Invasive alien species are the biggest potential threat to areas receiving the debris from the Japan earthquake and tsunami that happened two years ago, Environment Canada said.
"So far, the vast majority of the species are what we have expected to see on the beach, along with the debris," Xinhua quoted Paul Kluckner of Environment Canada as saying.
"But we are quite concerned about two or three items, and are still looking at them for further details," he said at a briefing at the Japanese consulate in Vancouver.
He identified them as mostly barnacles and shellfish that had been washed ashore on the British Columbia coastline by attaching to fishing boats, part of a dock, a cement tank and lumber among others.
"If a species from an ecosystem from somewhere in the world gets established in a new ecosystem, it may disrupt the old ecological balance and bring problems. We believe this poses the biggest environmental risk to us (Canada) as well as the US," said Kluckner.
In the aftermath of the 9.0-magnitude earthquake and tsunami that struck Japan and killed nearly 20,000 people in March 2011, an estimated 1.5 million tonnes of debris were washed into the Pacific Ocean.
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Since June 2011, the first tsunami debris was found washed ashore in British Columbia, along with Alaska to the north and Washington State, Oregon and California to the south.
All of this had received a consistent amount of flotsam and jetsam.
Kluckner said it was difficult to identify what came from Japan as the tsunami debris accounted for an estimated one sixth of the regular amount of marine garbage washed ashore.
He added that as of the items analyzed so far, none had been tested positive for radiation as they had been washed out to sea prior to the meltdown of Fukushima Daiichi nuclear plant.