They will only release them when the testing criteria has been met.
"Some individuals in this group have now been tested as many as four times.
"We want to thank them for their commitment to New Zealand's testing processes and for contributing to good health outcomes for them and their colleagues."
It follows the discovery a fortnight ago that eleven of the fishermen had returned positive results for Covid-19.
They are among 440 fishers from Russia and the Ukraine, 270 of whom are due to go out on three Independent Fisheries boats this month.
Four new Covid-19 cases were announced today in managed isolation.
The other three cases include:
• One case arrived on October 19 from Milan via Singapore and tested positive to routine testing at around day 12. The person is now in the Auckland quarantine facility.
• One case arrived on October 28 from London via Singapore and tested positive to routine testing at around day 3. The person is now in the Auckland quarantine facility.
• One case was detected in managed isolation in Auckland, after being given permission to join a family member recently arrived from overseas. The family member has previously been recorded in our positive case totals. Today's case will be recorded as an import-related case.
The total number of active cases in New Zealand is 81 - the total number of confirmed cases is now 1607.
Yesterday, the ministry's laboratories completed 3,046 tests for Covid-19, bringing the total number of tests completed to date to 1,104,113.
