Stock sizes of the chub mackerel (Scomber japonicus)from the East China Sea and the area off the mouth of Changjiang r iver were assessed with vir tual populat ion analysis .The r esult showed that stock sizes of chub mackerel fr om the East China Sea and the area off the mouth of Changjiang River were fluctuated between 132 000 -235 000 and between 41 000 -127 000 me tric tones respectively in the past decade .The stock sizes of chub mackerel in recent years were stable on the r elat ively high levels .However , since the actual catches are gradually close to the stock sizes , it seems tha t there is not very much potential for f urther exploitat ion of this species .