魚群探知機による魚群構造の調査-I : 1959年2月観察の東海中部のタチウオの群構造

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By use of fish finder (24 kc) carried by the Toko-maru, the inspection vessel of the Fishery Agency, trial observations of hair-tail shoal were done at the central part of the East China Sea on February 19th and 20th, 1959. The admissible conclusions derived from these resear-ches are reported as follows. 1) Each shoal restored from echo traces formed an ellipse in shape, about 4 to 5.5 miles along the transverse axis and 3 to 4 miles along the conjugate one, with its depth measuring 10 meters or so. 2) In the observed area covering about 170 square miles, more than three masses of fish were found to be arranged in succession from east to west or northwest, the distance between centers of such neighbouring masses beeing about 5 miles. 3) Hair-tail of this area distributed along sea bottom from after the sun-rise till sometime before the sun-set, while swam in middle layer of water by night. 4) The volume of fish contained in a single mass described above was estimated at about 1, 550 tons, being about 11, 000 times of the catch taken by 1 mile hauling through such mass.
公益社団法人日本水産学会の論文