Ryan Campbell McManaway, 36, was sentenced in his absence at the Invercargill District Court on 26 September 2025, after a Ministry for Primary Industries (MPI) investigation uncovered an unlicensed seaweed harvesting and sales operation. He faced four charges under the Fisheries Act, and the court imposed a $50,000 fine for those fisheries offences. A further $3,000 penalty followed after McManaway failed to comply with directives to attend an interview with fishery officers.
The case began in November 2022, when MPI officers came across an online advertisement offering liquid seaweed fertiliser for sale. The product was available in 1,000-litre containers priced at $500, or in 20-litre buckets for $20. A search warrant was subsequently executed at McManaway's property, where officers found 14 large containers of fertiliser derived from Macrocystis pyrifera, the species widely known as giant kelp and valued for both fertiliser and food uses. An industrial mincer carrying traces of seaweed and a range of other processing equipment were also discovered on site.
Central to the prosecution was the fact that McManaway was no longer a licensed commercial fisher when the offending occurred. Fisheries New Zealand's southern regional manager, Garreth Jay, was clear on that point.
"Mr McManaway had no legitimate right to harvest and sell this seaweed as a fertiliser," Jay said. "He could've potentially earned several thousand dollars from this operation. When we find evidence of people breaking the rules that protect our fisheries resources and the livelihoods of legitimate commercial operators, we will hold them to account."
Seaweed is a cornerstone of marine ecosystems, providing food and shelter for a wide range of coastal species, from small invertebrates to fish. New Zealand regulates commercial seaweed harvesting through a permitting and reporting system because of that ecological role. Illegal harvesting not only undermines sustainability but also puts licensed operators, who carry the full costs and obligations of compliance, at an unfair disadvantage. MPI has said it will continue to pursue and prosecute those who seek to profit at the expense of the marine environment and the legitimate businesses that depend on it.
