Seasonal movement patterns and habitat use of westslope cutthroat trout in two headwater tributary streams of the John Day River

Radiotelemetry was used to study the seasonal movements and habitat use of adult westslope cutthroat trout Oncorhynchus clarki lewisi in Roberts Creek and Rail Creek, headwater tributaries of the John Day River, Oregon, from September 2000 to December 2001. The objectives were to (1) describe adult cutthroat trout life history in headwater streams by comparing seasonal movement patterns, and (2) assess seasonal habitat selection by comparing habitat use to availability. For seasonal comparison, only fish that survived with an active transmitter throughout winter, spring, and summer were used in the analysis. Sample size was 17 (mean fork length, 241mm) on Roberts Creek and 9 (mean fork length, 252 mm) on Rail Creek. In winter and summer, radiotagged fish were relatively sedentary on both Roberts Creek (median home ranges, 35 and 104 m, respectively) and Rail Creek (median home ranges, 104 and 112 m). In spring, 65% of fish in both streams moved over 100 m upstream to spawn; upstream movements were as long as 1,138 m (median, 271 m) on Roberts Creek and as long as 3,771 m (median, 311 m) on Rail Creek. Postspawning movements downstream were common; 82% of fish on Roberts Creek and 57% on Rail Creek showed homing behavior, returning in summer to the same channel unit they inhabited in winter. Fish length was positively correlated to total movement distance in spring on Roberts Creek but not on Rail Creek. Over 86% of the surface area of both creeks consisted of fast-water channel units. Instream large wood created the majority of habitat heterogeneity in both streams and radiotagged cutthroat trout were strongly associated with large wood pools throughout the year. Plunge pools were positively selected throughout the year on both streams. Headwater-resident populations of cutthroat trout are often considered nonmigratory; however, these radiotagged fish showed fluvial migratory behavior. These results demonstrate that habitat heterogeneity and connectivity are important life history requirements for fluvial headwater resident cutthroat trout.Keywords: radio telemetry, westslope cutthroat trou

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

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

Middle Fork Hood River Irrigation District

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Wintering duration, in days, for fish from each study watershed.

<p>Wintering duration, in days, for fish from each study watershed.</p

Map of the study area.

<p>Map of the study area in the Columbia and Snake river basins.</p

Seasonal distribution of bull trout in Grande Ronde River tributaries and the Imnaha River.

<p>Seasonal distribution of bull trout in Grande Ronde River tributaries and the Imnaha River, which include the estimated spawning locations (solid triangle) and modal winter locations (hollow).</p

Pre- and postspawning migration duration, in days.

<p>Pre- and postspawning migration duration, in days.</p

Temporal pattern of annual life history phases of fluvial bull trout in relation to discharge.

<p>Temporal pattern of annual life history phases of fluvial bull trout in relation to discharge. Boxplots, consisting of the observed start dates of the prespawning migration, spawning, and wintering for individual fish, were overlaid on mean daily discharge (gray lines; log scale) of the Imnaha River (RK 31; 2001–02), Grande Ronde River (RK 70; 1998–99), Wallowa River (RK 7; 2001–2), Mill Creek (RK; 1998–99), Umatilla River (RK 94; 2002–03), and John Day River (RK 404; 1998–99). Sample sizes are in parentheses.</p