ヒメダカの蕃殖率に及ぼす群居密度の影響

抄録

I Studyed on the influence of the population density of Killie-fish (Oryzias latipes 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.
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.
Satisfied the equation y=ax^b, where y represents the number of eggs spawned per i female a day, or hatching-rate, x density of population, a and b are the characteristic constants.