Authorities say six adults and a teenage girl were rescued after drifting for four days in the blazing sun without water.
They scrambled aboard a small wooden dinghy as the ferry with an estimated 50 people on board went under.
The search for the missing Kiribati ferry is to resume at first light this morning.
A New Zealand Defence Force Orion aircraft located the survivors and the fishing boat was diverted to pick them up.
There is no sign as yet of any other survivors.
