A barge carrying hundreds of tons of marine debris collected on shorelines in Alaska and British Columbia has arrived in Seattle for sorting and recycling.

Volunteers are being organized to help sort, a process that could take weeks. Whatever can't be recycled will be taken by train for disposal in Oregon.

Despite the mass of debris collected, the president of the cleanup organization coordinating the project says it represents a small percentage of the cleanup work that remains.

Some of the debris collected likely was swept to sea by the 2011 tsunami in Japan.

But marine debris in general, including rubbish like plastics and fishing nets, is an ongoing environmental problem.