Current and future tasks in the stock assessment for chub mackerel in NPFC

This document overviews current knowledges and scientific issues for the stock assessment task of chub mackerel in the Northwest Pacific Ocean. In this kick-off meeting of Technical Working Group for Chub Mackerel Stock Assessment (TWG-CMSA), construction of future work plan is one of the most important issues to be discussed. This document aims to facilitate the discussion by recalling presentations by Japanese scientists in the Chub Mackerel Workshop held in Yokohama last February and summarizing data availability of Japan. Japan has a long history of chub mackerel fisheries, a fully developed data collection system, and an age-structured stock assessment model of tuned VPA (virtual population analysis). Considering the existing data and knowledges on the stock assessment accumulated in Japan, it would be reasonable to use tuned VPA as the primary assessment model and then to explore extensions from the model. Even when using tuned VPA, the full data reviews, CPUE standardizations, evaluation of data uncertainties, modification of stock assessment model, and discussion on scientific reference points are needed, which requires at least additional four sequential TWG-CMSA meetings in the next 2-3 years.

The document is relevant to agenda items 5, 6, 8.1, 8.2 and 9.