狭い場所から開放されたときの魚群の行動

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概要

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• This is an important problem when considered with practical fisheries, especially to find out the movements of fishes inside the net when they are gathered. Many investigations had been carried out regarding this problem (See references). For this experiment, Japanese Killifish Aplocheilus latipes was used. The equipments were 5 tanks of different sizes and two cylinders of diameter 13cm of which one was transparent made out of celluloid and the other was painted white inside so that the fishes were not allowed to see the environment. About 15 individuals were liberated in each cylinder and it was lifted above after some times. The time lapses from then to when they moved out were observed (Tables 3-5). Staying times were particularly to find out the difference of effects between the transparent cylinder and the cylinder painted white inside. The result obtained is as follows: …… Staying time, the time between lifting up of cylinder and swimming out of fish. ?? In the case of the transparent cylinder, it was observed that when the keeping time was increased, the staying time also increased. So it may be suggested that the fishes get more well accommodated the transparent cylinder than the painted cylinder. On the other hand, in the case of the painted cylinder even if the keeping time was increased, the staying time was found to be increased only by a few seconds. The sudden outburst of the fish that are kept in the painted cylinder, could be the result of the stimulus produced when they are allowed to escape suddenly from an enclosed place to a more open space.

著者

• 草下 孝也

  東京大学農学部

関連論文

• 垂直網の網目と魚体の大きさとの関係
• 傾斜沈垣網の効果について
• 彩色した沈垣網の効果について
• 狭い場所から開放されたときの魚群の行動
• 魚の種類による駆集網の駆集効果
• 駆集網に関する二つの実験方法による網目の大きさ
• 駆集網の色彩の濃さの効果について

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