Thirty-two of the 796 crew members and passengers were known to have survived, rescued by boats that had been in the area and responded to an alert.
A fierce storm sank an ocean ferry bound for Senegal, killing 10 and leaving at least 730 of the 797 passengers and crew missing, the prime minister's office said Friday.
Roughly 50 passengers and crew were rescued after the ferry, traveling from south to north Senegal, capsized before midnight Thursday, according to Prime Minister Mame Madior Boye's office.
Authorities said a passing Italian ship retrieved at least some of the survivors.
Senegal declared three days of national mourning at midday Friday as the search for victims continued.
The state-owned ferry, the Joola, was en route from Senegal's southern region of Casamance, bound for Dakar, the capital. It went down in the Atlantic Ocean off Gambia, a small former English colony that divides north and south Senegal.
Ferries are the main way of transportation between north and south Senegal, since travel by road is slowed by border checks passing through Gambia.
The prime minister and other officials went to Dakar's port to be with families of passengers and crew waiting for news. The first corpses retrieved from the accident were being taken back to the port Friday afternoon.
The sinking came amid strong gales that swept Dakar overnight.
Media reports said the ferry had undergone repairs, and had only recently returned to service after months in dock.