Many Kaikōura residents and visitors feel connected to Waiau Toa/Clarence River, winding its way through farmland, native bush, gorges, and rocky outcrops, then eventually out to the sea north of Kaikōura township.

Its catchment area is around 3,200km² and at more than 200km long, it is one of the longest and most remote rivers in New Zealand, with some of the best scenery in the world (I’m definitely not biased).

It has high cultural value for Ngāti Kurī, with a whakapapa status as the parent of many other rivers in the region. Any impact on Waiau Toa has an impact on the rivers that are linked to it through whakapapa, as well as iwi who are whakapapa to the river.

It embodies ki uta ki tai (from the mountains to the sea), and like all our waterways, it is essential to protect this wonderful waterway.

Waiau Toa/Clarence River hosts an array of at-risk species

The uniqueness of Waiau Toa is because it is an alpine braided river with diverse environments and rare ecosystems that support a range of different plant, bird, fish, and invertebrate life.

At least 10 native fish species recorded in the catchment are threatened or at-risk. Kōkopu, inanga/whitebait, bully, and tuna/eel all call Waiau Toa home.

An additional 13 threatened or at-risk bird species have also been recorded including the nationally endangered Black-fronted Tern. These birds have been the focus for some of the most recent pest control work in Waiau Toa.

One of the two remaining Hutton’s shearwater colonies falls just within the Waiau Toa catchment on private land. The Hutton’s Shearwater Charitable Trust is the local go-to for raising awareness of the species, the risks they face, and they ways we can help.

Waiau Toa also boasts at least 100 threatened or at-risk plant types in the catchment, some of which were once thought to have been extinct in the wild. Pygmy goosefoot/dysphania pusilla, and slender button daisy/leptinella filiformis were both rediscovered here in 2015.

Lastly, gingidia “aff enysii” is an unnamed member of the aniseed family, is nationally endangered and endemic to Waiau Toa catchment. Clarence forget-me-not/myosotis laingii was presumed extinct and has been recorded from the upper Waiau Toa catchment, with the possibility that it still exists there.

Pesty weeds are biggest threat to the braided river

The biggest threat to Waiau Toa is still the invasion of pest plants.

Pest plants can:

• alter the way a naturally dynamic braided river flows
• displace native plants that provide the cover, food, and breeding habitat for native braided river birds, and
• provide habitat for invasive pest predators.

Waiau Toa is considered one of the last remaining wild braided rivers in New Zealand due to its relatively untouched nature. The Department of Conservation manage a large part of the catchment, with several large and small stations and farms along the awa/river edges.

Due to the long-term nature of weed control in Waiau Toa, any management approach needs to consider local, regional, and national stakeholders, to ensure the approach is coordinated, timely and cost-effective for all involved.

Zone Committee devoted to controlling threats

In 2016, the Kaikōura Water Zone Committee (KWZC) recommended $250,000 of Environment Canterbury’s Immediate Steps (IMS) funding be allocated to a five-year collaborative weed management programme for Waiau Toa.

Along with contributions from neighbouring landowners, the project is making great progress. With ongoing work to control threats to Waiau Toa flora and fauna, we hope to be able to help keep the unique landscape as close to what nature intended.

Most recently, a creative method for controlling broom by using mites has been completed and further work is planned to help the unique plant, bird, fish, lizard and invertebrate populations thrive, alongside the environments they live in.

More information on the project and Waiau Toa will be shared soon, but in the meantime, keep your eyes peeled for my next river rant.

Until next time, Kev.

Featured image: Waiau Toa/Clarence River by Heath Melville