Method and apparatus for rearing large embryos of chondrichthyes and some osteichthyes marine fish

Abstract

[Problem] The present invention addresses the problem of providing a rearing method and a rearing device for artificially rearing: large embryos of marine fish including Chondrichthyes and some Osteichthyes that have been born prematurely; and large embryos of marine fish including Chondrichthyes and some Osteichthyes that are in pregnant maternal bodies that have died. [Solution] The present invention is characterized by being a rearing device for large embryos of marine fish including Chondrichthyes and some Osteichthyes that comprises a large embryo rearing container for rearing the large embryos, a water tank for accommodating the large embryo rearing container, a water circulation tank for circulating, replacing, and aerating a large embryo rearing solution, a water storage tank for storing replacement large embryo rearing solution, a purification filter for removing bacteria in the large embryo rearing solution, and a sterilization device for sterilizing the bacteria in the large embryo rearing solution, wherein the large embryos of marine fish including Chondrichthyes and some Osteichthyes are artificially reared by circulating the large embryo rearing solution, in which 30–60 g / L of urea has been dissolved in a mixed liquid of sea water and fresh water at a ratio of 1:0.86.

Description

Technical Field

[0001] The present invention relates to a breeding method and a breeding apparatus for artificially breeding large embryos of chondrichthyes and some osteichthyes marine fish.

Background Art

[0002] A variety of fish inhabit the world's hydrosphere. In particular, many chondrichthyes and some osteichthyes fish that produce few large eggs and juveniles have been pointed out in recent years to be at risk of decreasing populations and extinction in various parts of the world. The reasons include that the hydrosphere is a different environment from land, there is little information on the organisms living there, and in particular, many marine fish of chondrichthyes and some osteichthyes adopt a breeding strategy of producing few large embryos, making them difficult to handle and with little progress in the investigation and research of their breeding ecology.

[0003] In recent years, there have been an increasing number of examples of breeding chondrichthyes and some osteichthyes marine fish in aquariums. During breeding management or when collecting individuals in the ocean, pregnant females may be discovered, but they may become weakened due to premature birth or eventually die even if they survive, and cannot be saved. However, embryos born prematurely from this dead female or embryos found in the dead pregnant female may still be alive at the time of discovery. If these embryos can be saved, a lot of knowledge can be obtained, which will also contribute greatly to the conservation of chondrichthyes and some osteichthyes marine fish. For this purpose, it is necessary to artificially breed large embryos.

[0004] Patent Document 1 discloses a method for culturing fish using artificial culture water having an osmotic pressure substantially equal to the osmotic pressure of fish blood. According to this invention, by culturing and breeding in an environment where it is not necessary to adjust the osmotic pressure, the burden on the body of seawater fish and freshwater fish is reduced, and culturing and breeding can be performed more efficiently.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, although the invention of Patent Document 1 targets marine fish and freshwater fish including both edible and ornamental fish, it does not rear embryos. Embryos are inherently in a state where they need to grow in the uterus or eggs, and even with artificial rearing water having an osmotic pressure approximately equal to that of fish blood, they cannot be easily reared.

[0007] Therefore, as a result of intensive research, the inventor of the present invention invented a rearing method and a rearing apparatus for artificially rearing prematurely born embryos and embryos found in dead pregnant females in order to make use of them. Accordingly, an object of the present invention is to provide a rearing method and a rearing apparatus for artificially rearing large embryos of chondrichthyes and some osteichthyes marine fish in order to solve the above problems.

Means for Solving the Problems

[0008] In order to solve the above problems in the prior art, the present invention takes the following technical solutions. Note that the "large embryo" in the present invention refers to a large embryo, regardless of oviparity or viviparity, which is produced by chondrichthyes and some osteichthyes marine fish for reproduction.

[0009] The solution for rearing large embryos of chondrichthyes and some osteichthyes marine fish according to the present invention is in a mixed solution of seawater and fresh water at a ratio of 1:0.86 wherein 30 to 60 g / L of urea is dissolved and is characterized by this.

