Aquaculture system for marine products and aquaculture method for marine products

Abstract

The present disclosure provides an aquaculture system for marine products, the aquaculture system comprising an aquaculture tank and a feed supply mechanism that is configured to supply feed into the aquaculture tank and control the feed supply amount.

Description

Aquaculture system and aquaculture method for aquatic products

[0001] The present disclosure relates to an aquaculture system and an aquaculture method for aquatic products.

[0002] In recent years, the land-based aquaculture of fish and shellfish has attracted attention because it is not restricted by location and is easy to manage the breeding environment. In particular, in the land-based aquaculture of oysters, reducing the feed cost is emphasized to control the production cost, and the study of efficient breeding methods is in progress.

[0003] There are three methods for land-based aquaculture: the "flow-through type" in which breeding water is taken in from the outside and drained as it is, the "semi-closed circulation type" and the "fully-closed circulation type" in which breeding water is partially or fully treated and reused. Among these, the "flow-through type" is mainly adopted in the aquaculture of oysters. The flow-through type has a relatively simple system and is easy to introduce, but the drained water often contains uneaten feed, which is likely to cause an environmental burden. Also, the burden of feed cost is large, which is an issue.

[0004] On the other hand, although a method of switching to the fully-closed type is conceivable, oxygen deficiency and the accumulation of harmful substances may have an adverse effect on the breeding environment, and the introduction and maintenance of an advanced purification system require a great deal of cost. Against this background, a new feeding system that can efficiently utilize feed while suppressing the impact on the environment is required.

[0005] Summary of the Land-Based Aquaculture Study Session in 2013, Fisheries Agency, https: / / www.maff.go.jp / j / shokusan / sanki / pdf / 251010si1.pdf

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide an aquaculture system and an aquaculture method for aquatic products.

[0007] One aspect of the present disclosure is a system for cultivating aquatic products, comprising a cultivation tank and a feed supply mechanism configured to supply feed to the cultivation tank and to control the amount of feed supplied. Another aspect of the present disclosure is a method for cultivating aquatic products, comprising the steps of (a) supplying rearing water containing feed to the cultivation tank while cultivating the aquatic products in the cultivation tank to replace the rearing water in the cultivation tank, (b) stopping the supply of rearing water containing feed to allow the aquatic products to consume the feed, and (c) repeating steps (a) and (b) at least twice.

[0008] This disclosure provides a system for cultivating aquatic products and a method for cultivating aquatic products.

[0009] Figure 1 is a schematic diagram showing the aquaculture system of the embodiment. Thin lines indicate electrical connections, and thick lines indicate fluid connections. Figure 2 is a functional block diagram showing the control and supply paths of the aquaculture system of the embodiment. Solid arrows indicate the transmission of control signals, and dashed arrows indicate fluid flow. Figure 3 is a flowchart showing an example of the aquaculture method of the embodiment. Figure 4 shows the predation rate of algae feed in oyster farming using the aquaculture system of the embodiment (intermittent closed feeding system) or a control continuous feeding system. Figure 5A shows the change in water temperature in oyster farming using the aquaculture system of the embodiment (intermittent closed feeding system) or a control continuous feeding system. Figure 5B shows the change in carbon dioxide concentration in oyster farming using the aquaculture system of the embodiment (intermittent closed feeding system) or a control continuous feeding system. Figure 6A shows the change in the total length of oysters in oyster farming using the aquaculture system of the embodiment (intermittent closed feeding system) or a control continuous feeding system. Figure 6B shows the change in oyster weight in oyster farming using the embodiment's aquaculture system (intermittent closed feeding system) or a control continuous feeding system.

[0010] The following describes non-limiting embodiments of this disclosure. This disclosure is not limited to the embodiments described below.

[0011] <Aquaculture System for Aquatic Products> In one embodiment of the present disclosure, an aquaculture system for aquatic products is provided, comprising a cultivation tank and a feed supply mechanism configured to supply feed to the cultivation tank and to control the amount of feed supplied. According to this embodiment, it is possible to increase the rate at which oysters consume feed while maintaining water quality, and to reduce the total amount of feed required for feeding. This makes it possible to reduce feeding costs. Furthermore, since leftover feed can be reduced, the environmental burden due to wastewater can also be reduced.

