In 2009, the Australian Government (in collaboration with the Fijian Government, FFA, WWF and four major pelagic longline licence holders) embarked on a project to mitigate the economic and conservation impacts of toothed whale depredation and by-catch in pelagic longline fisheries. The impetus for the project arose from concerns tabled a workshop held in Apia (Samoa) in 2002. This project provides a rare opportunity to tackle both problems simultaneously. The aim was (i) to develop two devices that physically or psychologically deterred depredating whales by simulating gear tangles (several fisher reports indicate these are avoided), and (ii) assess their effectiveness under rigorous experimental conditions in an operational environment.