Quantification of sea turtle swimming patterns using a standardized arena to minimize effort in welfare assessment

Welfare assessment of captive sea turtles has become increasingly important as the need for lifelong care grows. The most valuable indicator of sea turtle welfare is behavioral assessment, as it is non-invasive and more cost-effective than other methods such as physical, nutritional, and environmental assessments. In particular, a higher proportion and longer duration of specific swimming patterns indicate negative sea turtle welfare. However, welfare assessment has been hampered by the efforts required to standardize behavioral criteria across observers and to monitor the environmental factors that influence behavior. To alleviate these efforts, a novel framework to automatically quantify sea turtle swimming within an environmentally standardized arena is proposed in this study. Applying this framework to hatchlings showed its ability to detect individual differences in swimming patterns. Some individuals, with a higher proportion and longer duration of specific swimming patterns, showed signs of poor nutritional or physical condition. These results suggest that accumulating quantitative data through this framework could facilitate the development of individual-level welfare assessment criteria.