Progress report of the development of the state-space age-structured stock assessment model for Pacific saury up to 2023

We report the progress of the age-structured model for Pacific saury stock assessment up to 2023. The key assumptions for the next-generation stock assessment of Pacific saury are 1. the steepness of the Beverton-Holt stock recruitment relationship, 2. the natural mortalities for age 0 and age 1 fish, and 3. the treatment of age 0 fish spawning. We narrowed down the candidate hypotheses on these assumptions based on biological point of view, and then observed the sensitivity of the model behaviors against these assumptions.