
Captain Noemie Cayabyab, a spokesperson at the PCG, said the total number of people on board had been revised to 344, down from the earlier figure of 359, after verifying that 15 people listed on the manifest did not board the vessel.
The number of rescued passengers remained at 316, Cayabyab told reporters.
The accident occurred at 1.50am (1750 GMT) on Monday while the passenger vessel, MV Trisha Kerstin 3, was en route to Jolo in Sulu province after departing from Zamboanga. The PCG said the vessel has an authorised passenger capacity of 352.
The PCG said it was not yet prepared to conclude why the ferry sank, with the investigation still ongoing.
Sea accidents are common in the Philippines, an archipelago of more than 7,000 islands with a patchy maritime safety record.