Undaria gone from Chalky Inlet, Fiordland

The invasive marine pest Undaria pinnatifida found in 2019 has been stamped out from Taiari / Chalky Inlet, Fiordland after almost five years of no mature plants being found during surveillance operations.

Undaria pinnatifida (Undaria) was first discovered in April 2019, on lines next to the Stella wreck in North Port, Taiari / Chalky Inlet, during a joint patrol with Environment Southland, Biosecurity New Zealand and Department of Conservation staff.

The three organisations promptly launched a joint elimination project to remove Undaria from North Port using divers.

Environment Southland team leader marine Kathryn McLachlan said being able to declare a site free from Undaria was proof that local elimination can be achieved with prompt and regular dive search and removal surveys.

“When Undaria was discovered, a technical advisory group advised that there would need to be five years of no mature plants before the site could be declared free of Undaria. We are excited to be able to say that the last time it was found was October 2019 despite frequent checks of the area.”

This is the first incursion in Fiordland to be declared Undaria-free, and the inter-agency groups remain committed to progressively containing Undaria in Tamatea / Dusky Sound and Te Puaitaha / Breaksea Sound.

Throughout the year, teams of divers work in both the Tamatea / Dusky Sound and Te Puaitaha / Breaksea Sound area, searching and removing any Undaria that is found. It is time consuming and resource intensive work, but still definitely worth it to reduce the impact of Undaria in the fiords. While work continues to remove this invasive pest, Environment Southland is encouraging the public to ensure they don’t further the spread.

“We want people to take steps not to transport Undaria when moving within and leaving the Dusky complex and to follow the Fiordland Marine Regional Pathway Management Plan rules to keep a clean hull, clean gear and maintain residual seawater standards.

“We’re also asking people to remain on the lookout in other areas and to alert us if they see any Undaria in sites outside of the Dusky/Breaksea complex.”

New sites can be reported to Environment Southland through www.pesthub.es.govt.nz. Members of the public should also remember to leave it in place and not try to remove it themselves.

To improve the chances of finding any new sites, reports should include GPS location, photographs, a description of where it was found (how deep, whether it was on natural substrate and an artificial structure) and how much was there.

“The removal of Undaria in Taiari / Chalky Inlet is proof that elimination is possible with early detection.”

In September 2020, Undaria was also identified on cray pots at Broad Bay, Rakiura Stewart Island. With no new growth in the past four years, this site is on-track to be declared Undaria-free next year.