蔭影及び浮游物に対する稚魚(カワハギ,イシダイ)の行動について
スポンサーリンク
概要
- 論文の詳細を見る
Most of fish are known to be in the habit of taking shelter under submerged materials or sticking around floating substances for various reasons. In the experiments conducted by Oshima (1948) to throw light on these phenomona, the test animals such as the black porgy, Sparus macrocephalus and a rock fish, Micracanthus strigatus, were often attracted to a black plate on the white bottom of an aquarium in their actin for feeding or keeping away from enemies. The black spot appeared as if it had served like a sort of habitat for the fish. The present study has been designed to contribute knowledge to the habit of some fishes sta-ying about a drifting object through observations of their reactions to a given stimulus. The area of a white aquarium was divided into nine squares with threads stretched between the upper ends of walls so as to determine frequency of the test fish visiting each square (Fig. 1). A series of preliminary tests with no stimulus given to the fish established the typical swimming behaviours of two groups of the test animals that might be compared with their behaviours when given a stimu-lus. Under the normal condition one group, parrot bass, Oplegnathus fasciatus, displayed a noticeable inclination for aggregating in the central square, while the other, filefish, Monacanthus cirrhifer, behaved to the contrary (Table 1). The kinds of stimuli included a shade cast from above the water, a white or black plate held on the surface or the bottom, and a noise, to esch of which the fishes reacted differently (Tables 2-5). Findings from the experiments are : 1) Feeding activities which occurred most frequently in the square where a plate was, appe-ared derendent on the kind of the plate, its relative position to the water, species of fish and their developmental stages. Because the filefish were attracted oftener than the parrot bass to the black plate on the surface, but in the case of the plate of the bottom, vice versa (Table 4). 2) The young of the filefish (4-5.5cm. in legth) and the parrot bass (1.8-2.5cm.) showed vigorous feeding around the white plate on the water. while large individuals of the parrot bass (3. 5-3. 8cm.) took the alarm at the sight of the plate (Table 3). The different reactions to the plate may be attributed to degrees of psychophysiological development and the amount of learning experiences. Particularly difference of the perception they might have from the plate seems to be an essential factor determining their reactions towards it. 3) When a certain amount of a noise or stirring of water was continuously given to the ani-mals, they appeared to take shelter under the shade. Both white plate and black one placed at certain parts on the surface or the bottom had the similar effect as the shade on their avoidance from the threatening stimuli. Comparative tests of the shelters revealed that the animals preferred a lower shelter to an upper one (Table 6). For this reason it may be said that one feeding place they like better than another seems to be also a better shelter for them.
- 公益社団法人 日本水産学会の論文