Standardized CPUE of Japanese commercial dip-net fishery targeting spawners of chub mackerel in the Northwest Pacific up to 2023

We conducted CPUE standardization of Japanese commercial dip-net fishery for Pacific chub mackerel using a generalized linear mixed-effect model. The analysis showed that the dip-net fishery CPUE was affected by month, area, sea surface temperature, and ship as well as year. The abundance index standardizing these influential variables except for year showed a great decline in 2022-2023 after a high-level decade from 2011 to 2021. We propose this standardized index to be used as an index of spawning stock biomass (SSB) in the Technical Working Group for the Chub Mackerel Stock Assessment (TWG CMSA) in NPFC.