Eleven people were on board the vessel. Three survivors were rescued after the incident in rough seas at Kaipara Harbour, north of Auckland.
Conditions were reportedly poor at the time, with wind gusts of up to 50km/h (31mph) and one-metre (3ft) swells.
One person is still missing. But poor weather could hamper rescue efforts.
The identities of those on board were not revealed. Officials are investigating the cause of the accident, which happened around 15:30 (02:30 GMT) on Saturday.
It reportedly involved Francie, a 12m (40ft) charter vessel.
Two of the injured have already been discharged from hospital, and the third is said to be in stable condition.
New Zealand: Bodies wash up from boat tragedy
27 November 2016
Read: 907
Two more bodies have washed up on a New Zealand shoreline after a fishing boat capsized killing at least seven people, police say.
