Adrian Gleiss

The most threatened family of the sharks and rays is the Pristidae (sawfishes), which is a unique family of batoid rays that are some of the largest chondrichthyans known. Western Australia has recently been identified as a global hotspot of sawfish diversity, with 4 of the world’s 5 species found here. Most pristids have declined globally , and although the susceptibility of the rostrum (or saw) to entanglement in fishing nets is a major reason that all five species have declined and are listed as either Critically Endangered or Endangered by the International Union for the Conservation of Nature (IUCN), other threatening processes have also contributed to their range contractions and rarity. Among these processes are loss of nursery habitats, barriers to migration and reduction in habitat quality as a function of river regulation, targeted fisheries including for cultural purposes and taking of rostra as curios. This project aimed to determine the impact of barriers to sawfish migration in Western Australia, and prioritise the barriers that are likely to have the highest impact in the region. It also summarises work in the Ashburton River and Fitzroy River, each of which offer globally significant habitat to sawfishes. The project was led by Murdoch University’s Freshwater Fish Group & Fish Health Unit with funding from Chevron Australia that was administered through the Western Australian Marine Science Institution (WAMSI). Project partners included the Nyikina-Mangala Rangers and Team Sawfish.

This report provides an overview and summary of the research that has been conducted to date on Freshwater Sawfish (Pristis microdon) in the Fitzroy River, Western Australia, by the Centre for Fish and Fisheries Research at Murdoch University. The report utilises this research to address knowledge gaps and questions arising from the Fitzroy River fishway review (see Background) and seeks to address the core question underpinning this review: “Is a fishway at the Camballin Barrage necessary?”