ニギスArgentina semifasciata kishinouyeの年令及び成長に就て

概要

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The life history of the argentine, one of the most important fish of the deep-sea drag-net fishery, is little known yet. The present writer deals with the age and growth of the fish. Having examined the specimens taken from either Kumano-Nada, a well exploited ground, or off Kii-Suido, an almost untouched ground, he obtained the following results. 1) Left-side and right-side otoliths are symmetrical in every detail. 2) The 1st ring or clear band in the otolith is formed rather regularly in winter, while the 2nd ring formation in the same season is apparently not quite regular; the opaque growth zone outside the 2nd ring is usually indistinct. 3) The diameters of the 1st and 2nd rings are 2-5mm and 5-6mm respectively and their ranges hardly overlap each other. 4) Sometimes a pseudo-ring is formed, but it can be distinguished by its weak formation and its diameter. 5) By virtue of the above facts age determination by otolith is possible and growth can be traced. Argentine grows rapidly for several months after hatching, followed by later slower growth, and attains 130-150mm by the end of the 1st year, and 170-190mm by the end of the 2nd year. Since those fish which have more than one ring are few, it may be probable that the life span of the argentine is chiefly between one and two years.
社団法人日本水産学会の論文