according to the water quality management system 100 of the second embodiment, deterioration of water quality due to insufficient water exchange can be prevented. As a result, deterioration of the health of crustaceans due to poor water quality can be prevented, which in turn reduces mortality and reduces a decrease in aquaculture yield.

[0047] C. Other Embodiments According to another embodiment of the present disclosure, a method for producing Crustaceans in land-based aquaculture is provided. This Crustacean production method reduces the amount of feed to the Crustaceans when the ammonia concentration in the rearing water is equal to or greater than a predetermined first threshold, compared to when the ammonia concentration is below the first threshold, and determines whether to perform a water change in the rearing water when the ammonia concentration in the rearing water is equal to or greater than a predetermined second threshold that is greater than the first threshold. This Crustacean production method uses the ammonia concentration to determine the amount of feed to the Crustaceans and whether to perform a water change in the rearing water, thereby simplifying control over feeding and water changes. As with the second embodiment, the Crustacean production method may also increase the amount of water change when the detected ammonia concentration is equal to or greater than a predetermined third threshold that is greater than the second threshold, compared to when the ammonia concentration is below the third threshold.

[0048] D. Modifications: The configurations of the water quality control system 100 and the aquaculture system 200 in the above-described embodiments are merely examples and can be modified in various ways. For example, the aquaculture system 200 may be configured to include multiple aquariums 210. In this configuration, the control unit 20 may be configured to be able to identify each aquarium 210 in order to manage the water quality of the multiple aquariums 210.

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

[0050] Furthermore, for example, the water quality control system 100 may be equipped with other sensors in addition to the ammonia sensor 10, and the water quality of the rearing water may be controlled using the detection results of sensors other than the ammonia sensor 10. Examples of other sensors include, but are not limited to, a nitrate sensor, a turbidity sensor, a dissolved oxygen sensor, a temperature sensor, a pH sensor, a conductivity sensor, a salinity sensor, and an image sensor.

[0051] Furthermore, in the water quality control system 100 of the above embodiment, a single-stage value was used as the first threshold. However, a multi-stage threshold, such as the third threshold shown in FIG. 7 , may be used. In an aspect in which a multi-stage threshold is used as the first threshold, the amount of feed may be reduced as the detected ammonia concentration increases. For example, in a flowchart in which three thresholds (first threshold a < first threshold b < first threshold c) are set as the first threshold, if the detected ammonia concentration is equal to or greater than first threshold a, it may be further determined whether the detected ammonia concentration is equal to or greater than first threshold b. If the detected ammonia concentration is equal to or greater than first threshold b, it may be further determined whether the detected ammonia concentration is equal to or greater than first threshold c. In this aspect, the amount of feed is reduced as the detected ammonia concentration increases, thereby further preventing deterioration of the water quality of the rearing water.

[0052] The present invention is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments and examples corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

[0053] 10...ammonia sensor, 12...water sampling section, 14...processing section, 15...diaphragm electrode, 16...communication section, 20...control section, 22...CPU, 24...storage section, 26...communication section, 100...water quality control system, 200...aquaculture system, 210...aquarium, 220...feeding section, 222...feeding reception section, 224...supply section, 230...water exchange section, 232...water exchange reception section, 234...drainage section, 236...water supply section

Claims

1. A water quality management system for the terrestrial aquaculture of crustaceans, comprising an ammonia sensor for detecting the ammonia concentration in the breeding water of the crustaceans and a control unit. The control unit reduces the feeding amount to the crustaceans when the detected ammonia concentration is equal to or higher than a predetermined first threshold value as compared with the case where the concentration is lower than the first threshold value, and determines to perform water change of the breeding water when the detected ammonia concentration is equal to or higher than a predetermined second threshold value which is larger than the first threshold value. A water quality management system characterized by the above.

2. In the water quality management system according to claim 1, the control unit increases the amount of water change as compared with the case where the concentration is lower than a predetermined third threshold value when the detected ammonia concentration is equal to or higher than the third threshold value which is larger than the second 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 terrestrial aquaculture, reducing 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 the concentration is lower than the first threshold value, and determining to perform water change of the breeding water when the ammonia concentration in the breeding water is equal to or higher than a predetermined second threshold value which is larger than the first threshold value. A method for producing crustaceans characterized by the above.

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