JP2018121578A - Oyster seedling collection method and aquaculture method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oyster seedling collection method that can stably perform oyster seedling collection, and in addition to that, can reduce a labor required for artificial management, and further can suppress an amount of bait to be artificially given to oyster larvae to suppress cost.SOLUTION: An oyster seedling collection method is provided in which oyster larvae are bottomed in a seedling-collection device to collect seedlings. The oyster seedling collection method is configured to pass through an initial breeding step of putting the oyster larvae in the seawater being kept in an initial breeding shielded pool with a partition wall formed of an impermeable material and breeding the oyster larvae in the initial breeding shielded pool until the oyster larvae become a predetermined size; and a bottoming step of immersing a bottoming filter-type pool with a partition wall being formed by using a filter material having a mesh of the size where the oyster larvae passing through the initial breeding step cannot pass while passing phytoplankton in the sea, and putting the seedling-collection device and the oyster larvae passing through the initial breeding step in the seawater being kept in the bottoming filter-type pool to thereby bottom the oyster larvae in the seedling-collection device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oyster seedling method in which an oyster larva is grounded on a seedling device for seedling, and an oyster culture method for culturing oysters using the seeded seed oysters.

  Cultured oysters (oysters) are generally harvested through a process called “seedling”, a process called “suppression”, and a process called “main farming (carp culture)”. Here, “seedling” means that a seedling device (scallop shell is often used) is submerged in the summer sea where oyster larvae drift, and the oyster larvae adhere to the seedling device (bottoming). ). “Suppression” refers to the growth of oysters by placing a seedling device after seedling in shallow water with tides and limiting the time that oysters attached to the seedling device are immersed in seawater. This is a process of suppressing oysters from becoming too large and imparting oysters with resistance to environmental changes. Furthermore, “main aquaculture (acupuncture aquaculture)” is a process of suspending a seedling device after restraint in the sea from a salmon or the like floating in a sea area rich in nutrients to grow oysters attached to the seedling device. In addition to requiring a period of about one year for “suppression”, “main aquaculture (carp culture)” also requires a period of more than one year. It takes more than a year.

  By the way, in Hiroshima Prefecture, which boasts the top oyster production nationwide, oyster production has been decreasing in recent years due to poor harvesting of seedlings. According to Hiroshima statistical data, oyster production in Hiroshima was 21,200 tons in 2013, but was 18,700 tons in 2014, and 17,100 tons in 2015 It has become. The statistics for FY2016 are unknown, but it is expected that the values will be even more severe considering that some of the seedlings in FY2014 two years ago fell to about 10% of the average year. Yes. Abnormal trends in harvesting seedlings can be seen not only in Hiroshima Prefecture but also in other oyster production areas. There are various theories as to why seedlings are starting to malfunction. Due to global warming and the accompanying abnormal weather, phytoplankton in the aquaculture area has decreased and the current in the aquaculture area has changed. Is said to be influential. For this reason, it is necessary to be able to carry out oyster seedling efficiently and stably without being affected by the environment such as the weather.

  In this regard, Patent Document 1 discloses an oyster culture method, an artificial fertilization process for fertilizing oyster sperm and eggs, a fertilized egg raising process for growing a fertilized egg in a water tank until it becomes a larva, and a larvae. A seeding process for making seed oysters by attaching them to oyster powder (crushed oyster shells into powder), and a primary culture process for growing seed oysters into adult oysters (about 4-6 mm in size) in the aquarium It has been proposed that the adult oyster that has undergone the primary aquaculture process undergoes a secondary aquaculture process that further grows in an aquaculture cage in the sea (see claim 1 and paragraphs 0010 to 0015 of the same document). This document also states that by adopting this aquaculture method, the process until the oyster becomes 4-6 mm in size can be carried out on land facilities that are not affected by weather changes. (See paragraphs 0008 and 0016 of the same document).

JP 2008-206437 A

  However, the oyster culture method described in Patent Document 1 keeps the temperature of the aquarium at an appropriate temperature or feeds phytoplankton for several weeks until the oyster becomes about 4 to 6 mm in size. For example, it is necessary to perform human management (see paragraph 0013 of the same document). During this time, a large amount of food is required. In addition, the oyster larvae cannot produce the cement material necessary for bottoming until about 17 μm after fertilization and the size reaches about 300 μm, but only a few hours have passed since fertilization. In the culture method of Patent Document 1 in which larvae are attached to oyster powder and immersed in an aquarium as it is, there is a question as to whether oyster larvae will grow properly until they become adults.

  The present invention has been made to solve the above-mentioned problems, and in addition to being able to stably oyster seedling without being affected by the environment such as the weather, it is possible to artificially manage temperature management and the like. It is an object of the present invention to provide a method for collecting oysters, which can reduce the labor required for proper management, and can also reduce the cost by reducing the amount of food artificially given to oyster larvae. It is also an object of the present invention to provide a method for collecting oysters that can appropriately grow oysters in a suppression process and a main culture (carp culture) process that can be performed after seedling. Furthermore, it is also an object of the present invention to provide a method for culturing oysters that cultivates oysters using seed oysters that have been seeded by the seedling method.

