Conclusion of Ground-breaking Native Seaweed Pilot in Hauraki Gulf

Our pioneering Greenwave Aotearoa project has concluded its successful three-year pilot to trial native seaweed cultivation in the Hauraki Gulf and can ultimately answer the question – how do you grow it?

The initiative, co-funded by the Ministry for Primary Industries’ Sustainable Food and Fibre Futures Fund and EnviroStrat, aimed to pave the way for a new seaweed farming industry in New Zealand.

EnviroStrat Project Manager Rebecca Barclay-Cameron said the pilot proved that the brown kelp Ecklonia radiata can be farmed, and that there was more success in areas that are multitrophic – where two or more species are grown together - in this case mussels.

“Greenwave Aotearoa’s regenerative ocean farming pilot has laid the foundation for a new aquaculture industry, demonstrating that seaweed aquaculture is not only feasible but holds significant promise for New Zealand’s economic and environmental future.”

In the final year, the pilot successfully added the native red seaweed Gigartina atropurpurea at trial sites near mussel farms off the Coromandel coast. The project involved growing fertile seedlings on twine around ropes, marking New Zealand’s first commercial planting of this native species.

“Our journey has been a learning curve in every sense,” said Barclay-Cameron. “Over the past few years, we’ve fine-tuned our methods, adapted to shifting environmental conditions, and tackled regulatory hurdles to establish a viable seaweed farming business. It’s been so rewarding to witness the team adapting to the challenges of growing native seaweeds that have never been commercially farmed before.”

The pilot’s main focus was on the keystone species of native New Zealand brown kelp Ecklonia radiata. Seedlings grown in a Tauranga and Coromandel-based hatcheries were planted in consented aquaculture zones off Ponui Island and south of Coromandel Town in the Firth of Thames.

Team members from the University of Waikato, Premium Seas and EnviroStrat worked closely and tried various sites beyond the original scope of the project in a bid to test the impact of different environmental and biophysical conditions on growth and productivity.

While the pilot concluded with numerous successes, it also faced challenges, including marine pest species grazing on young seedlings and a marine heatwave which led to new scientific insights on seaweed growth in different marine temperatures. Researchers from the University of Waikato, led by Dr Marie Magnusson and Dr Rebecca Lawton, contributed to the trial’s scientific design, bringing expert oversight to the growing and harvesting processes.

The growth of Ecklonia radiata was challenged from the start by a late start because of supply chain issues driven by Covid. The marine heatwave and marine pests – biofouling – also inhibited any impressive growth in the sites which were consented for the trial.

“Ultimately I think it comes down to picking a great site and focusing on what you can control,” said Peter Randrup from UoW. “Ocean farming is like land farming. Nature is complex and different regions suit different crops. The areas we tried aren’t the easiest for farming Ecklonia - in reality, some sites don’t work.”

Seaweed sector framework author and Greenwave Aotearoa founder Dr Nigel Bradly of Auckland-based impact investor EnviroStrat said the innovation in seaweed has grown exponentially in the three years of Greenwave Aotearoa.

“Unlike land-based farming, seaweed aquaculture does not have decades of science, trial and error to inform commercial growing methods in New Zealand,” said Dr Bradly.

“What’s historic here is the cultivation of not just one but two native seaweed species in a commercial hatchery and its transfer to a farm setting. Really, this is a new era for sustainable marine farming in New Zealand, with potential impacts on marine biodiversity and ocean health.”