The ships were hit by the storm on Wednesday and Thursday, which cut radio contact to the mainland, said an official from the regional Search and Rescue Center in the central city of Danang, asking not to be named.
"Vietnamese fishing vessels that survived the storm picked up the bodies and rescued 30 people," said the official. The boats were on the way back to Danang in the central Vietnam region many of the fishing crews came from.
Three of the shipwrecks were reported Thursday, with 22 people missing, mostly from central Quang Ngai province.
Officials said they learned on Friday afternoon of the 20 deaths and 69 more missing sailors from six additional boats that were sunk.
More than 70 Vietnamese fishermen were also stranded on the remote Chinese island of Dong Sa.
Vietnam has asked China to help the stranded fishermen and search for more survivors, said an official of the National Search and Rescue Centre in Hanoi.