[0012] Figure 1 is a schematic diagram showing the overall configuration of the aquaculture system according to this embodiment. Figure 2 is a functional block diagram showing the control and supply paths in the system. The aquaculture system of this embodiment includes an aquaculture tank 1, a feed supply mechanism 2, a seawater tank 3, an algae tank 4, and a wastewater tank 5. The aquaculture tank 1 is equipped with a chlorophyll turbidimeter 11, a CO2 sensor 12, a water temperature sensor 13, a pH sensor 14, a DO (dissolved oxygen) sensor 15, and a water flow pump 16. The feed supply mechanism 2 includes a feed tank 21, a pump 22, a timer 23, a flow path 24 that fluidly connects the pump 22 and the feed tank 21, a flow path 25 that fluidly connects the pump 22 and the aquaculture tank 1, and a water flow pump 26 and a chlorophyll turbidimeter 27 installed inside the feed tank 21. The algae tank 4 is equipped with a chlorophyll turbidimeter 41.

[0013] Aquaculture tank 1 is a tank for cultivating aquatic products, and multiple aquatic products are contained within it and cultivated in rearing water. The aquatic products cultivated in aquaculture tank 1 may be those that feed on microalgae. Alternatively, the aquatic products cultivated in aquaculture tank 1 may be those that feed on zooplankton such as fish. The aquatic products cultivated in aquaculture tank 1 may be shellfish, including oysters. Cultivable shellfish may be those that feed on phytoplankton including microalgae, such as ark clams, red clams, pearl oysters, Manila clams, Japanese oysters, Japanese scallops, Japanese anemones, oysters, freshwater clams, pen shells, moon oysters, cockles, Japanese scallops, surf clams, American scallops, hard clams, geoduck clams, razor clams, and purple mussels. Depending on the type of marine product, seawater or diluted seawater may be used as rearing water, but deep-sea water may also be used. Alternatively, artificial rearing water with adjusted composition and temperature, such as artificial seawater, may be used as rearing water. Salts, minerals such as calcium, and pH adjusters may be added to the rearing water. The aquaculture tank 1 may be equipped with aquaculture equipment known to those skilled in the art, including an aeration device, a temperature control device, and rearing cages for housing shellfish.

[0014] The chlorophyll turbidimeter 11 is an optical measuring device for measuring the chlorophyll turbidity of the water in the aquaculture tank 1. This device may include a light-emitting unit and a light-receiving unit, and may calculate the chlorophyll concentration by irradiating the water with light of a specific wavelength and detecting the transmitted and scattered light. The CO2 sensor 12 may be an electrochemical sensor for measuring the carbon dioxide concentration in the aquaculture tank 1. The water temperature sensor 13 is for measuring the water temperature, and the temperature sensing unit, such as a platinum resistance thermometer, may be housed in a corrosion-resistant protective tube to withstand long-term continuous use. The pH sensor 14 is for measuring the hydrogen ion concentration and may be a glass electrode type hydrogen ion concentration meter. The DO sensor 15 is for measuring the dissolved oxygen amount, and an optical sensor may be used. These sensors can be measuring instruments known to those skilled in the art for use in aquaculture. The measurement data from each sensor is collected in a control device and can be used for monitoring and controlling the aquaculture environment. The control device may have a function to issue an alarm if the measured value deviates from the set range. The water flow pump 16 is a device that circulates the water in the aquaculture tank 1, and may consist of a water-resistant housing and pump components suitable for use underwater.

[0015] The feed supply mechanism 2 is configured to supply feed for aquatic products to the aquaculture tank 1 and to control the amount supplied. The amount of feed supplied can be controlled according to a preset schedule, or it can be controlled based on the chlorophyll concentration in the aquaculture tank 1. The feed supply mechanism 2 can also be manually adjusted or automatically controlled. As a means of supplying feed to aquatic products, the feed supply mechanism 2 can employ either a liquid feeding method that supplies liquid feed or a solid feeding method that supplies solid feed.

