Habitat models for predicting the occurrence of blotchside logperch (Percina burtoni) and tangerine darters (P. aurantiaca) in the North Fork Holston River and Little River, Virginia

Basin-wide visual estimation techniques developed in the Pacific Northwest for small streams were modified to survey about 180 river kilometers (rkm) of the North Fork Holston River and about 16 rkm of lower Little River (Clinch River tributary) in southwestern Virginia during the summer of 1992 and 1993, respectively. Presence-absence models were developed, using stepwise logistic regressions, from habitat characteristics measured on a scale ranging from large-scale (geographic location) to local-scale (habitat-unit characteristics) for blotchside logperch (Percina burtoni) and tangerine darter (P. aurantiaca) in the North Fork Holston River. Transferability of models, developed for both species in the North Fork Holston River, to Little River were tested by comparing the models' predictions with the data collected during the Little River survey.