That's exactly what Florida based human traffickers did to Haitians back in the 80's and 90's. They would sail them a few hundred miles from the US coast, stop the boat, draw their guns, and then tell the Haitians to start swimming. It killed a lot of otherwise useless people. Those men may have been monsters, but they provided everyone a service. Only the fittest survived, and only the most useful were allowed to stay.