Biological Opinions - Bureau of Reclamation

12.1.1.1 Risk Analyses for Endangered and Threatened Species
NMFS’ jeopardy determination must be based on an action’s effects on the continued existence
of the listed species, which can include true biological species, subspecies, or distinct population
segments of vertebrate species. Because the continued existence of listed species depends on the
fate of the populations that comprise them, the viability (that is, the probability of extinction or
probability of persistence) of listed species depends on the viability of the populations that
comprise the species. Similarly, the continued existence of populations are determined by the
fate of the individuals that comprise them; populations grow or decline as the individuals that
comprise the population live, die, grow, mature, migrate, and reproduce (or fail to do so).
NMFS’ risk analyses reflect these relationships between listed species and the populations that
comprise them, and the individuals that comprise those populations. NMFS identifies the
probable risks that actions pose to listed individuals that are likely to be exposed to an action’s
effects. NMFS then integrates those individuals’ risks to identify consequences to the
populations those individuals represent. NMFS’ analyses conclude by determining the consequences
of those population-level risks to the species those populations comprise.
NMFS measures risks to listed individuals using the individual’s reproductive success which
integrates survival and longevity with current and future reproductive success. In particular,
NMFS examines the best available scientific and commercial data to determine if an individual’s
probable response to stressors produced by an action would reasonably be expected to reduce the
individual’s current or expected future reproductive success by one or more of the following:
increasing the individual’s likelihood of dying prematurely, having reduced longevity, increasing
the age at which individuals become reproductively mature, reducing the age at which
individuals stop reproducing, reducing the number of live births individuals produce during any
reproductive bout, reducing the number of times an individual is likely to reproduce over its
reproductive lifespan (in animals that reproduce multiple times), or causing an individual’s
progeny to experience any of these phenomena (Stearns 1992, McGraw and Caswell 1996,
Newton and Rothery 1997, Clutton-Brock 1998, Brommer 2000, Brommer et al. 1998, 2002;
Roff 2002, Oli and Dobson 2003, Turchin 2003, Kotiaho et al. 2005, Coulson et al. 2006).
When individuals of a listed species are expected to have reduced future reproductive success or
reductions in the rates at which they grow, mature, or become reproductively active, NMFS
would expect those reductions, if many individuals are affected, to also reduce the abundance,
reproduction rates, and growth rates (or increase variance in one or more of these rates) of the
populations those individuals represent (see Stearns 1992). Reductions in one or more of these
variables (or one of the variables NMFS derive from them) is a necessary condition for
increasing a population’s extinction risk, which is itself a necessary condition for increasing a
species’ extinction risk.
NMFS equates the risk of extinction of the species with the “likelihood of both the survival and
recovery of a listed species in the wild” for purposes of conducting jeopardy analyses under
section 7(a)(2) of the ESA because survival and recovery are conditions on a continuum with no
bright dividing lines. Similar to a species with a low likelihood of both survival and recovery, a
species with a high risk of extinction does not equate to a species that lacks the potential to
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