Standardized CPUE for the winter-spring cohort of neon flying squid caught by Japanese squid jigging fishery in the North Pacific from 2005 to 2025

We standardized the catch per unit effort (CPUE) of the winter–spring cohort of neon flying squid (Ommastrephes bartramii), based on logbook data from the Japanese squid jigging fishery in the North Pacific since 2005. Data collected from the waters west of 150°E were used in this study. We used generalized additive models to standardize the nominal CPUE, incorporating temporal (year and month) and spatial (longitude and latitude) variables for both calendar-year and fishing-year (April to March) frameworks. The model with the lowest AIC value was selected as the best model. We found that the annual standardized CPUE derived from the best model exhibited a trend similar to the nominal CPUE on both a calendar-year and fishing-year basis, characterized by high interannual variability. Model performance metrics indicated that the fishing-year model clearly outperformed the calendar-year model. To better reflect the biological and operational seasonal dynamics of this cohort, the adoption of a fishing year instead of a calendar year is recommended for future stock assessments.