Anthropogenic Vessel Strike as a Threat to Spotted Seals (Phoca largha) in Korean Waters: A Multimodal Forensic Investigation

The spotted seal (Phoca largha) is a flagship species and natural monument inhabiting Korean coastal waters. Due to its conservation importance and the rarity of carcass discoveries, determining the cause of death of each individual is critical. A juvenile female spotted seal carcass was discovered on the eastern coast of Korea in May 2025. External examination revealed multiple parallel lacerations consistent with propeller strike injuries. Post-mortem computed tomography (PMCT) was performed prior to necropsy to provide a comprehensive forensic analysis. CT imaging revealed the longest wound measured 10.49 cm in length and 1.58 cm in depth, suggesting a minimum propeller diameter of approximately 19 cm. Skeletal injuries included a coccygeal vertebral fracture and subluxation of the left astragalus and calcaneus. CT images of the respiratory tract showed frothy fluid in the nasal cavity and trachea, as well as ground-glass opacity and consolidation in the lung parenchyma. Necropsy findings confirmed severe pulmonary edema, congestion, and abundant frothy foam throughout the respiratory tract. Histological analysis revealed pulmonary edema with eosinophilic fluid and erythrocytes in alveolar spaces, markedly distended blood vessels, and intra-alveolar hemorrhage. This comprehensive approach demonstrated that the cause of death was drowning, secondary to propeller strike by a small vessel (<4.5 m). To the authors’ knowledge, this is the first case report providing a detailed forensic analysis of a juvenile spotted seal found on the eastern coast of Korea. This case highlights the importance of integrating PMCT with conventional necropsy to improve cause-of-death determination in marine mammal conservation.