Abstract Group hunting is a widespread phenomenon, fundamentally shaping predator social dynamics and trophic interactions with their prey. The foraging behaviour of killer whale (Orcinus orca) groups feeding upon herring has been described as cooperative. In this study, we used animal-borne audio and video data to evaluate cooperative interactions and feeding rates of herring-eating killer whales in Icelandic waters. From video observations, whales appeared to stop herding herring following a t