The Western King Prawn is a short-lived, highly valued crustacean that exists at its latitudinal limit in South Australia’s unique gulf systems. Unlike most other prawn trawl fisheries, the Spencer Gulf Prawn Fishery (SGPF) has had a remarkably stable history of catches, most likely the result of appropriately conservative management strategies, suitable environmental conditions for spawning and recruitment and highly productive juvenile habitats. Regardless of this stable history, threats to sustainability include anthropogenic effects such as the impacts of industry, introduction of disease and the potential for over-fishing and environment effects such as climate change. Historically, fishery-independent surveys were conducted in juvenile habitats in the intertidal zone. Also, fishery independent surveys conducted on the fishing grounds provide data on the number of new recruits entering the fishery and data on the catches of prawns just below harvest size. Reliable indices of future harvest are not only essential for determining fishery sustainability, they also increase income certainty to the industries that harvest them. In this study we aim to compare the effectiveness of three indices of future harvest: abundance of juvenile prawns in intertidal habitats, abundance of newly recruited prawns to the fishery and abundance of prawns just below harvest size.