In the second such incident in as many days, a people smuggler reportedly "deliberately drowned" 50 teenage African migrants, mainly from Somalia and Ethiopia.
The smuggler had forced more than 150 passengers altogether off his boat.
The International Organisation for Migration's Chissey Mueller says it happened as the boat was approaching Yemen.
"These migrants had been pushed off a boat that a smuggler was bringing into Yemen. Apparently, there was an incident between the migrant smuggler and the authority-type figures along the coastal areas. The migrant smuggler, who then got scared or intimidated by the authority-type figures, then asked the migrants -- and pushed the migrants -- off the boat. Some of the survivors were able to get to the shore, which is where the IOM teams had encountered some of them and asked for their story."
That incident comes barely 24 hours after smugglers forced a barely smaller group of Somali and Ethiopian migrants into the sea off Yemen.
They were approaching the coast of Shabwa, a Yemeni governorate along the Arabian Sea.
The average age of the group was just 16.
The IOM's head of mission in Yemen, Laurent de Boeck, says a bad situation has just become worse.
"It's maybe linked with the fact that there is reinforcement of control at the borders and that smugglers are panicking, but the reaction is actually worse, because, instead of preventing them entering, they basically continue their business by killing people."
The United Nations says, since the beginning of the year, 55,000 people have made the journey across the Gulf of Aden.
More than half were under age 18 and came from Somalia or Ethiopia.
One-third of them were women.
In March, more than 40 Somali refugees were killed off the Yemeni coast when a helicopter patrol fired on their boat.
The agency says it has encountered nearly 2,000 migrants each month during its coastal patrols.
Another IOM spokeswoman, Olivia Headon, says Yemen's catastrophic civil war has not deterred the flow of people from the Horn of Africa hoping to reach countries in the Gulf region.
"Youth unemployment is quite high in the places where they're coming from, Ethiopia and Somalia. They don't see opportunities for their future, and they get sold this false idea by smugglers that the place they can go to -- in this case, Gulf countries -- has all these opportunities that they can't be afforded at home."
She says the migrants are often well aware of the dangers.
"What we're really seeing here -- it's similar to other routes as well, with people moving from West Africa up to Libya and across to Europe -- often, people are aware of the dangers but they just don't see any other option. It again comes back to this idea that's sold to them, this false promise, this idea of what is almost sold to them as 'heaven.' We often hear migrants that we work with to provide assistance, who've been abused on these routes, talk about how Europe is heaven, how the Gulf country is heaven. And this is what the smugglers are telling them. And they balance out this idea of what their life could be with the risks they know on these routes, and they see this better future as the way to go and to help themselves, help their families."
IOM chief William Lacy Swing has perhaps the most stinging indictment of the smugglers.
"What is a teenager's life worth? On this route to the Gulf countries, it is US$100, or even $1,000, following rape and torture that forces their families back home to pay more than they have. There is something fundamentally wrong with this world if countless numbers of children can be deliberately and ruthlessly drowned in the ocean when they are an easy source of income and nothing is done to stop it from ever happening again."