[0010] Although the plasma of marine chondrichthyans has a salt concentration of about half that of seawater, it contains osmotic regulators such as urea and trimethylamine oxide (TMAO). Due to their action, the osmotic pressure is maintained at approximately the same level as that of seawater. As a result, marine chondrichthyans can inhabit seawater, which has a high salt content and high osmotic pressure, without dehydrating. Focusing on this point, the inventor, after intensive research, invented a breeding solution in which only urea is dissolved in a mixture of seawater and fresh water.

[0011] The large embryo breeding device for chondrichthyans and some osteichthyan marine fish according to the present invention is a device that uses the above-mentioned breeding solution for large embryos of chondrichthyans and some osteichthyan marine fish. Specifically, the large embryo breeding device for chondrichthyans and some osteichthyan marine fish according to the present invention An embryo breeding container for breeding large embryos, the inner surface of which is formed into a smooth surface or a villous shape, An aquarium for accommodating the large embryo breeding container, A solution replacement water tank for replacing the solution for breeding large embryos, A solution storage tank for storing the solution for water replacement, Two or more purification filters with different pore sizes for removing bacteria in the solution, A biological filtration filter for removing bacteria in the solution, An ultraviolet sterilization device for sterilizing bacteria in the solution, The large embryo breeding device consisting of Circulates a breeding solution for large embryos in which urea is dissolved at 30 - 60 g / L in a mixture of seawater and fresh water at a ratio of 1:0.86 This is characterized by

[0012] Since urea is a substance that facilitates the growth of bacteria and easily becomes harmful ammonia when decomposed, the inventor invented a breeding device to prevent this. Since embryos are vulnerable to damage to their yolk and bodies, the inventor invented a breeding device that can breed them in an optimal container.

[0013] ​The method for culturing large embryos of chondrichthyes and some osteichthyes marine fish according to the present invention is as follows: In a large embryo culturing container with a smooth or villous inner surface, In a mixed solution of seawater and fresh water at a ratio of 1:0.86, A large embryo culturing solution in which 30 - 60 g / L of urea is dissolved is circulated, While periodically changing the water, By using two or more purification filters with different pore sizes, a biological filtration filter, and an ultraviolet sterilization device, Bacteria in the large embryo culturing solution are removed and sterilized. This is the characteristic.

Brief Description of the Drawings

[0014]

Figure 1

Modes for Carrying Out the Invention

[0015] In this embodiment, an apparatus and method for culturing embryos of the skate ray, a chondrichthyes elasmobranch that is a yolk-dependent viviparous fish, will be described.

[0016] Figure 1 is a diagram showing the configuration of the large embryo culturing device. The large embryo culturing device includes a large embryo culturing container 1 for culturing large embryos, a water tank 2 for accommodating the large embryo culturing container, a return water tank 3 for circulating, changing water, and aerating the large embryo culturing solution for culturing large embryos, a water storage tank 4 for storing the large embryo culturing solution for water change, a purification filter 5 for removing bacteria in the large embryo culturing solution and purifying the water quality, an ultraviolet sterilization device 6 for sterilizing bacteria and viruses in the large embryo culturing solution, a flow meter 7 for keeping the flow rate of the large embryo culturing solution constant, and a pump 8 for circulating and changing the water of the large embryo culturing solution. The arrows in the figure indicate the direction in which the large embryo culturing solution flows.

[0017] The inner surface of the large embryo rearing container 1 is formed into a smooth surface or a villous shape so that the yolk sac and the embryo body of the large embryo are not damaged or compressed. The top surface of the large embryo rearing container 1 is open, and the opening is covered with a net. In addition, the large embryo rearing container 1 can be closed at the opening, and a tube for allowing the large embryo rearing solution to flow in and out of the container can be attached. The large embryo rearing container 1 is installed in the water tank 2 in a state of being submerged in the water tank 2. The size of the large embryo rearing container 1 can be changed according to the large embryo to be reared and its growth stage. In this embodiment, a transparent polyvinyl chloride resin container with a diameter of 9 cm, a height of 11 cm, and a capacity of 500 mL was used.

[0018] The water tank 2 only needs to be large enough to accommodate the large embryo rearing container 1. In the water tank 2, a conduit of a titanium coil through which cold water passes was installed to keep the temperature of the large embryo rearing solution constant, and the temperature in the water tank 2 was adjusted to be 11 - 14°C. Note that when using a high - resistance filter for sterilization and purification of the large embryo rearing solution and performing high - circulation while maintaining the cleanliness of the solution, the mechanical heat of the high - lift magnetic pump and the heat dissipation from the filter become strong, heating the large embryo rearing solution. Therefore, thorough cooling is required to maintain the optimal water temperature for the breeding target.

