Vigilant fisherman helps protect Rakiura from marine pest threat

A vigilant fisherman’s report of a suspected marine pest has helped safeguard one of Aotearoa New Zealand’s most treasured marine environments, with an Environment Southland investigation finding no further signs of the invasive seaweed, Undaria, at the reported site in southern Rakiura.

The investigation began after a fisherman discovered and reported a single juvenile Undaria plant attached to a mooring line near Pukeweka Island, off Taukihepa/South Cape Island. The plant was removed and specialist divers found no further signs of Undaria in the surrounding area.

Environment Southland Team Leader Marine Kathryn McLachlan said the positive outcome highlights the critical role boaties, fishers and other water users play in protecting Murihiku Southland’s marine environment.

"We're incredibly grateful to the fisherman who reported what they found. Their quick action meant we could respond straight away and investigate whether there was a wider infestation."

Undaria pinnatifida is an invasive seaweed that can spread rapidly and damage marine ecosystems, competing with native species and altering marine ecosystems. It is already established in parts of Southland and remains a significant biosecurity risk.

Kathryn McLachlan said early detection is one of the most effective tools available for managing marine pests.