CANBERRA, Australia (AP) — Nine Indonesian fishermen are feared drowned and another 11 have been rescued after spending six days without food or water on a barren island off the northwest Australian coast in the aftermath of a powerful tropical cyclone, authorities said Wednesday.

Two primitive wooden Indonesian fishing boats were caught in the path of Cyclone Ilsa, which on Friday became the most powerful storm in eight years to cross the Australian coast, with winds gusting at an apparent record of 289 kilometers (180 miles) per hour.

One of the boats, Putri Jaya, sank in “extreme weather conditions” on April 11 or 12 while Ilsa was gathering strength over the Indian Ocean as it tracked southeast toward the coast, Australian Maritime Safety Authority said in a statement, citing survivors.

The other boat, Express 1, ran aground with 10 men aboard in the early hours of April 12 on Bedwell Island, a sandy outcrop some 300 kilometers (200 miles) west of the Australian coastal tourist town of Broome, the authority said. The only known survivor from the Putri Jaya spent 30 hours in the water before washing ashore on the same island, the statement said.

"They all remained (on Bedwell Island) for six days without food and water before being rescued on Monday night,” the authority said.

The survivors were spotted Monday by the Australian Border Force, which patrols Australia’s northern approaches for smuggling and other illegal activity, from a plane on a routine surveillance mission. A Broome-based rescue helicopter was deployed and winched all 11 aboard in failing light.

Gordon Watt, a manager at helicopter provider PHI Aviation, said the rescue helicopter crew had been unable to land on the sand.

“They had to conduct winch recoveries which, in itself, is a challenging task,” Watt told Australian Broadcasting Corp. “The time of day meant that nightfall was upon the crew during the rescue, so they had to transition to using night vision goggles."

The survivors were taken to Broome Hospital where authorities reported them in good health. They are expected to be flown back to Indonesia soon.

The missing Indonesian fishermen are expected to be the only fatalities from Ilsa, which was a maximum Category 5 cyclone when it crossed the Pilbara region coast of Western Australia state southwest of Broome.

A gust of 289 kph (180 mph) recorded on an island off the Pilbara coast was the fastest ever recorded by Australia's weather bureau equipment in the country. While the reading remains preliminary and requires further analysis, the bureau said Tuesday it beats the previous record of 267 kph (166 mph) set by Cyclone Vance on the Pilbara coast in 1999.