At last there was self-defense against sharks. Power heads which detonated cartridges upon impact were fitted to hand spears then to spears. Grey Nurse sharks were easy targets at first. Faster swimming Bull sharks and other whalers presented a challenge. Confidence to explore the sea came with these devices but soon explosive power heads were causing accidents and became more dangerous to be near than sharks would ever be.
Large fish were not excluded from power head tests either. Giant groper would have been numerous victims.