Biological Opinions - Bureau of Reclamation

10 LRS AND SNS INTEGRATION AND SYNTHESIS (Jeopardy and Destruction or
Adverse Modification Determinations)
This LRS and SNS integration and synthesis section of this BiOp is the final step of USFWS’
assessment of the risk posed to listed species and their critical habitat as a result of implementing
the proposed action. In this section, we add the Effects of the Action (sections 0 and 9) to the
Environmental Baseline (sections 7 and 9) and the Cumulative Effects (sections 8.6 and 9.4), to
formulate our BiOp as to whether the proposed action is likely to: (1) result in appreciable
reductions in the likelihood of both survival and recovery of the species in the wild by reducing
its numbers, reproduction, or distribution; and (2) appreciably reduce the value of designated
critical habitat for the conservation of the species. These assessments are made in full
consideration of the status of the species and their conservation needs, and the ability of critical
habitat to provide for the recovery and survival of the species (ESA Section 4). Also considered
here is the USFWS Director’s memo of March 6, 2006, that reiterates the need for the 7(a)(2)
analysis to include the effects of an action on the capacity of the recovery units to provide
assigned survival and recovery functions.
10.1 Range-wide Status of the LRS and SNS and Their Environmental Baseline in the
Action Area
In our Status of the Species (section 7), we described the factors that have led to the current
status of the LRS and SNS as endangered throughout their range under the ESA, including a
critical lack of resiliency and redundancy due to severe reductions of self-sustaining populations
range wide and dramatic population declines and loss of important habitats and populations in
large parts of their range (USFWS 2013). Self-sustaining populations with frequent recruitment
only occurs in Gerber Reservoir and Clear Lake for SNS. LRS in Clear Lake show frequent
recruitment, but recruitment is highly variable in magnitude, and one large cohort that appeared
in population in 2007, had disappeared by 2009, so some unknown factor reduced their survival.
Neither LRS nor SNS have recruited in significant numbers into the adult populations in UKL
since the late 1990s. There is a population of LRS and SNS in Tule Lake Sump 1A, although the
fish appear healthy, there is no evidence of spawning and it is believed that these fish immigrated
to this sump from areas above it. Although suckers in Tule Lake are not known to reproduce, the
2013 Revised Recovery Plan identifies the importance of conserving these fish for redundancy to
prevent extinction until other populations can be recovered. Thus, the only populations that
appear to be stable are SNS in Clear Lake and Gerber Reservoir.
Specific factors limiting LRS and SNS recovery in UKL include higher than natural mortality of
age-0 juveniles due to degraded water quality, algal toxins, disease, parasites, predation,
competition with native and introduced species, and entrainment into water management
structures. Adult populations in UKL are limited by negligible recruitment, stress and mortality
associated with severely-impaired water quality, and the fact that adult suckers are approaching
the limits of their life span. However, current survival rates of adult suckers in UKL are not
unusually low in comparison to other long-lived species (Hewitt et al 2011). Additionally, these
species are limited by a lack of connectivity throughout their range by dams, periodic low flows,
and degraded habitat.
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