In Miyagi Prefecture, administrative regions were classifiable into three groups according to the relative proportion of workers engaging in agriculture, fishery or forestry in the total economically active population (SUZUKI and MATSUYAMA, 1974). The different pattern on some indices of population structure and growth including fertility, population decrease, and ratio of population aged 65 and over to that aged 0-14 years old was observed in fishery zone by comparing with other areas. All these phenomena implied that young adults in fishery zone had different attitudes to migration from that of other area where agriculture is the most prevailing industry in the area. Because no available data on age-specific numbers of migrants was in the official mobility statistics, we devised the fluctuation ratio of regional population for analysis of the mobility. The term ; fluctuation ratio was def ind as a notation : P
x/P
x+5 (P
x: Number of regional population of x years old in 1965 census, P
x+5 : Number of x+5 years old population in 1970 census in the same region). Since this fluctuation ratio changed by death and migration, age-specific death rates from 10 to 19 years of age tested, because the person of this age-group was exposed to migration to the greatest extent, but no correlation was found between death rates and rates of population in primary industries to total. Young adults of this age group were less migratory in fishery zone than in other area in both sexes. This was likely to be resulted from the difference of the demand for young labor force in each area, and this might also bring about disparity of family sizes. By the census of fishermen and cultivators, the size was the greatest in the household engaging mostly in aquiculture of sea-weeds and shellfish, the second greatest in the household of agriculture, and the smallest in the household of non-tidal fishery. Thus, the requirement of young labor force was considered to differ even in the household of fishery, and by that reason, it is necessary to further elucidate the difference in fertility and migration depending upon various types of fishery.
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