Company harvests ‘sea gorse’
Demand is growing for organic fertiliser made from an invasive seaweed that chokes out native species and clogs mussel farms.
Harvesting is under way in the Marlborough Sounds of the pest species wakame, commonly known as wakame seaweed or ‘‘the gorse of the sea’’.
Introduced to New Zealand waterways in the 1980s via ballast water from cargo ships, the weed is now widespread along the eastern and southern coastlines from Auckland to Bluff.
Although classified as an unwanted organism under the Biosecurity Act, wakame is edible and can also be used to make fish food and fertiliser.
Nelson-based company Waikaitu harvests the seaweed every year and chief executive Alex Pressman said this year’s collection could be the biggest yet. ‘‘We’re expecting to get about 100 tonnes this season, the average is about quarter of that,’’ he said.
Most of what was harvested would be made into organic plant care products at the company’s production facility in Tasman and sold on the domestic market. Pressman said consumers and primary producers were looking for cleaner alternatives to chemical products as concern over fertiliser use and nitrogen leaching grew.
‘‘Most of it goes to big growers in viticulture, kiwifruit industries and pastoral farming now,’’ he said.