In September 2020, a single craypot in Broad Bay was found to have undaria. Immediate removal and treatment followed, and extensive follow-up surveillance conducted from 2023 to 2025 found no further evidence of the pest in the area.
Environment Southland marine biosecurity team leader Kathryn McLachlan said in a statement the absence of undaria during recent dive surveys confirmed the prompt response was highly effective.
“Undaria is a rapidly growing seaweed that disrupts marine ecosystems. Its removal after initial detection shows that eradication can be achieved with swift, co-ordinated efforts.
“We can celebrate Broad Bay’s return to undaria-free status. This result demonstrates what can be achieved when regional authorities, local communities, and marine users work together,” Ms McLachlan said.
Ongoing vigilance was essential to prevent reintroduction and ensure permanent eradication and annual surveillance of both Broad Bay and the wider southern Rakiura area would continue, she said.
“We want people to take steps not to transport undaria when moving around Rakiura, especially from the northern parts of the island, where undaria is established. Remember to maintain a clean hull, and clean gear.”
