Significant reduction in shark (cucut) depredation rates when using an electrical deterrent device at Cocos (Keeling) Islands, Australia

Context Shark depredation is a human–wildlife conflict occurring in many fisheries around the world. At Cocos (Keeling) Islands in the Indian Ocean, high shark (known as cucut in the local Cocos–Malay language) depredation rates are causing costly loss of target catch and fishing gear for artisanal fishers, increased mortality for target species and negative attitudes towards sharks. Aims This study tested the effectiveness of an electrical shark deterrent device (RPELX) for reducing shark depredation during line fishing for demersal fish species. Methods A randomised experimental design was used to test the RPELX against a control treatment, during 11 days of deepwater fishing for demersal fish. Key results Across 51 fishing sessions, 262 fish were caught. Results of a generalised linear model indicated that treatment and skipper had a significant effect on the number of fish depredated, with the RPELX reducing the probability of a depredation event occurring by 63%. The RPELX device also reduced shark bycatch and loss of fishing gear. Conclusions Overall, the RPELX device can provide substantial environmental and socio-economic benefits to the marine ecosystem and community at Cocos (Keeling) Islands. Implications Further testing of the RPELX in other demersal line fisheries, where depredation is occurring around the world, is strongly recommended.