Miss Jess Fish1, Mr Zach Clark1, Dr Paul Butcher3, Dr Craig Sherman1, Dr Andrew Weeks2, Dr Adam Miller1
1Deakin University, Warrnamool, Australia, 2EnviroDNA, Melbourne, Australia, 3NSW DPI, Coffs Harbour, Australia
The white shark (Carcharodon carcharias) is a key apex predator found in the world’s temperate and sub-tropical oceans. However, C. carcharias has suffered significant declines in recent decades, and effective conservation efforts are needed to protect C. carcharias populations and the ecosystems they support. Unfortunately, conservation management is complicated by increasingly frequent human-shark interactions and shark attacks globally, and a general lack of information on the species’ biology and ecology. In this presentation, I will present the findings from a current research program using eDNA technologies to characterise key trophic interactions supporting C. carcharias populations and influencing shark spatial ecology. Firstly, DNA metabarcoding analyses of C. carcharias cloacal swabs was performed to address current knowledge gaps around shark diet and feeding behaviour, suggesting the species is a generalist, opportunistic feeder, with potential for some targeted predatory behaviour toward particular fishes. Next, trophic links between C. carcharias and potential prey species were assessed via eDNA analysis of seawater samples collected weekly from 4 set locations from northern NSW over an 18-month period. A combination of eDNA metabarcoding and TaqMan assays were used to characterise spatio-temporal trends in marine community assemblages and biotic associations with C. carcharias presence and absence. This study highlights the power of eDNA technologies for assessing the spatial and trophic ecology of large marine pelagic species and provides a framework for guiding management geared towards conserving C. carcharias populations and reducing risks of shark attack in Australian waters.
Biography:
Jess is a PhD candidate conducting genetic research on eastern Australian sharks. Jess completed a Bachelor of Environmental Science (Marine Biology) and an Honours degree investigating the diet of eastern Australian white sharks using DNA metabarcoding. Currently, she is working closely with the New South Wales Department of Primary Industries and other collaborators to further understand the biology and ecology of white sharks (Carcharodon carcharias), tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas) using a range of molecular genetic techniques. Specifically, Jess’s research is focused on using eDNA metabarcoding to identify shark diet composition and marine community assemblages to determine biotic factors that influence near shore shark visitations.