The Clutha flathead galaxias, a critically endangered species found nowhere else in the world, has been discovered in three separate locations in the Cardrona Valley, two new sites and one where the species had not been seen in more than 20 years.
The discovery was made during an extensive field survey led by University of Otago postgraduate researcher Isaac Davies, supported by the inaugural Donald Scott Memorial Scholarship in Freshwater Ecology.
Mr Davies and his research team surveyed 30 streams across the Cardrona Valley, ultimately detecting the elusive galaxias in small, trout-free headwaters protected by natural barriers.
These findings underscore the importance of such barriers in shielding vulnerable native species from introduced predators such as brown and rainbow trout.
Mr Davies said the Cardrona remained a valued sports fishery, "but this project demonstrates there’s also room to recognise and protect the special native species that are still holding on in some of the valley’s more remote corners".
The Clutha flathead galaxias may be small, seldom exceeding 10cm, but its presence is a critical indicator of freshwater ecosystem health. With trout known to prey on or outcompete native species, the galaxias’ survival often depends on remaining in isolated habitats above natural fish barriers.
The project was made possible through a generous donation by Patricia Scott, who established the scholarship in memory of her late husband, Donald Scott, a long-serving Fish & Game councillor and passionate advocate for freshwater conservation.
"The outstanding work in the discovery of these new populations of rare galaxiids by the first scholar of the Donald Scott Memorial Scholarship proves the worth of Fish & Game’s ongoing commitment to scientific research and to being kaitiaki of the taiao," Mrs Scott said.
Otago Fish & Game chief executive Ian Hadland welcomed the findings, noting they aligned with the organisation’s approach to balancing the needs of both native species and the region’s popular trout fisheries.
"We’re committed to supporting resilient ecosystems that support both native fish and a world-class sports fishery.
In addition to mapping galaxias populations, Mr Davies’ research is shedding new light on the species’ life history — including spawning age, egg size and the downstream drift of larvae — which will help guide future conservation efforts and fishery management strategies.
University of Otago’ department of zoology professor Gerry Closs said the support from the scholarship and partner organisations made a tangible difference.
"Supporting students enables these critical discoveries to be made."
The research also identified priority sites for future environmental DNA (eDNA) sampling, which will help provide a clearer picture of where native fish populations persist and how best to protect them.
Key findings
• Three Clutha flathead galaxias populations found — two new, one rediscovered
• All located in trout-free headwaters protected by natural barriers
• 30 streams surveyed across Cardrona Valley
• Additional species recorded: brown and rainbow trout, kōaro, upland bullies, longfin eels
• Research to inform future native and sports fish co-management — APL