[0016] The feed tank 21 of the feed supply mechanism 2 can contain feed for aquatic products. The feed used for raising aquatic products is typically non-sessile algae. The feed used for raising aquatic products may also be microalgae. Examples of microalgae include diatoms, haptophytes, and prasinophytes. More specifically, algae of the genera Chaetoceros, Isochrysis, Pavlova, Pyramimonas, and Tisochrysis can be used. In addition, powdered feed mainly composed of zooplankton and fishmeal, powdered feed mainly composed of plant protein, liquid feed containing nutrients such as amino acids or fatty acids, liquid feed obtained by dispersing the above powdered feed in water, or mixed feeds combining these can also be used. These feeds can be appropriately selected according to the type or growth stage of the aquatic products being cultivated. The feed tank 21 can be detachably installed on the aquaculture tank 1.

[0017] Pump 22 is controlled by timer 23 to supply feed from feed tank 21 to aquaculture tank 1. A pump capable of supplying liquid feed can be used as pump 22. The amount of feed supplied can be adjusted by controlling the operating time and operating speed of pump 22. In addition to the supply mechanism including pump 22, the feed supply mechanism 2 may also include a quantitative supply mechanism including a flow control valve, a screw feeder, etc. If a flow control valve is used, the amount of feed supplied can be adjusted by controlling the opening degree and opening time of the valve. If a quantitative supply mechanism such as a screw feeder is used, the amount of powdered feed supplied can be adjusted by controlling its operating speed.

[0018] The timer 23 may be a timer outlet connected to the power supply of the pump 22, valve, or quantitative feeding mechanism, or it may be an information processing device such as a personal computer. When a timer outlet is used, a feeding system can be realized with a simple configuration, and short feedings can be automatically repeated. The timer 23 can control the timing and duration of feeding. More specifically, it can set the number of feedings per day, the duration of each feeding, or the start and end times of feeding. Control by the timer 23 can be applied to the control of any of the quantitative feeding mechanisms such as the pump 22, flow control valve, and screw feeder, and the feeding schedule can be appropriately set according to the type and growth stage of the farmed aquatic products. In addition, the timer 23 may have a function to automatically adjust the feeding timing based on information from various sensors.

[0019] The flow path 24 may be a fluid connection between the pump 22 and the feed tank 21. The flow path 24 can be formed by piping or hoses, and can also be configured to allow feed to flow down via a valve. The flow path 25 may be a fluid connection between the pump 22 and the aquaculture tank 1. The flow path 25 can also be formed by piping or hoses, and can also be configured to allow feed to flow down via a valve. The water flow pump 26 may circulate the water in the feed tank 21. The water flow pump 26 can circulate the water in the feed tank 21 to maintain a uniform feed concentration.

[0020] The seawater tank 3 may store seawater used in the feed tank 21. The algae tank 4 may be used to cultivate microalgae that serve as feed. The algae tank 4 may be equipped with lighting equipment necessary for cultivation and may also be equipped with a ventilation system. The chlorophyll turbidimeter 41 may measure the chlorophyll concentration of the water in the algae tank 4. When transferring the algae cultivated in the algae tank 4 to the feed tank 21, they can be diluted with seawater from the seawater tank 3. At this time, based on the set final concentration, the required amount of seawater to be transferred can be calculated from the algae concentration in the algae tank 4 measured by the chlorophyll turbidimeter 41 and the algae concentration in the feed tank 21 measured by the chlorophyll turbidimeter 27. The supply of seawater from the seawater tank 3 can be controlled according to the amount transferred. The wastewater tank 5 may temporarily store wastewater from the aquaculture tank 1.

