マサバの摂餌行動について

概要

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In the previous paper, it was reported that in the stomach of Scomber 8 hours was required for the main digestion and 21 hours for the complete digestion and food intake changed with the process of digestion. In this study, we attempted to express the feeding activity with the speed at which Scomber catches five pieces of bait given. Two groups of Scomber were prepared, one composed of 159 fish and the other 122 fish. During the first 2 or 3 days of captivity the fish showed little interest in feeding. Both groups were trained to take foods given by experimenters. The conditioning of the fish was completed in less than a week. Under fasting conditions, they formed a tight, compact school at a depth of 1 meter. In early stages of feeding, each fasting individual fish rushed at the food given and took it vigorously at a depth of about 0.3 meters. Rushing speed decreased with the time elasped. After 4 seconds, some fishes begun to form a loose school at a depth of about 1 meter, while others were still swimming freely at a depth of about 0.3 meters. Then the feeding activity grew slower. At last, all fish formed a tight, compact school again at a depth of about 1 meter and took no notice of the food. The time required for satiation rate of fish food to reach levels below 60% was constant, being only 1-4 seconds. As satiation rate increased over 70%, the time increased rapidly.
社団法人日本水産学会の論文