Biological Opinions - Bureau of Reclamation

7.1 Regulatory History
The LRS and the SNS were federally listed as endangered throughout their entire ranges on July
18, 1988 (53 FR 27130). They are also listed as endangered by the States of California (1974)
and Oregon (1991). In 2007, the status of each of these species was reviewed by the USFWS
(USFWS 2007a, b). A new 5-year status review of the LRS and the SNS has been initiated by
the USFWS, and this review will be completed in 2013. A draft revision of the 1993 recovery
plan for these species was published by the USFWS in 2011, and a final revised plan published
in 2013 (USFWS 2013). The USFWS proposed critical habitat for the LRS and the SNS on
December 1, 1994 (59 FR 61744), but the proposal was not finalized. On December 7, 2011, a
revised proposal was published that included critical habitat in Klamath and Lake Counties,
Oregon, and Modoc County, California (76 FR 76337). The final designation of critical habitat
for the LRS and the SNS was published on December 11, 2012 (77 FR 73740).
7.2 Reasons for Listing
Although not explicitly stated in the final listing rule, the LRS and the SNS were listed because
of the loss of populations of both species, a decline in numbers within both species’ populations,
and loss of habitat all of which resulted in a critical lack of resiliency and redundancy for each
species (USFWS 2013). In this context, resiliency is the ability of a population or species to
rebound after stressful environmental conditions, such as adverse water quality, increased
predation, disease, drought, or climate change. Redundancy, in this context, involves multiple
populations spread over the landscape to reduce the likelihood of simultaneous extirpation from
catastrophic events, such as adverse water quality, drought, or disease.
Of the few populations of the LRS and the SNS that remain, most are very restricted in
distribution and many lacks the ability to successfully reproduce. This condition was caused by
several factors, including habitat loss, construction of barriers, overharvesting of adults, and
entrainment of young individuals.
Suitable habitat for the LRS and the SNS was drastically reduced in extent and functionality due
to the historical conversion of wetlands to agricultural use and construction of irrigation and
hydroelectric facilities, which drained lakes and wetlands, created barriers to spawning habitat,
and caused mortality by entraining fish. Chiloquin Dam on the Sprague River was cited as the
most influential barrier at the time of listing because it blocked access to approximately 95
percent of potential river spawning habitat for UKL populations of the LRS and the SNS (53 FR
274130); the dam was removed in 2008. Nevertheless, many other significant physical barriers
persist throughout the range of these species, limiting the ability of populations to reproduce or
disperse, such as the Tule Lake populations (NRC 2004).
Overharvesting of adult LRSs and SNSs potentially contributed to declining population levels in
UKL, especially for the LRS, but harvest has not been authorized since 1987 (USFWS 2007a, b).
Entrainment of larval and juvenile suckers into irrigation and hydroelectric structures was also
cited as a threat at listing, and this loss of young fish continues to threaten these species even
51