Project Title:  Evaluate Factors Limiting Columbia River Gorge Chum Salmon Populations
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BPA Project Number:  2000-012-00
BPA Project Title:  Evaluate factors limiting Columbia River gorge chum salmon populations
Contract Number:  19727
Contract Title:  Evaluate factors limiting Columbia River gorge chum salmon populations


Contract Background Section:

Chum salmon (Oncorhynchus keta) were thought to historically spawn in areas of the Columbia River basin, from tributaries in the lower basin upstream to the Walla Walla River.  However, spawning is presently limited to areas downstream of Bonneville Dam, located 232 km upstream from the confluence.  Although relatively low numbers of chum salmon spawn in several areas of the lower basin, substantial numbers of chum salmon spawn in the Grays River basin in the lowermost portion of the basin and in three areas directly downstream of Bonneville Dam, Hardy Creek, Hamilton Springs, and the Columbia River channel at Ives Island.  

The National Marine Fisheries Service listed chum salmon in the Columbia River basin as threatened in 1999.  One of the primary factors contributing to the decline of chum salmon in the basin is degradation of freshwater habitats, which chum salmon use for spawning and early rearing.  Thus, efforts to conserve chum salmon have focused on investigating manage activities that provide quality spawning habitat conducive to successful reproduction.

The Columbia River Fisheries Program Office (CRFPO) has been involved in such investigations.  The CRFPO began estimating adult and juvenile chum salmon abundance in Hardy Creek in 1997.  The Bonneville Power Administration has provided funding for the CRFPO to continue work investigating chum salmon in Hardy Creek and Hamilton Springs since 1999.  This statement of work describes proposed activities.

The overall goal of our investigations is to evaluate factors limiting Columbia River gorge chum salmon populations.  This is to provide an understanding of factors affecting chum salmon spawning primarily in Hardy Creek and Hamilton Springs, which is intended to assist in developing habitat and water management activities that improve conservation of the species.  Addressing this goal entails accomplishing three broad categories of actions.  The first category is to monitor status of chum salmon through time.  Status can be inferred from estimates of adult and juvenile abundance in conjunction with various attributes of population health, such as population age structure, sex ratio, and various indices of recruitment and survival (e.g., egg-to-emergence survival, spawner-to-smolt production).  A second category of action is the identification of appropriate population units for conservation.  It is uncertain whether chum salmon using the three spawning areas exhibit spawning site fidelity and function independently as reproductive units, or actually consists of a single interdependent unit.  The third category of action is analysis of habitat features influencing chum salmon, that is, identification of how specific habitat features affect chum salmon status and indices of population health.  We propose six objectives to address these actions.

Objective 1:
Calculate estimates of abundance for adult chum salmon spawning in Hardy Creek and Hamilton Springs with appropriate measures of confidence, and describe behavioral and biological characteristics of adult chum salmon.

Objective 2:
Examine habitat features associated with redds in Hardy Creek and Hamilton Springs, estimate egg-to-emergence survival of juveniles in individual redds, and investigate relations among juvenile survival, emergence time, and habitat features.

Objective 3:
Produce estimates of abundance for chum salmon smolts emigrating from Hardy Creek and Hamilton Springs with appropriate measures of confidence, and describe behavioral and biological characteristics of smolts.

Objective 4:
Calculate indices of performance to estimate survival and production of various life-history stages of chum salmon in Hardy Creek and Hamilton Springs.

Objective 5:
Evaluate chum salmon use of the Hardy Creek spawning channel if sufficient flows are available for channel operation.

Objective 6:
Compile and analyze data.