Bull trout population assessment in northeastern Oregon: a template for recovery planning Annual Progress Report for 2010

There are critical gaps in information that potentially limit our ability to effectively

manage bull trout and ensure their continued persistence (Porter and Marmorek 2005;

Al-Chokhachy et al. 2008). These gaps include quantification of population abundance

and trend for all but a few populations, estimates of larval and juvenile survival rates,

estimates of dispersal rates between populations, and life-history-specific information,

such as the contribution of migratory versus resident fish to overall population growth

and persistence. Our research seeks to address some of these knowledge gaps

through long-term monitoring of a relatively large bull trout population in the South Fork

Walla Walla River (SFWW). We provide essential information on abundance, trend,

vital rates, habitat needs, and information on the potential for improving survival at one

or more life stages. In addition, we gather information related to population structure

(e.g., age, life history, and genetic components). We provide a template against which

different strategies for monitoring and evaluation can be assessed in terms of accuracy,

precision, cost/effort, and limiting factors. Our goal is to provide the data and

conservation assessment tools to aid in the efforts of the US Fish and Wildlife Service,

to determine the necessary management actions for recovery of bull trout populations

throughout the study area and the rest of the species’ range. The project was initiated

in 2002 and has continued through 2010, with plans to continue work through 2012 (10

years). To meet our goals, we have developed and implemented a comprehensive

mark- recapture program conducted yearly, which includes two tag types, multiple

capture techniques (both passive and active) and systematic sampling of two large

study areas (SFWW and North Fork Umatilla rivers) with a high degree of effort. 2008

marked the fifth and final year of sampling and study in the North Fork Umatilla River.

The efforts of this project have been part of a completed PhD dissertation (Al-

Chokhachy 2006) and Master’s thesis (Homel 2007) and are currently part of an ongoing

PhD dissertation (Bowerman, in preparation; Appendix 3) conducted through Utah

State University. Results and syntheses of different components of the project are

available in previous annual reports (Budy et al 2003, 2004, 2005, 2006, 2007, 2008,

2009, and herein) as well as in the peer-reviewed manuscripts: Al-Chokhachy et al.

2005; Al-Chokhachy and Budy 2007; Homel and Budy 2008; Homel et al. 2008; Al-

Chokhachy and Budy 2007; Al- Chokhachy and Budy 2008; and Al-Chokhachy et al.

2009; and Al-Chokhachy et al. 2010.