Undaria seaweed survey finds more infestations

10 August 2005

Parks and Heritage Committee Chair Sandra Coney says the committee decided today to go ahead and remove the Kawau infestation to help prevent its further spread.

"The infestation at one jetty in Bon Accord harbour on Kawau is fairly extensive, but is well contained and we believe we could completely eradicate it," Cr Coney says.

The cost of getting rid of the Undaria at Kawau is estimated to be $20,000 to $40,000. The final cost will depend on the age of the infestation and the time needed to destroy it.

"The survey found that the spread within the Waitemata Harbour was so great that prospects for elimination are dim, especially since Auckland can be re-infested from other areas.'

"The large number of vessels moving into our harbours makes reinvasion likely, even with a successful management programme."

An integrated management option is considered the only feasible option, to prevent the further spread of the seaweed to high value sites in the region, she says.

"The cost of the programme would be very high. It is estimated at between $1.62million and $2.67million."

Cr Coney says the ARC plans to discuss options for sustainable management of Undaria with Biosecurity New Zealand, the Department of Conservation and Ports of Auckland.

The July meeting of the Parks and Heritage Committee requested the urgent survey on the spread of Undaria and the estimated costs of containing it.

The Asian seaweed, farmed as a food crop in Japan, China and Korea, was first discovered in Wellington Harbour in 1987 and has progressively spread around the country.

Undaria can displace native kelps, restrict the lifecycle of shellfish like paua and poses a significant threat to aquaculture.

The need for a national approach will be taken up with Biosecurity NZ and the Department of Conservation. Other regional councils are also concerned about the Undaria problem.

ARC Environmental Science and Marine Operations staff carried out the survey from 14 to 22 July. The locations surveyed included all Waitemata Harbour wharves and jetties not included in the Biosecurity NZ survey of October 2004, Onehunga Wharf, Rangitoto, Motutapu, Waiheke, Rakino, Pakatoa, Kawau, Great Barrier Island (Tryphena, Whangaparapara, Port Fitzroy), Leigh Harbour, Sandspit, Gulf Harbour, Ti Point, Scott's Landing, Pine Harbour, Half Moon Bay, Tiritiri Matangi and Moutureka Islands.

Undaria was also found in the Firth of Thames at Wilson's Bay, in 2002.

The public can help by calling 366 2000 if they see Undaria.

ENDS

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