The Ministry of Health has confirmed 16 of the 18 crew on the Spanish-flagged shipping vessel Playa Zahara have tested positive for Covid-19.
In a statement, the ministry said as with the Viking Bay vessel earlier this week, the public health risk from these results was considered to be low.
"The swabs were taken in Port Taranaki on Tuesday after reports of a flu-like illness on board as a precursor to a scheduled crew change. Standard Infection Prevention and Control (IPC) protocol, including the appropriate use of PPE, was used throughout the crew's testing.
"After the tests were taken, the ship again departed from Port Taranaki and is now on its way to Lyttelton where the appropriate level of support can be provided."
Port Taranaki chief executive Guy Roper said no workers had contact with anyone aboard the Playa Zahara when it docked, as the vessel was piloted in and out remotely.
He said those tying up the vessel wore full protective equipment and had no contact with the crew. The vessel moored at a special quarantine area at Moturoa Wharf which was washed down when the vessel left, he said.
MPI has confirmed the Playa Zahara wasn't fishing in New Zealand waters or doing any work on behalf of a New Zealand venture, when it asked to dock here.
A spokesperson said the vessel was fishing in the high seas and its catch is being kept on board.
The ship is now making its way to Lyttelton Port. The ministry said health authorities were working on arrangements for the crew's arrival.
"This includes whether they quarantine aboard the ship or are transferred to a quarantine facility on shore. If any confirmed cases are to be transferred, that will also be done using standard IPC protocol."
MPI said the fish will be dumped if the crew can't prevent it spoiling when it docks in Lyttelton tomorrow.
It said the Playa Zahara's shipping agent and its crew were cooperating with officials.
Whole genome sequencing is under way.