Description on Japanese chub mackerel fisheries with emphasis on those seasonality and fishing grounds

This document provided the decadal monthly catch from Japanese chub mackerel fisheries and the pictures of fishing grounds. The monthly catch showed a periodic change annually over recent decade, which started to increase after July to October, when it touched bottom annually, reached peak in the 3rd quarter to the 4th quarter of the following year and finally dropped to the bottom. The fishing year reflecting this seasonal change of catch has been applied in the Japanese domestic stock assessment. It was recommended that the introduction of fishing year should be considered in development of the NPFC stock assessment of chub mackerel according to seasonal variation of catch and biological background of target species.