Pacific saury is immediately graded into several commercial size categories (by weight) on board in the saury far sea fishery, e.g., the Chinese Taipei saury fishery (CTSF). In this study, a stratified random sampling approach with proportional allocation was employed to refine the estimator of the catch-at-size/age data for the CTSF. We increased the sample size of saury length from ~300-500 per year in 2007-2019 to 2,492 in 2020, amounting to an approximately 5-fold increase, particularly for the abundant categories. Two sample fishing vessels with their own specifications of commercial size categories were employed to involved the potential monthly and/or between-vessel variation. In addition, both age-length keys for saury from Chinese Taipei and Japan were used to estimate the catch-at-age data. The age-0 and age-1 saury accounted for 63.3 % and 36.7 % of the 2020 CTSF catch, respectively. The mean percentage of age-1 fish in the 1o x 1o grids was greater than 91% in June and July, decreased to about 39-47% from August to October, and was less than 29% in November and December.