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Umatilla National Forest Watershed Vulnerability Assessment, Pacific Northwest Region (R6)<br />

• Little Lookingglass<br />

• Upper Walla Walla<br />

Discussion/Management Objectives<br />

It is important to apply this knowledge to active restoration and to highlight the importance of stream<br />

connectivity and aquatic organism passage. Resilience of local bull trout populations to disturbance is<br />

linked to the condition, structure, and interaction of populations and habitats at larger scales (Dunham and<br />

Rieman 1999; Neville et al. 2009; Isaak et al. 2010). Thus, active riparian restoration and improvement to<br />

passage barriers are important in addressing any thermal or anthropogenic barriers that may alter bull<br />

trout movement. In addition, because bull trout on the UNF are on the edge of their “bioclimatic<br />

envelope,” they may provide a leading edge for range shifts with warming temperatures, and it is<br />

important to establish this baseline. These peripheral populations may be our best avenue for maximizing<br />

future adaptive potentials for high temperature tolerance. Implementing a monitoring protocol or making<br />

habitat improvements to bull trout habitat can be costly and prioritizing management response is<br />

important, especially because this analysis shows that some watersheds have more temperature resilience<br />

than others.<br />

Prioritize Key Watersheds: Upper NFJD<br />

The responses of most salmonid populations to habitat alteration due to temperature increases have been<br />

difficult to quantify, and most efforts with bull<br />

trout have focused on linkages between habitat<br />

condition and survival of life stages. For<br />

example, a slow-growing resident population<br />

may not persist even after modest habitat<br />

change, while migratory or fast-growing stock<br />

might be viable in similar or worse situations<br />

(Rieman and McIntyre 1993). The bull trout<br />

populations in the upper NFJD and Desolation<br />

Creek are examples of small, isolated, slowgrowing<br />

populations and are especially<br />

vulnerable to anthropogenic disturbances such<br />

as road density and nonnative fish<br />

introductions. There have been many efforts in<br />

active stream restoration in the upper Granite<br />

Creek drainage to improve stream habitat Lookingglass Creek springs , Fall spawning survey, 2009<br />

complexity. Continued restoration efforts are<br />

essential for persistence of this bull trout population and are necessary because this population is one of<br />

the last strongholds on the NFJD. It is also important to mention that John Day bull trout populations have<br />

different allele frequencies from Walla Walla and Umatilla populations and are similar to only a few<br />

Grande Ronde populations (Spruell and Allendorf 1997).<br />

The Lookingglass drainage and the Upper Walla Walla rivers show a strong resilience to future critical<br />

habitat loss, possibly due to groundwater influence, few cumulative stresses (nonnative fish threats), and<br />

intact stream complexity. Because of these drainages, a thorough monitoring program is needed.<br />

221 Assessing the Vulnerability of Watersheds to Climate Change

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