Hidden biodiversity revealed in Waitarakao catchment
To protect freshwater life in Waitarakao catchment, we first need to know what’s there—and recent mahi by scientists and local farmers has revealed some surprises.
Why Waitarakao
Waitarakao is a unique and diverse catchment just north of Timaru, where urban, industrial, farming, and wetland areas surround a special coastal lagoon.
Streams flowing through these varied landscapes feed into the lagoon, which has been shrinking over time. The health of the lagoon, its wildlife habitat, and the streams themselves are in decline.
Following 18 months of community engagement, a strategy to restore the mauri of the lagoon and catchment is now being put into action.
As part of this work, staff are partnering with farmers in the catchment to use eDNA and fish sampling to collect data to better understand local biodiversity, identify important habitats, and guide restoration efforts.
How we go about it
Every living creature leaves behind traces of DNA from things like skin, scales and droppings in soil and water. Scientists can now capture these genetic breadcrumbs from water samples and identify which species are present - without ever seeing them. These traces are known as environmental DNA, or eDNA.
Traditional fish sampling involves setting nets in waterways to live-capture and release fish to determine what species are present.
Using both techniques, the Our Waitarakao project team were pleasantly surprised to find a wide diversity of native fish species are persisting in the catchment, including kōwaro/Canterbury mudfish, banded kōkopu, inanga, short and long-fin tuna/eels and a range of native bully species.
The survey showed tuna in even temporary waterholes on catchment farmer Andrew Steven’s farm.
"It came as a bit of a surprise in this catchment that there’s actually as much life in the creeks as there is.”
Looking forward
Fish surveys and eDNA sampling give us data to guide restoration—helping us prioritise areas for planting, water quality improvements, and weed and pest control.
According to senior scientist Dr Sriyan Jayasuriya the results in Waitarakao catchment were truly inspiring.
"The eDNA survey showed us the distribution patterns of fish across the catchment, and opportunities for improving native fish habitat and migratory pathways important to complete their life cycles.”
Every action – like sediment control, planting natives, or managing pests – helps steadily improve the habitat for these fish species as well birds and insects.
This data gives us a baseline to measure progress, and we hope to see growing fish populations with future monitoring.
Our Waitarakao
Our Waitarakao is a partnership project between Te Rūnanga o Arowhenua, the Department of Conservation, Timaru District Council and us, working in close collaboration with the community.
Learn more about the Our Waitarakao partnership.