Utilization of constructed large woody debris structures by cottids and juvenile salmonids in a coastal western stream

Submitted by Shaun Korman, Katharine Scotton and Dave Taylor in May 2006. Large woody debris (LWD) in streams provides critical habitat for many fishes. This habitat feature is now largely missing in western North American coastal streams compared to historic levels due to human activities relating to land clearing, damming and outright removal. In the South Alouette River near Maple Ridge, British Columbia, thirty triangular LWD structures were placed in this stream in 1997 and 1998 to address this deficiency of natural wood. In order to determine the effectiveness of this wood in creating habitat, this study assessed fish utilization of these structures during the fall and winter of 2005/2006 throughout four defined habitat types: riffle with LWD, riffle without LWD, pool with LWD and pool without LWD.