[0019] In the water tank 2, the large embryo rearing solution for rearing large embryos is highly circulated. In the large embryo rearing container 1 installed in the water tank 2, an appropriate amount of the optimized large embryo rearing solution flows in and out. The circulation of the large embryo rearing solution to the large embryo rearing container 1 is only through natural inflow and natural outflow from the opening on the top surface of the large embryo rearing container 1 covered with a net, and is carried out by injecting and draining the large embryo rearing solution. In addition, a water supply pipe and a drain pipe can be attached to the large embryo rearing container 1 to forcibly flow the large embryo rearing solution into and out of the large embryo rearing container.

[0020] For the solution for rearing large embryos, a solution prepared by mixing seawater and fresh water at a ratio of 1:0.86 and dissolving 35 g of urea per liter was used. In addition, for the solution for rearing large embryos, it is desirable to dissolve 30 to 60 g of urea per liter in a mixed solution of seawater and fresh water at a ratio of 1:0.86. Furthermore, for the solution for rearing large embryos, when the ratio of the mixed solution of seawater and fresh water is 1:0.7 to 1, 32 to 38 g of urea can also be dissolved per liter.

[0021] The substances in seawater dissolved in the solution for rearing large embryos are more than half of seawater. Also, the osmotic pressure of the solution for rearing large embryos was set to the same as seawater, 940 to 1,100 mOsm.

[0022] In order to remove the nitrogen compounds accumulated in the solution for rearing large embryos, a return water tank 3 for changing the water of the solution for rearing large embryos is provided. In this embodiment, in order to change the water while artificially continuing the rearing, an overflow pipe was installed in the return water tank 3.

[0023] Since a large amount of water is required for changing the water, a water storage tank 4 for storing the solution for rearing large embryos for changing the water is provided. Although it is desirable to change the frequency and amount of water change according to the growth stage and fish species of the large embryos, in this embodiment, the water was changed once every about 10 days, and a maximum of 110 L of the solution for rearing large embryos was used for each water change. While rearing the large embryos, since the ammonia concentration in the solution for rearing large embryos increases, the solution for rearing large embryos was exchanged so that the ammonia concentration does not exceed 400 μg / dL.

[0024] Thus, although a large amount of the solution for rearing large embryos is required for changing the water, as time passes during the rearing of the large embryos, not only nitrogen compounds such as ammonia nitrogen accumulate in the solution for rearing large embryos, but bacteria also proliferate. In particular, in this embodiment, since a large amount of urea is dissolved in the solution for rearing large embryos, bacteria are likely to proliferate. Therefore, a purification filter 5 is provided to remove bacteria in the solution for culturing large embryos.

[0025] A plurality of purification filters 5 can be provided, and in order to prevent clogging of the filters, the pore size is changed from a large pore size to a fine pore size. However, it is desirable that the minimum diameter of the purification filter 5 is 0.65 μm or less, which can capture many bacteria. In this embodiment, a solution for culturing large embryos is filtered at 10 L per minute using a total of three filters: a first filter 5a (pore size 25 - 10 μm), a second filter 5b (pore size 2 - 1 μm), and a third filter 5c (pore size 0.65 μm) with different pore sizes.

[0026] Also, in this embodiment, in order to be able to replace the purification filter 5 without stopping the circulation of the solution for culturing large embryos, each of the first filter 5a, the second filter 5b, and the third filter 5c is provided with two filters of the same pore size in parallel. As a result, each of the first filter 5a, the second filter 5b, and the third filter 5c is in a state where it can be replaced without stopping the circulation even if an accident occurs where one of the two filters becomes clogged.

