北西部太平洋におけるビンナガ鮪漁場動態に関する研究-3-
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概要
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The purpose of this study is to clearly explain the variety of the main fishing grounds and fishery condition of albacore during the summer period under the influence of the changes of oceanographical conditions, these oceanographical changes can be observed by watching the shifting of albacore fishing grounds during the winter-spring period in the eastern waters off the mainland of Japan (Lat. 30-40°N, Long. 140-160°E) from 1951 to 1959. The principal data, which have been obtained from the analysis of yearly fluctuations of isotherms of sea surface, are as follows: 1) Oceanographic conditions can be classified into four patterns of HL, HLHLH, LHL and LHLHLH type, by the high and low sequence of surface temperature in the eastern water off Japan (Figs. 1-4). 2) It is found that the migration of albacore during the winter period is controlled largely by the water zone under 16.3°C which can be regarded as "environmental resistance" and water zone between 16.3-22.8°C extends from south to north in the area north of Lat. 35°N are regarded as "environmental induction"***, which induces the fall albacore shoals. 3) It seems reasonable to assume that the main fishing ground of summer albacore moves to the west or east and principally bring about variations of the fishery conditions (Table 1) above-mentioned. 4) As one of the most important conditions which produces favorable summer albacore fishery condition, it can be said that the formation of two or three winter albacore gathering place moves to the south west in adjacent waters of Japan. 5) As one of the most important conditions which get a bad catched fish in summer albacore fishery conditions, it can be said that the formation of the winter albacore gathering place moves eastward waters off Japan, or that density gathering place does not extend from the most adjacent sea to the eastern waters off Japan, and then by those shoals dispersing and moving southward from there, therefore the summer albacore gathering place disperses and its grounds become like those are found in the eastern waters off Japan.
- 社団法人 日本水産学会の論文