1953 年 19 巻 2 号 p. 75-78
The scale of pond smelt, Hypomesus olidus (PALLAS), shows no definite annual-ring in such a manner as the scale of salmon or herring. Two different zones, one of which grows in summer and the other in winter, are recognized on the scale of the fish in Lake Kasumigaura by F. MATSUZAKI (1916), while, according to H. KOBAYASHI (1936), the fish of Lake Shironuma shows the spawning mark which may probably be formed by the spawning. The present study aims to find the local difference of scale structures of pond smelts. The fishes of three localities of Hokkaido, the anadromous type of the river Ishikari, the land-locked-form Lake Junsai and the fishes of Lake Abashiri connecting with the sea, were taken up as the materials under three different ecological conditions.
The marks on the scales of pond smelt from Lake Abashiri (Fig. 3) ought to be thought as the spawning mark, but those of the fishes of Lake Junsai (Fig. 5) are the interstitial mark bet-ween the winter and summer zones, and the material from the River Ishikari (Fig. 1) lacks these marks. There, the scales of pond smelts differ with their localities and appear the different cha-racteristic structure.