Southern Seaweed

April 2023

The vast potential for a New Zealand algaculture industry.

The potential for a New Zealand algaculture industry is being demonstrated by a small number of operators, including the late Roger Belton, managing director of Dunedin-based Southern Clams. After seven years of research and development under a special permit, he has a clear idea of the potential for a particular seaweed, Undaria pinnitifda currently classified as an invasive species. 


Roger’s company, Southern Clams has been harvesting wild populations of Littleneck clams  (Austrovenus stutchburyi)  in the cold waters of the Otago coast for 35 years and supplies both the domestic market and niche markets in Europe, Asia and North America. With a stated aim to pioneer environmental responsibility in the clam industry, the company has put this into practice since it was founded in 1984. 


In 2011 it invested in its own (approximately) 92ha bio-diverse forestry venture in the Waitaki District. The forest is planted with 12 different species of tree, and will mature in about 50 years.  Carbon credits surrendered from the forest mean that clams sold in New Zealand are carbon neutral to the first point of sale. 


More recently, an 8-year research project on the viability and sustainability of harvesting Littleneck clams from Otago Harbour was carried out, which resulted in the Ministry of Primary Industries granting approval for Southern Clams to commercially harvest from two local clam beds. The additional harvest grounds are an important step for Southern Clams, both increasing options to meet orders in a changing, growing market, and decreasing demand on individual clam populations, ensuring a sustainable shellfishery into the future.

Southern Clams commitment to sustainability was rewarded by winning the Sustainability and Resilience Business Practice Award at the Otago Business Awards 2020. 


Seaweed, notably wild-harvested Wakame (Undaria pinnatifida), is a developing market for the company. Undaria pinnitifda is also known as Japanese kelp, or Wakame, is one of the species that Roger Belton’s company is permitted - under strict conditions - to remove, harvest and transport for sale. 


In its native country, Undaria is farmed for use in Japanese cuisine. In addition to food, it is also used in pet food and as a fertiliser enhancer. Arriving in New Zealand around the late 1980s, it spread throughout the country’s sheltered coastal waters from the north to the south. It has a complex life cycle, is virtually impossible to eliminate, and notoriously difficult to control. The macro alga is considered a pest species by Ministry for Primary Industries (MPI).


Undaria can be found from the low intertidal area to subtidal depths of around 15 metres. They attach themselves by a holdfast on any hard surface, including shells, reefs, ropes, wharf piles, vessel hulls, moorings and other artificial structures. Dense "forests" can form in sheltered areas.


Mature plants can be brown, green or yellow in colour and reach one to two metres in length. The species looks similar to New Zealand kelp Ecklonia radiata, but Japanese kelp has a distinctive midrib up the middle of the blade that can be seen when it reaches around 5 cm in size. In addition to the midrib (also called a stipe or stem) up the middle of the plant, they have a holdfast (that attaches the plant to a surface) and a sporophyll (a spiral shaped reproductive structure which produces spores) at the base of the stipe. 


With Undaria growing wild in Otago Harbour, Roger Belton believes the best way to manage and control the species is to make commercial use of it. He says, as it’s here to stay, there is a need to integrate it into our food production system. Belton draws a parallel between this invasive seaweed and red deer. He explains that New Zealand threw an enormous amount of money at trying to rid itself of red deer, without much headway being made. However, once the industry was commercialised and the species better managed, control became more feasible – and at the same time, a new industry worth hundreds of millions of dollars to the country was created. He adds, while New Zealand lags behind other countries in developing an algalculture industry, there is immense potential here.


Seaweed has many health benefits when incorporated into the diet. Dried wakame has high levels of iodine and tyrosine, essential for healthy thyroid function. Seaweeds generally are also an important source of antioxidants, vitamins, and minerals. There are indications that other human health benefits include lowering cholesterol levels, decreasing blood sugar, and aiding in weight loss. Other uses for seaweed include agar production, biomass for fuel, cosmetics, and raw materials for bio-plastics. 


Permitted wild harvest (through MPI) of Undaria is carried out in Otago Harbour from mid-September through to December.  Harvested seaweed (from artificial surfaces such as harbour walls and piles) is returned to the Dunedin factory before being washed, chilled, assessed and sorted into what a customer requires – whether fresh, dried, or frozen, as a high quality food, or processed for pet food or as a fertiliser enhancer for horticultural and agricultural application. 


Southern Clams sees algaculture both as an exciting and necessary area of growth, with vast potential for New Zealand primary production. After seven years of operation, Belton says demand for Undaria is very high, and product is gathered from Bluff to Marlborough, so current orders can be filled.


Roger Belton identifies a number of challenges for the industry, primarily in the regulatory and research areas. The research undertaken by his company has to date been supported by the clams and fishing side of the business, and he would like to see more research funds made available to or driven by commercial operators’ input, as it is they who are most closely connected to customers’ needs and aware of the gaps in the processing chain. There is also much that is still unknown about the life cycle of this, and other seaweed species that show enormous promise as part of a diverse primary industry in New Zealand.