Abstract
Sharks play a vital ecological role in marine ecosystems but are increasingly vulnerable to anthropogenic stressors, particularly those associated with fisheries interactions. One underexplored consequence following capture and release is the retention of fishing gear (i.e., hooks and trailing lines). While prior studies have documented the post-release physical injuries and mortality associated with gear retention, the behavioral and kinematic consequences remain poorly understood. This thesis investigates the sub-lethal impacts of retained fishing gear on swimming behavior and performance in small sharks held in captivity. Quantitative analyses were conducted to assess changes in swimming speed, tailbeat frequency (TBF), and tail amplitude (TA) using video tracking and linear mixed-effects modeling. Results show that treatment sharks (i.e., with retained gear) exhibited acute behavioral responses immediately following gear attachment, including elevated TBF and swimming speeds and reduced TA. Thereafter, TBF and speed returned to baseline values, but TA rose above baseline values, suggesting a compensatory shift toward greater thrust per tailbeat. By contrast, control sharks (i.e., without retained gear) maintained consistent swimming behavior (i.e., no change in TBF, swimming speed, or TA). Together, these results demonstrate that even a single retained hook and relatively small amount of trailing line (i.e., 2.5 body lengths) can immediately alter swimming and induce compensatory adjustments in kinematics. These findings indicate how retained fishing gear may alter normal swimming kinematics, with implications for energy expenditure, predator avoidance, and survival. By linking retained gear to changes in speed, TBF, and TA, this work increases our understanding of how post-release interactions can impose sub-lethal burdens on small sharks. This research highlights the need for improved handling and gear practices to minimize gear retention and informs conservation strategies to reduce long-term impacts in shark populations.