[0027] Since large embryos originally grow in eggs or the uterus where there are no bacteria, in order to make the inside of the large embryo culturing container 1 approach a sterile state, an ultraviolet sterilization device 6 is provided to sterilize viruses that cannot be captured by the purification filter 5 and bacteria that have passed through the purification filter 5. The filtered bacteria generated by the first filter 5a are removed and sterilized by the second filter 5b, the third filter 5c, and the ultraviolet sterilization device 6. Agents such as bactericides and antibacterial agents cannot be used because they have a significant adverse effect on the embryos and the device internal environment. Therefore, in this embodiment, a filter that physically removes bacteria with little impact on the embryos and the device internal environment, and ultraviolet sterilization with little local impact on the solution for culturing large embryos are performed.

[0028] In addition, in order to maintain the aseptic state inside the large embryo breeding container 1, the circulation volume of the large embryo breeding solution is set to about 320 turns per day (the amount that is replaced 320 times a day. Considering that it is 24 - 50 turns in normal fish breeding, it is about 7 - 13 times.). High circulation is being carried out.

[0029] In this embodiment, the large embryo breeding solution is filtered by a third filter 5c with a pore size of 0.65 μm that can finally remove many bacteria, and then bacteria and viruses that have passed through the third filter 5c are sterilized by an ultraviolet sterilizer 6. If the purification filter 5 and the ultraviolet sterilizer 6 are not used, bacteria of 10 5 / mL or more will occur in the large embryo breeding solution within a few days. However, when a purification filter 5 (third filter 5c) with a pore size of 0.65 μm and an ultraviolet sterilizer 6 were provided, according to the test results using a simple medium for measuring the number of bacteria in urine (trade name "Uricult E"), no bacteria were detected in the large embryo breeding solution.

[0030] In addition, nitrite nitrogen generated by filtered bacteria was detected in the large embryo breeding solution that passed through the purification filter 5, but nitrite nitrogen was not detected in the large embryo breeding solution that did not pass through the purification filter 5. This is presumably because due to the biological filtration function of the purification filter 5, nitrification occurs in which toxic ammonia nitrogen is changed into a more safe nitrogen compound.

[0031] In this embodiment, a flow meter 7 for keeping the flow rate constant and a pump 8 for circulating the large embryo breeding solution are provided. The pump 8 has a high discharge pressure considering its resistance in order to pass through the third filter 5c with a pore size of 0.65 μm, and a high - lift magnetic pump with a high discharge pressure is used to keep the large embryo breeding solution clean. The magnetic pump has a driving part made of a resin with very low solubility and is completely isolated from the large embryo breeding solution, so it has a structure that can maintain the cleanliness of the large embryo breeding solution.

[0032] In this embodiment, a bypass pipe that returns to the water return tank 3 is piped between the first filter 5a and the second filter 5b. This is to breed filter bacteria in the first filter 5a, and when circulating the large embryo rearing solution through the first filter 5a, not only physically remove harmful substances in the large embryo rearing solution, but also make it possible to be utilized as a biological filtration filter that decomposes harmful substances. By enabling the first filter 5a to be utilized as a biological filtration filter, an increase in ammonia nitrogen is reduced.

[0033] Next, a method for rearing large embryos of the skate, Raja pulchra, which is a yolk-dependent viviparous fish, will be described.

[0034] The large embryos are reared in a large embryo rearing container 1 whose inner surface is formed into a smooth surface or a villous shape. The top surface of the large embryo rearing container 1 is open, and the opening is covered with a net. From this opening, the large embryo rearing solution is allowed to naturally flow in and out, and the large embryo rearing solution is filled and drained. The temperature of the large embryo rearing solution is adjusted to 12°C. Also, the large embryos are always reared in a state where the large embryo rearing solution is circulating.

[0035] The large embryo rearing solution used was a mixture of seawater and fresh water at a ratio of 1:0.86, with 35 g of urea dissolved per liter. Note that it is desirable to dissolve 30 to 60 g of urea per liter in the large embryo rearing solution, which is a mixed solution of seawater and fresh water at a ratio of 1:0.86. Furthermore, when the ratio of the mixed solution of seawater and fresh water in the large embryo rearing solution is 1:0.7 to 1, 32 to 38 g of urea can also be dissolved per liter.

[0036] The substances in seawater dissolved in the large embryo rearing solution are more than half of seawater. Also, the osmotic pressure of the large embryo rearing solution was made the same as that of seawater, 940 to 1,100 mOsm.

