Police say the man, who is 62, was visiting his brother, a Whitehorse resident, and the two were paddling in a canoe to Dawson City.
RCMP Sgt. Dave Wallace said they have been using all their resources to find the man. He said boats covered more than 1,000 kilometres of shoreline Monday.
Their canoe capsized about 100 kilometres upstream of Dawson City and they were unable to right it. The Quebec man tried to swim ashore, but he hasn’t been seen since. The man was wearing a red lifejacket over a black fleece sweater, black pants and a white tilley hat.
RCMP Staff Sgt. Maj. Ken Foster said the Whitehorse man clung to the sunken canoe for at least five hours before being rescued by a passing boater at about 2 a.m. Saturday.
Foster said police and Dawson volunteers started a search by boat and helicopter early Saturday morning. He said extreme high water in the Yukon River has hampered efforts because it has flooded shorelines on the hundreds of islands in the area.
Police are not releasing any names at this time.