鹿児島湾内産主要魚類の漁況と環境要因についての研究-4-

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(1)Pluctuation in the catch of young horse-mackerels in Kagoshima Bay has been studied through a survey of statistical data on the catch at twenty fishing ports on the coast of the bay (Figs. 1&2). Young fish are chiefly caught in the waters where the depth ranges from 30 to 50 m (Fig. 3). In the inside of the bay the fishing is principally performed during the months from April to October, while fishing season at the entrance of the bay is mainly confined to a period from November to March. (2) The distribution of body-lengths in the catch was studied monthly between March and December 1959 (Fig.4, Table 1). The great majority of the catch is occupied by small-sized (6-14cm in the body-length) individuals, a small portion consisting of large-sized (15-21cm in the body-length) animals. Referring also to the culture experiment of young fish (Fig.5, Table 2), it is postulated that the above stated small-sized fish are in their first year and the large-sized animals are in their second year. (3) Seasonal variations in the hydrographical conditions in the bay as observed in the monthly oceanographic surveys are shown in Fig. 6 and Fig. 7. The migration of young horse-mackerels into the bay takes place in spring, most probably when a water temperature at 25m depth is raised over 17°C ; the migration to the outside of the bay seems to occur in autumn with the lowering of the water temperature.
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