The above issues
A oyster seedling method in which oyster larvae are grounded on a seedling device to collect seedlings,
Oyster larvae (including eggs) are put in seawater stored in a shielded pool for initial breeding with a partition wall made of water-impermeable material, and the oyster larvae until the oyster larvae reaches a predetermined size. An initial growth process for growing oyster larvae in a shield pool for initial growth;
A filter-type pool for bottoming in which partition walls are formed with a filter material having an eye size that cannot pass oyster larvae that have passed through the initial growth process while passing through the phytoplankton is immersed in the sea, and the filter-type pool for bottoming Put the seedling device and the oyster larvae that have undergone the initial growth process into the seawater stored in the seawater (the oyster larvae that have also passed through the latter part of the construction process and the selection process, as will be described later) This is solved by providing a method for seedling oysters, characterized in that it includes a bottoming step of bottoming oyster larvae on a seedling device.

  In the oyster seedling method of the present invention, as described above, the oyster larvae are grown in the shield pool for initial growth until they reach a predetermined size, and then the oyster larvae are further grown by replacing with the filter-type pool for bottoming. It has become a bottom. Each of the above-described initial growth shielding pool and bottoming filter pool has a structure in which oyster larvae cannot escape to the outside. For this reason, it is possible to increase the number of oyster larvae that settle on the seedling device and to perform seedling in a state that is not easily affected by the environment such as the weather. In addition, oyster larvae in the early stage of growth (during the initial breeding process) can grow without artificial feeding, so there is no need to feed in the initial breeding process. In addition, since the bottoming step after the initial growing step is performed in a filter-type pool for bottoming having a structure in which phytoplankton serving as a bait can invade, it is not necessary to artificially supply a large amount of bait. Therefore, the amount of artificially fed food can be greatly reduced. In addition, not only phytoplankton but also seawater can enter the filter pool for bottoming (if phytoplankton can invade, water molecules smaller than that can naturally enter), so The temperature of the seawater in the bottoming filter type pool is naturally adjusted according to the temperature of the external seawater. For this reason, it is also possible to reduce the trouble of managing the temperature of seawater. Furthermore, since the oyster larvae that have grown to a predetermined size in the initial growing process are grown in the bottoming filter type pool, the size of the filter material forming the partition wall of the bottoming filter type pool is increased to some extent. Is possible. For this reason, it is also possible to use a bottomed filter-type pool that is not easily clogged and easy to maintain.

  In the oyster seedling method of the present invention, the specific time for finishing the initial growing process is not particularly limited. However, as already mentioned, oyster larvae can reach the bottom only about 17 days after fertilization, where the size is around 300 μm, so before that, it is necessary to finish the initial growth process There is. In this regard, it is preferable to finish the initial growth process when 5 to 15 days have passed after fertilization. This is because, if it is about 5 to 15 days after fertilization, the oyster larvae can grow without artificial feeding (the oyster larvae themselves have been put in a nutrient pool or an initial breeding shield pool for their initial growth) This is because it can grow only with nutrients from seawater. Oyster larvae are usually about 100 μm 5 days after fertilization and about 200 μm 15 days after fertilization. For this reason, the condition “when 5 to 10 days have passed since fertilization” can be roughly rephrased as “when the oyster larva becomes 100 to 200 μm in size”.

In the oyster seedling method of the present invention, as described above, the filter material forming the partition wall of the filter-type pool for bottoming cannot pass oyster larvae that have undergone the initial growing process while passing the phytoplankton. It is assumed that the eye has a size. In this respect, the size of the phytoplankton serving as the food for the oyster larvae is approximately 10 μm. For this reason, the opening of the filter material is usually 10 μm or more. However, if the opening of the filter material is too small (too close to the size of the phytoplankton), the phytoplankton may not easily enter the inside of the filter pool for bottoming, and the filter material may easily clog. There is a fear. For this reason, the opening of the filter material is preferably 50 μm or more, and more preferably 80 μm or more. On the other hand, switching from the initial growth step to the bottoming step needs to be performed before the growth to a size of about 300 μm that allows the oyster larvae to bottom. For this reason, the opening of the filter material is usually set in a range not exceeding 300 μm. However, if the opening of the filter material is too large (too close to the size of the oyster larvae at the bottom), it will be necessary to perform the initial growth process for a long period of time. Oyster larvae may be undernourished. Moreover, there is a risk that the oyster larvae will easily escape to the outside of the bottomed filter-type pool. For this reason, the aperture of the filter material is preferably 200 μm or less, and more preferably 150 μm or less. The filter material having such an opening has a water permeability coefficient and is generally in the range of 0.5 × 10 ⁻² to 1 × 10 ⁻² cm / s.

  In the oyster seedling method of the present invention, the material of the filter material forming the partition wall of the bottoming filter-type pool is not particularly limited as long as the above-described opening can be realized. As the filter material, various knitted fabrics, woven fabrics, nonwoven fabrics, and the like can be suitably used. Among these, the shrink sheet which heated the surface of the nonwoven fabric which consists of a fiber of a thermoplastic resin can be used suitably as a filter material. This is because this type of shrink sheet is small in size because the fibers are shrunk on the heat-treated surface, but a large gap remains in the middle of the thickness direction. The seawater and phytoplankton that have entered the midway can move in all directions. For this reason, such a shrink sheet is unlikely to be completely clogged. Moreover, since the surface of a shrink sheet is smooth compared with the nonwoven fabric which is not heat-processed, it has the advantage that a seaweed, a floating dust, etc. do not adhere to the surface easily. The shrink sheet may be heat-treated only on one side of the non-woven fabric, but it is more preferable that both sides are heat-treated.

