Our Rivers Are Still Speaking: What eDNA Reveals About Life Beneath the Surface
Rivers have always carried knowledge. Long before formal monitoring, the health of a place was understood through its wai, through the presence of tuna, kōkopu, and the seasonal rhythms that sustained life. Today, science offers an additional way to understand what is happening beneath the surface.
As part of He Rau Ake Ake, our 100-Year Whenua Optimisation Plan, Whāngārā Farms commissioned a Rapid Biodiversity Assessment (BioRAP) across five of our farm blocks. Among the tools used was environmental DNA, or eDNA, a method that allows scientists to identify species present in waterways by analysing the microscopic traces organisms leave behind.
In practical terms, eDNA enables us to confirm what lives in our rivers, even when those species are not directly observed. It provides a precise, evidence-based picture of ecological health.
Across streams and rivers flowing through Rototahe, Pakarae, Whāngārā B5, and along the edges of Tapuwae Whitiwhiti, eDNA sampling revealed a clear and encouraging result. These waterways continue to support taonga species, including:
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Longfin tuna
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Īnanga
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Kōkopu, torrentfish, kākahi, and other native fish
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A diverse assemblage of species dependent on clean, connected freshwater systems
These findings matter because of the context in which they sit. The rivers and streams sampled flow through landscapes shaped by generations of farming. In some areas, riparian margins are narrow or open. In others, vegetation cover is limited. Despite these pressures, the waterways remain ecologically active.
This tells us two important things.
First, our waterways retain resilience. Even in modified environments, they can continue to function as ecological corridors.
Second, that resilience has limits.
As Roger MacGibbon has observed through his work across our farms, species such as longfin tuna and īnanga depend on connected systems. They require safe passage between freshwater and the sea, cool shaded streams, stable margins, and suitable habitat for feeding and spawning. When these conditions are compromised, populations decline.
eDNA does more than confirm presence. It highlights what is at risk.
This is precisely why He Rau Ake Ake exists. The plan is designed to act before decline becomes irreversible. It provides a framework for strengthening ecological systems alongside productive land use.
The BioRAP identifies clear, practical priorities: restoring riparian margins, fencing waterways from stock, reducing sediment and nutrient runoff, and improving connections between bush, wetlands, and streams. These actions are not cosmetic. They determine whether waterways remain functioning ecosystems or become degraded channels.
For whānau, this work affirms that our whenua continues to carry taonga. The stories of our rivers are not confined to the past. They are ongoing.
For partners and funders, the findings provide evidence. Evidence that long-term, place-based planning matters. Evidence that investment in land stewardship produces measurable outcomes. Evidence that productive farming and ecological responsibility can be advanced together.
eDNA gives us a baseline. It creates a point of reference for the future. In five, ten, or twenty years, we will be able to ask whether our actions have strengthened these systems.
He Rau Ake Ake is built for that horizon.
This mahi has always been intended as a collective endeavour. The plan was never conceived as Whāngārā Farms acting in isolation, but as a way of aligning our long-term direction with the wider catchment community.
Work already underway across the Whāngārā catchment has revealed important insights, including around Īnanga spawning and the specific places our rivers continue to nurture new life.
Alongside the wider Whāngārā catchment community, including leaders and practitioners such as Kirsty Gaddum, Sarah Williams, Steph Gardner, Arihia Poi, and Amy Hardy, we are continuing this work across our awa. Together, this collective effort reflects a shared commitment to the health of our waterways and to a future where land, water, and people are supported as one interconnected system.
Our responsibility is clear: to ensure that in 100 years’ time, these rivers still support tuna, still shelter kōkopu, and continue to sustain life across the catchment.
