Four Mediterranean fanworms, known as aggressive marine pests, have been found in Gisborne's Harbour.
Divers from the Bay of Plenty scoured the Gisborne harbour last week after Gisborne District Council found one fanworm on the training wall in the port in June last year.
The following month divers were brought in and an extensive search of the inner harbour found no sign of any more worms. A second dive operation was conducted late last year.
A single fanworm was found and the latest search was a follow-up operation.
"Unfortunately the dive team found four more last week," said council shared services science manager Lois Easton.
The fanworm is an aggressive marine pest with potential to cause significant environmental and economic harm if established here, she said.
"The four worms were found in three locations: on the training wall, under wharf shed 3 and alongside the slipway," Ms Easton said.
"They were unable to search the overseas berths because a log ship was being loaded, and [they] will return for a further day-long dive soon to check that area as well."
Ms Easton said it was disappointing but not surprising to have found more of the worms.
"The good news is that the Ministry for Primary Industries will continue to jointly fund the eradication campaign to remove the fanworm from our port."
The council meets half the cost of the work. The worm is widespread in Auckland Harbour and is contained in Whangarei and Lyttelton.
Tauranga Harbour is being actively managed to prevent establishment as recreational vessels from Auckland frequently arrive with infestations.
Small incursions in Marlborough and Nelson have been contained. The marine pest attaches itself to marine structures, the hulls of boats and to underwater terrain.
- Gisborne Herald