In the oyster seedling method of the present invention, it may be allowed to shift directly from the initial growth step to the bottoming step,
Between the initial growth process and the bottoming process,
A late growth filter type pool in which partition walls are formed with a filter material having an eye size that cannot pass oyster larvae that have passed through the initial growth process while passing through the phytoplankton is immersed in the sea, and the late growth filter type pool A late-stage growing process in which oyster larvae are put into seawater stored in the larvae, and the oyster larvae are grown in the latter-stage growing filter type pool until the oyster larvae has a predetermined size larger than that after the initial growing process,
A sorting step of applying oyster larvae that have undergone the late growth process to a filter material for sorting, and sorting oyster larvae that have grown to a size that does not pass through the filter material for sorting,
Provided,
It is preferable to transfer the oyster larvae sorted in the sorting step to the bottoming step.

  Thereby, it becomes possible to make the size of the oyster larvae subjected to the bottoming process more uniform, and to efficiently perform the bottoming of the oyster larvae to the seedling device. Therefore, it is possible to collect high quality seed oysters that are densely packed with oyster larvae of appropriate size.

  In the oyster seedling method of the present invention, it is also preferable to perform aeration of seawater in the shield pool for initial growth, the filter pool for late growth, and / or the filter pool for bottoming. This not only prevents mold from occurring in the initial growth shielded pool, late growth filter type pool and bottoming filter type pool, but also prevents oyster larvae from staying in the same place in those pools. It becomes possible. In particular, when aeration is performed in a filter-type pool for bottoming, it becomes possible to make it easier for oyster larvae to settle on the seedling device without bias. As will be described later, in the oyster seedling method of the present invention, since the initial growing process to the bottoming process is usually carried out with a kite floating in the sea, the power of the aeration apparatus (aeration means) for aeration is secured. It is difficult. For this reason, it is preferable that the aeration means is driven by a solar power generation panel or a wind power generator.

  As described above, according to the present invention, in addition to being able to stably harvest oysters without being affected by the environment such as the weather, it is possible to reduce the labor required for artificial management such as temperature management, Furthermore, it is possible to provide a method for collecting oysters that can reduce the cost by reducing the amount of food artificially given to oyster larvae. In addition, it is possible to provide a method for collecting oysters that can appropriately grow oysters in a suppression process and a main culture (carp culture) process that can be performed after seedling. Furthermore, it is also possible to provide a method for culturing oysters that cultivates oysters using the seed oysters seeded by this seeding method.

It is a flowchart explaining the cultivation method of the oyster which concerns on this invention. It is the figure which showed the example of arrangement | positioning of each pool in the cultivation method of the oyster which concerns on this invention. In the oyster culture method according to the present invention, it is a cross-sectional view showing a filter pool for bottoming when performing a bottoming step. It is a flowchart explaining the seedling collection process of other embodiment. It is the figure which showed the example of arrangement | positioning of each pool in the seedling raising process of other embodiment. It is the figure which showed the apparatus used at the selection process in the seedling process of other embodiment. It is the nonwoven fabric which forms the filter material used as partition walls, such as a filter type pool for bottoming, Comprising: It is the photograph which image | photographed the state before heat-processing. It is the nonwoven fabric which forms the filter material used as partition walls, such as a filter type pool for bottoming, Comprising: It is the photograph which image | photographed the state after heat-processing.

  A preferred embodiment of the oyster culture method of the present invention will be described more specifically with reference to the drawings. FIG. 1 is a flowchart for explaining a method for culturing oysters according to the present invention. As shown in FIG. 1, the oyster culture method of the present embodiment includes a seedling process, a suppression process, a main culture process (acupuncture culture process), and a harvesting process. Hereinafter, these steps will be described in order.

1. Seedling process (Seedling process of the first embodiment)
The seedling process is a process in which oyster larvae adhere (bottom) to a seedling device. As shown in FIG. 1, the present invention has the greatest feature in performing the seedling process in an initial growing process and a bottoming process. This seedling process is normally performed in the summer from June to August.

1.1 Initial growth process In the initial growth process, seawater is stored in an initial growth shielding pool 10 (Fig. 2) whose partition walls are formed of a water-impermeable material, and oyster larvae (of oysters just after fertilization are collected). Fertilized eggs) and for initial growth until the oyster larvae have a predetermined size (the size that cannot pass through the partition wall (filter material) of the filter pool 10 for bottoming used in the bottoming step described later). This is a process of growing oyster larvae in the shielding pool 10. In the oyster culture method of this embodiment, the initial growing process is performed while aeration apparatus (not shown) aeration of the seawater in the initial growing shielding pool 10. This not only prevents mold from occurring in the initial growing shield pool 10, but also prevents oyster larvae in the initial growing shield pool 10 from staying in the same place. The aeration apparatus is normally driven by electric power. However, in the oyster cultivation method of this embodiment, the aeration apparatus is connected to a photovoltaic power generation panel (not shown).

  The acquisition method of the oyster larvae put in the initial growth shielding pool 10 in the initial growth process is not particularly limited. Although oyster larvae collected from natural waters can be used, it is very difficult to collect large amounts of oyster larvae from natural waters. For this reason, the oyster culture method of this embodiment used oyster larvae (fertilized eggs) obtained by artificial insemination. Thereby, a large amount of oyster larvae required for seedling can be secured. Artificial insemination of oysters includes an incision method and a spawning induction method. In the oyster culture method of this embodiment, filtered seawater is placed in a bucket, and eggs and sperm collected from the adult oyster by the incision method are used in the bucket. Fertilized by placing it in the sea water. A bucket for artificial insemination was stimulated by adding ammonia. The size of oyster larvae (eggs) immediately after fertilization is usually around 55 μm.

