Summer–autumn habitat utilization of subyearling steelhead trout in tributaries of the Clearwater River, Idaho

Publisher Website
Google Scholar
Abstract
The summer-autumn habitat utilization of 801 subyearling steelhead trout was examined in three tributaries of the Clearwater River, Idaho. During both summer and autumn most subyearling steelhead occupied water depths < 20 cm and mean water velocities < 20 cm/s. Trout were generally associated with gravel and cobble substrates in summer and cobble and boulder substrates in autumn. The transition to larger size substrate materials in autumn from smaller size substrate during summer was significant (p < 0.05) in each stream. Subyearling steelhead generally did not occupy depths, water velocities, or substrate types in proportion to availability and consequently trout were selecting certain habitats. Habitat selection was most pronounced in autumn when no significant differences were observed among straems for the three habitat parameters utilized by steelhead even though available habitat among streams differed significantly in most cases. Substrate size appears to be the most important habitat parameter affecting the autumn habitat utilization of subyearling steelhead trout in Clearwater River tributaries.