魚の摂餌に関する生態学的研究-II

魚群の慣れと飽食量との関係

抄録

It has been found¹⁾ that a relatively constant value for the amount of food consumed can be obtained if a school of fish is fed to satiation. In the present investigation, the pattern of the change of the satiation amount during acclimatization of a school of fish is examined. The results obtained are summarized as follows:
A school of fish freshly caught and transferred to the experimental tank does not normally take to food well in the initial stages even when a suitable food is given. At the beginning the satiation amount increases gradually each day until a constant value is reached within about 10 days (Fig. 1). The time taken, however, depends on the species of fish (Fig. 1 and Table 4). Under fixed conditions a relatively constant value for the satiation amount can be obtained with a well acclimatized school of fish. If acclimatization is insufficient, the satiation amount is not constant and even slight external stimuli cause temporary fluctuations in the value. Even with an acclimatized school of fish, the satiation amount is reduced by transferring them from one pond to another, but this variation can be corrected after a day.