Trout Removal Project
Upper Waihemo Shag River catchment
Supported by the Otago Regional Council (ORC) ECO Fund, the East Otago Catchment Group's Upper Shag Trout Removal Project works to protect the rare, threatened Taieri flathead galaxiid (a native non-migratory freshwater fish found in parts of Otago) by eliminating invasive trout from local waterways.
The Taieri flathead galaxiid is classified as ‘nationally vulnerable’, with brown trout being one of the greatest threats to the species. Without intervention, local populations are at risk of disappearing from these waterways.
The project focuses on Pig Root and Siberia Creeks, where work is underway to remove self-sustaining brown trout populations and improve habitat conditions for the galaxiid.
Following an ORC feasibility study completed in 2022, which assessed habitat, trout populations, fish barriers, and galaxiid populations across upper tributaries of the Waihemo Shag River catchment, we identified Pig Root and Siberia Creeks as priority sites for trout removal, with high trout numbers posing a major risk to native fish populations.
Year One:
Year Two:
Year Three:
Year One
Trout removal work began in January 2024 using electric fishing methods across both creeks.
Key results from Year One included:
2698 brown trout removed
107 Taieri flathead galaxiid recorded
28 hours of electric fishing completed
The first year of the programme provided a strong start, significantly reducing trout numbers and helping improve conditions for native fish.
Year Two
In Pig Root Creek, only smaller trout were found during follow-up removal work, suggesting spawning had not occurred since the initial removals. In Siberia Creek, trout numbers remained high in upper reaches that had not previously been fished, while lower reaches showed major reductions compared with Year One.
Monitoring undertaken by the ORC Science team also showed encouraging signs for the Taieri flathead galaxiid population.
Key Year Two results included:
825 brown trout removed
358 Taieri flathead galaxiid recorded
The increase in galaxiid numbers is a promising sign that reducing trout pressure is helping support native fish recovery within the catchment.
Year Three
Year Three trout removal focused on the upper reaches of Siberia Creek, where access had previously been challenging and trout numbers remained higher. Monitoring continued to show encouraging results for the Taieri flathead galaxiid population, with numbers remaining well above those recorded before the programme began.
Key Year Three results included:
530 brown trout removed
257 Taieri flathead galaxiid recorded
The success of the programme has secured an additional year of trout removal and monitoring, helping protect and restore habitat for this nationally vulnerable native fish.
What’s next
Further trout removal is planned across both creeks for one more year. The project will then move to the monitoring phase using eDNA to detect trout presence.
The project team is also investigating options to improve a natural barrier beneath SH85 to help prevent trout moving back upstream into Pig Root and Siberia Creeks.
The project is a collaborative effort involving the East Otago Catchment Group, Otago Regional Council Science team and local landowners.
A special thank you to landowners Dave and Judy Andrew, and Tony and Julie Kearney, for their ongoing support of the project.
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