Migrants arriving on boats in southern Italy say that 81 other people traveling with them are either died or have gone missing during their sea journeys from North Africa, the U.N. refugee agency (UNHCR) said Wednesday. Twenty-seven migrants picked up Tuesday by Italy's naval rescue mission and brought to the town of Catania said that there had been 75 other people on their boat, who were feared drowned, the UNHCR said in a statement. Other migrants arriving in Sicily's Porto Empedocle said that two of the party they traveled with had died and four had disappeared. Authorities said that the death toll on another packed fishing boat, discovered by an Italian rescue mission Monday, had reached 45. The victims are believed to have suffocated. All those found dead Monday by the Mare Nostrum (Our Sea) naval operation were men from Subsaharan Africa, according to the United Nations. UNHCR says that around 500 migrants have died so far this year in the Mediterranean.