脊椎骨数の頻度比による回遊経路の追跡-I : マイワシの発生地を異にする群を判定する方法について

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Up to the present time and by using the averages of vertebral counts, the migration routes of fishes have not been fully traced. So, the author attempted to employ the following method. Individuals having vertebral number of 50 or 51 occupy approximately 95 per cent in the samples. Variables k, l, m and n represent the number of fish individuals of a group having vertebral number of 49, 50, 51 and 52. Then each of the ratios, k/l, m/l and n/l is designated as the “frequency ratio of vertebral number.” The author considered it more reliable to use the “frequency ratio of vertebral number” instead of the old method of average vertebral number, in plotting the migration course of a sardine group. The results are the following: (1) The “frequency ratio of vertebral number” peculiar to regions. (Table 1, Fig. 1) The difference in frequency does not appear very large when reckoned according to year the fishes are hatched as seen between the 1939 and 1940 year classes. However a large difference is seen when analysed according to regions. (2) A group having a large “frequency ratio of vertebral number” disappears by the time the fishes attain 10cm body-length.
公益社団法人日本水産学会の論文