Tracking free-ranging sharks with hand-fed intra-gastric acoustic transmitters

To estimate tag retention time, 39 acoustic transmitters were hand-fed to bull sharks <i>Carcharhinus leucas</i>, lemon sharks <i>Negaprion acutidens</i> and tiger sharks <i>Galeocerdo cuvier</i>, in the Shark Reef Marine Reserve, Fiji. Minimum tag retention times ranged from less than 24 h to 34 days, and bull sharks could be tracked for a minimum mean duration of 6.8 days. Feeding acoustic transmitters wrapped in bait to free-ranging sharks is an alternative and viable method to obtain presence–absence data from free-ranging sharks.