Environment Southland has run a partnership programme with the Department of Conservation and Biosecurity NZ, with support from the Fiordland Marine Guardians. They will now put a renewed focus on preventing further spread and protecting the wider marine environment.
U. pinnatifida is a fast-growing invasive seaweed that competes with native species and disrupts marine ecosystems.
It has spread across many parts of New Zealand over the past 30 years, but Fiordland’s waters remain largely free of marine pests, with only Breaksea Sound and Dusky Sound containing U. pinnatifida.
The group have worked to contain U. pinnatifida within these sounds. Thanks to large-scale biomass removal and a targeted control programme, significant progress had been made, the group said in a statement.
There has been successful local elimination of U. pinnatifida from Chalky Inlet, which was declared free of the seaweed in April 2024.
But there have now been discoveries of new U. pinnatifida populations across the affected sounds, leading to a new strategy.
Environment Southland marine team leader Kathryn McLachlan said the two-year funding received through the Jobs for Nature programme in 2021 provided a much-needed boost to U. pinnatifida control efforts in Fiordland. With the seaweed continuing to spread though, it was no longer feasible to contain it within the current management area using existing resources.
"From a resourcing and budgetary perspective, the Fiordland undaria programme is a significant joint-agency response. This has provided the employment and training of scientific divers during the Covid-19 pandemic.
"Progressive containment has helped slow undaria’s spread. The time is right to shift our focus, by targeting high-risk areas such as key anchorages and moorings and increasing surveillance. We will be able to act quickly to eliminate any new marine pests and prevent undaria from reaching other fiords outside of the Breaksea Sound and Dusky Sound.”
The proactive approach would focus on stopping U. pinnatifida from hitching a ride on vessels and gear to locations outside the Te Puaitaha/Tamatea complex and detecting new incursions early for management.
This method had proven effective in past responses and would help safeguard Fiordland’s unique marine ecosystems, Ms McLachlan said.
"While stepping back from large-scale biomass control may appear to some as giving up on undaria, it’s actually a strategic move. By focusing our efforts on early detection and preventing the spread outside of Breaksea/Dusky, we’re strengthening our ability to protect the wider fiords."
— Allied Media
