Standardizing abundance index for recruitment of chub mackerel in the Northwest Pacific

In this document, we provide the summary of the CPUE standardization for Pacific chub mackerel following the “CPUE Standardization Protocol for Chub Mackerel”. The year trends of the recruitment indices were derived from standardized CPUE, by applying the delta-GLM-tree models to the data from surface trawl surveys in summer (June and July) and autumn (September and October). Since we found no significant problems during the standardization, we recommend these indices to be utilized in the Technical Working Group for the Chub Mackerel Stock Assessment.