First Commercial Planting of Native Red Seaweed in New Zealand Marks Milestone in Sustainable Ocean Farming

The first-ever commercial planting out of a native red New Zealand seaweed was a milestone achieved off Tīkapa Moana Hauraki Gulf in the Coromandel.

Fertile seedlings of Gigartina were reared in a commercial hatchery onto twine that was deployed on grow ropes in the Greenwave Aotearoa seaweed growing trial site near mussel farms off the Coromandel coast.

“Our goal is setting up an Aotearoa New Zealand seaweed farming industry that allows farmers to be small business owners,” says Greenwave Aotearoa Project Manager Rebecca Barclay-Cameron. “To do that, we are trying to establish an economically viable seed to sale seaweed industry.”

As Greenwave shared in its last update on the cultivation of Gigartina, it’s a slow tender process to get to the hatching stage.

“So reaching this milestone of being the first to get them out-planted is a really exciting moment for us.”

As the name purpurea alludes, Gigartina atropurpurea is a beautiful red seaweed with a leafy blade that grows in rock, cobbles and shell areas of sheltered sites through to open coasts. It grows from the North Island, northern South Island and Chatham Islands.

Getting the species growing from seed stock sourced from licensed local kina fishermen in the Hauraki Gulf involved collaboration by staff from EnviroStrat as project initiators and managers, the University of Waikato assisting in research and Premium Seas providing the operations support. All were on-board for the release of the Gigartina babies.

“This seaweed is really rubbery so it’s got some quite interesting carrageenan’s and thickeners in it, which means it’s got some potential in food ingredients and cosmetics as well,” says Peter Randrup from the University of Waikato.

As the baby Gigartina seedlings were about to be placed out into the ocean space, he added: “These guys are about two months old and growing at a reasonable pace for a seaweed and they’re looking really good.”

The seaweed growing industry is in its infancy in New Zealand, which has a small but dedicated number of established businesses currently using native species for products such as food ingredients and bio stimulants for soil and animals.

“Seaweed is an incredible species and the regenerative ocean farming model we are using requires zero inputs,” says Barclay-Cameron. “You use seaweed as a foundation crop and then you can add a shellfish species like mussels or oysters, and when they grow they’re removing nitrates and phosphates from the water.

“Seaweed creates an environment for more species to come, shelter and grow so it actually increases fish populations as well.”

Seaweed source tissue was collected under permit in May this year and was dried (desiccated) and rehydrated in sea water in the small Greenwave Aotearoa commercial laboratory on the Coromandel. Only a small amount is required for the process.

Stress-induced reproduction can be a natural response of plants to ensure their survival. The desiccation process is used to stress the cells of the seaweed source material to release their spores.

New Zealand-based impact investors EnviroStrat will support Greenwave Aotearoa to further drive the seaweed sector through regenerative ocean farming in New Zealand with training and support for seaweed farmers, and innovations to create a value chain in coastal communities.

Regenerative ocean farming grows seaweeds that require zero inputs - no nutrient or feed additions are required to grow - that yield meaningful economic, social and environmental impacts. Greenwave’s commercial farming model aims to restore ocean ecosystems and capture nutrients by growing seaweed that can in turn be used for food, biostimulants, animal nutritional supplements, pharmaceuticals and more.