Forty-six migrants drowned and 16 are missing after their boat capsized off the shore of Yemen on Wednesday, the United Nations Migration Agency said.
At least 100 migrants were crammed into a smuggler's boat that left the port of Bossaso in Somalia on Tuesday, travelling through the night.
The boat overturned in high waves in the Gulf of Aden at around 5am as it approached its destination.
"IOM staff reported that 46 migrants had drowned, 37 men and nine women. A further 16 remain missing, presumed dead," the agency said in a statement, adding that they were all believed to be Ethiopian.
"Survivors said the passengers, who were without lifejackets in the smuggler's boat, started panicking as high waves struck close to the shore. As the boat took on water, they were pitched headlong into the rough seas where so many succumbed."
IOM staff provided medical assistance, health, food and psychosocial support to the survivors.
The group were attempting to cross the Horn of Africa to find employment in Yemen and the Gulf.
Read more: At least 30 African migrants drown after boat capsizes off Yemen
More than 7,000 migrants take the perilous journey every month, facing horrendous conditions and appalling treatment at the hand of people traffickers, said Mohammed Abdiker, IOM's head of operations and emergencies.
Both while travelling to and in Yemen, migrants are routinely abused by smugglers and other criminals, including physical and sexual abuse, as well as torture for ransom, arbitrary detention for long periods of time and forced labour.
Some migrants are also taken to official and unofficial detention centres.
Through its Voluntary Humanitarian Return programme, the IOM has been providing return transport from Yemen to the migrants' home countries.
Earlier this week, IOM helped some 101 Ethiopian migrants leave Yemen, which is on the brink of famine following three years of war, through Al Hodeidah port as clashes approached the area.
The group included nearly 51 women and 33 children, who had become stranded in the country and are among the most vulnerable cases from a larger group of about 300 migrants trapped in detention.