One person was rescued and the bodies of 11 people were recovered on Wednesday afternoon, Xinhua reported.
Rescuers were still searching for the five missing people on Wednesday afternoon.
The only person rescued was in stable condition and being held for observation at a local hospital.
The boat set out from Houershi Port at around 1 am and those aboard were about to transfer to a bigger fishing vessel before huge waves overturned it.
One fisherman used his satellite mobile phone to call for help.
Ten of the fishermen and women were migrant workers, and seven people, including the owner of the boat, were from the local fishing village.
The wooden boat was 10 meters long and powered by a 10 horsepower engine.
Sun Caihui, a local fishing boat owner who took part in the rescue, said that strong winds and rough seas made the rescue effort very difficult.
"We received a call from the village head at around 5 am and started our boat immediately.
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