The Taiwan Transportation Safety Board (TTSB) released its final report on the investigation into the missing crew member occurrence involving the fishing vessel Yu You in the Southern Indian Ocean.

At approximately 1100(Taipei time) on May 19, 2025, the Taiwan-flagged fishing vessel Yu You (Fishing Vessel Registration Number: CT6-1501, Gross Tonnage 304, hereinafter referred to as “the vessel”) was operating on the high seas of the Southern Indian Ocean when the vessel experienced a degradation in propulsion performance, suspected to be caused by the entanglement of main and branch lines from longline fishing. The captain stopped the engine and instructed a crew member (hereinafter referred to as “the crew member”) to dive and clear the obstruction. The crew member, equipped with an air-supply mask and a safety line, entered the water at 1116. At 1121, the crew member was observed surfacing near the port quarter but subsequently was no longer visible. Despite emergency rescue operations initiated by the captain at 1126 and a search lasting until 1130 on May 22, the crew member was not found, and the search was terminated.

In accordance with the Transportation Occurrence Investigation Act, the Taiwan Transportation Safety Board (TTSB) is the independent transportation occurrence investigation agency responsible for conducting the investigation. The investigation team also included members from the Fisheries Agency, the Occupational Safety and Health Administration, and Yu Fu Fa Fishery Co., Ltd.

Based on a comprehensive analysis of the factual information, the investigation identified 7 findings and issued 6 safety recommendations. The final report was reviewed and approved at the 84th TTSB Board Meeting held on March 13, 2026.

Ⅰ.Investigation Findings

Findings Related to Probable Causes

1. At the time of the occurrence, sea conditions were unfavorable (Beaufort Force 5 winds, waves approximately 2 meters high, and strong currents), which may have caused the crew member's safety line and air hose to become entangled with the vessel's propeller during his underwater operations. Given his limited mobility and disrupted air supply, evidence suggests that the crew member may have used a knife to sever the safety line, detaching himself from the vessel and surfacing in an attempt to breathe and survive.
2. The crew member was not wearing a wetsuit during the operation, making it difficult for him to remain afloat and await rescue after the occurrence. He also failed to reach a lifebuoy in time and was gradually swept away from the vessel by the current. When the captain steered the vessel back to the vicinity of the lifebuoy, the crew member was no longer visible.

Findings Related to Risks

1. Despite the nature of its fishing operations frequently requiring underwater work, the vessel was not equipped with necessary breathing apparatus, diving equipment, or personal positioning devices, significantly reducing the probability of locating the crew member after the occurrence.
2. The captain and crew failed to immediately deploy a lifebuoy upon the crew member’s surfacing to mark the location and provide immediate flotation support.
3. There were no established underwater operation procedures or equipment checklists on board to ensure the safety of such tasks.

Other Findings

1. The captain and crew held valid certificates of competency issued by the relevant national authorities.
2. Mechanical factors, such as propeller rotation or foreign objects on the hull, were excluded as causes for the safety line parting, as the engine was stopped and the captain was observing from the stern.

Ⅱ.Transportation Safety Recommendations

To Yu Fu Fa Fishery Co., Ltd.

1. Comply with Article 286-1 of the Occupational Safety and Health Facilities Rules by providing necessary breathing, diving, emergency rescue, and communication equipment for crew members performing underwater operations to clear entangled nets or lines.
2. Establish procedures and equipment checklists for crew members performing underwater operations to clear entangled nets or lines, and implement pre-operation inspection mechanisms to ensure the safety of underwater operations.

To the Fisheries Agency, Ministry of Agriculture

1. Develop regulations and inspection standards for underwater operations on national fishing vessels, including requirements for necessary safety and communication equipment.
2. Review and enhance training courses for fishing vessel officers to strengthen risk assessment for underwater clearing operations and man-overboard (MOB) rescue procedures.
3. Supervise Yu Fu Fa Fishery Co., Ltd. to establish procedures and equipment checklists for crew members performing underwater operations to clear entangled nets or lines.

To the Occupational Safety and Health Administration, Ministry of Labor

1. In accordance with the Occupational Safety and Health Act, assist the Fisheries Agency in strengthening regulations and inspection standards for underwater operations on national fishing vessels.

The complete final report (available only in Chinese) can be downloaded at https://www.ttsb.gov.tw.

Eric SHEN, Specialist

Secretariat

Tel: +886-2-7727-6229

E-mail: ericshen@ttsb.gov.tw

Carlos LIN, Investigator-in-Charge

Marine Occurrence Investigation Division

Tel: +886-2-7727-6252

E-mail: carlos@ttsb.gov.tw