Record-sized fish captured at Yappala Indigenous Protected Area

A freshwater fish listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and critically endangered in South Australia under the Fisheries Management Act 2007, it is also known as Wirti Udla Varri in Adnyamathanha.

In 2021, as part of the Commonwealth-funded Bounceback and Beyond project, 300 fish were translocated from source populations in the northern Flinders Ranges to Hookina Creek.

The record fish measured 13cm and 13.5cm and were the biggest observed at the Yappala Indigenous Protected Area. While the fish are known to grow up to 15cm, the average size is just 5-8cm.

They were captured during an SA Arid Land Landscape Board-led survey in April, held in partnership with Yappala Rangers, National Parks and Wildlife Service SA, Friends of Vulkathunha and other volunteers, to monitor the Flinders Ranges Mogurnda at sites along the Hookina Creek.

The results were promising, with 813 individual fish captured or observed across all size ranges. Large fish captures made up 14 per cent of the total number, which show there are adult fish remaining that would have been part of the original translocation.

Thirty per cent of the fish were of medium size, while small sized fish made up 56 percent of the capture. The number of fry (baby fish) seen and captured indicate that breeding has occurred post flooding in the area.

For the first time, fish were also found near the springhead, just upstream from the original release pools. The floods cleared dense vegetation allowing access to sites that had not been surveyed previously and in addition to confirming that the population continues to survive and breed, one of the most significant findings was evidence of upstream movement. All size cohorts were recorded at newly colonised sites, demonstrating that dispersal is not limited to juveniles - adult fish are also capable of moving upstream. This represents an important new understanding of the species’ behaviour in this system.

It showed the fish are naturally moving upstream and these were able to be monitored because reeds and other vegetation that usually made the ponds inaccessible were flattened or removed during flooding earlier in the year.

Historically, the species was known from only two spring systems in the northern Flinders Ranges of South Australia, along with a small, isolated population in south-west Queensland.

The species faces a range of threats, including competition and predation from introduced fish such as gambusia (Gambusia holbrooki), as well as habitat loss and degradation caused by feral herbivores.

These impacts can alter water quality, reduce habitat availability, and disrupt natural flow regimes. The species' small, fragmented, and isolated distribution further increases its vulnerability to hydrological changes and extreme weather events, pressures that are expected to intensify under a changing climate.

Board staff, along with the Yappala Rangers, will continue to monitor the fish, and changes in pool sizes and vegetation structure across Hookina, as the systems are dynamic. Collecting information on habitat condition, threats, and water quality will inform future management actions.

The Flinders Ranges Mogurnda is one of the priority species targeted through the Discovery 4 Recovery project.

Discovery4Recovery is funded by the Australian Government Natural Heritage Trust and delivered by the SAAL Landscape Board, a member of the Commonwealth Regional Delivery Partners panel.