  The initial growth shielding pool 10 used in the initial growth process has a partition wall made of a water-impermeable material, so that the seawater inside does not leak to the outside, as well as the initial growth shielding type. The structure is such that oyster larvae (fertilized eggs of oysters around 55 μm) placed in the pool 10 cannot escape to the outside. By performing this initial growing process, the size of the partition wall (filter material) of the bottoming filter-type pool used in the bottoming process, which will be described later, is increased to some extent, so that the partition wall (filter) of the bottoming filter-type pool It is possible to prevent the oyster larvae during the bottoming process from escaping from the inside to the outside of the bottoming filter-type pool, even if the material is not easily clogged.

  The installation location of the initial breeding shielding pool 10 is not particularly limited, and the initial breeding shielding pool 10 may be installed on land. However, the bottoming process performed after the initial growing process is performed at sea. However, if the initial growing process is performed on land, the switching operation from the initial growing process to the bottoming process cannot be performed smoothly. Moreover, it takes time and effort to put seawater in the shielding pool 10 for initial growth. For this reason, in the oyster culture method of this embodiment, the shield pool 10 for initial growth which performs an initial growth process is installed in the sea. Specifically, as shown in FIG. 2, the initial growing shield type pool 10 is installed in the same basket 30 as the one where the bottoming filter type pool 20 in which the bottoming process is performed is installed. FIG. 2 is a view showing an arrangement example of the pools 10 and 20 in the oyster culture method according to the present invention. In FIG. 2, the shielding pool 10 for initial growth is drawn inside the filter type pool 20 for bottoming, but the filter type pool 20 for bottoming is not yet installed in the basket 30 in the initial growth process. . This will be described later. The initial breeding shield pool 10 is open at the top of the sea (above the sea), but the bottom is submerged in the sea. A plurality of initial breeding shielding pools 10 are provided in each ridge 30. These initial breeding shielding pools 10 are selectively used according to the time when the seedling process is started.

  The partition (impermeable material) of the initial growth shielding pool 10 is not particularly limited as long as it does not have water permeability, and may be formed of a hard material. However, when the partition walls of the initial growth shielding pool 10 are formed of a hard material, the cost required for transportation, installation, and disposal of the initial growth shielding pool 10 increases. For this reason, it is preferable to form the partition (water-impermeable material) of the shielding pool 10 for initial growth with a sheet material (water-impermeable sheet). As the water-impermeable sheet forming the initial growth shielding pool 10, various resin sheets and the like having no openings can be suitably used. In the oyster culture method of this embodiment, the partition walls of the initial growth shielding pool 10 are formed by a resin sheet (so-called blue sheet (tarp)) in which a fabric knitted with flat yarn is sandwiched between synthetic resin films. .

However, if the initial growth shielding pool 10 is installed in a state where a flexible sheet material such as a water-impermeable sheet is suspended in the sea, the initial growth shielding pool 10 is likely to fluctuate due to waves or ocean currents. Become. For this reason, a water-impermeable sheet can be supported with respect to support materials, such as a mesh material and a frame material, or a weight can also be attached to a water-impermeable sheet. Capacity of the initial development for shielded pool 10 is not particularly limited, usually about 1-30 m ^3, and preferably, about 5 to 20 m ^3. In the method for culturing oysters of this embodiment, as the initially cultivated shielding pool 10, a vertically long 1.7 m long, 3.5 m wide, and 1.7 m depth (height) is used. . As shown in FIG. 2, the end portion of the initial growth shielding pool 10 is formed in a round shape, and when an aeration process described later is performed, oyster larvae are formed at the corners of the initial growth shielding pool 10. Without stagnating, the inside of the initial growing shield pool 10 is smoothly circulated. The partition walls (water-impermeable sheet) of the shielding pool 10 for initial growth may have a single layer structure (single layer structure), but may also have a multilayer structure (multiple structure). As a result, the shape retention of the initial growth shielding pool 10 is improved, and even if any layer is torn or the like, the oyster larvae in the initial growth shielding pool 10 do not escape to the outside. It becomes possible.

  The initial growth process described above allows oyster larvae to grow without artificially feeding them (growth with only the nutrients the oyster larvae themselves have or the nutrients of seawater previously placed in the shield pool 10 for initial growth) Preferably) within a period. Specifically, when about 5 to 15 days have passed since fertilization (in other words, when the size of the oyster larvae becomes 100 to 200 μm), it is preferable to finish the initial growth step, and about 5 to 10 days after fertilization. It is more preferable to finish the initial growing step when the time elapses (in other words, when the size of the oyster larva becomes 100 to 150 μm). This eliminates the need for artificial feeding in the initial growing process. In the oyster culture method of the present embodiment, as will be described later, as the filter-type pool for bottoming used in the bottoming step, a filter material having an opening of about 100 μm is used as the partition wall. By the way, the initial growing process is finished at the timing when the oyster larvae has a size of about 150 μm (the timing when 10 days have passed after fertilization).

1.2 Bottoming process As shown in FIG. 3, the bottoming process is performed by immersing the bottoming filter-type pool 20 whose partition walls are formed of the filter material 21 in the sea and collecting the bottomed filter-type pool 20 in the bottoming filter-type pool 20. The seedling device 40 and the oyster larvae that have undergone the initial growth process are put into the seawater, and the oyster larvae are settled on the seedling device 40. FIG. 3 is a cross-sectional view showing the bottoming filter-type pool 20 during the bottoming step in the oyster culture method according to the present invention.

