Habitat utilization by brook char (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) in Newfoundland streams

Abstract

Recent range extension of introduced salmonid species in insular Newfoundland has caused concern over their effects on native fish species. The present study was designed to investigate the stream habitat utilization of the exotic rainbow trout and the native brook char. Results of underwater field observations in a stream where the two species coexisted showed that brook char occupied positions with significantly lower water velocities and more cover than similar-sized rainbow trout. Brook char showed similar microhabitat preferences in a nearby stream where they were allopatric. The extent of species segregation was largely affected by local stream morphology, specifically the availability of preferred habitat. The implications for future introductions of exotic salmonids to native brook char streams are discussed.