Biological Opinions - Bureau of Reclamation

ecome viable. Instead, a high risk of extinction indicates that the species faces significant risks
from internal and external processes and threats that can drive a species to extinction. Therefore,
NMFS’ jeopardy assessment focuses on whether a proposed action appreciably increases
extinction risk, which is a surrogate for appreciable reduction in the likelihood of both the
survival and recovery of a listed species in the wild.
On the other hand, when listed species exposed to an action’s effects are not expected to
experience adverse effects, NMFS would not expect the action to have adverse consequences on
the extinction risk of the populations those individuals represent or the species those populations
comprise (for example, see Anderson 2000, Mills and Beatty 1979, Stearns 1992). If NMFS
concludes that listed species are not likely to be adversely affected, NMFS would conclude the
assessment.
12.1.1.1.1 Effects Analysis for the SONCC coho salmon ESU
For the SONCC coho salmon ESU, the effects analysis is based on a bottom-up hierarchical
organization of individual fish at the life stage scale, population, diversity stratum, and ESU
(Figure 12.1). The guiding principle behind this effects analysis is that the viability of a species
(e.g., ESU) is dependent on the viability of the diversity strata that compose that species; the
viability of a diversity stratum is dependent on the viability of most independent populations that
compose that stratum and the spatial distribution of those viable populations; and the viability of
the population is dependent on the fitness and survival of individuals at the life stage scale. The
SONCC coho salmon ESU life cycle includes the following life stages and behaviors, which will
be evaluated for potential effects resulting from the proposed action: adult migration, spawning,
embryo incubation, juvenile rearing, and smolt outmigration.
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