[0037] Water change is carried out by a water storage tank 4 for storing a large embryo breeding solution for water change. Although it is desirable to change the frequency and amount of water change according to the growth stage and fish species of large embryos, in this example, water change was carried out once every about 10 days, and a maximum of 110 L of large embryo breeding solution was used for each water change. While breeding large embryos, since the ammonia concentration in the large embryo breeding solution increases, the large embryo breeding solution was exchanged so that the ammonia concentration did not exceed 400 μg / dL.

[0038] In this way, a large amount of large embryo breeding solution is required for water change. However, as the breeding time progresses, not only nitrogen compounds such as ammonia nitrogen accumulate in the large embryo breeding solution, but bacteria also proliferate. In particular, in this example, since a large amount of urea is dissolved in the large embryo breeding solution, bacteria are likely to proliferate. Therefore, the purification filter 5 is used to remove bacteria in the large embryo breeding solution.

[0039] A plurality of purification filters 5 can be provided, and in order to prevent clogging of the filters, the pore size is changed from a coarse one to a fine one. However, it is desirable that the minimum diameter of the purification filter 5 is 0.65 μm or less for capturing many bacteria. In this example, a total of three filters, namely a first filter 5a (pore size 25 - 10 μm), a second filter 5b (pore size 2 - 1 μm), and a third filter 5c (pore size 0.65 μm) with different pore sizes were used to filter the solution for breeding large embryos at 10 L per minute.

[0040] In addition, in order to be able to replace the purification filter 5 without stopping the circulation of the large embryo breeding solution, each of the first filter 5a, the second filter 5b, and the third filter 5c is provided with two filters of the same pore size in parallel, so that even if an accident occurs where one of the two filters is clogged, it can be replaced without stopping the circulation.

[0041] Since large embryos originally grow in eggs or the uterus where there are no bacteria, in order to approximate the inside of the large embryo rearing container 1 to a sterile state, an ultraviolet sterilizer 6 is provided to sterilize viruses that cannot be captured by the purification filter 5 and bacteria that have passed through the purification filter 5. Thus, the filtered bacteria generated in the first filter 5a are removed and sterilized by the second filter 5b, the third filter 5c, and the ultraviolet sterilizer 6.

[0042] Also, in order to maintain the sterile state inside the large embryo rearing container 1, a high circulation of about 320 turns per day (the amount that is replaced 320 times a day. Considering that in normal fish rearing, it is 24 - 50 turns, it is about 7 - 13 times.) of the circulation amount of the large embryo rearing solution was performed.

[0043] In this embodiment, the large embryo rearing solution is filtered through a third filter 5c with a pore size of 0.65 μm that can finally remove many bacteria, and then the bacteria and viruses that have passed through the third filter 5c are sterilized by the ultraviolet sterilizer 6. Without using the filtration by the purification filter 5 or the ultraviolet sterilizer 6, bacteria of 10 5 / mL or more will occur in the large embryo rearing solution within a few days. However, when a purification filter 5 (third filter 5c) with a pore size of 0.65 μm and an ultraviolet sterilizer 6 were provided, according to the test results using a simple medium for measuring the number of urinary bacteria (trade name "Uricult E"), no bacteria were detected in the large embryo rearing solution.

[0044] Also, nitrite nitrogen generated by filtered bacteria was detected in the large embryo rearing solution that passed through the purification filter 5, but nitrite nitrogen was not detected in the large embryo rearing solution that did not pass through the purification filter 5. This is considered to be because due to the biological filtration function of the purification filter 5, nitrification occurs in which toxic ammonia nitrogen is changed to a more safe nitrogen compound.

[0045] In this embodiment, a flow meter 7 and a pump 8 are provided to circulate the large embryo breeding solution while keeping the flow rate constant. In order for the pump 8 to pass through the 0.65 μm third filter 5c, considering its resistance, a high discharge pressure is set, and a high-lift magnetic pump with a high discharge pressure is used to keep the large embryo breeding solution clean. The magnetic pump has a structure in which the driving part is made of a resin with high insolubility and is completely isolated from the large embryo breeding solution, so the cleanliness of the large embryo breeding solution is maintained.

