JP2005333910A - Method for culturing shell such as oyster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for culturing oysters by increasing the dissolved amount of oxygen a close to natural state by generating fine bubbles. <P>SOLUTION: This method for culturing the oysters comprises partitioning a water region by spanning a protective net around culturing rafts from which the oysters are hung down, installing a bubble-ejecting port at the bottom of the partitioned water region and generating fine bubbles easy to fuse with water to aim at the enrichment of the dissolved oxygen within the partitioned water region and at protection from a foreign enemy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for culturing shellfish such as oysters, and more particularly to a method and apparatus for increasing the amount of dissolved oxygen in aquaculture water area.

In the past, oysters have been cultivated in the natural environment by culturing scallops and oyster shells with oyster larvae attached to the brackish water and seawater. However, in recent years, the amount of dissolved oxygen, etc., the red tide and the accompanying oxygen deficiency phenomenon have become problems, and as one of the countermeasures, oxygen supply by aeration has been attempted. Aeration from the bottom of the water is also being attempted. (See JP 2004-49980)
Japanese Unexamined Patent Publication No. 2004-49980 Japanese Patent No. 3156058 "Bubble" technology Use, make, and exclude Authors Hideki Tsuge, Satoshi Unno Publication Office Industrial Research Co., Ltd. Publication Date April 1, 2004 First edition first edition issued

However, oxygen supply by aeration is not an effective oxygen supply method because a large amount of bubbles are mixed in the water, and the buoyancy is increased and the air is released into the air in a short time. In addition, when bubbles from aeration are discharged from the bottom, vertical flow can be generated, but this bubble can lead to the occurrence of unnatural upflows or overflow areas. It is not. Provided is a method for culturing oysters that increases the amount of dissolved oxygen in a state close to nature by generating fine bubbles.

By arranging a protective net around the persimmon-cultured trough and partitioning the water area, installing a foam outlet at the bottom of the partitioned water area to generate fine bubbles that are easy to fuse with water, Enrich dissolved oxygen in the partitioned water area and protect it from external enemies.

By placing a protective net around the persimmon-cultured trough and partitioning the water area, the dissolved oxygen amount in the partitioned water area is stabilized and protected from external enemies, and at the bottom of this partitioned water area By installing a foam spout and generating fine bubbles that are easy to fuse with water, the amount of dissolved oxygen is increased, and photosynthesis is performed by algae attached to the net, thereby further enriching dissolved oxygen.

In the present invention, a protective net is stretched around an aquaculture cage where oysters are suspended to partition a water area, and fine bubbles are generated from a foam outlet installed at the bottom of the partitioned water area to generate dissolved oxygen. The amount is increased and oysters are raised.

Hereinafter, an oyster culture method for increasing the amount of dissolved oxygen in the aquaculture area according to the present invention and cultivating oysters according to the present invention will be described in detail. The present invention is not limited to the examples.

FIG. 1 is a schematic diagram of the present invention. By placing a protective net 8 around the cultivated trough 2 with oysters suspended and partitioning the water area, the dissolved oxygen amount in the partitioned water area is stabilized and protected from external enemies. By installing a foam jet 6 at the bottom and generating fine bubbles that are easy to fuse with water, the amount of dissolved oxygen is increased, and photosynthesis is performed by algae adhering to the protective net 8, further increasing the amount of dissolved oxygen. Oysters grow steadily.

Oysters 4 are suspended in the cultivated trough 2 by a pendant-type aquaculture method, with a phytoplankton-rich water depth of around 2 m, and a protective water net 8 is stretched around the persimmon 2 to form a cultured water area.

Protective net 8 is generally used in the fishery, but it prevents the outflow of fine bubbles generated in the aquaculture area, protects oysters from prey from black enemies, etc. Therefore, it is preferable to have a mesh of 2 cm square or less. In this case, due to the outflow of fine bubbles, oxygen is supplied to the surrounding water area beyond the bounded water area, leading to the generation of zooplankton.

In the drooping culture method, the oyster drooping should be about 2-4m in depth. Therefore, the protective net will be stretched to a depth of 4-5m. However, oysters are cultivated in brackish waters, and it is difficult to identify them in general, taking into account fluctuations in the water level due to tides and rivers. Nylon and dark colors are generally used as the material, but natural materials such as hemp and cotton are also selected in consideration of the adhesion of algae.

The method for cultivating shellfish according to the present invention partitions a water area using a protective net, and installs a foam outlet at the bottom of the partitioned water area to spout fine bubbles to increase dissolved oxygen in the water area. Is intended to foster When shellfish are cultivated on the seabed, the protective net must be specially installed so as not to escape from below. When following the oyster drooping culture method, it can be said that it is suitable to use a basket-like container that cannot escape.

