The research and development of automated fishing equipment is a key factor in promoting the high-quality development of offshore fishing. In order to improve the efficiency and quality of tuna fishing in offshore operations, this study proposes an intelligent throwing-rope control system based on the hook depth model for south Pacific albacore tuna （Thunnus alalunga）.The system employs a fuzzy PID control method that integrates real-time data collected by sensors deployed on operating fishing vessels, and dynamically adjusts the rope throwing speed through a PLC controller to ensure that the hook depth matches the habitat depth of the target fish species.The study first validated the effectiveness of the fuzzy PID control method in the intelligent throwing-rope control system through simulation and verification experiments, and then deployed the system for sea trials on the "Zhongshui 747" fishing vessel owned by CNFC Overseas Fishery Co., Ltd., comparing the rope throwing speed control precision, stability, hook depth, and fishing outcomes between the intelligent system and traditional manual operations. The results are as follows： （1） The rope throwing speed can be automatically adjusted to the optimal speed based on the ship's speed, control the steady-state error range of the ropethrowing speed to around 2%； （2） The average depth of the deepest hook was 230.20 m, and 53.57% of the hook depths between the two floats coincided with the albacore tuna's feeding depth； （3） The hook rate of albacore tuna increased by 31.85% and the target catch body mass range increased from （14, 18] kg to （18, 22] kg, improving the catch quality. This study shows that the intelligent throwing-rope control system outperforms traditional manual operations and the intelligent throwing-rope control system can effectively improve fishing efficiency and catch quality for target tuna species. This study provides a scientific basis forthe intelligent control of tuna fishing equipment, driving technological innovation and intelligent upgrades in pelagic fishing equipment.