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Habitat utilization and diel behavior of juvenile bull trout ( Salvelinus confluentus ) at the onset of winter
Author(s) -
Thurow R. F.
Publication year - 1997
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/j.1600-0633.1997.tb00136.x
Subject(s) - diel vertical migration , trout , habitat , juvenile , fishery , nursery habitat , environmental science , biology , ecology , fish <actinopterygii>
— Underwater observations were used to describe habitat use and diel behavior of juvenile bull trout ( Salvelinus confluentus ) at the onset of winter (0.8°C) in a second‐order central Idaho stream. All fish observed during daytime counts were concealed beneath “home stones” (mean dimensions 32.3 by 21.9 cm) in primarily pool and run habitats. Focal point depths and velocities averaged 57.2 cm and 4.7 cm/s (home stone removed). Fish maintained stations over substrate with low percentages of fine (< 2 mm, mean= 5.2%) sediment. Concealed bull trout were not evenly distributed across the stream channel. Significantly more home stones were distributed near the midline of the channel, compared to the channel margins. Fish size was positively correlated with home stone size. At night, bull trout exhibited a diel behavioral shift, some fish moved out of daytime concealment cover into the water column. At night, bull trout were observed feeding and resting, primarily in pool and run habitats. During both day and night, bull trout used riffles significantly less frequently than those habitats were available.