Use of three types of stream-margin habitat by age-0 brown trout late in the growing season

The use of stream-margin habitat by age-0 salmonids has been studied, but differences in use among various types of habitat along stream margins has not been addressed. We described the nighttime use of habitat features by age-0 brown trout (Salmo trutta) among three types of stream-margin habitat late in the growing season (August–September) and assessed the extent to which use of habitat features within each type differed over the sampling period. Differences in water depths, water velocities, distances from shore, and substrate at the locations of fish along the margins of pools, the margins of riffles, and in backwaters were studied. Variation in habitat use also was observed during the study period as fish increased in length. Our observations are important considerations when developing habitat suitability criteria for assessment of instream-flow needs of age-0 brown trout.