Use of Small, Temporary, Floodplain Tributaries by Juvenile Salmonids in a West Coast Rain-Forest Drainage Basin, Carnation Creek, British Columbia

Abstract

Seasonal movement of trout (Salmo clarki and S. gairdneri) into and out of three tributaries which drain areas ranging from 15 to 100 ha within the lower Carnation Creek catchment basin were monitored periodically from 1972 to 1985. The number of trout entering the three tributaries relative to total trout was as high as the number of coho salmon (Oncorhynchus kisutch) entering these tributaries relative to total coho. The percentage of the salmonid population represented by trout was highest in the two largest tributaries and lowest in the smallest. Trout were most clearly associated with nonvegetated sand and gravel bottom portions of the three tributaries. Coho were associated with this habitat too, but they also frequented portions of the tributaries that were vegetated and had a mud substrate. In the two largest tributaries, trout were represented by more age classes than were coho salmon. The paper considers some of the implications of use of small drainages by trout to habitat managers.