  The bottoming filter-type pool for performing the bottoming step is installed in a sea with a lot of nutrients (phytoplankton) (at least so that its lower side is in the sea). The bottoming filter-type pool 20 is usually installed in a state where the upper part thereof is opened on the sea (above the sea) and the lower part thereof is submerged in the sea, like the initial growth shielding-type pool 10. A plurality of bottoming-type filter-type pools 20 are provided in one cocoon 30 so as to be selectively used according to the time when the seedling process is started. The bottoming filter-type pool 20 may be set in advance in the basket 30, but in this case, the period during which the bottoming filter-type pool 20 is immersed in seawater becomes long, and the bottoming filter-type pool 20 The risk of clogging the filter material 21 forming 20 increases. For this reason, in the oyster culture method of this embodiment, the bottoming filter-type pool 20 is constructed at the timing when the initial growth process is completed. Specifically, the construction of the bottomed filter-type pool 20 is performed as follows.

  That is, by covering the outside of the initial growth shielding pool 10 after the initial growth process with the filter material 21, the bottoming filter pool 20 is constructed. The initial growth shielding pool 10 is removed after the bottoming filter pool 20 is constructed on the outside thereof. The removal work of the initial growth shielding pool 10 is carried out by using a water-impermeable sheet forming the initial growth shielding pool 10, and seawater (oyster larvae in the seawater) accumulated in the interior of the impervious sheet 20 for bottoming. It is done by slowly pulling up so that it does not leak outside. Thereby, it is possible to efficiently transfer oyster larvae from the initial growth shielding pool 10 that performs the initial growth process to the bottom filter type pool 20 that performs the bottom formation process.

The capacity of each bottoming filter-type pool 20 is usually about 1 to 50 m ³ , and preferably about 5 to ³⁰ m ³ . In the oyster culture method of the present embodiment, as described above, the bottoming filter-type pool 20 is constructed in such a manner that the bottoming filter-type pool 20 is constructed so as to surround the outside of the initial growth shielding-type pool 10. The capacity is usually larger than the capacity of the initial breeding shielding pool 10. In the oyster culture method of the present embodiment, the bottomed filter-type pool 20 has a vertical length of 1.8 m, a horizontal length of 3.8 m, and a depth (height) of 1.8 m. The one having a capacity of 3 m ³ is used.

  The partition wall (filter material 21) of the bottom-flooring filter-type pool 20 passes phytoplankton (usually having a size of about 10 μm) that feeds oyster larvae while passing through the initial growth process ( In the oyster culture method of this embodiment, the oyster is grown until it reaches a size of about 150 μm in the initial growth step. In addition, the bottoming filter-type pool 20 is in a state where at least the lower side thereof is immersed in the sea. Therefore, natural phytoplankton floating in the sea around the bottoming filter type pool 20 can enter the inside of the bottoming filter type pool 20. It is now possible to avoid feeding artificially. Further, seawater can naturally enter and exit from the inside and outside of the bottoming filter-type pool 20, and waste products of oyster larvae are naturally discharged out of the bottoming filter-type pool. Therefore, it is not necessary to perform maintenance such as replacement of seawater in the bottom filter type pool 20.

  As long as the partition wall (filter material 21) of the bottoming filter-type pool 20 has the above filter property, the material is not particularly limited, and may be formed of a hard material. However, if the partition wall of the bottoming filter-type pool 20 is formed of a hard material, the cost required for transportation, installation, and disposal of the bottoming-type filter pool 20 increases. For this reason, it is preferable to form the partition wall (filter material 21) of the bottomed filter-type pool 20 with a sheet material (filter sheet). As the filter sheet used for the filter material 21, a shrink sheet obtained by heating the surface of a nonwoven fabric made of thermoplastic resin fibers is suitable as described above. Examples of the thermoplastic resin forming the nonwoven fabric include polyolefins such as polypropylene (PP) and polyethylene (PE). Among these, polypropylene is preferable because it is not only inexpensive but also excellent in strength.

In the oyster culture method of this embodiment, as shown in FIG. 7, the front and back of a nonwoven fabric made of polypropylene fibers (nonwoven fabric having a water permeability of 1.17 × 10 ⁻² cm / s and a basis weight of about 190 g / m ² ). As shown in FIG. 8, a filter sheet (shrink sheet) that has been subjected to heat treatment on both sides is used as the filter material 21. FIG. 7 is a photograph of a non-woven fabric that forms the filter material 21 used as a partition wall for the bottoming filter-type pool 20 and the like before the heat treatment. FIG. 8 is a photograph of a non-woven fabric forming the filter material 21 used as a partition wall for the bottoming filter-type pool 20 and the like after the heat treatment. This filter material 21 has an opening of about 100 μm on the front surface and back surface (water permeability coefficient after heat treatment is about 7.23 × 10 ⁻³ cm / s), and is in the filter type pool 20 for bottoming. While the oyster larvae that have been put in have an eye size that can not pass through, in the middle of the thickness direction, a large gap is still formed by fibers that are not shrunk, the middle part Seawater and phytoplankton that have invaded can be moved in all directions, making clogging less likely. Although the thickness of the filter material 21 is not specifically limited, Usually, it is about 100 micrometers-2 mm. The thickness of the filter material 21 used in the oyster cultivation method of this embodiment is about 400 μm.

