JPS58138326A - Method of breeding eel and covering material used therein - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to eel farming, and more particularly to a method for cultivating high-quality eels in a short period of time, and a covering material used for the same.

In recent years, with the increase in global population, a shortage of fish for food has become apparent. As one means of solving the fish shortage, cultivation of useful fish has been put into practical use in some areas, with the aim of artificially mass-producing useful fish.

There are two kinds of fish that are farmed (eels). When eels are raised in the wild, they begin to eat more when the water temperature exceeds 20℃, and the eel is raised in the middle of July when the water temperature does not drop below 0℃. By the end of September, they eat well and grow well. However, /1
From around the middle of the month, I almost no longer eat feed, and from December to q
During the month, they have the habit of overwintering in the bottom of the pond. Also, eels, like many other fishes, are nocturnal, and as kings, they engage in nighttime sea activities and feed on livestock. The growth stages of eels are called whitebait (juvenile) - Kuroko Issuke and adult.

Traditionally, eels cultured in aquaculture ponds are grown in the ocean around 10-// months. ! r - / 11/whitebait are caught, released into an aquaculture pond, raised, and shipped to the market as adults when the weight reaches 1□〇~2Sθg/fish. In a normal aquaculture pond, it takes about one month to one month to turn whitebait into an adult fish.

Later, a so-called house culture system was developed, in which the aquaculture pond is covered with a covering material such as glass or synthetic resin film, and the growth period from whitebait to adult C was changed from the traditional half-slope period to 1-months. It became possible to shorten the length of the kernels, and the method of cultivating eels in greenhouses quickly became popular.

In this greenhouse cultivation method for eels, it is relatively easy to adjust the water temperature, feeding according to each growth stage, breeding density, etc., but there are still problems as follows.

The first problem is that when an aquaculture pond is covered with a transparent coating material, blue-green algae, which is a type of diatom, grows in the water, which causes a problem.

When sunlight enters the water in the pond, it flourishes due to photosynthetic ζ2, which has the effect of keeping the inside of the aquaculture pond dark and creating an environment where eels are more likely to be active, but the situation is increasing the breeding density. First, there is a risk of a lack of oxygen at night, or eels do not eat artificial feed that is high in nutrients.(Secondly, they eat algal blooms, which slows down their growth.)

The second problem is that when covered with a transparent coating material, sunlight reaches close to the bottom of the aquaculture pond, turning even the ventral side of the eel, which should be silvery white, black, reducing the commercial value of the adult fish. It is.

Under such circumstances, the inventors of the present invention have completed the present invention as a result of intensive studies to provide a method for sea-farming eels, which have high commercial value, for a short period of time.

The gist of the present invention lies in the transparency of sunlight.

The eels to which the method of the present invention is applied refer to fish belonging to the family Eelidae (2).Specific examples include eel (from Asia), giant eel, European eel, American eel, Japanese eel, conger conger, and triggerfish. say.

The eel cultivation according to the method of the present invention is carried out under a light-quality atmosphere that blocks at least 50% of the transmission of sunlight.

In the present invention, "the transmission of sunlight is reduced by at least go%".
"Shielding light quality atmosphere" means / ~ 110 of the sun's rays
0 nm ultraviolet light, 1.10θ~g00
The transmission of light in the visible light range of nm is at least S0
It means a light quality atmosphere that shields %.

Therefore, under solar irradiation, the transmission of solar radiation can be reduced by at least 0%, preferably 90%, particularly preferably 95% to 95%.
It is desirable to culture under ioo% shielded light conditions.

However, when feeding eels during cultivation, it is not possible to prevent instantaneous incidence of sunlight, artificial light, etc.

The coating material used in the present invention is not particularly limited in its material as long as it has the above-mentioned light shielding properties, and any type of coating material can be used. Such covering materials are usually made of inorganic or organic films, sheets or other molded objects, lath plates, glass plates laminated with synthetic resin films containing dyes or pigments, and organic films or As the sheet, a synthetic resin film or sheet containing a dye or pigment is suitable.

The above covering material should be installed above the water surface (or floating).
A place far away from the water surface is also fine.

When coating while floating on the water surface, use auxiliary means to provide buoyancy to the coating material. This aid is box-shaped,
Good floating shapes such as spherical and rod shapes.

In the present invention, particularly preferred as the covering material is a film or sheet made from a film-formable thermoplastic synthetic resin blended with a dye or pigment.

Film-formable thermoplastic synthetic resins that can be used include:
For example, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyester, polyamide, polycarbonate, polymethyl methacrylate, polyacrylate, polyvinyl acetate, polyvinyl alcohol, fluorine-containing resin, cellulose resin, or polymers with the same core as these resins. Contains blends. In particular, light resistance,
Due to reasons such as strength and ease of handling, polyvinyl chloride,
Polyethylene, polypropylene, polyester, etc. are suitable.

In order to impart the above-mentioned solar ray-shielding properties to the film-formable thermoplastic synthetic resin, dyes and pigments with high light M-shielding properties may be blended.

Dyes suitable for use in the present invention include cxzo
IIIo), carbon black, titanium oxide, zinc white, red iron oxide, litharge, yellow lead, and conc.

As the coating material according to the present invention, it is preferable to use a combination of synthetic resin and carbon black to form a film or a sheet.

Can be changed. In the case of a film or sheet having a thickness of θ, θ~jn, it is preferable to selectively blend carbon black in the range of 0.75 to S parts by weight per ioo parts by weight of the synthetic resin material.

