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Piharau Conservation Project
Final Report from Te Rūnanga o Ngāti Mutunga
by Annettw Lamb
Cultural Significance of Piharau
Piharau are recognised through the Ngāti Mutunga Iwi Environmental Management Plan as a priority taonga species and are one of six species specifically mentioned in the Ngāti Mutunga Deed of Settlement with the Crown (2005). Traditionally served at hākari during tangi when in season, Piharau represent an important and personalised way for Ngāti Mutunga to practice manaakitanga.
During Mauri Compass surveys of the Urenui and Mimitangiatua awa, Ngāti Mutunga whānau raised concerns about declining Piharau numbers and their absence from customary fishing sites along the Mimitangiatua river. This observation sparked a comprehensive investigation into the current state of Piharau populations within the rohe.
Traditional Catching Methods
Based on whānau wānanga of customary fishing sites, a traditional catching site called Whakaparu was constructed on the Mimitangiatua river. The method involved placing Aruhe (bracken fern) in the shallow areas by boulders and creating a pathway with rocks to monitor for adult Piharau.
Unfortunately, attempts to capture Piharau using this traditional method were unsuccessful. However, environmental factors and time constraints limited opportunities to test the approach, making results inconclusive. Whānau have committed to repeating these methods each season to master the technique.
Traditional Methods Identified:
  • Digging holes in mud for Piharau to settle
  • Using nets at collection sites
  • Whakaparu method with Aruhe and rock pathways
Scientific Testing Approaches
eDNA Testing
Initial testing at 9 sites across five catchments (Onaero, Urenui, Mimitangiatua, Waiau, Taramoukou) did not detect Piharau markers. Methodology was refined to filter more water than the recommended 1 litre to improve accuracy.
Pheromone Detectors
A single pheromone detector was deployed on Taramoukou Stream, informed by 1980s records from the NZ Freshwater Fish database. All test results analyzed by NIWA were negative for Piharau presence.
Electric Fishing
No electric fishing was carried out as there was no detected pheromone marker indicating a juvenile population. This method remained unused throughout the project duration.
Discussions with Taranaki Regional Council and DOC staff revealed that while eDNA produces accurate positive results, the method can generate false negatives. This was confirmed when a Ngāti Mutunga staff member caught Piharau at a lower Onaero river site that had previously returned negative eDNA results.
Community Engagement & Knowledge Sharing
In September 2022, Ngāti Mutunga hosted a Piharau workshop at Urenui Marae with support from the Department of Conservation. NIWA expert Cindy Baker presented to 26 attendees, sharing expertise on Piharau biology and conservation efforts.
A follow-up meeting at DOC Ngāmotu in November 2022 brought together iwi representatives to consider catchment selection for intensive sampling. The Ngāti Mutunga Pou Taiao also attended a two-day Taranaki Piharau wānanga, including a practical session catching Piharau in the Waiwhakaiho awa. These gatherings provided excellent opportunities to share stories and mātauranga around Piharau, sparking discussions about halting their decline and supporting population recovery.
Department of Conservation Collaboration
Positive Detection Results
Interest in Piharau peaked among the DOC Freshwater team, leading them to carry out further testing on three awa that Ngāti Mutunga had originally tested, plus other sites in the wider Taranaki region.
In September 2022, DOC testing returned positive results for Piharau presence, demonstrating that the species still exists in some waterways despite earlier negative findings from alternative testing methods.

The collaboration between Ngāti Mutunga and DOC highlighted the importance of combining multiple testing approaches and sharing results across organizations to build a more complete understanding of Piharau populations.
Key Learnings from the Project
01
Testing Methodology Limitations
Both eDNA and pheromone sampling proved problematic for accurately showing Piharau presence or absence. Focusing on a single catchment may have increased accuracy and delivered positive detection results.
02
Baseline Data Collection
Prior to this project, Ngāti Mutunga had very little data on current Piharau populations. The project quantified existing knowledge and enriched the team's freshwater monitoring capabilities despite not detecting juvenile populations.
03
Traditional Knowledge Validation
Traditional mātauranga such as seasonal tohu and kōrero tuku iho proved most effective. A kaumatua successfully caught Piharau in the Onaero river when all scientific evidence showed none were present.
04
Increased Community Awareness
The project created increased interest among whānau about why Piharau collection has declined, highlighting access issues to traditional sites and knowledge gaps among younger generations.
Project Outcomes & Challenges
What Was Achieved
The field work increased skill and experience levels of Ngāti Mutunga participants in collecting information about awa and taonga species. Knowledge of tipuna awa and traditional Piharau collection sites was shared, giving whānau confidence in using western science methods successfully.
This project utilized Mātauranga Māori methods to provide good quality baseline data of fish species throughout the rohe and water quality. Results have been shared with other hapū and iwi considering similar methods, as well as DOC and Taranaki Regional Council.
Challenges Encountered
  • No juvenile Piharau populations detected
  • Unable to add Piharau as second taonga species to Mauri Compass
  • False negative results from testing methods
  • Limited access to traditional collection sites
Skills Developed
Freshwater monitoring techniques and Mauri Compass assessment capabilities
Knowledge Shared
Traditional collection sites and fishing methods documented
Community Impact
26 attendees at workshop, increased whānau engagement
Future Investigation Plans
After consultation with experts from DOC and NIWA, the Ngāti Mutunga Taiao team would refine the project to concentrate on a single catchment: the Onaero, where Piharau had been recently caught. The revised approach would involve sampling more intensively for longer periods to gather greater quantities of information.
The refined methodology would include eDNA testing followed by electric fishing on multiple sites in the Onaero catchment, including the upper main stem and two tributaries—the Mangahewa and Mangapaoa. This concentrated effort should enable more accurate and detailed conclusions about Piharau locations and support the long-term goal of protecting spawning habitat and rebuilding populations within the Ngāti Mutunga rohe.
"Traditional mātauranga, seasonal tohu, and kōrero tuku iho proved to be the best method, as demonstrated by our kaumatua who caught Piharau when all scientific evidence showed there were none present."