JPS5878523A - Sunshade for breeding fish - 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 an awning for improving the coloration of farmed fish.

Cultivation of colored fish such as red sea bream, which live above a certain depth below the sea surface, is carried out under the conditions of the natural environment in which these fish live, for example at a depth of 30 to 50 meters. There are many difficulties in management. Therefore, the cultivation method is usually carried out in a shallow place with a depth of about 5 to 15 meters. As a result, the conditions are different from the natural environment in which red sea bream live, so the coloring of colored fish will not be as bright as under natural conditions. In particular, the color of red fish is hard to come out,
These red sea bream and other red sea bream are valued for their unique coloration, as if they were grown under natural conditions, and if this color is poor, the commercial value of red sea bream will decrease. We aim to improve the body color of red sea bream by feeding them with red and yellow carotenoids such as red shrimp and krill during cultivation for two to four months before harvesting. However, with this feeding method alone, the color is not as vivid as that of natural products, and is usually still blackish.

The inventor believes that this is due to the amount of light produced by the growing environment, which is shallower than the water surface than in the natural state, and by bringing this amount of light closer to the natural light amount, a bright color similar to that of natural red sea bream can be obtained. The present invention was developed by focusing on the fact that red sea bream can be cultivated to have the following characteristics.

That is, the present invention is a sun cover for farmed fish that has an average visible light transmittance of 5 to 60%.

The sun cover for farmed fish of the present invention has an average coverage of visible light within the above range, and may be in the shape of a burr, but specifically includes films, sheets, non-woven fabrics, nets, etc. . Among these, nets or nonwoven fabrics are preferred.

Sunscreens that achieve this kind of transmittance include polyethylene,
Use a synthetic resin such as polypropylene, nylon, acrylic resin, vinylon, etc., mixed with a black dye pigment such as carbon black, or metal powder such as aluminum, and molded into the above shape.0.1 to 10% by weight based on the fat. , preferably in an amount of 1 to 5 weight. In addition, when using the above-mentioned metal powder, aluminum powder is particularly preferable.
It is preferable to blend 0.1 to 5.0% by weight, preferably 0.5 to 3.0% by weight of particles with a particle size of ~6 microns, preferably 2 to 3 microns, to the above synthetic resin. .

Since the awning of the present invention is spread over a fish cage, if it does not have air permeability and water permeability, there will be great resistance from waves and wind, and a stable spreading effect will not be obtained. Therefore, it is usually advantageous to use a non-woven fabric or a woven net-like material.Since it is most appropriate for these awnings to be stretched within the height Is above the water surface of the fish tank, the materials used for the awnings are It is advantageous to choose one that is light and strong. The net-like material is made of synthetic resin containing the dye and pigment and has a denier of 500 to 3,000, preferably an ij of 800.
~ 2,000 denier flat yarn is used as the weft yarn, and monofilament made of synthetic resin containing the same pigment is used as the warp yarn, and is obtained by raschel knitting or karami weaving,
Alternatively, it is preferable to use a breathable and water-permeable sun cover such as one obtained by raschel knitting using only monofilaments.

The timing and period of covering these awnings is 3 to 4 months regardless of the inquiry when there is a lot of light in summer, and 3 months or more before harvesting of farmed fish when adjusting the sand body color by feeding.゛The period of coating will vary slightly depending on the type of coating required, the level of shading rate of the net, the amount of natural light, and the focus. In places with a lot of light, it can be coated for more than 6 months.Example-1: 2.5% by weight of black pigment masterbatch manufactured by Tokyo Ink Co., Ltd. on high-density polyethylene EY-40 grade manufactured by Mitsubishi Yuka Co., Ltd.
A flat yarn of 1000 denier was prepared. Next, using this as the weft yarn, and using a commercially available (1) 450f Neal black monofilament as the warp yarn, we made raschel knitting so that there were 5 warp stitches in 1 inch and 6 weft flat yarns in each stitch Ill. did.

The visible light transmittance of this net was measured to be 16%.
Met.

Approximately 60 second-year red sea bream, 1 fish, 5 por before and after, were placed in a fish tank measuring 12 m square and 5 deep, with the above net floating in the sea.
I released up to 00 fish. The water surface of the cage was covered with the above-mentioned net, and the fish were cultured for about 4 months until the fish grew to an average weight of 1100 f/fish.

The results are shown in Table 1.0 Example-2 High-density polyethylene EY-40 grade manufactured by Mitsubishi Yuka Co., Ltd., silver master patch manufactured by Tokyo Ink Co., Ltd., grade 326
A flat yarn of 1000 denier was prepared by blending 10 parts by weight of 2 silver.

This was used as a weft thread, and a commercially available 450 denier black monofilament was used as a warp thread to create a kalami weave so that there were 7 filaments per inch. The average visible light transmittance of this net was measured and was 32%.

Using the above net, red sea bream was cultivated in the same manner as in Example-1.

The results are shown in Table-1.

Patent applicant: Mitsubishi Yuka Co., Ltd. Agent: Patent Attorney Hidetoshi Furukawa Agent: Patent Attorney Masahisa Nagatani

Claims (1)

[Claims] A shade cover for farmed fish with an average visible light transmittance of 5 to 60%.