It is a notable character of anchovy to swim forming a shoal, the members of which sometimes jumping out of the water and another time rippling the water surface.
The one shoal in which fish are jumping is called as “Hane Iwasi” by the fisherman in Tokyo Bay and the other with rippling as “Seri Iwasi”.
The present paper describes about the conditons leading to these interesting features and also about the peculiar construction of the anchovy shoals in which fish are jumping or marking ripples.
The data used here were collected from a sardine purse seine boat which was operated in Tokyo Bay during 1950-1957.
In this treatment the authors employ the following notations for these anchovy shoals:
The shoal in which fish are jumping-Sj
The shoal in which fish are causing rippling-Sr
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