Studying the elusive culturally-important freshwater sawfish
Aims and overview
Laura Rangers partner with Sharks and Rays Australia (SARA), QPWS and Rinyirru Rangers to study the critically endangered freshwater sawfish (Pristis pristis).
Until the 1980s, freshwater sawfish were an important food source in the Laura area, and images of sawfish feature in local rock art. Commercial fishing and recreational trophy hunting drastically reduced numbers and they are now listed as critically endangered (IUCN Red List).
The project aims to collect data on sawfish population numbers and distribution to develop a conservation recovery plan. Additionally, data on freshwater whip rays (Himantura dalyensis) is recorded. Little information about either species has been collected from Queensland’s east coast. The project is important to Traditional Owners and the community because freshwater sawfish are part of the cultural landscape.
Activities and outcomes
The fieldwork was conducted in locations including Rinyirru (Lakefield) National Park (CYPAL).
Laura Rangers undertook detailed planning for the fieldwork. All rangers received training in animal handling, DNA sampling, stable isotope sampling, and dart and acoustic tagging. DNA sampling allows for the number of breeding animals to be extrapolated from genetic diversity and stable isotape sampling is used to identify where the animal has been living and what it has been eating
Previously, two sawfish and two whip rays have been dart-tagged. After a gap of two years, a tagged sawfish was caught during the June 2024 fieldwork.
Seven acoustic receivers were deployed at the study locations. Rangers swapped out three acoustic receivers to retrieve the data. They tagged one sawfish (1.4m long) with an acoustic tag, which will allow movement within the river system to be tracked.
SARA now has clearance to operate on the water at night, and discussion is underway to build a private research boat ramp for future studies.
The fieldwork has strengthened the relationship between all the research partners. Additionally, the number of sightings/captures of sawfish reported has increased.
Learning and next steps
Rangers have discussed with the project partners, various options for improving equipment, including considering optimal gill net size for reducing by-catch and purchasing a hand winch to retrieve entangled acoustic receivers.
Sawfish are stronger than they look, highlighting the need for correct handling techniques. Freshwater crocs caught in the gill net attract estuarine crocs. Discussions are underway for Laura Rangers to undertake crocodile handling training with QPWS rangers.
Laura Rangers will continue to tag and release sawfish and whiprays. The number of acoustic receivers in the Laura/Normanby catchment will be increased. If funding can be sourced, receivers will also be deployed in Princess Charlotte Bay to track marine species of sawfish.