by Joly Ghanawi, Editorial Contributor, International Aquafeed, UK
Aquaculture in New Zealand is one of the country’s most valuable and sustainable primary industries, contributing significantly to regional economies and export growth. In 2023 the sector generated approximately NZ$763 million in revenue and supported more than 3000 jobs across coastal and rural communities. The industry farms three main species, Greenshell Mussels (Perna canaliculus), Pacific Oysters (Crassostrea gigas) and Chinook Salmon (Oncorhynchus tshawytscha), all of which are cultivated using environmentally responsible methods that have earned international recognition for their low carbon footprint and minimal ecological impact. New Zealand’s pristine waters, sheltered harbours and long coastline provide ideal conditions for aquaculture, which occupies less than 0.1 percent of the country’s coastal area yet delivers high export returns.
Government policy aims to expand aquaculture to NZ$3 billion in annual revenue by 2035, as outlined in the Aquaculture Development Plan 2025–2030. This national strategy seeks to maximise the value from existing farm space, extend farming into the open ocean, strengthen Māori participation and commercialise new species and technologies. The sector already farms in marine, inland canal and land-based systems, and is increasingly characterised by innovation, research investment and partnership between industry, government and iwi.
The Greenshell Mussel, known to Māori as kuku or kūtai, is the dominant aquaculture species and is unique to New Zealand. In 2023, over 93,000 tonnes were harvested, accounting for the majority of total aquaculture volume. Mussels have a moderately complex life cycle: adults release eggs and sperm into the sea, and the larvae drift for about three to four weeks before settling as spat on fibrous material such as seaweed. Juveniles can re-enter the drift until they find a suitable substrate, eventually attaching themselves permanently using byssus fibres. In aquaculture, mussels are grown on long-line systems, where a strong backbone rope is suspended from floats and anchored at both ends. Dropper ropes hang vertically from the backbone, providing surfaces for the mussels to grow.
Most mussel spat are still collected from the wild, particularly from 90 Mile Beach (Te Oneroa a Tohe), where seaweed encrusted with spat washes ashore. Farmers wrap this material around droppers in degradable mesh socks; as the sock disintegrates, the spat attach naturally. Over time, juvenile mussels are stripped, thinned and reseeded to optimise growth and reduce crowding. Crops reach market size of 8–10cm shell length after 18–30 months, depending on local conditions. The main products are frozen half-shell mussels, mussel oil and mussel powder, the latter two being high-value nutraceuticals exported worldwide. Mussel farming provides ecological benefits by filtering seawater, improving clarity and offering habitat for marine life. Challenges include periodic shortages of wild spat, biofouling and changing ocean conditions, which the government addresses through investment in hatcheries and nurseries to ensure consistent seed supply.
The Pacific Oyster, or tio, was introduced from Japan in the 1960s and rapidly replaced the slower-growing native rock oyster as the preferred farmed species. In 2023, New Zealand produced about 1500 tonnes of Pacific Oysters, primarily in Northland, Coromandel and Bay of Plenty, with smaller farms in Marlborough and Tasman Bay. Pacific oysters mature quickly, reaching reproductive age at six to eight centimetres after 12–20 months. They spawn by releasing eggs and sperm into the water, and their larvae remain planktonic for roughly three weeks before settling as spat around 0.5mm in size. Once attached to a hard surface, they grow rapidly and cannot re-attach elsewhere.
Traditional oyster farming uses the rack-and-stick method, in which farmers place bundles of wooden sticks in the sea to capture wild spat. These sticks are later fixed to racks set at intertidal levels, optimising exposure to air and water to reduce pests and fouling. While inexpensive, this technique often produces unevenly shaped oysters and inconsistent yields. To address this, many growers have shifted toward single-seed culture, either by stripping spat early from sticks or by using hatchery-produced larvae. Single-seed oysters are grown individually in baskets, trays or mesh bags attached to long-lines or racks. This method, though more labour-intensive, allows better control of density, uniformity and shell quality, and supports selective breeding for disease resistance and temperature tolerance. Some farms use semi-automated equipment and floating systems, improving productivity and reducing handling time.
Oyster aquaculture provides important ecosystem services, including nutrient filtration and habitat creation, while producing a high-protein, low-fat food with one of the lowest environmental footprints in global seafood. It also plays a key cultural and economic role for Māori, who have traditional connections to oyster harvesting. Through the Aquaculture Settlement, iwi are entitled to 20 percent of all new aquaculture space, supporting Māori-led growth and reinforcing kaitiakitanga, the principle of environmental guardianship.
The third major farmed species is Chinook Salmon (Oncorhynchus tshawytscha), also called King salmon or hāmana. Introduced from California in 1901, it has established both wild and cultured populations. New Zealand is now the world’s leading producer of this premium species, accounting for over 50 percent of global Chinook Salmon production and harvesting about 14,500 tonnes annually. Salmon farming began in earnest in the mid-1970s with hatcheries and sea-cage farms at Big Glory Bay on Stewart Island and in the Marlborough Sounds.
Chinook Salmon are anadromous: they hatch in freshwater, migrate to sea to grow and return to rivers to spawn. In aquaculture, hatcheries rear juveniles to around 100–150 grams before transferring them to sea cages. These cages are maintained at low stocking densities, usually below 25kg of biomass per cubic metre, to protect water quality and fish health. The fish grow to market size of three to five kilograms in about 14–20 months. Some operations use freshwater raceways or hydro-canal systems in Canterbury and Otago for early growth. New Zealand salmon products like chilled whole fish, frozen fillets and smoked portions fetch premium prices internationally for their rich flavour, high omega-3 content and sustainable credentials. The Monterey Bay Aquarium lists New Zealand salmon as a ‘Best Choice’ seafood for environmental sustainability.
The national aquaculture strategy outlines several key pathways for future growth. First, it seeks to maximise the value of existing space by improving productivity, reducing regulatory costs and investing in hatchery capacity, with an expected seven percent annual revenue increase. Second, it aims to expand into the open ocean, where deep, clean waters could support large-scale mussel and salmon farms worth up to NZ$1.4 billion by 2035. Third, it focuses on Māori-led aquaculture, ensuring iwi receive timely settlements and access to viable farming areas. Finally, it encourages innovation and diversification, including land-based aquaculture, automation, selective breeding and the development of new species such as seaweed and other finfish.
Environmental sustainability remains central to aquaculture’s success. All farms operate under strict regulations covering water quality, biosecurity and habitat protection. Mussels and oysters are recognised for their ecosystem benefits, while salmon farms are tightly monitored to maintain minimal ecological impact. The industry is also addressing climate-change resilience through selective breeding for temperature tolerance and research into new farming locations and technologies.
Aquaculture’s social and cultural dimensions are equally important. Many coastal Māori communities view aquaculture as a means of economic self-determination and cultural renewal. Collaborative ventures between iwi and private operators integrate traditional stewardship values with modern marine science.
In summary, aquaculture in New Zealand has evolved into a globally respected industry based on three complementary species – Greenshell Mussels, Pacific Oysters and Chinook Salmon – each contributing unique ecological and economic strengths. Mussels dominate production volume, oysters provide premium half-shell exports and salmon deliver high-value protein for global markets. Together they exemplify sustainable food production that aligns with New Zealand’s clean-green image. With continued investment in innovation, hatchery infrastructure and Māori partnership, and by expanding into the open ocean while safeguarding the environment, New Zealand is well positioned to achieve its vision of a NZ$3 billion aquaculture industry by 2035, producing world-class seafood that nourishes both people and the planet.
