Description
Species identification following shark-related incidents is critical for effective incident management, but often requires more reliable techniques than simple human observations. Analyses of morphological or genetic characteristics left in the wake of an incident can be used to inform species identification, and complex cases may require a combination of both approaches. The collection and processing of genetic material has unique limitations in shark attack cases—samples often contain large quantities of human DNA due to victim injuries or post-incident contamination or DNA loss from limited access to appropriate collection resources or environmental influences.Following an incident where the ski of a paddler was bitten by a shark, which was not visually identified by witnesses, a new DNA sampling approach was applied to determine the efficacy of widely available gauze for species identification. In addition to the bite mark impressions left on the ski, a tooth was found and assumed to be associated with the incident.
The characteristics of the bite impression, including shape and tooth indentation pattern, inferred the involvement of a white shark (Carcharodon carcharias). The morphology of the recovered tooth, however, was instead identified as belonging to a wobbegong (Orectolobus spp.). Although the discovery and identification of a tooth is typically suggestive of the shark of interest, genetic analysis of DNA transferred from the shark to the ski identified the presence of C. carcharias, which supported the conclusions drawn based on the bite morphology. Genetic analysis of the tooth also corroborated its morphological identification.
This case study facilitated a unique opportunity for an experimental design to compare the effectiveness of gauze and forensically-standard swabs in collecting genetic material for species identification. The results were congruent between sampling methods with respect to species identification and the level of activity inferred by the donor-specific DNA contribution. This study represents the first application of gauze as a sampling media after such an event and supports the translation of these methods to the field.
| Period | 13 Nov 2023 |
|---|---|
| Event title | White Sharks Global 2023 |
| Event type | Conference |
| Location | Australia, South AustraliaShow on map |
| Degree of Recognition | International |