[0021] Flow path 6 may fluidly connect the seawater tank 3 and the feed tank 21. Flow path 6 can be formed by piping or hoses, and can also be configured to allow seawater to flow through a valve. Flow path 6 can function as a seawater supply path from the seawater tank 3 to the feed tank 21. Flow path 7 may fluidly connect the algae tank 4 and the feed tank 21. Flow path 7 can be formed by piping or hoses, and can also be configured to allow algae to flow through a valve. Flow path 7 can function as a path for transferring algae cultivated in the algae tank 4 to the feed tank 21. Flow path 8 may fluidly connect the aquaculture tank 1 and the wastewater tank 5. Flow path 8 can be formed by piping or hoses, and can also be configured to allow wastewater to flow through a valve. Flow path 8 can function as a path for transferring wastewater from the aquaculture tank 1 to the wastewater tank 5. Pumps may also be provided in each of these flow paths.

[0022] <Method for Cultivating Aquatic Products> In another embodiment of the present disclosure, a method for cultivating aquatic products may be provided, comprising the steps of (a) supplying rearing water containing feed to the rearing tank while cultivating the aquatic products in the rearing tank to replace the rearing water in the rearing tank, (b) stopping the supply of rearing water containing feed and allowing the aquatic products to consume the feed, and (c) repeating steps (a) and (b) at least twice. The elements of this embodiment (aquatic products, feed, rearing water, etc.) may be described in the section <Aquatic Product Cultivation System>.

[0023] The aquaculture method of the embodiment includes (a) a step of supplying rearing water containing feed to the aquaculture tank while rearing the aquaculture products in the tank, thereby replacing the rearing water in the tank. In this disclosure, the replacement of the rearing water in the aquaculture tank may include either a total replacement, in which the entire amount of rearing water is replaced with new rearing water, or a partial replacement, in which a portion of the rearing water is replaced with new rearing water. In the case of partial replacement, the water level in the aquaculture tank can be kept constant by supplying new rearing water while discharging a portion of the rearing water in the tank. In this step, rearing water containing feed can be supplied to the aquaculture products in the aquaculture tank 1 from the feed tank 21. The feed in the feed tank 21 can be supplied by a pump 22 or a valve, and the supply time can be controlled by a timer 23. The water in the aquaculture tank 1 can be replaced with newly supplied rearing water. At this time, a portion of the rearing water in the aquaculture tank can be discharged to the drainage tank 5 through the flow path 8.

[0024] The feed supplied in step (a) may include algae. Microalgae can be used as the algae. Examples of microalgae include diatoms, haptophytes, and prasinophytes. More specifically, algae of the genera Chaetoceros, Isochrysis, Pavlova, Pyramimonas, and Tisochrysis can be used. These algae can be used individually or in combination.

[0025] The aquaculture method of the embodiment includes a step of (b) stopping the supply of rearing water containing feed and allowing the aquatic products to consume the feed. In this step, the supply of rearing water containing feed is stopped, allowing the aquatic products in the aquaculture tank 1 to consume the supplied feed. In this step, the aquatic products in the aquaculture tank 1 can consume the feed supplied in step (a). The rearing water containing feed supplied to the aquaculture tank 1 in step (a) remains in the aquaculture tank 1 for a certain period of time because the supply of new rearing water containing feed is stopped in step (b). As a result, the aquatic products can efficiently consume the retained feed. Furthermore, during this period, by generating a water flow with the water flow pump 16 in the aquaculture tank 1, the settling of the feed supplied in step (a) can be suppressed, and the efficiency of feed consumption by the aquatic products can be improved. After step (b), the feed concentration in the aquaculture tank 1 can be restored by performing step (a) again.

[0026] The chlorophyll turbidimeter 11 can measure the change in feed concentration in the aquaculture tank 1 over time. This makes it possible to understand the rate at which the aquatic products consume the feed in process (b). Based on this consumption rate, the amount of feed to be given in the next process (a) may be adjusted.

[0027] The aquaculture method of the embodiment includes (c) repeating steps (a) and (b) at least twice. The number of repetitions of the steps may be two or more times per day. For example, it may be two, three, four, five, or six times per day. Step (a) may include changing the rearing water for 0.5 to 0.7 hours, 0.7 to 0.9 hours, 0.9 to 1.1 hours, 1.1 to 1.3 hours, or 1.3 to 1.5 hours. Step (b) may include consuming feed for 2.5 to 2.7 hours, 2.7 to 2.9 hours, 2.9 to 3.1 hours, 3.1 to 3.3 hours, or 3.3 to 3.5 hours. By setting the feed consumption time in step (b) to around 3 hours, it is possible to achieve both an improved rate of algae predation by aquatic products and maintenance of water quality.