  However, if the bottomed filter-type pool 20 is installed with the filter material 21 having flexibility such as a filter sheet suspended in the sea, as in the case of the shield pool 10 for initial growth, waves, ocean currents, etc. As a result, the bottom filter-type pool 20 is likely to fluctuate. For this reason, a filter sheet etc. can be supported with respect to support materials, such as a mesh material and a frame material, or a weight can also be attached to a filter sheet etc. In particular, as shown in FIG. 3, when the outside of the filter material 21 such as a filter sheet is covered with a mesh material 60 having a mesh size of about several mm, barnacles and the like can be prevented from adhering to the filter material 21. The partition wall (filter sheet) of the bottoming filter-type pool 20 may have a single layer structure (single layer structure) or a multilayer structure (multiple structure).

  By the way, the seedling device 40 to be placed in the bottoming filter-type pool 20 in the bottoming step is not particularly limited as long as oyster larvae can be established. In conventional oyster culture methods, shells such as scallops are often used as the seedling device 40. Also in the oyster culture method of this embodiment, the scallop shell is used as the seedling device 40. Specifically, as shown in FIG. 3, the bottomed filter-type pool 20 is formed by connecting several other scallop shells (seedling device 40) with a wire 50 such as a wire at an interval of about 2 cm. It is hung in the sea water inside. A scallop shell (seedling device 40) connected by a wire 50 is called a "seedling series".

  In the oyster cultivation method of this embodiment, the bottoming step is performed while aeration of seawater in the bottoming filter-type pool 20 is performed by an aeration apparatus (not shown). This not only prevents mold from being generated in the bottoming filter-type pool 20, but also stimulates the oyster larvae so that the oyster larvae in the bottoming process do not stay in the same place, so that the oyster larvae become a seedling device. It is also possible to make it easy to fix without bias. The same aeration apparatus as that used in the initial growth step is usually used. It is the same as that of an initial growth process that this aeration apparatus is connected to the photovoltaic power generation panel.

  The bottoming process described above is performed until the oyster larvae settle in the seedling device 40. As already described, oyster larvae are usually in a state where they can put out the cement material necessary for bottoming when the size reaches around 300 μm after about 17 days after fertilization (bottoming). Is possible). For this reason, the bottoming process usually needs to be performed until about 17 days after fertilization elapses. In order to increase the certainty that the oyster larva settles on the seedling device 40, the bottoming step is preferably performed until 18 days after fertilization, and more preferably 19 days after fertilization. It is more preferable to carry out until 20 days have passed. In the oyster culture method of this embodiment, as described above, when the bottoming process is started when 10 days have passed since fertilization, this bottoming process is performed until 20 days after fertilization has passed. Yes.

2. Suppression process The suppression process is a process of installing a seedling device after seedling in shallow water (tidal flat) where the tide is full. In the oyster culture method of this embodiment, a shelf called a “restraint shelf” installed in a tidal flat while the seedling device that has finished the seedling process is connected with a wire (in a state of seedling continuous) The restraining process is performed by suspending it on. By performing this suppression step, it is possible to limit the time during which the oysters attached to the seedling device are immersed in seawater. For this reason, while suppressing the growth of an oyster so that it may not become too large, it becomes possible to provide the oyster with resistance to environmental changes.

  The suppression process is usually started without a gap after completing the seedling process. The period for performing the suppressing step is not particularly limited. In old oyster farming, the duration of the suppression process was as short as about one month, but in recent oyster farming, the suppression process is often performed for about three months even if it is short, more than a year at most. . In the oyster culture method of the present embodiment, the suppression process is started from around June to August of the year in which the seedling process is performed, and is suppressed for about 8 to 9 months from around March to around April of the following year. The process is performed.

3. Main aquaculture process (carp culture process)
In this aquaculture process (acupuncture aquaculture process), the size of the seedling device that can be used to hang oysters attached to the seedling device (usually) And a shell length of about 70 to 90 mm). In the method for culturing oysters of this embodiment, shells to which oysters are well attached are selected from the seedling series that have finished the suppression step, and the shells are separated by new wires (wires, etc.) at intervals of about 20 cm. This aquaculture process is carried out by suspending a thing formed in a connected state (this state is referred to as a “droop”) from a coral underwater.

  This aquaculture process is usually started without a gap after the suppression process is finished. This aquaculture process is usually carried out over one year. In the oyster culture method of this embodiment, the main culture process is started from March to April of the year after the seedling process (second year), and from December of that year (second year). The main aquaculture process is carried out from the next year (third year) to around March.

4). Harvesting process The harvesting process is a process of harvesting oysters that have finished the main aquaculture process (aquaculture process). In the oyster culture process of this embodiment, the harvesting process is performed by lifting the drooping series suspended in the sea in the main culture process to the sea with a crane or the like. The harvesting process is usually performed from the end of October to January to the winter. Oysters that have finished the harvesting process are routed to later processes depending on the application.

5. Experiment An experiment was conducted to confirm whether the oyster cultivation method of the present invention can actually raise a seedling. The experiment was carried out by borrowing an aquaculture cage installed on the sea near Kurahashi Island in Hiroshima Prefecture. Experiments were carried out from 2015 to winter 2016 while changing various conditions. As a result, oyster larvae were put on the seedling device in good condition on September 3, 2016 under the conditions of the above-described embodiment. It was confirmed that it was bottomed.

6). Seedling process of other embodiment (second embodiment) By the way, oyster culture of the embodiment described above (the embodiment described with reference to FIG. 1; hereinafter may be referred to as “first embodiment”). In the method, in the seedling process, the initial growth process directly shifts to the bottoming process. However, another step can be provided between the initial growing step and the bottoming step in the seedling step, as shown in FIG. FIG. 4 is a flowchart for explaining a seed-seeking process of another embodiment (hereinafter, may be referred to as “second embodiment”). FIG. 5 is a diagram showing an arrangement example of each pool 10, 20, 90 in the seedling process of another embodiment (second embodiment). FIG. 6 is a view showing an apparatus used in a selection process in a seedling process of another embodiment (second embodiment).

