Shoes containing human bones from people killed by the 2011 Japanese tsunami are likely to begin washing up on the US West Coast later this year, an expert said Thursday.

Curt Ebbesmeyer, a retired oceanographer and expert on marine currents, drift patterns and beachcombing, said the leading edge of a debris field from last year's killer tsunami should begin arriving in October.

"I think there will be bones in sneakers washing up over the years," said Ebbesmeyer, who spoke at a symposium on the subject earlier this week in Washington state.

"There are still 3,000 people missing from the tsunami, so these may be the last remains that a family has," he told AFP.

Debris swept across the Pacific could wash ashore anywhere from northern California to Alaska.

"Bones and sneakers can float for years, so I expect them to wash ashore," Ebbesmeyer said. "I expect the main mass of debris to start arriving in October, so I would guess later this year, and for the next several years."

He urged beachcombers to be on the lookout -- but urged them to contact police with any finds so the authorities can follow up through the proper channels, if necessary through Japanese consulates here.

Ebbesmeyer said he had briefed Japanese consular officials in Seattle.

"They only really want to deal with police and medical examiners... You don't want to contact a family with any false expectations," he said.

"Imagine if you lost your whole family over there, and a sneaker washed up with bones that were traced to, say, your mother, what would you do? You'd probably get right on an airplane and go over.

"It's a very delicate subject, and one the authorities need to handle with care," said the expert, founder of the Beachcombers' and Oceanographers' International Association.

Millions of tonnes of debris are expected to wash up in the coming months and years from the Japanese quake. Researchers in Hawaii have developed computer models to forecast where and when it could come ashore.

In early April, the US Coast Guard sunk a deserted Japanese trawler that had appeared off the coast of Alaska more than a year after being set adrift by the tsunami.

Also last month, a Japanese schoolboy was told he was getting his ball back, after it was spotted by an observant beachcomber on Middleton Island in the Gulf of Alaska.