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

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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^b</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.