It has been speculated that Sagmariasus verreauxi (Eastern Rock Lobster) is an important predator of the barrens-forming urchin species Centrostephanus rodgersii (Long-Spined Urchin) and Heliocidaris erythrogramma (Short-Spined Urchin). Both urchin species can cause extreme habitat modification when occurring at high densities and this is considered a problem within NSW marine parks. Elsewhere, lobster predation on urchin by similar species Jasus edwardsii (Southern Rock Lobster) is considered key in controlling urchin populations, but whether S. verreauxi has a similar trophic impact is unknown. In this study, I for the first time investigate the likely value of S. verreauxi as an urchin control agent. I use a holistic approach that investigates lobster diet and feeding behaviour by using dissections and feeding trials and investigate urchin predation rates inside and outside of No-Take Sanctuary Zones (SZ’s) using diver surveys and urchin tethering experiments. I also use external