A surfboard was found at Wylie Bay near the town of Esperance and a search was underway for the man who had been riding it, a police statement. Ambulance officers reported the suspected shark attack at Kelp Beds Beach late on Friday morning.
The crew on the KRI Nanggala 402 could have enough oxygen until early Saturday, but time was quickly running out as rescuers scoured the coast off holiday island Bali where it disappeared.
Military chief Hadi Tjahjanto said the presence of an oil slick as well as debris near the site where the submarine's last dive on Wednesday off the island of Bali were clear proof the KRI Nanggala 402 sank. Indonesia earlier considered the vessel to be only missing.
Neither local authorities nor the UN could account for the whereabouts of the refugees from the stateless Muslim minority from Myanmar, who are feared to have enlisted traffickers to help them cross the Malacca strait into Malaysia.
Torrential rains from Tropical Cyclone Seroja turned small communities into wastelands of mud, uprooted trees and sent around 10,000 people fleeing to shelters across the neighbouring Southeast Asian nations.
The United States Coastguard and a fleet of volunteers were deployed to search for the 18 crew on board after the vessel capsized in a storm near Port Fourchon, about 160 kilometres (100 miles) south of New Orleans.
The visit of a team of Members of the European Union Parliament (MEPs) to Jammu and Kashmir created a major controversy on Wednesday as the opposition said internationalising Kashmir was a sin, and the sponsor of the Europeans went missing.
Six Cambodians have been held for questioning in connection with the disappearance of a 21-year-old British woman who went missing on an island popular with backpackers, as police on Tuesday said hopes were fading of finding her alive.
Officials later found cable ties used to secure netting over the enclosure housing the turtles had been removed at several spots.