[0028] Referring to Figure 3, the method for cultivating aquatic products according to this embodiment will be described. First, algae at a concentration of 200,000 cells / mL are prepared in the feed tank 21 (S1). Next, repeated feeding is started (S2). The pump 22 is driven by the timer 23 (S3), and while cultivating aquatic products in the cultivation tank 1, seawater containing feed is supplied to replace the cultivation water (S4). This replacement continues for 1 hour. Then, the supply of seawater containing feed is stopped by the timer 23 (S5), the cultivation tank 1 is closed, and cultivation is carried out for 3 hours (S6). After repeating these steps 6 times, the process is completed (S7).

[0029] According to this embodiment, the aquatic products in the cultivation tank 1 can efficiently consume the feed supplied in S4 during the closure period in S6. Furthermore, by repeating these processes six times, efficient feeding can be carried out throughout the day. In addition, by combining the one-hour replacement in S4 with the three-hour closure in S6, it is possible to improve the rate at which aquatic products consume the feed while maintaining water quality.

[0030] Examples of the present disclosure are described below, but the present disclosure is not limited to the examples described below.

[0031] Figure 1 is an overall diagram of a system according to one embodiment of the present disclosure. In this embodiment, an oyster farming experiment was conducted using the system shown in Figure 1 (an intermittent closed feeding system).

[0032] Specifically, a high-concentration algal culture solution obtained from an algae tank is mixed with seawater obtained from a seawater tank, and 200,000 cells / mL (2 × 10⁶) are added in a feeding tank. 5 A culture water containing algae (cells / mL) was prepared. This algae-containing culture water from the feed tank was supplied to the aquaculture tank over a period of one hour, and after the water change, the tank was closed for three hours. This "one-hour water change + three-hour closure" cycle was repeated six times per day, and the algae-containing culture water in the feed tank was replaced with fresh algae-containing culture water every day.

[0033] As a comparative example, a continuous feeding system for continuously supplying algae was prepared, and culture water containing algae at the same concentration as in the example (200,000 cells / mL) was continuously supplied to the cultivation tank in a 24-hour flow-through manner. At this time, a system was operated in which a high-concentration algae culture solution from the algae tank was mixed with seawater from the seawater tank to constantly supply culture water containing algae at a constant concentration.

[0034] The experimental results showed that the required number of algal cells per day in a continuous feeding system was 4.8 × 10⁶. 11 In contrast to cells, the intermittent closed feeding system was 4.8 × 10⁶ 10 It was confirmed that the continuous feeding system requires 10 times the amount of food compared to the intermittent closed feeding system, due to the cells' restraint.

[0035] To evaluate the rate of algal predation by oysters, chlorophyll fluorescence values ​​were measured using a chlorophyll turbidimeter.

[0036] In the intermittent closed feeding system, a chlorophyll turbidimeter was installed in the aquaculture tank, and the predation rate was calculated using the following formula 1: Formula 1: Predation rate (%) = [(chlorophyll fluorescence value in the aquaculture tank at the start of closure - chlorophyll fluorescence value in the aquaculture tank after 3 hours) / chlorophyll fluorescence value in the aquaculture tank at the start of closure] × 100

[0037] On the other hand, in the continuous feeding system, chlorophyll turbidimeters were installed in the feed tank and wastewater tank, and the predation rate was calculated using the following formula 2: Formula 2: Predation rate (%) = [(chlorophyll fluorescence value in feed tank - chlorophyll fluorescence value in wastewater tank) / chlorophyll fluorescence value in feed tank] × 100

[0038] As shown in Figure 4, the predation rate in the intermittent closed feeding system was 72.8%, while the predation rate in the continuous feeding system was 11.9%. These results clearly demonstrate that adopting an intermittent feeding method significantly improves the predation efficiency of oysters.

