Undaria control vital to protecting spectacular Rakiura marine habitat
It sounds like a typical Southland adventure – but the work that goes into protecting the pristine waters of the south from invasive marine species is more complicated than any ordinary day trip.
Loading the dive gear, getting the crew together and packing supplies happens ahead of many diving missions.
But the logistics of removing tonnes of Undaria pinnatifida (Undaria) from southern sea waters mean a huge amount of training, planning and organising go into every Environment Southland biosecurity dive trip.
Undaria is an introduced seaweed that thrives in New Zealand waters, with its rapid growth upsetting the structure of ecosystems and displacing native species.
The destructive weed is considered a progressive containment pest under the Southland Regional Pest Management Plan. Environment Southland’s biodiversity and biosecurity team have been fighting the battle with Undaria for many years, with thousands of kilograms removed from key locations like Fiordland.
One recent trip to Rakiura/Stewart Island showed the progress Environment Southland has been making. Seeing those gains makes all of the planning, the preparing and the logistical work that goes into its control worthwhile, Environment Southland's marine team leader Kathryn McLachlan says.
“Our diving trips are a big logistical challenge. You are working with the weather which can be very changeable and challenging, and in remote waters which can be very rough."
“We rely on the experience and the skill of our crew to keep us safe.
“Each trip is a big effort, but when we are able to see the progress we have made, it makes the work and the planning well worthwhile.”
On their dive trips, the team extensively survey marine areas while also removing large amounts of Undaria.
That requires divers to be in sea waters for long periods of time, and naturally, they encounter their share of the local wildlife.
“We come across some big marine species like sea lions, which can be quite territorial, as well as sevengill sharks which generally aren’t quite as hostile.
“There is obviously a great white shark presence around Rakiura as well." The marine wildlife is spectacular, and these species make up the unique biodiversity in the waters surrounding Rakiura, she says.
“We even got to meet some Tawaki (Fiordland crested penguins) which was incredible.
“Protecting their habitat is an important aspect of Undaria control work.”
The recent Rakiura trip saw Environment Southland’s skilled team check on key sites in the quest to eradicate and contain Undaria.
“We left Bluff and made our way around the west coast of Rakiura to the southern sites that we have been monitoring."
“We completed Undaria removal at a known incursion site in Easy Harbour and undertook surveillance at Broad Bay and Port Pegasus.
“We saw no marine pests around the east coast which was really satisfying."
“Port Pegasus is visited by fishers and tourist boats, so to see a high-risk area like that free of Undaria was very pleasing.”
Environment Southland’s ability to send a skilled diving team to Rakiura is directly linked to the success of the Jobs for Nature Fiordland Undaria Control Programme.
The Covid-19 pandemic and lockdowns led to drastic changes being made to Environment Southland’s marine biosecurity operations.
A successful application for Jobs for Nature funding enabled a new approach at a time when funding was light and maintaining progress was critical.
The programme recruited and trained 15 divers from the local community to a scientific diver standard, which provided thousands of hours of work to businesses and individuals.
This was all in the effort to remove 45,000 kg of Undaria from Te Puaitaha/Breaksea Sound.
Environment Southland has been actively fighting the spread of Undaria alongside the Department of Conservation and the Ministry for Primary Industries for many years.
"The residual benefit from our work at that time is that we now have a highly skilled team that we can call on as we continue to contain Undaria.”
Marine pests like Undaria are not always visible to those above water, but there are important actions that recreational and commercial boaties can take to help contain the pest species.
Boaties can play their part by ensuring they have a clean hull, clean gear and clean on-board seawater, before venturing to the pristine waters of Rakiura and Fiordland.
If divers and boaties see any unusual marine species, they’re encouraged to report this to Environment Southland as soon as possible.
“This gives us the best chance of eradication success so we can ensure that our beautiful marine environment stays this way for years to come,” Kathryn says.
