Abstract

Reported numbers of cetacean strandings and mortality cases have increased dramatically in recent years in the waters of Hong Kong (HK) and near regions, possibly due to increasing awareness of local cetaceans, along with increasing levels of vessel traffic and other anthropogenic activities.^1,2,3,4,5 Postmortem examination of stranded cetaceans provides invaluable information for analysis of biological health status and life history of a population. Long-term systematic recording of this information may provide invaluable insights to establish factors that may have contributed to mortality and diseases of these local cetacean populations.

Since March 2014, virtopsy has emerged as a new postmortem examination technique to augment conventional necropsy in stranded cetaceans in the HK waters.⁶ Whole body postmortem computed tomography (PMCT) and postmortem magnetic resonance imaging (PMMRI) were conducted to create a number of volumetric image datasets. Two- and three-dimensional volume reconstruction was performed with advanced visualization technology to facilitate objective visualisation and recapitulation of postmortem results. Field examination and conventional necropsy results detailing a wide range of diseases and lesions from stranded cetaceans should be compared and integrated with postmortem imaging. Generating this quantifiable information allows advancement of the use of these imaging technologies in necropsy and biological profile investigation of stranded cetaceans.

Literature relating to strandings, mortality and morbidity of HK local cetaceans has been reported, but the data has not been updated and results have always been hindered by advanced decomposition of carcasses.^2,3,4,5 While some limited long-term regional marine mammal health monitoring datasets exist worldwide, information regarding virtopsy-driven postmortem investigation of stranded cetaceans is yet available. It is time critical to incorporate both conventionally collected postmortem examination data (i.e., field and necropsy multimedia and reports) and virtopsy data, in order to analyze and interpret as a meaningful whole both necropsy and biological profile investigation in HK stranded cetaceans.

An online content management platform connected to advanced visualization technology (TeraRecon Aquarius system) was established to address the gap, which served as the first-of-its-kind database in the HK waters. The main goals of the web-based database are (1) to establish a digital and standardized documentation tool for both necropsy and virtopsy findings; (2) to compile, categorize, and annotate image and multimedia datasets acquired for comparison of the necropsy and radiological findings i.e. evaluating the accuracy of the virtopsy approach in comparison with the currently accepted gold standard necropsy approach for validation of cross-sectional imaging as a non-invasive examination method in necropsy and biological profile investigation of stranded cetaceans; (3) to provide a centralized location for on-going postmortem data collection for research and review on resource management in related governmental agencies.

Since CPMAP has been implemented in spring 2017 for human interaction related injury and mortality in stranded cetaceans, a pilot study was conducted using postmortem multimedia from a virtopsy-driven stranding response program in the HK waters from 2014 to 2016. The architecture of this platform and workflow of access, indexing, search, and retrieval for stranding case will be demonstrated in this presentation. We will present a case study of evaluation of cranial cervical dislocation in stranded cetaceans, showing how the platform underpins the research and integrates with the stranding response workflow.

The outcome may eventually be beneficial to the scientific community for better integration and communication of postmortem informatics of stranded cetaceans in the HK waters. Valuable insights will be gained from this all-in-one platform and may contribute to potential conservative measures/policy establishment for local cetaceans.

Acknowledgements

The authors would like to thank the Agriculture, Fisheries and Conservation Department of the Hong Kong SAR Government for the continuous support in this project. Professional advice on database establishment and programming given by Mr. Andrew Chin and his team from Evergreat Creative HK Ltd. has been a great help in this project. Sincere appreciation is also extended to veterinarians, staff and volunteers from Ocean Park Hong Kong, Ocean Park Conservation Foundation Hong Kong, and Tung Wah College for paying great effort on the stranding response and necropsy in this project. Special gratitude is owed to technicians from Hong Kong Veterinary Imaging Center for operating the CT and MRI for this research.

* Presenting author
+ Student presenter

Literature Cited

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