NLC’s Timber Creek rangers and the CSIRO have established a sawfish monitoring program on the Victoria River to record population estimates and to study its behaviour and breeding.
The first survey, in August 2018, captured 25 dwarf and largetooth sawfish and provided the first recorded evidence of the critically endangered speartooth shark and northern river shark in that waterway
Sawfish are one of the most endangered species on the planet. Australia has some of the last remaining populations of sawfish. However, populations in most areas are fragmented and declining with commercial fishing and habitat modification the primary threats. The largetooth sawfish is the largest species found in Australia, reaching up to seven metres in length and is known for use of freshwater habitats. It has been found several hundred kilometres upstream in major drainages. The Victoria River is one of the few rivers in the country that still supports largetooth sawfish populations at levels where their capture is not incredibly rare. A survey of the lower reaches of the Victoria River by CSIRO and Timber Creek Rangers in 2018 recorded dwarf and largetooth sawfish, as well two species of river shark.
CSIRO researcher Richard Pillans says: “We caught more in two weeks than I’ve caught in 20 years.”
The presence of sawfish in the Victoria River, combined with their importance to Indigenous culture, provides a unique opportunity to develop a monitoring program involving the Timber Creek Indigenous rangers. The project will undertake surveys of the Victoria River to:
collect tissue samples for population estimates;
establish whether catch rates of largetooth sawfish warrant long-term research into movement and mortality using acoustic telemetry; and
coordinate a training program that will enable Timber Creek rangers to collect data required to obtain estimates of largetooth sawfish. Data collected will be used to inform management and conservation of this species across Northern Australia.
The partnership between the CSIRO and Timber Creek rangers means Indigenous rangers will be trained in survey methods, capture, handling, measurement and tissue sampling of sawfish and speartooth sharks.
Floyd Rogers, one of the Timber Creek rangers who took part in the survey, says: “I’ve been a full-time ranger for three years now. I enjoyed every trip we have done, but this seven days on the river was the greatest I have done and learned a lot on this wonderful Vic River. Now I know there are two sorts of sawfish – freshwater and saltwater sawfish – and it’s great to know their scientific names, Pristis pristis (freshwater) and Pristis clavata (dwarf saltwater). Good to know that other animals on the river are also endangered, like speartooth shark and northern river shark. I had a good time on the river and I’m looking forward to it again next year. And I hope we can catch more freshwater sawfish with Dr Richard Pillans.”
Fellow ranger Aron Harrison says: “It was a great exercise for me working on the river for the first time. It was really good and I really enjoyed it, and I hope I will be doing more surveys on the river and get to know the waterways more. Best time of my life.”