Biosecurity officials have given up the fight against a highly invasive marine pest that has the potential to smother native species and disrupt marine farming.
Biosecurity New Zealand says the Mediterranean fanworm is now too established to be eradicated.
A population was discovered in Lyttelton Harbour two years ago and an eradication programme was launched.
But Biosecurity New Zealand has found more in Waitemata Harbour and says that means the pest is here to stay.
The head of the eradication programme, Doug Lush, says the worms could harm marine farms but the real problem is their effect on the marine environment.