  In the seedling process of the second embodiment, as shown in FIG. 4, a late growth process and a selection process are provided between the initial growth process and the bottoming process. Thereby, it becomes possible to make the size of the oyster larvae subjected to the bottoming process more uniform, and to efficiently perform the bottoming of the oyster larvae to the seedling device. Hereinafter, the seedling collecting process of the second embodiment will be described.

6.1 Initial breeding process In the seedling process of the second embodiment, the initial breeding process is performed using the initial breeding shielding pool 10 shown in FIG. The initial growing shielding pool 10 used in the initial growing process in the seedling process of the second embodiment is the same as the initial growing shielding pool 10 used in the initial growing process in the seeding process of the first embodiment described above. Because there is, detailed explanation is omitted. However, in the seedling process of the first embodiment, as shown in FIG. 2, one bottoming filter-type pool 20 corresponds to one initial growth shielding-type pool 10. In the seedling process of the second embodiment, as shown in FIG. 5, one bottoming filter-type pool 20 corresponds to two initial growing shielding-type pools 10. In FIG. 5, groups G _{1 to} G ₅ are groups in which the seedling process is started at the same time. In the present embodiment, first, the initial growth step starts with the initial development for shielded pool 10 belonging to the group G _1, followed by starting the initial growth step in the initial development for shielded pool 10 belonging to the group G ₂ and so on ... which, from the group G ₁ to the group G _5, are the initial training process to be started in order.

6.2 Late growth process In the late growth process, the oyster larvae that have finished the initial growth process are placed in the seawater stored in the filter pool 70 for late growth (Fig. 5), and the oyster larvae are placed after the initial growth process. This is a step of growing oyster larvae in the late growth filter-type pool 70 until the oyster larvae becomes a larger predetermined size (in this embodiment, until the oyster larvae have a size of about 230 μm). The late growth filter type pool 70 can adopt the same structure as the bottoming filter type pool 20 used in the seedling step of the first embodiment in the structure, dimensions, and the like. In this embodiment, the late growth filter type pool 70 is constructed by covering the outside of the initial growth shielding type pool 10 after the initial growth process with a filter material, and the construction method is also the first embodiment. It is the same as the filter type pool 20 for bottoming. For this reason, in this embodiment, one late growth filter type pool 70 corresponds to one initial growth shielding type pool 10.

6.3 Sorting process In the sorting process, the oyster larvae that have passed through the late growing process are applied to the filter material for sorting and have grown to a size that does not pass through the filter material for sorting (a size of about 230 μm in this embodiment). Is a process of sorting Oyster larvae sorted in this sorting process are transferred to the bottoming process. In the seedling process of the present embodiment, the selection process includes a first selection process and a second selection process as shown in FIG. The first sorting step is a step of sorting oyster larvae that have grown to a predetermined size (a size of around 230 μm). In addition, the second sorting step is a step of sorting oyster larvae that are less than a predetermined size (a size of about 230 μm) but have become somewhat large (oyster larvae larger than about 150 μm in this embodiment). It has become.

  Means for performing the first sorting step and the second sorting step are not particularly limited, but in the present embodiment, the first sorting step and the second sorting step are performed using the apparatus shown in FIG. In FIG. 6, the pump 100 is for sucking seawater (oyster larvae) from the late growth filter type pool 70. The pump 100 is driven by the electric power generated by the photovoltaic power generation panel as in the aeration unit described above. Seawater (oyster larvae) sucked up by the pump 100 is put into the upper part of the first sorting pipe 110. The first sorting pipe 110 is provided with a first sorting filter material 111 (in this embodiment, a filter material having a mesh size of 230 μm), and oyster larvae grown to a predetermined size (more than 230 μm). Largely grown oyster larvae) are captured on the upper side of the first sorting filter material 111 (part A in FIG. 6).

On the other hand, the seawater (oyster larvae) that has fallen to the lower part of the first sorting pipe 110 without being captured by the first sorting filter material 111 is the second that is disposed below the first sorting pipe 110. It enters the upper part of the sorting pipe 120 (arrow a _{2 in the} flowchart of FIG. 4). Inside the second sorting pipe 120, a second sorting filter material 121 (in this embodiment, a filter material having an opening of 150 μm) is provided and grows larger than the eyes of the second sorting filter material 121. The oyster larvae (oyster larvae grown larger than 150 μm) are captured on the upper side of the second sorting filter material 121 (B portion in FIG. 6). Oyster larvae that have not been captured by the second sorting filter material 121 fall from the lower part of the second sorting pipe 120 together with seawater. In this embodiment, oyster larvae falling from the lower part of the second sorting pipe 120 are discarded (released) into the sea (arrow a _{5 in} FIG. 4).

