The U.S. Coast Guard is searching the waters off western Puerto Rico for a boat that is reportedly missing with at least 40 Dominican migrants, a spokesman said Monday.

Rescue crews were using helicopters, a cutter and several aircraft to look for any sign of the makeshift wooden boat — or survivors — in the rough 80-mile passage between the Dominican Republic and Puerto Rico.

A woman who said her boyfriend was on the boat when it left Wednesday night was the first to alert authorities Saturday night, Guard spokesman Ricardo Castrodad said. Several other relatives have since reported that the vessel did not arrive in Puerto Rico as planned, and the Coast Guard search began Sunday.

"We're taking it seriously," Castrodad said.

Hundreds of Dominican migrants brave the perilous ocean voyage to Puerto Rico each year to seek better lives in the more affluent U.S. Caribbean territory.

A boat carrying 33 Dominican migrants got lost last month as they tried to reach Puerto Rico. Five survivors who were rescued after 15 days at sea said they ate one of the dead passengers to stay alive.