Greenwave Seaweed

May 2023

Exploring the viability of a domestic seaweed farming industry with Envirostrat.

The GreenWave NZ pilot project is investigating the viability of a seaweed farming industry in New Zealand. The pilot, funded predominantly from the Ministry for Primary Industries (MPI) Sustainable Food & Fibre Futures Fund (SFFFF), is looking at infrastructure and seeding through to scientific analysis of end products.


In 2019 Envirostrat CEO Nigel Bradly was introduced to GreenWave USA and their model for farming seaweed to assure ocean regeneration and a fair living for smaller farmers. New Zealand does not have a seaweed industry, and companies that rely on seaweed are at the mercy of seaweed gathered from the wild, or harvested as mussel farm bycatch.

Nearly 30% of global aquaculture production volume is seaweed, with a global value estimated at US$14 billion in 2019 and with a growth rate of 7% per year (on average ) over the last decade. 

Seaweed farming is a low tech farming option, opening up opportunities for a wide range of players within New Zealand. Seaweeds absorb excess nutrients and CO2 in the ocean – making it also a regenerative farming option. 

GreenWave USA has allowed Envirostrat to take their model to adapt for a New Zealand context and to explore the viability of developing an industry here.

Initial investigation was carried out as a feasibility study with Auckland Council. “We asked ourselves what it would take to adapt the GreenWave model for New Zealand, taking into account our different regulatory systems, bicultural context, climate, market and species” says Nigel. 

Seaweed is not a significant food item in New Zealand and the restaurant market that dominates off-shore, would be minimal here. Seaweed is utilised in New Zealand in fertilisers, nutraceuticals and agar. The pilot is looking at a variety of applications beyond fertilisers.

With funding from the MPI SFFF Fund, Envirostrat have joined forces with collaborators to assess an economically viable seed-to-harvest model farming native seaweed at scale. Partners on the three- year project are Ngāti Pūkenga, Ngai Tai ki Tamaki Iwi, seaweed product developer Premium Seas Limited, the University of Waikato, the University of Auckland, and seaweed processor AgriSea NZ Ltd.

The project is testing a range of parameters and carrying out research to assess the viability of farmed seaweed, working firstly with the ubiquitous New Zealand kelp species, Ecklonia radiata, to develop farming protocols. "Although there is much knowledge to draw from internationally regarding kelp aquaculture, none of the major global commercial seaweed crops are native to New Zealand. This means that both hatchery and seeding protocols and farm designs need to be developed and tested for our local kelp species and conditions,” says Dr Marie Magnusson from the University of Waikato (UOW).

The scope of the project is broad and involves; seed supply and production (including the use of hatcheries), regulatory frameworks, environmental conditions, infrastructure for growing, workforce requirements, understanding the benefits and possible negatives of seaweed farming (biodiversity, ocean regeneration), post-harvest logistics and product development, and the quantification of improvements in water quality from seaweed farming.


Dr Marie Magnusson and Dr Rebecca Lawton (both at UOW) have been supplying seed for production. They set up a hatchery on campus and also a commercial hatchery on a mussel farm. Brood stock is currently sourced from the wild but future plans include sourcing from farmed populations, and maintaining long-term ‘seed-banks’ of cultivars. In consultation with involved iwi, brood stock is sourced from the areas where it will be farmed.


Drs Magnusson and Lawton are successfully using the tissue from the brood stock to induce formation of reproductive structures and spore release into a solution, ready for seeding. Twine is wrapped around polyurethane pipes to produce seed spools, which are immersed into the spore solution to allow the free-swimming spores to settle on the twine. These seed spools with germinated juvenile plants are kept in the laboratory under optimal conditions of temperature and light until they’re ready for planting out onto the marine farm.


Knowledge transfer and training of farm crew has begun to ensure methods are transferable, so future work can be done independently by commercial hatcheries.

In total, over two kilometres of hatchery-grown native Ecklonia radiata seaweed has now been out-planted on existing consented aquaculture farm sites in the Hauraki Gulf. The infrastructure is similar to mussel farming infrastructure - seaweed is grown on ropes utilising anchors and buoys with seeding and harvesting carried out from barges.

The UOW will perform biochemical analysis on the harvested seaweed to assess iodine levels, any heavy metal concentrations, and protein content, among other markers. They’ve already run the analysis of the wild stock and published research on the genetic make-up of the cultivars in the area.

In looking at workforce requirements, the project is seeking ways (such as combined mussel and seaweed farms) to provide significant and stable work that doesn’t compete for seasonal workers. The University of Auckland is leading work on assessing the biodiversity impacts of co-locating mussels and seaweed farming.

Agrisea, a long-established seaweed processor in the Bay of Plenty, is contributing their post-harvest production, market, and processing expertise, and have agreed to purchase all product for the duration of the pilot. At January 2023, the project is currently half-way through its three-year timeframe.

See also: Greenwave USA