When the sorting process is performed using the above apparatus, oyster larvae larger than 230 μm are captured in the upper part A of the first sorting filter material 111, and the upper part B of the second sorting filter material 121 is captured. Is in a state where oyster larvae that have grown larger than 150 μm while not exceeding 230 μm are captured. The former oyster larvae (oyster larvae larger than 230 μm) are transferred to the bottoming filter-type pool 20 in FIG. 5 (see arrow a _{1 in} FIG. 4). In the seedling process of the first embodiment, the bottoming filter-type pool 20 is provided in a state of enclosing the outside of the initial growing shielding pool 10, but in the seedling process of the present embodiment, it is described above. As described above, since the late growth filter type pool 70 is provided outside the initial growth shielding pool 10, the bottoming filter type pool 20 is provided in another place near the initial growth shielding pool 10. ing. The first sorting pipe 110 and the second sorting pipe 120 have a separable structure, and the first sorting pipe 110 is separated from the second sorting pipe 120 and carried (the bottomed filter pool 20 Can be carried around).

On the other hand, the latter oyster larvae (oyster larvae having a size of 150 to 230 μm) are placed in the pre-growing filter-type pool 80 in FIG. 5 (arrow a _{3 in} FIG. 4). As described above, the first sorting pipe 110 and the second sorting pipe 120 have a separable structure, and the second sorting pipe 120 is separated from the first sorting pipe 110 and carried ( It can be carried to the filter-type pool 80 for preliminary growth). In this embodiment, the preliminary growing filter-type pool 80 uses the same structure and dimensions as the bottoming filter-type pool 20 used in the seedling process of the first embodiment described above. ing. In the preliminarily growing filter-type pool 80, oyster larvae are cultivated additionally (preliminary nurturing step) for a maximum of one week, usually two to three days. This makes it possible to bring the size of the oyster larva closer to a predetermined size (230 μm) at which the bottoming process should be started. In the present embodiment, the pre-growing filter-type pool 80 is common to the groups G _{1 to} G ₅ . For this reason, the period during which oyster larvae are grown in the pre-growth filter-type pool 80 (preliminary growth process) is set to be shorter than the period in which the start time is shifted in each of the groups G _{1 to} G ₅ . The oyster larvae that have finished the preliminary growing process are moved to the bottom-bottom filter-type pool 20 belonging to the next group, and the bottoming process is performed (arrow a _{4 in} FIG. ₄ ). For example, oyster larvae preliminary growing step is carried out in group G ₁ is bottom landing step in wearing bottom filter type pool 20 belonging to the group G ₂ is performed.

6.4 Bottoming Step In the seedling step of the second embodiment, the bottoming step is performed using the bottoming filter-type pool 20 shown in FIG. The bottoming filter-type pool 20 used in the bottoming step in the seedling step of the second embodiment has a size that is slightly larger, or is provided at a location different from the initial growth shielding-type pool 10. Since it is the same as the filter type pool 20 for bottoming used in the bottoming process in the seedling process of 1st embodiment except that it exists, detailed description is omitted.

10 Initial growth shielding pool 20 Bottoming filter pool 21 Filter sheet (filter material)
30 ４０ 40 Scallop shell (seedling device)
50 Wire material 60 Mesh material 70 Late growth filter type pool 80 Preliminary growth filter type pool 100 Pump 110 First sorting pipe 111 First sorting filter material 120 Second sorting pipe 121 Second sorting filter material

Claims (8)

A oyster seedling method in which oyster larvae are grounded on a seedling device to collect seedlings,
Oyster larvae are put in seawater stored in a shield pool for initial growth, in which a partition wall is formed with a water-impermeable material, and the oyster larvae are kept in the shield pool for initial growth until the oyster larva reaches a predetermined size. An initial training process for training;
A filter-type pool for bottoming in which partition walls are formed with a filter material having an eye size that cannot pass oyster larvae that have passed through the initial growth process while passing through the phytoplankton is immersed in the sea, and the filter-type pool for bottoming A method for seedling oysters, wherein a seedling device and oyster larvae that have undergone an initial growth process are placed in seawater stored in the seam, and a squirting process for bottoming the oyster larvae onto the seedling device is performed.
The method for collecting oysters according to claim 1, wherein the initial growing process is finished when 5 to 15 days have passed since fertilization.
The method for collecting oysters according to claim 1 or 2, wherein when the oyster larvae have a size of 100 to 150 µm, the oyster larvae are switched from the initial growing step to the bottoming step.
As a filter material forming the Chakusokoyo filter type pools of the partition wall, adoption of oysters according to any one of claims 1 to 3 permeability is used as the ^{0.5 × 10 -2 ~1 × 10 -2} cm / s Seedling method.
The method for collecting oysters according to any one of claims 1 to 4, wherein a shrink sheet obtained by heating the surface of a nonwoven fabric made of thermoplastic resin fibers is used as a filter material for forming a partition wall of a bottoming filter-type pool.
Between the initial growth process and the bottoming process,
A late growth filter type pool in which partition walls are formed with a filter material having an eye size that cannot pass oyster larvae that have passed through the initial growth process while passing through the phytoplankton is immersed in the sea, and the late growth filter type pool A late-stage growing process in which oyster larvae are put into seawater stored in the larvae, and the oyster larvae are grown in the latter-stage growing filter type pool until the oyster larvae has a predetermined size larger than that after the initial growing process,
A sorting step of applying oyster larvae that have undergone the late growth process to a filter material for sorting, and sorting oyster larvae that have grown to a size that does not pass through the filter material for sorting,
Provided,
The oyster seedling method according to any one of claims 1 to 5, wherein the oyster larvae selected in the selection step are transferred to the bottoming step.
The method for collecting oysters according to any one of claims 1 to 6, wherein aeration of seawater in the shield pool for initial growth, the filter pool for late growth and / or the filter pool for bottoming is performed.
  An oyster culture method for culturing oysters using the seed oysters seeded by the oyster seedling method according to claim 1.