Spatiotemporal distribution of two mackerel species, Scomber japonicus and Scomber australasicus, in the Bungo Channel, western Japan

Abstract

　To reveal the distribution patterns of mackerel in the Bungo Channel, western Japan, we investigated catch statistics and specimens of chub mackerel Scomber japonicus and spotted mackerel Scomber australasicus sampled at fish markets from 2007 to 2017. Chub mackerel were caught mainly in the northern part of the Bungo Channel while spotted mackerel were caught in the southern part of the channel. Spotted mackerel were observed at higher latitude in the eastern channel (Ehime Prefecture) compared to the western side (Oita Prefecture). This pattern suggested a correlation with the asymmetry in water temperature between the eastern and western sides of the channel. The distribution of 0-year-old mackerel was observed chiefly around nearshore areas from April to June, and thereafter it gradually shifted to offshore areas in July, indicating that 0-year-old fish expanded their habitat to offshore waters as they grew.