From pest to cash
An invasive weed in New Zealand’s waters may be turned into a marketable high-value food product by Ngāi Tahu in the future. Louisa Steyl reports.
It is a frigid morning off the coast of Dunedin when a wetsuit-clad diver rises to the surface clutching a slimy prize.
The trophy is a seaweed known as undaria pinnatifida – a pest native to Japan and Korea – and physically cutting it out is the only way to control it.
On board the Polaris 2, a research vessel stationed a few metres away, members of Ngāi Tahu are processing and packing the seaweed for research.
The research is trying to determine the possible uses of undaria in the hope that harvesting it could pay for control efforts.
Nga¯ i Tahu is working with international and domestic clients who are experimenting with the undaria grown in New Zealand to see how marketable it is.
‘‘Some want the ruffle, some want the blade, some want it wet and some want it frozen,’’ said Nigel Scott, the principal adviser to the hapori’s environmental unit.
He and Brendan Flack – a researcher and chair of the East Otago Taia¯ pure Committee – packed 300 kilograms of the undaria aside.
The remaining tonne of weed will be hung to dry for a Japanese company – the Kataoka Corporation – which may sell it as food.
Flack visited the corporation in Japan during the Rugby World Cup where the business signed a memorandum of understanding with Nga¯ i Tahu to turn the weed into a highvalue food product.
In Asia, processed undaria is known as wakame and is often used in soups and salads.
‘‘We feel that the only way we can really control this without relying on external funding is to somehow create a useful product from this invasive weed,’’ Flack said.
The weed can also be used as a stock supplement, as fertiliser, or as a growth enhancer for plants.
‘‘Southland offers pretty good conditions for growing seaweed,’’ Scott said, adding that New Zealand’s climate resembles that of northern Japan where the weed is originally from.
Should Nga¯ i Tahu be able to turn a profit from the weed, the money will go into controlling and managing it again the following season.
‘‘The vision would be a vessel of some sort that would be able to go to locations that are important,’’ marine scientist Dr Chris Hepburn explains. ‘‘We could take off the the high value part of the undaria and then mince up the rest of it, heat it up, make it inactive so it can’t produce spores, and release it back into the water.’’
Ngāi Tahu has had to obtain a permit under the Ministry for Primary Industries’ Biosecurity Act, which limits the tribe’s activity to research and control.
Scott said that suits him just fine since the focus of the project is conservation.
Undaria first arrived on New Zealand’s shores via Japan in 1987 and slowly spread along the coast of the South Island all the way down to Fiordland.
With its broad, muddy-coloured leaves, it resembles any other seaweed but its ruffled reproductive sections can release in excess of 70,000 spores.
The problem with undaria is that it replaces native kelp forests.
Indigenous species can grow up to 30 metres long, creating nets that are used as breeding grounds for crustaceans.
Undaria, however, only grows up to 2m. Its flat, slimy surface makes it difficult for anything to cling to.
Sea creatures which do manage to make the pest a home lose their habitat in the summer when the weed dies out.
Native kelp, which is perennial, floats up to the surface and then washes up on beaches where it becomes a meal for all sorts of little creatures. Undaria does not do this.
Because it is genetically similar to native kelp, bio-chemical management would put indigenous species at risk.
‘‘If we are going to control it, we need to remove a significant amount of biomass,’’ Hepburn said.
‘‘The work we are doing is trying to understand how we do that, and what are some of the economic values of the stuff we take out that we can put back into control programmes.’’
Past control projects in Bluff and Stewart Island have been successful but ultimately too expensive to continue.
‘‘Environment Southland have put in a massive effort with control and they are still trying really hard to keep things going,’’ Hepburn said. ‘‘But they can’t fund this forever.’’
The agency introduced new rules under the Southland Regional Pest Management Plan in December to help manage undaria in Breaksea Sound, Fiordland.
All vessels and equipment must be free of the seaweed before leaving the area.
‘‘Although we have to accept that the levels of undaria around Stewart Island and in Breaksea Sound are beyond the point where we can completely remove this pest, we need boaties to make every effort to keep it from spreading into other areas,’’ Environment Southland biosecurity and biodiversity manager Ali Meade said.
Nga¯ i Tahu is working with the University of Otago’s marine science students who are researching the impact of undaria in relation to other native species on important reefs and fishing grounds.
Their research will also help determine which location and what time of the year are best for harvesting specific parts of the plant. While the cultivation plan is still very much in its infancy or ‘‘basement level’’ stage, as Flack said, the advantages extend beyond conservation.
Harvest operations could open up new jobs in the fishing and production industries. ‘‘It could create opportunities for communities that once relied on the ocean for their work and wellbeing,’’ Flack said.
Nga¯ i Tahu is not the only group exploring the benefits of undaria harvesting.
Coromandel company Wakame Fresh was granted $75,000 from the Government’s Sustainable Food & Fibre Futures fund in August. The funding will go towards investigating the commercial viability of undaria for the export industry.
Seaweed agriculture could be positive for marine ecology. ‘‘Seaweed provides a habitat for fish and animals but it also cleans the water,’’ Hepburn said.
‘‘It absorbs nutrients and pollution, so it can be used to clean estuaries, or clean up a harbour.’’
Hepburn does not think New Zealand is close to creating an industry on the back of undaria just yet but said it may be possible in the future.