Most of the survivors were found clinging to the hull, and another was found in an air pocket beneath the boat, officials said.
One survivor was taken by boat to Miami Beach, where he was treated at a hospital and released to federal law enforcement, Barney said.
The rest of the survivors were in good condition and were taken into custody aboard a Coast Guard vessel while authorities investigated whether they were part of a human smuggling operation. It was not immediately clear whether they would be brought to the U.S. or repatriated to their home countries.
"Well, obviously, 15 people on a boat, transiting in the middle of the night with no life jackets is a very, very unsafe condition," Caprara said.
Caprara said that authorities were working to confirm that the people on the boat were Haitian and Jamaican.