Seasonal distribution and habitat selection by the redside shiner, Richardsonius balteatus, in a small Oregon stream

Graduation date: 1983Seasonal habitat availability, utilization, and selection by young\ud of the year (< 25 mm) and adult (>25 mm) redside shiner, Richardsonius\ud balteatus, were studied for 1 year in sections of Greasy Creek, Benton\ud County, Oregon. Intensive stream mapping procedures and snorkling\ud observations provided most of the quantitative measures for habitat\ud availability and utilization respectively.\ud A multivariate discriminant analysis and classification suggested\ud spatial segregation of young of the year and adult redside shiners\ud along gradients of water velocity and depth of the water column.\ud Throughout the year, young redside shiners occupied shallower water\ud than adults and utilized areas with lower mean water velocities.\ud Associated with increased winter stream flows and lowered water\ud temperatures (< 10° C), redside shiners were inactive and found in\ud habitats offering the most cover and refuge from current.\ud Overwintering areas populated by redside shiners included undercut\ud banks, root wads, bank failures, fallen trees, and backwaters. During the transitional period between winter and summer, adult redside\ud shiners shifted from overwintering habitats to the faster water of the\ud main channel. Activities related to spawning and aggressive defense\ud of space accompanied this shift. Young redside shiners continued to\ud utilize protected margins.\ud A multivariate discriminant analysis and classification comparing\ud available and utilized stream habitats provided indices of habitat\ud selection. Both young of the year and adult redside shiners were\ud relatively selective in the stream habitats they utilized. The\ud importance of four physical components (depth, current velocity,\ud substrate composition, and cover forms) varied seasonally and with the\ud life stage considered.\ud Similar patterns of habitat utilization for redside shiners were\ud observed in four larger streams and rivers. The availability of\ud large, deep pools was important, new habitat for both young and adult\ud redside shiners during periods of reduced stream flow in larger\ud streams and rivers