New strategy for Undaria management in Fiordland
The multi-agency programme to manage the invasive seaweed Undaria pinnatifida in the Fiordland (Te Moana o Atawhenua) Marine Area is entering a new phase. The partnership programme has a renewed focus on preventing further spread and protecting the wider marine environment.
Since 2017, Environment Southland, the Department of Conservation (DOC), and Biosecurity New Zealand, with support from the Fiordland Marine Guardians, have worked together to contain Undaria within Te Puaitaha / Breaksea Sound and Tamatea / Dusky Sound. Thanks to large-scale biomass removal and a targeted control programme, significant progress has been made. This has included the successful local elimination of Undaria from Taiari / Chalky Inlet, which was declared free of the seaweed in April 2024.
However, recent discoveries of new Undaria populations across Te Puaitaha/Breaksea Sound and Tamatea/Dusky Sound have prompted a strategic shift.
Environment Southland marine team leader Kathryn McLachlan said that the two-year funding received through the Jobs for Nature programme in 2021 provided a much needed boost to Undaria control efforts in Fiordland. However, with the seaweed continuing to spread, it is 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 multi-agency Undaria team has recommended this transition to vector management and enhanced surveillance, a proactive approach that focuses on stopping Undaria from hitching a ride on vessels and gear to locations outside of the Te Puaitaha/Tamatea complex and detecting new incursions early so they can be managed.
This method has proven effective in past responses and will help safeguard Fiordland’s unique marine ecosystems, Kathryn 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."
The updated strategy includes: targeted Undaria removal at high-risk anchorages and moorings within Breaksea Sound and Dusky Sound, increased surveillance across the wider Fiordland area, including marine reserves such as Moana Uta / Wet Jacket Arm and Taumoana / Five Fingers Peninsula and continued collaboration between agencies.
Early detection and rapid response are key to preventing long-term establishment of marine pests.
Editor’s note:
Undaria 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 remote and pristine waters remain largely free of marine pests with only the waters of Te Puaitaha/Breaksea Sound and Tamatea/Dusky Sound containing Undaria.
ENDS
For further information contact the Environment Southland communications team on 0800 76 88 45 or communications@es.govt.nz
