Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Identifying shark species responsible for fisheries depredation off Queensland Australia.  (#87)

Jaeden Vardon 1 , Samuel Williams 2 , Jess Morgan 2 , Daniel Bucher 3 , Adam Barnett 4 , Bonnie Holmes 1 , Christine Dudgeon 1
  1. University of the Sunshine Coast , Sippy Downs
  2. Department of Agriculture and Fisheries , Brisbane
  3. Southern Cross University , Lismore
  4. James Cook University , Townsville

Anecdotal reports from fishers in Queensland, Australia suggest that shark depredation is a significant issue, however little is known about which species are responsible for depredating catches. This research aimed to identify depredating species in Queensland line based fisheries, by undertaking a genetic analysis of depredated samples collected by commercial, charter and recreational fishers. The genetic analysis successfully identified at least nine depredating shark species, mostly from the genus Carcharhinus. The species identified using mitochondrial DNA included C. leucas (bull sharks), C. plumbeus (sandbar sharks), C. amboinensis (pigeye sharks), C. brevipinna (spinner sharks), C. amblyrhynchos (grey reef sharks), C. sorrah (spot-tail sharks), C. limbatus/tilstoni (blacktip sharks), C. falciformis (silky sharks), C. obscurus (dusky sharks), Sphyrna mokarran (great hammerhead sharks) and an unconfirmed C. plumbeus/C. altimus (bignose shark). While several species of Carcharhinus have been found to depredate catches in Australia, C. leucas has not been highlighted until this research as a potential problematic species. The optimised protocol allowed for the confident identification of shark species responsible for depredation in fisheries, using a citizen science approach combining the collection of frozen fish samples and swabs taken off depredated fish remains and donated by fishers.