Vertebral compression syndrome in the Atlantic bonito, Sarda sarda (Bloch, 1793) from the Southwest Black Sea coasts of Türkiye

This study documents the first recorded case of vertebral compression syndrome (VCS) in an Atlantic bonito (Sarda sarda) from the southwestern Black Sea. The affected specimen exhibited distinct morphometric deviations, including a shortened vertebral column and an increased body depth, compared to a normal conspecific. Radiographic analysis revealed mild compression initiating at the 13th vertebra, which progressed to severe compression affecting vertebrae 21–40. Within this region, vertebrae showed a marked reduction in width and an increase in height, accompanied by localized dislocations and abnormal bulging along the spinal column. The deformity is consistent with a response to altered mechanical load, which likely disrupted bone growth zones and prompted the replacement of intervertebral tissue with cartilage. This study underscores the utility of high-resolution digital radiography as a nondestructive tool for detailed biological investigation. The exact etiology of the mechanical load, whether from an acute pressure event or chronic overexertion, remains unknown and warrants future investigation.