On the Boots of Fishermen: The History of Didymo Blooms on Vancouver Island, British Columbia

In 1989 blooms of the river benthic diatom Didymosphenia geminata (didymo) first appeared and rapidly spread among rivers on central Vancouver Island, covering the bottoms with thick, woolly‐looking mats. Although didymo is native to North America, extensive field surveys of rivers on Vancouver Island and other data indicate that didymo blooms are new. No known environmental changes were associated with the onset of didymo blooms. However the pattern of didymo spread among rivers on Vancouver Island correlates with the activity of fishermen and the commercial introduction and widespread use of felt‐soled waders in the late 1980s. Since 1994 nuisance blooms of didymo have appeared in numerous other places in the Northern Hemisphere and South Island, New Zealand, all areas frequented by fishermen. Actions by government agencies to educate the public and restrict the use of felt‐soled waders have been undertaken in some jurisdictions and at least one commercial manufacturer of waders will discontinue production of felt‐soled models in the near future.