This study focuses on the sinking of the Geumseong 135 vessel in November 2024 in the waters off Jeju Island, analyzing the causes of capsizing in large-scale mackerel purse seine fishery operations and proposing measures to enhance safety. Large-scale mackerel purse seine fishing inherently carries risks of load shifts and stability loss due to the nature of high-volume catch operations, which can act as primary causes of vessel capsizing. While the exact cause of the Geumseong 135 incident has yet to be clearly identified, initial findings suggest a combination of concentrated loads from the massive catch and stability loss as contributing factors. This study proposes specific improvement measures, including the adjustment of auxiliary boat (deungseon) positioning, the implementation of automated tension control devices, real-time load monitoring systems, and enhanced stability standards tailored to the characteristics of purse seine fishery operations. These measures aim to effectively mitigate the risks posed by load shifts and stability deterioration, improving both the safety and operational stability of high-volume fishing activities. In conclusion, the Geumseong 135 incident highlights the necessity of establishing safety standards and technical improvements that reflect the unique characteristics of large-scale purse seine fishing. The proposed measures are expected to prevent similar incidents in the future and improve overall safety at sea. This study provides practical and technical policy recommendations to enhance stability and safety in large-scale purse seine fishery operations.