Summary of the possible ranges of the key parameters in the age-structured stock assessment models for Pacific saury

We summarized the key parameters in the age-structured models for Pacific saury and their possible ranges to be considered, based on our best biological knowledge and discussion so far. The key parameters we focus on in this document are: 1. natural mortalities for age 0 and age 1 fish (M₀ and M₁, respectively), 2. the treatment of age 0 fish spawning, and 3. the steepness of the Beverton-Holt stock recruitment relationship (h). We recommend to consider [1.71, 2.75] and [0.5, 1] as the possible range of M₀ and M₁/M₀, respectively. We also recommend to consider [0.05, 0.2] as a possible range for a degree of relative contribution of age 0 to age 1 egg production, interpreted as the product of maturation rate, relative fecundity per weight, and relative times of spawning in a spawning season. We also created a prior distribution of steepness parameter based on our best knowledge on PS biology to present a possible range of the steepness to be considered. The 0.025, 0.5, 0.975 percentiles of the distribution of h were 0.26, 0.96, and 0.99, respectively, indicating that we should not ignore the possibility that the steepness of PS might be smaller than is estimated from phylogeny. We recommend to check model sensitivities inside these ranges when the parameters are fixed, or, if they are estimated, to check whether the estimated values are inside the ranges or not.