Sink and swim: Tracking submergence patterns and anomalous behavior in sea turtles

Sea turtle rehabilitation efforts face challenges in evaluating the long-term success and ecological impact of released individuals. This study presents an integrated analytical approach to study submergence behavior using satellite tracking data. We analyzed data from Wet/Dry sensors embedded into the widely used Wildlife Computers' SPOT-6 satellite transmitters to examine patterns of surfacing and diving. Post-release acclimatization was assessed through submergence behavior in rehabilitated turtles (n = 55), with nesting females (n = 12) and published data as a healthy reference group. Among the predictors tested–species, sex, life stage, injury category, and season–only season significantly explained submergence, with air exposure lowest in winter (3.7 %) and highest in summer (5.9 %), a pattern consistent with seasonal changes in ectothermic physiology. Rehabilitated turtles were generally comparable to nesting females, exhibiting even fewer “outlier days”, days with unusually high air exposure (median ratio 0 % vs. 1 %, p = 0.026). Seven rehabilitated individuals were classified as outliers, displaying atypical submergence behavior and irregular movement patterns indicating potential buoyancy issues. This methodology enables the inclusion of rehabilitated individuals, after testing their behavior, into tagging studies, reducing the risk of misinterpreting abnormal behavior as natural. Our findings indicate that post-rehabilitation, turtles display distinct movement and submergence patterns consistent with physiological recovery and adaptation to the wild. These results highlight the importance of post-release monitoring for evaluating individual variation, survival prospects, and the effectiveness of rehabilitation programs. Overall, this approach advances understanding of sea turtle reintroduction outcomes and can help inform and refine conservation strategies.