In addition to dyes and pigments with high light-shielding properties, the synthetic resin used in the present invention may contain other conventional resin additives, such as plasticizers, lubricants, and oxidizing agents, if necessary.

When blending a plasticizer with polyvinyl chloride, the blending amount of these resin additives is determined by the resin material io.

Up to 70 parts by weight can be added to the weight part, but up to about 5 parts by weight for other components.

The synthetic resin film or sheet used in the present invention can be produced by various methods known per se, such as melt extrusion methods such as calender molding method, inflation molding method, and T-die molding method;
It can be manufactured using a press molding method, a solution casting method, or the like.

The film or sheet formed in this manner can be varied in the range of 0.02 to S depending on the usage pattern E thereof.

This film or sheet can also be used by laminating it on other synthetic resin films, sheets, glass, etc. for the purpose of reinforcement, if necessary. Furthermore, the synthetic resin film or sheet ζ2 formed as described above may be reinforced with reinforcing fibers, such as wire mesh or a filamentous fiber structure.

Methods for using the coating material of the present invention include building a frame on the water surface of an eel breeding area (pool, pond, etc.) and spreading the coating material of the present invention on the frame; A method of expanding the device by floating it, a method of installing a support in the water and expanding it, or a combination of these methods are adopted.

According to the present invention described above, the following particularly remarkable effects are achieved, and its utility value in fisheries is extremely large.

(1) When cultivating eels according to the method of the present invention, the amount of sunlight that enters the culture area is small, so it is possible to suppress the growth of algae, especially blue-green algae, which is a type of diatom, in the culture water. can.

If these trees do not overgrow, there is less worry about oxygen shortages in the water (therefore, it is possible to raise the breeding density of eels, and
Artificial feed (2) can further promote growth.

(2) According to the method of the present invention (2), when eels are cultured, the bellies of the cultured eels do not turn black, but can be kept silvery white, and adult fish with high quality and value can be obtained.

(3) The present invention (-When using a film or sheet made by blending 0.1 to 13 parts by weight of carbon plaque as the coating material, the coating material has excellent solar ray shielding properties and The durability of the film or sheet is also excellent, and the temperature of the eel farming area can be easily controlled, making it easy to create a favorable environment for eel farming.

Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to examples of reduction unless it exceeds the gist thereof.

Example 1-g, Comparative Example 1-da (Preparation of coating material) Polyvinyl chloride CP-tqoo) too Part by weight Dioctyl phthalate jOl Epoxidized soybean oil jl Barium-zinc based composite stabilizer CoI Barium stearate 0.2
〃Zinc stearate 0. ! t #Ethylene bisstearamide F,, 0@J
A composition consisting of # was prepared. This composition-2, furthermore,
11th per 100 parts by weight of resin! (Heavy weight with a trowel (However,
In Comparative Example 1, each mixture that was not blended was
The film was supplied onto a calender roll heated to 160° C., and a type of film having a thickness of o and i wm was prepared by a calender forming method.

The light shielding rate of each film obtained (100 (%) - wavelength 55
Shows the value of the light intensity ratio (%) at 5w5. ) is shown in Table 7.

Each of the obtained films was exposed outdoors (2 times, and the elongation rate of the film after 7 years was determined according to J-8, -A? J2).
was measured and expressed as the residual percentage relative to the elongation percentage of the film before exposure.

(Covering of eel farming ponds) There are g eel farming ponds located in the Shizuoka region, each with a width of 7.2 doors and a water depth of trocm, each with a frontage of <1. tm, depth 3.3m1
We constructed an eel farming house frame with a height of &m.

Each frame was covered with one of the five types mentioned above (Showa!fS July 2, 2013) I made it possible to cycle through.

Four whitebait fish were released into each pond (July 23, 1999).The culture conditions, sometimes the amount of feeding, the feeding interval, etc., were the same as in conventional greenhouse culture covered with transparent film. bred.

On June 3, 1981, the weight of the eel grown in each aquaculture pond was measured, and the proportion of the eel in the weight aooyH was calculated.
Table 1 ζ: Shown as growth promoting effect.

In addition, the transparency of the aquaculture pond at this point was observed from the inside, and the results were shown as the ``effect of inhibiting the growth of blue-green algae.''

The evaluation criteria were as follows.

A: You can clearly see to the bottom of the pond.

B...I can somehow see the bottom of the pond.

C...I can't see the bottom of the pond.

From Table 1, the following is clear.

0) According to the method of the present invention, the effect of promoting the growth of eel is extremely high.

(2) According to the method of the present invention, the occurrence of blue-green algae in the aquaculture pond is extremely low.

(3) It is preferable to use, as the coating material, a mixture of 0.2 to S weight of carbon black to ioo parts by weight of a synthetic resin, since the weather resistance of the film will be excellent.

Applicant Mitsubishi Monsanto Chemicals Co., Ltd. Representative
Person Patent Attorney Hase - (2 people)

Claims (4)

[Claims] (1) A method for cultivating eels, which comprises cultivating eels in a light atmosphere that blocks at least 0% of the transmission of sunlight. (2) The method for cultivating eels according to claim (1), characterized in that the eels are cultured under a coating that blocks at least 80% of sunlight from passing through. (3) A coating material used for eel cultivation, which is characterized by blocking at least 0% of sunlight from passing through. (4) Claim (3) characterized in that carbon black o, it-s parts by weight are blended per 100 parts by weight of the synthetic resin material and formed into a film or sheet.
Covering material used for eel aquaculture as described in section.