There are no new cases of COVID-19 in the community and three in managed isolation.
In addition to the three cases in managed isolation, one person has been classed as a historical case.
New Zealand now has a total of 62 active cases.
Three more crew members of the Mattina have tested positive for the virus, making the total case number on board 12.
"One further result is currently under investigation due to a high CT value; and three more have serological evidence of past infection and therefore are not deemed infectious at this stage," said a statement from the Ministry of Health.
The ship is docked in Bluff, and health authorities are monitoring it closely.
Two of the crew were taken to hospital on Wednesday but have since returned to the ship, having been assessed as not requiring hospital care.
"All crew who have tested positive will remain quarantined on board the vessel at this time, where they will maintain the minimum functions at the port."