Variations in distributions and behaviours of Atlantic salmon Salmo salar in allopatry (homogeneous) and in sympatry with brown trout Salmo trutta (mixed) were observed before, during and after 2 day periods of dewatering in a large glass‐sided indoor stream at densities typical of Scottish upland streams. Brown trout utilized pools more than Atlantic salmon at normal flows and in both species the majority of fishes moved into...

When two or more species coexist, there is often a differentiation in habitat use, temporally and/or spatially, either due to differences in habitat preference or in competitive abilities. Trout and salmon, for example, often coexist in the same river but whereas trout generally occupy pools, salmon are more often found in riffles. This segregation might be due to differences in habitat preference but could also occur as a con...

Competition between species of animals can be predicted to be intense under extreme environmental conditions during which niche overlap increases. Fluvial aquatic systems fluctuate naturally across a broad range of time‐scales. Land management activities impose further extreme fluctuations, particularly when water is abstracted for irrigation during summer. This study focused on the interaction between Atlantic salmon and brow...