2 0 0 0 ヒメダカの蕃殖率に及ぼす群居密度の影響
- 著者
- 川尻 稔
- 出版者
- The Japanese Society of Fisheries Science
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.15, no.4, pp.166-172, 1949
I Studyed on the influence of the population density of Killie-fish (<i>Oryzias latipes</i> T & S) upon the number of spawn eggs, hatching-rate, and consequentry upon the reproduction. In the present study these fishes were cultured a pail (1 ?? and -1 ?? ) 1, 2 and 4 pairs respectively in 3 glass bowls (diameter 30cm, depth 15cm) filled with 7 L. of water, and were given food daily into each groups at the ratio of 1, 2, 4, and the rearing water of each bowl were changed 2-3 times in a week at the same ratio as above. Their spawned eggs were counts 3-4 times every day, and transfered into each 3 glass bottles (capacity 200cc) which filled water at the above ratio also, and disinfected by 0.5% of formalin solution every 4-5 days, and the fry which hatch out were counted every day. These experiments were carryed on two times in the same way.<br> Putting these results together, the number of eggs spawned one female a day decreases, so, accordingly, the number of eggs spawned one female decreases, and besides the hatch-rate have a tendency of depresses, in proportion to the population density of the fishes increases, and by the accumlation of these factors the rate of reproduction of the fish decreases.<br> Satisfied the equation <i>y=ax<sup>b</sup></i>, where <i>y</i> represents the number of eggs spawned per i female a day, or hatching-rate, <i>x</i> density of population, <i>a</i> and <i>b</i> are the characteristic constants.
1 0 0 0 OA 千曲川に於ける石塚漁業に就て
- 著者
- 川尻 稔
- 出版者
- 公益社団法人 日本水産学会
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.17, no.7, pp.206-210_2, 1952-03-25 (Released:2008-02-29)
The catch of Tribolodon hakonensis has shown a great decrease recently in Chikuma River, middle Japan. From the fact that many young fishes have been caught by the “Ishizuka”, Nagano Prefectural Government prohibited this particular gear since 1946, however, there were heard varied opinions among fishermen as to its effect and, as the result, to remove the regulation. The “Ishizuka”, set up in early winter, is a mound composed of stones as, large as or larger thna humna head, measuring 50cm high and 100 to 150cm in diameter at bottom, the mound is built in the water 70 to 80cm deep with graduated slope toward the mainfolow of the river, also the entire “Ishizuka” is covered with straw-mat except the sloped part where the stones are flattened mixed with smaller gravels. In early spring, the mound is surrounded by bamboo-blinds and a trap is set against sloped part, then the stones are picked up piece by piece. The fish, mostly T. hakonensis, which conceal themselves in the space of stones during the winter, escape the mound and are easily trapped. Experimental “Ishizuka” numbering 17 were set in November 1948-'49, and the fish 4699 caught following spring were studied on age and length. The age determination by scale on these fish showed 59.5% of one year old, 19.8% of two, 16.6% of three and other older. It is thus apparent that the “Ishizuka” destroys tie younger generation of fish. 1 propose to regulate strictly the fishing by “Ishizuka” but rather utilize the mound for the protection of young by the hand of fishermen.
1 0 0 0 千曲川に於ける石塚漁業に就て
- 著者
- 川尻 稔
- 出版者
- 公益社団法人 日本水産学会
- 雑誌
- 日本水産学会誌 (ISSN:00215392)
- 巻号頁・発行日
- vol.17, no.7, pp.206-210_2, 1952
The catch of <i>Tribolodon hakonensis</i> has shown a great decrease recently in Chikuma River, middle Japan. From the fact that many young fishes have been caught by the “Ishizuka”, Nagano Prefectural Government prohibited this particular gear since 1946, however, there were heard varied opinions among fishermen as to its effect and, as the result, to remove the regulation.<br> The “Ishizuka”, set up in early winter, is a mound composed of stones as, large as or larger thna humna head, measuring 50cm high and 100 to 150cm in diameter at bottom, the mound is built in the water 70 to 80cm deep with graduated slope toward the mainfolow of the river, also the entire “Ishizuka” is covered with straw-mat except the sloped part where the stones are flattened mixed with smaller gravels. In early spring, the mound is surrounded by bamboo-blinds and a trap is set against sloped part, then the stones are picked up piece by piece. The fish, mostly <i>T. hakonensis</i>, which conceal themselves in the space of stones during the winter, escape the mound and are easily trapped.<br> Experimental “Ishizuka” numbering 17 were set in November 1948-'49, and the fish 4699 caught following spring were studied on age and length. The age determination by scale on these fish showed 59.5% of one year old, 19.8% of two, 16.6% of three and other older. It is thus apparent that the “Ishizuka” destroys tie younger generation of fish.<br> 1 propose to regulate strictly the fishing by “Ishizuka” but rather utilize the mound for the protection of young by the hand of fishermen.