Another 55 migrants are thought to have died after being deliberately drowned, the UN’s migration agency says.
Up to 180 migrants were forced from a boat off the coast of Yemen.
It is the second incident in as many days after about 50 people died on Wednesday after being pushed from a boat by smugglers who feared arrest.
A spokeswoman for the International Organisation of Migration (IOM) told Reuters the incidents “may be the start of a new trend”.
“Smugglers know the situation is dangerous for them and they could be shot at, so they drop them near the shore,” she said.
The organisation uncovered bodies of 29 of migrants in shallow graves on a beach on Wednesday.
They estimated the average age of those on board to be 16.
Only five bodies have been recovered from Thursday’s incident, with 50 reported missing, presumed dead.
Despite ongoing conflict and dire humanitarian issues, Yemen is still seen by many Africans as a gateway to other Gulf states or Europe.
About 55,000 migrants have left the Horn of Africa to come to Yemen so far this year, more than half of them under the age of 18 and a third thought to be female, the IOM estimates.
Many others also try to reach Europe via Libya and the Mediterranean Sea. (BBC)