Source: Northland Regional Council
News the Northland Regional Council will receive more than $6M in government funding for groundbreaking work to tackle invasive exotic Caulerpa seaweed is being welcomed even as news comes it has spread to nearby Urupukapuka, Motukiekie and Moturua Islands.
Biosecurity Minister Andrew Hoggard announced yesterday (subs: Tues 25 Feb) the council had been awarded $6.2 million to progress its large-scale mechanical suction dredging technique centred on Omakiwi Cove, Te Rāwhiti in the Bay of Islands, about 3km from Urupukapuka.
The funding news comes as authorities reveal exotic Caulerpa has been found recently at Paradise Bay, on the western side of Urupukapuka, at Army/Waiwhapuku Bay (off Moturua Island) as well as at the southern end of Motukiekie Island (west of Urupukapuka.)
Council chair Geoff Crawford says the exotic Caulerpa was discovered after a member of the public reported what they thought was the seaweed on an anchor at Paradise Bay earlier this month.
Since then, the council had been diving around the island and working hard with Biosecurity New Zealand to try to determine the extent of the seaweed’s spread and ensure the most effective response. (Previous dives of the area – as recently as April last year – had not revealed any exotic Caulerpa.)
Chair Crawford says it is still not clear how the exotic Caulerpa had spread there, but likely possibilities included hitching a ride with an unsuspecting yachtie or boatie, or natural dispersal from another site.
“While this latest development is very concerning, our focus is on ensuring we continue to develop the tools that can fight exotic Caulerpa – without these we haven’t any effective response.”
He says ongoing government investment in new technologies is critical and with that in mind the council is grateful to Government for the funding announced yesterday.
“It gives us a chance to remove exotic Caulerpa at scale and prevent the further spread – and the devastating effects – of it.”
The Minister’s announcement details projects that are financed by a $10 million funding injection last year aimed at driving improvements to technology and getting new tools in the water.
Chair Crawford says the funding will enable the council to continue an existing relationship with Ōpua-based marine contractor Johnson Bros, which has been working with the council and local mana whenua partners Ngāti Kuta and Patukeha hapū to remove exotic Caulerpa in Omakiwi Cove.
The relationship saw Andrew Johnson last year develop a world-first large-scale suction dredge technology system, essentially vacuuming the seaweed from the sea floor, using a digger on a barge sporting a custom-built dredge head. (That technology was used to treat approximately two hectares of exotic Caulerpa – discovered there in May 2023 – over six months last year.)
The latest funding will allow development of a new tool called a ‘submersible dredge planer’ (SDP) which will operate remotely on the seafloor and aims to remove exotic Caulerpa in a single pass.
The new system will include a remotely operated SDP, dredge head, pumping arrangement, GPS position system, dredge spoil processing plant, and disposal system.
Chair Crawford says the advantage of an SDP over the current barge system is it has the ability to move more quickly, accurately and easily across the sea floor under its own power. Additionally, it is less likely to be affected by poor weather conditions.
“While work on the concept is still in the development phase, it’s expected that the tool will be operationally tested at Omakiwi from September.”
Chair Crawford says the council appreciated the ongoing and tireless efforts of Ngāti Kuta and Patukeha hapū who had worked closely with authorities since exotic Caulerpa’s original discovery in Northland.
“Our mana whenua partners have been informed of the latest discovery, and we look forward to continuing these relationships as we collectively work to deal with the latest find.”
He says it is too soon to say what management approach will be taken as a result of the find at Urupukapuka Island, which is about 7km from Paihia and a popular destination for yachties and other holidaymakers.
“The council is liaising with Biosecurity New Zealand on the appropriate measures to take.”
In the meantime, boaties and fishers are urged to be cautious when using the affected areas as they have a key role in avoiding the spread of this pest.
Chair Crawford says exotic Caulerpa can get snagged on anchors, chains and dive and fishing gear and be accidentally moved to new locations.
He says there are a few simple actions people can take to avoid this.
“When out at sea – before leaving a location, check your vessel’s anchor and anchor chain, and any equipment you’ve used in the water for any tangled seaweed.” “If you have an automatic retrieval system, still look out for any attached pieces of seaweed.”
He says if any type of seaweed is found, it should be removed, bagged or contained securely so it can’t get back into the water and taken ashore for disposal in a rubbish bin.
“If you can’t securely contain it so it can’t get back into the water – put it back into the water it came from.”
If someone finds they’ve picked up seaweed when they arrived back at shore, they should remove it and put it in the rubbish.
Chair Crawford says suspected sightings of exotic Caulerpa – including any washed up on beaches – should be reported to Biosecurity New Zealand.
“Take a photo, if possible, and note the location then either call them on freephone (0800) 809 966 or complete the online form at: report.mpi.govt.nz “
