A new report shows there’s a big opportunity to improve whitebait spawning habitat in the Whanganui River.
In the city centre, the Whanganui River is big, brown and slow-flowing. Locals still spend time whitebaiting in the main river but they don’t catch much.
It hasn’t always been that way.
A local food basket
The river was once a plentiful food source and sustained generations of local people with species like tuna, piharau (lamprey) and whitebait. In fact, whitebait have their own local name here – karohi instead of īnanga. They’re called atutahi when they grow into adult fish.
“Atutahi were once more plentiful and really important as kai for our people”, says Hannah Rainforth, a freshwater ecologist from Kāhu Environmental who has whakapapa to the river.
“Our olds talk about the river turning black with shoals of returning karohi. They used to dry them on corrugated iron and eat them like chips. When I was little I used to go whitebaiting with Nanny all the time and when we had enough for some fritters we’d go home.”
Hannah describes how polluted the river used to be with waste from industry, including the meat works, dumped straight into it. Her stepfather was involved in a long running campaign to get the sewage out of the river.
Taking a look at the river’s potential spawning area
In 2021 and 2022, she worked with hapū and the Whanganui DOC team to find out just how hard things currently are for atutahi and karohi in the river.
“They’re not in a good way. The river is healthier now, but we need to help the atutahi by making sure they have good places to lay their eggs (spawn) in the tidal zone. They need a gentle slope, some nice thick grass, no stock and no trees shading the bank.”
The Whanganui River could be a massive spawning site. Most rivers have about 200 metres of potential spawning habitat, but here there’s about 30 kilometres of riverbank where spawning could take place. Not much of it is in good condition.
The work started with a wānanga
Ngā Awa river ranger Jane Taylor, and Geoff Hipango, kaitiaki at Te Ao Hou marae in Aramoho, ran a wānanga about atutahi at the marae in 2021. The marae is in a beautiful setting next to the river.
“It was educative for ourselves”, says Geoff. “We understood the connection with planting and the river life, and our īnanga and tuna. It was quite easy to see that the mahi was part of our responsibility as kaitiaki here. It also allowed us as a marae to host our wider family to come along and participate.”
The wānanga highlighted the need to know more, including the total potential spawning area in the river. Because the area is so big, it was proposed that 30 randomised sites be surveyed, which could then be extrapolated to the total potential spawning area.
Surveying randomised sites in the river’s tidal zone
Hapū members joined Hannah, Jane and others from DOC to carry out the survey work up and down the river. It took them more than 10 days. Some sites were only accessible by boat and many involved clambering up steep, muddy banks to get a close look at the vegetation and search for tiny, translucent atutahi eggs.
“It was a bit depressing and disheartening for the field workers,” says Jane, “site after site with no eggs.”
When Hannah crunched the numbers, the result was that there were eggs at only 1 percent of the total spawning area. It’s a low result that highlights the urgent need to restore spawning sites and revitalise a species that’s in decline.
But Hannah is quick to point out that the fixes aren’t particularly hard.
“Keeping the stock out, letting the grass grow, controlling the weeds – they’re all achievable for iwi and hapū and community members. In some places we also need to take out the willows and change the shape of the bank so it’s not so steep.”
Getting into some positive action
Jane has started talking to farmers about keeping stock away from the river and begun discussions with the council and an engineer to look at where making some improvements might be feasible.
“Doing the surveys made it really clear how the riverside areas are impacted by flooding, pedestrian access, dogs and mowing. It’s also provided us with a robust scientific report that we can use to talk to the councils about the work, comment on consents and proposed river works and advocate for atutahi. It’s made it really clear how vulnerable they are.”
Caretakers for the next generation
Geoff’s hapū have already planted harakeke by the river and they’re growing nicely. “The plants are just enough to lift the fish out of the river so they have a chance to spawn without predatory fish feeding on them. Our weavers like it too – the plants are a good source of materials.”
“It’s a win-win for the marae that utilises mātauranga Māori, science and our collaboration with agencies like Horizon and DOC”, he says. “The hope is to carry on the planting further up the river and get rid of some of the pampas and willows. We have good relationships with our neighbours upstream and this is an opportunity to contribute to the wellness of the river – it’s part of our kaitiaki responsibility.”
“If we lay the groundwork, the next generation will hopefully inherit an awa that’s in better condition. One indicator is that the aquatic life is vibrant. Ko te awa te mātāpuna o te ora – the river is the spring of our wellness. Not just for our people but for the river herself.”
For more information on the mahi happening along the Whanganui River see Ngā Awa river restoration programme.