Beach-cast debris surveys on Triangle Island, British Columbia, Canada indicate the timing of arrival of 2011 Tōhoku tsunami debris in North America.

We conducted beach-cast debris transect surveys on Triangle Island, British Columbia, Canada in 2012-2017 to (1) establish a baseline against which to track future changes in stranded debris on this small, uninhabited island; and (2) time the arrival in western North America of debris released by the 2011 Tōhoku tsunami. Most (90%) of the six-year total of 6784 debris items tallied was composed of Styrofoam or plastic. The number of debris items peaked in 2014 (waste Styrofoam, rope) and 2015 (waste plastic, wood), and cumulative totals for all debris types were ca.