Seasonal Movement and Distribution of Fluvial Adult Bull Trout in Selected Watersheds in the Mid-Columbia River and Snake River Basins

摘要: From 1997 to 2004, we used radio telemetry investigate movement and distribution patterns of 206 adult fluvial bull trout (mean, 449 mm FL) from watersheds representing a wide range habitat conditions in northeastern Oregon southwestern Washington, region for which there was little previous information about this species. Migrations between spawning wintering locations were longest fish the Imnaha River (median, 89 km) three Grande Ronde tributaries, Wenaha (56 Lostine (41 rivers Lookingglass Creek (47 km). Shorter migrations observed John Day (8 km), Walla (20 Umatilla river (22 systems, where relatively extensive human alterations riverscape have been reported. November through May, displayed station-keeping behavior within narrow (basin medians, 0.5–6.2 Prespawning began after snowmelt-driven peak discharge coincided with declining flows. Most postspawning by late September. Migration rates individuals ranged 0.1 10.7 km/day. Adults migrated grounds consecutive years strong fidelity areas winter locations. In basin, most an unusual pattern: After exiting tributary entering main stem river, moved upstream habitat, often substantial distance (maximum, 49 Our work provides additional evidence migratory capacity trout, but short suggest migration may be restricted basins anthropogenic alteration. More research into ecology large habitats is needed improve our understanding how adults establish patterns, what factors influence spatial winter, managers can protect enhance populations.