Explanation of symbols

[0046] 1 Large embryo breeding container 2 Water tank 3 Water changing tank 4 Water storage tank 5 Purification filter 5a First filter 5b Second filter 5c Third filter 6 Ultraviolet sterilizer 7 Flow meter 8 Pump

Claims

1. 1: A solution for rearing large embryos of chondrichthyes and some osteichthyes marine fish, in which urea is dissolved at 30 - 60 g / L in a mixed solution of seawater and fresh water at a ratio of 1:0.

86.

2. A large embryo rearing container for rearing large embryos, An aquarium for housing the large embryo rearing container, A solution for rearing large embryos, in which urea is dissolved at 30 - 60 g / L in a mixed solution of seawater and fresh water at a ratio of 1:0.86, A return water tank for circulating, changing water, and aerating the solution for rearing large embryos, A water storage tank for storing the solution for rearing large embryos for water change, A purification filter for removing bacteria in the solution for rearing large embryos to purify water quality, An ultraviolet sterilization device for sterilizing bacteria in the solution for rearing large embryos, comprising A large embryo rearing device for chondrichthyes and some osteichthyes marine fish, characterized by the above.

3. A large embryo rearing container for rearing large embryos, with its inner surface formed into a smooth surface or a villous shape, An aquarium for housing the large embryo rearing container, A solution for rearing large embryos, in which urea is dissolved at 30 - 60 g / L in a mixed solution of seawater and fresh water at a ratio of 1:0.86, A return water tank for circulating, changing water, and aerating the solution for rearing large embryos, A water storage tank for storing the solution for rearing large embryos for water change, A purification filter for removing bacteria in the solution for rearing large embryos to purify water quality, A sterilization device for sterilizing bacteria in the solution for rearing large embryos, comprising a large embryo rearing device for chondrichthyes and some osteichthyes marine fish, characterized by the above.

4. A large embryo rearing container for rearing large embryos, with its inner surface formed into a smooth surface or a villous shape, An aquarium for housing the large embryo rearing container, A solution for rearing large embryos, in which urea is dissolved at 30 - 60 g / L in a mixed solution of seawater and fresh water at a ratio of 1:0.86, A return water tank for circulating, changing water, and aerating the solution for rearing large embryos, A water storage tank for storing the solution for rearing large embryos for water change, Two or more purification filters with different pore sizes for removing bacteria in the solution for rearing large embryos to purify water quality, An ultraviolet sterilization device for sterilizing bacteria in the solution for rearing large embryos, comprising a large embryo rearing device for chondrichthyes and some osteichthyes marine fish, characterized by the above.

5. A large embryo rearing container for rearing large embryos, with its inner surface formed into a smooth surface or a villous shape, An aquarium for housing the large embryo rearing container, ​ 1. A solution for rearing large embryos in which urea is dissolved at 30 to 60 g / L in a mixed solution of seawater and fresh water at a ratio of 1:0.86, and a water-changing tank for changing the water of the solution for rearing large embryos, a water storage tank for storing the solution for rearing large embryos for water change, two or more purification filters with different pore sizes for removing bacteria in the solution for rearing large embryos, a biological filtration filter for removing bacteria in the solution for rearing large embryos, an ultraviolet sterilizer for sterilizing bacteria in the solution for rearing large embryos, comprising a device for rearing large embryos of chondrichthyes and some osteichthyes marine fish, characterized in that.

6. In a large embryo rearing container for rearing large embryos, the inner surface of which is formed into a smooth surface or a villous shape, in a mixed solution of seawater and fresh water at a ratio of 1:0.86, a solution for rearing large embryos in which urea is dissolved at 30 to 60 g / L, while periodically changing the water, the bacteria in the solution for rearing large embryos are removed and sterilized by a purification filter and an ultraviolet sterilizer and circulated. A method for rearing large embryos of chondrichthyes and some osteichthyes marine fish, characterized in that.

7. In a large embryo rearing container for rearing large embryos, the inner surface of which is formed into a smooth surface or a villous shape, in a mixed solution of seawater and fresh water at a ratio of 1:0.86, a solution for rearing large embryos in which urea is dissolved at 30 to 60 g / L, while periodically changing the water, by two or more purification filters with different pore sizes, a biological filtration filter, and an ultraviolet sterilizer the bacteria in the solution for rearing large embryos are removed and sterilized and circulated. A method for rearing large embryos of chondrichthyes and some osteichthyes marine fish, characterized in that.

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