[0039] Also, as shown in FIGS. 5A and 5B, in the intermittent closed feeding system of the embodiment, the water temperature and the carbon dioxide concentration tended to increase slightly compared to the comparative example. However, the increase in both of these was within a range that did not interfere with the growth of oysters. Also, it was confirmed that even when the carbon dioxide concentration increased significantly, appropriate countermeasures could be taken by increasing the output of the water flow pump.

[0040] Finally, in order to examine the effect on the growth of oysters, the total length and weight of oysters were compared between the intermittent closed feeding system and the continuous feeding system. As shown in FIGS. 6A and 6B, no significant difference was observed between the two systems. Therefore, it was shown that the fluctuations in water temperature and carbon dioxide concentration in the intermittent closed feeding system are within a range that does not adversely affect the growth of oysters.

[0041] From these results, it was demonstrated that the intermittent closed feeding system is an effective system that can achieve a high predation efficiency of algae, maintain water quality, and reduce the cost and environmental load associated with feeding.

[0042] Although the present disclosure has been described with reference to several of the above embodiments, the present disclosure is not limited to the exemplification in the above embodiments. Various changes can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0043] This disclosure includes the following embodiments: (1) A system for cultivating aquatic products, comprising: a cultivation tank; and a feed supply mechanism configured to supply feed to the cultivation tank and to control the amount of feed supplied. (2) The system for cultivating aquatic products according to claim 1, wherein the feed supply mechanism includes a feed tank fluidly connected to the cultivation tank. (3) The system for cultivating aquatic products according to claim 2, further comprising: a seawater tank fluidly connected to the feed tank; and an algae tank fluidly connected to the feed tank. (4) A method for cultivating aquatic products, comprising: (a) supplying rearing water containing feed to the cultivation tank while cultivating the aquatic products in the cultivation tank to replace the rearing water in the cultivation tank; (b) stopping the supply of rearing water containing feed to allow the aquatic products to consume the feed; and (c) repeating steps (a) and (b) at least twice. (Clause 5) The aquaculture method according to Claim 4, wherein step (a) includes changing the rearing water for 0.5 to 1.5 hours, and step (b) includes consuming the feed for 2.5 to 3.5 hours. (Clause 6) The aquaculture method according to Claim 4 or 5, wherein the feed includes algae. (Clause 7) The aquaculture system according to any one of Claims 1 to 3, wherein the feed tank is equipped with a chlorophyll turbidimeter. (Clause 8) The aquaculture system according to any one of Claims 1 to 3 or Claim 7, wherein the aquaculture tank is equipped with at least one selected from the group consisting of a CO2 sensor, a water temperature sensor, a pH sensor, and a DO sensor. (Clause 9) The aquaculture system according to any one of Claims 1 to 3 or Claims 7 to 8, wherein the amount of feed supplied is controlled by a pump or valve, and the pump or valve is controlled by a timer.

[0044] 1. Aquaculture tank 2. Feed supply mechanism 3. Seawater tank 4. Algae tank 5. Drainage tank 6. Flow channel 7. Flow channel 8. Flow channel 11. Chlorophyll turbidimeter 12. CO ２ Sensor 13 Water temperature sensor 14 pH sensor 15 DO sensor 16 Water flow pump 21 Feed tank 22 Pump 23 Timer 24 Flow path 25 Flow path 26 Water flow pump 27 Chlorophyll turbidity meter 41 Chlorophyll turbidity meter

Claims

1. An aquaculture system for aquatic products, comprising a cultivation tank and a feed supply mechanism configured to supply feed to the cultivation tank and to control the amount of feed supplied.

2. The aquaculture system according to claim 1, wherein the feed supply mechanism includes a feed tank fluidly connected to the aquaculture tank.

3. The aquaculture system according to claim 2, further comprising a seawater tank fluidly connected to the feed tank, and an algae tank fluidly connected to the feed tank.

4. A method for cultivating aquatic products, comprising: (a) supplying rearing water containing feed to the rearing tank while raising the aquatic products in the rearing tank to replace the rearing water in the rearing tank; (b) stopping the supply of rearing water containing feed and allowing the aquatic products to consume the feed; and (c) repeating steps (a) and (b) at least twice.

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