A Study on Stock Assessment of Chub Mackerel(Scomber japonicus) in South Korea Using CMSY and BSS Models

This study attempted to assess the stock status of chub mackerel(Scomber japonicus), which is one of commercially important fish species in South Korea. Recent studies on stock assessment of chub mackerel have been done, but they have several limitations such as setting up prior information and distributions for major variables. In this study, stock assessment models, Monte Carlo method (CMSY) and Bayesian state-space (BSS) method, that can be analyzed even in limited data and based on prior information and distributions with relatively clear evidence were used. To evaluate the stock status of chub mackerel, annual changes in the amount of biomass and the ratio of the amount of biomass in the last year to BMSY (the biomass which can produce maximum sustainable yield) were estimated. Results showed that the status of chub mackerel was assessed to be 'Grossly overfished' by CMSY model and 'Overfished' by BSS model, respectively. That is, the biomass of chub mackerel is decreasing and the current level of biomass is much lower than that of BMSY.