Four more bodies have been recovered off the coast of Florida after a boat carrying 39 people capsized on the weekend, the United States Coast Guard announced, but it said it would end its search operations by sunset on Thursday unless new information surfaces.

Authorities have now found a total of five bodies, which leaves 34 people missing, Coast Guard Captain Jo-Ann Burdian said during a news briefing in Miami.

The incident is believed to be linked to human smuggling, US authorities have said.

“We’ve had good visibility. We know we’re searching in the right area. We’ve overflown the vessel a number of times and have found additional deceased persons. It does mean we don’t think it’s likely that anyone else has survived,” Burdian said.

“If we don’t receive additional specific information to help redirect our search, we’ll suspend that active searching.”

Rescue crews on Wednesday recovered the body of one person, while a lone survivor was found clinging to the hull of the overturned boat on Tuesday.

The incident comes as more Haitians have been attempting to reach the US by sea as the Caribbean island nation faces worsening economic and political crises, as well as gang-related kidnappings.

Migrants seeking passage to Florida have been boarding flimsy vessels travelling through the Caribbean by way of the Bahamas.

Rescue crews have been looking for survivors since the boat overturned in rough seas on Sunday morning. The vessel left the Bahamas’s Bimini islands, about 80km (50 miles) east of Miami, on Saturday night.

It capsized about 72km (45 miles) east of Fort Pierce Inlet, off Florida’s Atlantic coast, about midway between Miami and Cape Canaveral.

A lone survivor was spotted on Tuesday morning by crew members of a private tugboat. The survivor told authorities after his rescue that he was one of 40 people on board the boat, none of whom had been wearing a life jacket, the Coast Guard said.

Migrants seeking passage to Florida have been boarding flimsy vessels travelling through the Caribbean by way of the Bahamas

The turbulent waters of the Gulf Stream can be treacherous even on a calm, sunny day. Throw in an overloaded boat, inexperienced mariners, stormy weather and the dark of night, and they can become deadly.

The Miami office of Homeland Security Investigations (HSI) has launched an inquiry, saying the migrants’ journey was most certainly part of a human smuggling operation. Under federal law, a smuggler convicted of causing a death is eligible for execution.

“The goal of this investigation is to identify, arrest and prosecute any criminal or criminal organisation that organised, facilitated or profited from this doomed venture,” said HSI Miami Special Agent in Charge Anthony Salisbury.

He said he would not comment on the nationalities of the people on board the boat, as this was part of the probe.

In a separate incident, the Coast Guard reported intercepting a sailing vessel off the Bahamas overloaded with 191 Haitians believed to be headed for Florida on Wednesday.