Stock Assessment of Chub Mackerel ( Scomber japonicus ) in the Northwest Pacific Ocean Based on Catch and Resilience Data

This study aimed to evaluate the stock status of chub mackerel ( Scomber japonicus ) in the Northwest Pacific Ocean. Chub mackerel is a commercially important fish species in South Korea. The fishing grounds of chub mackerel are in the Northwest Pacific Ocean, off South Korea and the neighboring countries of China and Japan. Previous chub mackerel stock assessments have mostly been based on catch data from a single country. However, in this study we used the total catch data on chub mackerel in the Northwest Pacific Ocean to assess the stock status, owing to their migrations and occurrence in the waters of several different countries. We used a catch and maximum sustainable yield model, which is based on catch and resilience data, using the Monte Carlo method. Moreover, sensitivity analysis was conducted according to the availability of catch data by sea area and country. The results showed that the current level of chub mackerel biomass is lower than the biomass required to achieve a maximum sustainable yield based on median values. Furthermore, analysis of all scenarios showed the same results, while the current biomass showed a decreasing trend. These results indicate that improved cooperative resource management is required to prevent further stock status decline.