Review and update on fishery-independent and fishery-dependent indices of the chub mackerel of Japan

Japan had four potential abundance indices of the chub mackerel in the Northwestern Pacific. Two are the recruitment indices that are derived from midwater trawl surveys in summer and autumn, one is the index of spawning stock biomass (SSB) from egg surveys off the Pacific coast of Japan, and the remaining one is a fishery-dependent SSB index. In this paper, we show a brief description of the abundance indices including updated results. All indices are standardized and have time series longer than or equal to 15 years. The indices provide useful information on the stock assessment of the Pacific chub mackerel.