Recovery and Management Options for Spring/Summer Chinook Salmon in the Columbia River Basin

Abstract

Construction of four dams on the lower Snake River (in northwestern United States) between 1961 and 1975 altered salmon spawning habitat, elevated smolt and adult migration mortality, and contributed to severe declines of Snake River salmon populations. By applying a matrix model to long-term population data, we found that (i) dam passage improvements have dramatically mitigated direct mortality associated with dams; (ii) even if main stem survival were elevated to 100%, Snake River spring/summer chinook salmon (Oncorhynchus tshawytscha) would probably continue to decline toward extinction; and (iii) modest reductions in first-year mortality or estuarine mortality would reverse current population declines.

Relating Size of Juveniles to Survival Within and Among Populations of Chinook Salmon

“…These analyses commonly recommend how improvements in a particular age-or stage-specific survival rate will lead to increased population growth rate and hence enhanced population viability (Lande 1988, Crowder et al 1994, Doak et al 1994, Kareiva et al 2000, Wisdom et al 2000. However, to actually achieve these im- provements, we need to gain an understanding of stagespecific mortality processes and how they might respond to mitigation efforts.…”

“…Mortality is considerable during this freshwater rearing phase of wild chinook salmon populations, but mechanisms of this mortality are poorly understood (Healy 1991). Kareiva et al (2000) predicted that modest improvements in survival during this life stage would substantially improve the probability of recovering this ESU. By relating individual and population-level traits to juvenile survival, we provide an overview of factors that explain variation in survival both among and within salmon populations.…”

Bounds on the dynamics of sink populations with noisy immigration

“…The paper by Kareiva et al (2000) considers the management of a declining population of Chinook Salmon (Oncorhynchus tshawytscha) in the Columbia River Basin of North America. Part of this species' decline is attributed to damming of the river basin, and the resulting prevention of migration.…”

Comparative Survival Study (CSS) of PIT-Tagged Spring/Summer Chinook and Summer Steelhead : 2008 Annual Report.

“…A D equal to one indicates that there is no difference in survival rate after hydrosystem passage; a D less than one indicates that transported smolts die at a higher rate after passing BON than smolts that have migrated through the hydrosystem; a D greater than one indicates that transported fish have higher survival after passing BON. The parameter D has been used extensively in modeling the effects of the hydrosystem on Snake River Chinook salmon (Kareiva et al 2000;Peters and Marmorek 2001;Wilson 2003;Zabel et al 2005).…”