Ecuadorian Navy Capt. Armando Elizalde told Colombian RCN television on Wednesday that most of the 113 people aboard "sank with the boat."
The disaster that hit the boat — whose passengers were believed to be heading for the United States — occurred Friday night more than 100 miles off the coast of southwest Colombia.
"The boat, with way too many people aboard, was unable to resist a strong wave and it tipped over," Elizalde said, adding that most of those aboard were in the ship's hold when it capsized and couldn't escape. Thirteen people emerged on the surface but four of them later slipped under the waves, he said.
An Ecuadorian fishing boat found the survivors — seven men and two women — on Sunday, Elizalde said. They were later transferred to an Ecuadorian Coast Guard cutter and on Wednesday returned to Ecuador, their faces scorched and peeling from sunburn.
The youngest survivor was 15 year-old Rosa Cuzco, while the others were mostly in their 20s.
Julio Cisalima, 25, said he held onto a gas container to keep afloat.
"The boat tipped, there were lots of people. We then spent two days at sea and had to swim a lot," he told Ecuadorian television.
Another survivor, whose name was not given, said he held on to a buoy.
"I jumped from the boat and I saw a buoy ... and I grabbed hold of it," he told Colombia's Caracol television. "There was a little bag of water floating and that's what we were surviving on."
The Colombian Navy said the immigrants' boat was meant to hold only 15 people. A Colombian Navy plane and boat were being deployed in a search-and-rescue operation. Ecuador's Coast Guard was also participating.
The disaster highlighted the perilous journey that migrants seeking to escape poverty in their homeland undertake to reach the United States.
Immigrant traffickers often use Ecuador's coast as a launching point, frequently taking illegal aliens to Guatemala or Mexico, who then travel overland into the United States.
Last May, a Costa Rican fisherman rescued 88 would-be migrants from Ecuador and Peru from their foundering vessel after he found a message in a bottle they had tied to a float marking one of his long fishing lines.
The migrants said that they had paid traffickers as much as $3,000 each as a down payment for the trip, with a promise to pay another $7,000 more after completing the journey. But the boat's crew abandoned them at sea after the engine failed.
In August 2004, a U.S. Coast Guard ship intercepted a disabled Ecuadorian boat carrying 106 illegal immigrants from Ecuador. The Coast Guard boarded the 40-foot fishing boat some 415 miles off Ecuador's Pacific coast. The drifting boat had apparently been abandoned by its crew.
Rear Adm. Eduardo Navas, general director of Ecuador's merchant marines, said those aboard the boat that sank in the nighttime darkness Friday, plunging the occupants into the cold waters of the Pacific, were presumably heading to the United States.
The passengers had departed from a beach near Esmeraldas, on Ecuador's northern coast.
Navas told Ecuadorian TV it was "a crime to have placed" so many Ecuadorians in such a small boat, measuring no more than 65 feet in length.
Jorge Altamirano, port chief in Esmeraldas, said the nine survivors on Wednesday were transferred on Tuesday to the Ecuadorian Coast Guard vessel 24 de Mayo from the Don Felix, the fishing boat that found the survivors.