Looking Through the Carapace: Virtopsy in Sea Turtle Stranding Investigation
IAAAM 2024
Tabris Yik To Chung1*; Brian Chin Wing Kot1,2; Henry Chun Lok Tsui1; Heysen Hei Nam Ho2,3
1Centre for Applied One Health Research and Policy Advice, City University of Hong Kong, Kowloon Tong, Hong Kong; 2Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong; 3Royal Veterinary College, UK

Abstract

Sea turtle populations around the world are threatened by many anthropogenic stressors, including marine pollution, habitat destruction, fishery bycatch, vessel strike, and climate change.1 Understanding sea turtle health and the threats they are facing are fundamental to studying their population biology and facilitating conservation efforts. Stranding investigation is one of the tools that can provide empirical information for monitoring the health condition and causes of morbidity and mortality in sea turtles by examining live-stranded and deceased individuals.2 Diagnostic imaging has always been utilised in sea turtle medicine, especially during the rehabilitation of live-stranded or rescued sea turtles.3 Noninvasive imaging techniques can be used to investigate abnormalities in the gastrointestinal system relating to marine debris ingestion or evaluate traumatic injuries caused by boat strike, offering valuable information for clinical assessment, decision-making, intervention and rehabilitation of sea turtles.4,5 Cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have also been widely used to study the anatomy and morphology of sea turtles.6,7 However, there has yet to be a systematic approach of utilising diagnostic imaging techniques during the postmortem investigation of stranded sea turtles to facilitate conventional necropsy and provide information regarding their health and cause of mortality.

Virtopsy refers to the application of imaging and scanning technologies, including CT, MRI, and three-dimensional surface scanning (3DSS), during the postmortem investigation of humans or animals to supplement conventional autopsy or necropsy. Originating from human forensic medicine, virtopsy has been increasingly utilised in veterinary medicine, not only limited to companion animals but also in wildlife species such as cetaceans. Since 2014, virtopsy has been integrated into the cetacean stranding-response programme in Hong Kong and augmented the postmortem investigation of stranded cetaceans.8 The application of virtopsy in stranding investigation has since then been extended into sea turtles since August 2019. CT scans and 3DSS have been routinely performed in both live-stranded and deceased sea turtles to facilitate documentation, clinical assessment, and postmortem investigation.9 As of December 2023, virtopsy has been performed in 95 sea turtles (52 live stranded and 43 deceased) of five different sea turtle species (Caretta caretta, Chelonia mydas, Dermochelys coriacea, Eretmochelys imbricata, and Lepidochelys olivacea).

For deceased individuals, 3DSS is particularly useful in documenting the external surface of carcasses (especially traumatic injuries related to vessel collision and entanglement-related lesions) and is able to generate 3D models that are superior to photographs. Postmortem CT aids in the evaluation of internal structures and pathology prior to necropsy (such as identifying foreign bodies or pathological gas embolism); thus, it can facilitate detailed targeted examination and sampling. For live-stranded individuals under rehabilitation, CT has been used in the clinical assessment of individuals with buoyancy disorder, as well as evaluation on traumatic injuries caused by boat strikes to inform intervention and rehabilitation. Digitalised virtopsy data serves as a unique repository of stranding data that can be retrospectively and repeatedly analysed for scientific research. In addition, 3D models generated have also been used in education and outreach to enhance public interest and knowledge of sea turtle conservation. Overall, the application of clinical imaging and virtopsy has improved the conservation value of sea turtle stranding investigation, offering valuable insights that can ultimately help in the monitoring of sea turtle health and facilitate sea turtle conservation.

Acknowledgements

This project is funded by the Environment and Conservation Fund (ECF 10/2019, ECF 2467), the Marine Conservation Enhancement Fund (MCEF21005) and the Marine Ecology Enhancement Fund, Marine Ecology and Fisheries Enhancement Funds Trustee Limited (MEEF2023003). Any opinions, findings, conclusions, or recommendations expressed in this material/event do not necessarily the views of the Government of the Hong Kong Special Administrative Region and the Environment and Conservation Fund; the views of HKLTL, Capco, HK Electric, and the Marine Conservation Enhancement Fund; and the views of the Marine Ecology Enhancement Fund or the Trustee. The authors would like to thank AFCD HKSAR for their continuous support in this project. Sincere appreciation is extended to personnel from the Aquatic Animal Virtopsy Lab, City University of Hong Kong, and Ocean Park Corporation.

*Presenting author

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Speaker Information
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Tabris Yik To Chung
Centre for Applied One Health Research and Policy Advice
City University of Hong Kong
Hong Kong


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