The Effects of Vertebral Deformities on Swimming Kinematics in Lumpfish, <i>Cyclopterus lumpus</i>

Vertebral deformities such as abnormal curvatures and shapes may influence kinematics of fishes during swimming. Our study examines the vertebral deformities of hatchery-reared lumpfish (Cyclopterus lumpus) to better understand the effects of vertebral deformity on swimming kinematics. We recorded and analyzed videos of 50 juvenile lumpfish that were being raised as cleaner fish for salmonid farms. Each lumpfish was observed in 10-s video intervals and then euthanized for X-ray visualization of the skeleton. We used midline tracking to calculate speed, tailbeat amplitude, stride length, tailbeat frequency, and tail curvature during volitional swimming. Body shape analysis using 2D landmarking and principal component analysis showed that there was a significant relationship between the number of deformities and body shape from a dorsal view. We also found that body shape from a lateral view was a significant predictor of speed and stride length. We expected that an increase in deformity would cause a change in tail curvature and a decrease in speed, stride length, tailbeat frequency, and tail amplitude. Instead, we found that the lumpfish swimming was mostly unaffected by the deformity. There was only a significant relationship between tailbeat amplitude and number of early compressed vertebrae. Since vertebral deformities had a significant relationship with body shape, there was also an indirect effect of deformity on swimming speed.