人工魚礁に対する魚群行動の実験的研究-VIII : 模型魚礁に対するハマチの行動

概要

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Using Hamach, young yellow-tail, body weight 450-1200g, Seriola quinqueradiat TEMMINCK et SCHLEGEL, experiments were carried out in an outdoor tank (L. 8×W. 6×D. 1.5m or L. 4×W. 4×D. 1.5m) with pooled water, in order to obtain the foundamental knowledges about the model fish reefs (Fig. 2 and 3), to reaction of fish schools. Method of experiment: In this experiment, two occasions were compared with each other, the one the distributions of fish schools when model fish reefs were not set in the tank and the other those when they were set. Observations were made 50 time in total at every one minute, recording the positions of the fish. The results of experiments are as follows: 1. Young yellow-tail was most frequently distributed on the more bright, area in the experimental tank on both conditions, when model fish reefs were not set and when those were comparatively small, even if they were set. 2. Young yellow-tail was more attracted to the increase of hight than that of area of model fish reefs. 3. Young yellow-tail was the more attracted to the increase of area, when the model fish reefs were of the same height. 4. The sense of “sight” has the important role for the attracted movements of young yellow-tail to the model fish reefs.