The fine bubbles used in the present invention are obtained by using air compressed to a pressure of about 0.3 MPa on the surface of a breathable film formed by forming a craze on a polymer resin film mounted as a gas permeable material at the foam outlet 6. By pressurizing, the voids (fine pores) constituting the craze are expanded and forcibly ejected into water. Since the bubbles ejected from the foam outlet are as fine as about 5 to 50 μm, the coalescence and absorption of the bubbles are small, and therefore the presence of the bubbles is long and the dispersibility is excellent. Many will remain in the water in the form of single bubbles. It is known that the specific gravity increases within 10 minutes after the fine bubbles are generated, and the specific gravity decreases with the passage of time.

The polymer resin used as the material of the polymer resin film is not particularly limited as long as it is a thermoplastic resin capable of forming a film or a sheet. Examples of such thermoplastic resins include polyolefins, polyesters, polyamides, styrene resins, polycarbonates, halogen-containing thermoplastic resins, and nitrile resins. Among these thermoplastic resins, it is preferable to use polyolefins, polyesters, styrene resins, and halogen-containing thermoplastic resins from the viewpoints of moldability to films and sheets and economy. These thermoplastic resins may be used alone, combined and used as a composition, or may be blended with another polymer resin, and two or more types of resins may be multilayered. It may be used. In view of the ease of formation of crazes, it is desirable to use a resin having a glass transition temperature of −45 ° C. or higher, preferably −30 ° C. or higher, particularly preferably −15 ° C. or higher. When used as a composition or in a multilayered form, it is preferable that the glass transition temperature of the thermoplastic resin, which is the main component, is within the above range. In the case of a thermoplastic resin exhibiting a glass transition temperature lower than this, it is difficult to efficiently form a craze because it is too flexible.

The craze generated by subjecting the polymer resin film to crazing treatment is basically the same as that disclosed in Japanese Patent No. 315658, and is substantially the same as the molecular orientation direction of the polymer resin film. In parallel, the width is generally 0.5-100 μm, preferably 1-50 μm. The ratio of the number of crazes penetrating in the thickness direction of the film is 10% or more, preferably 20% or more, particularly preferably 40% or more with respect to the number of all crazes. When the ratio is less than the above range, it is difficult to obtain sufficient air permeability. The craze is formed in a direction substantially parallel to the direction of molecular orientation because the craze is formed by pulling in a direction perpendicular to the direction of molecular chain orientation, and the craze is formed in a direction perpendicular to the direction of molecular chain orientation. This is because it is difficult to form. The craze mentioned here includes a surface craze appearing on the surface of the polymer resin film and an internal craze generated inside, and refers to a region having a fine crack-like pattern. This craze is composed of molecular bundles (fibrils) and voids, and the gas permeability of various gases is generated in this portion.

The gas permeation performance of the craze varies depending on the type of resin used. For example, when a homopolymer of polyvinylidene fluoride is used, the gas permeability of oxygen and nitrogen gas is generally 0.3 to 100,000 × 10 ⁻⁴ cm ³ / m ^2.・ In the range of 24 hr · atm, in terms of moisture permeability, generally in the range of 10-100,000 × 10 ⁴ g / m ² · 24 hr, in tensile strength, generally 5-50 MPa, preferably 6-50 MPa, particularly preferred Can be in the range of 7.5-50 MPa.

The oxygen supply of the present invention begins with the detection of the pressure in the tank by the pressure sensor. As a result, the generator activates the air compressor, and the air tank (100L) is filled with air compressed by the air compressor. In this case, the air tank (100L) is compressed to about 9 atm. The amount of gas permeation is restricted by a breathable film attached as a gas permeable material at the jet outlet, and the gas is gradually ejected into water in the form of fine bubbles. By gradually reducing the air that is compressed and filled in the air tank, it is possible to supply oxygen to the water for a long time without replenishing the air tank at all times. Connected.

By using the water quality environment remote monitoring device (manufactured by NOF Co., Ltd.), it is possible to grasp various data in addition to the water temperature, and immediately when an abnormal value is detected from the preset water quality range Because it is notified, it is possible to take an appropriate action.

The present invention is characterized in that a protective water net is used to divide the water area and fine bubbles are jetted into the area to supply oxygen, such as a fine bubble jet and algae attached to the protective net. Oxygen enrichment in the area is achieved by photosynthesis. The farm is cultivated under the same conditions, with a protective net installed around the farm. It can be used for growing pearls, and for tuna farming using a protective net.

Schematic diagram of the present invention

Explanation of symbols

2 Aquaculture
4 Oysters
6 Bubble spout
8 Protective net
10 Weight for protective net
12 Water quality monitoring equipment

Claims (4)

Using a protective net to divide the water area where oysters are drooped, and install a foam outlet at the bottom of the partitioned water area to increase the dissolved oxygen in the water area by ejecting fine bubbles , How to cultivate oysters. The method for culturing oysters according to claim 1, characterized in that a protective net is stretched around the culture trough to divide the water area. The foam injected into the water is a fine foam generated by compressing air and forcibly permeating the craze generated in the polymer resin film. Oyster culture method. A method for cultivating shellfish, characterized by partitioning the water area using a protective net and installing a foam outlet at the bottom of the partitioned water area to spout fine bubbles to increase dissolved oxygen in the water area .

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