Biological Opinions - Bureau of Reclamation

2001 to 2004. Using reports from USFWS, Ackerman et al. also assumed that spawning in the
mainstem was limited to 100 fish or fewer.
Using similar data and assumptions as Ackerman et al. (2006), NMFS estimates the numbers of
adult spawners returning to the Upper Klamath River Population in 2009 to 2012 are below the
low risk abundance threshold of 8,500 (Table 12.3). Although the count of coho salmon on
Bogus Creek was probably not complete in 2009, seven coho salmon were observed. In 2010, a
total of 154 adults returned to Bogus Creek, although approximately 28 percent were hatcheryorigin
fish. Preliminary estimates show that 134 adult coho salmon, 33 percent of which were
hatchery-origin fish, returned to Bogus Creek in 2011. Using Bogus Creek as an indicator of the
abundance and percentage of hatchery origin spawners, the Upper Klamath River Population has
a high risk of extinction.
Coho salmon are currently spatially restricted to habitat below IGD. Coho salmon in this
population spawn and rear primarily in several of the larger tributaries between Portuguese
Creek and IGD, namely Bogus, Horse, Beaver, and Seiad creeks. Spawning surveys also give an
indication of the population size and productivity. Spawning has been documented in low
numbers within the mainstem Klamath River. From 2001 to 2005, Magneson and Gough (2006)
documented a total of 38 coho salmon redds between IGD (RM 190) and the Portuguese Creek
confluence (RM 109), although over two-thirds of the redds were found within 12 river miles of
the dam. Many of these fish likely originated from IGH. A population of coho salmon parr and
smolts rear within the mainstem Klamath River by using thermal refugia near tributary
confluences to survive the high water temperatures and poor water quality common to the
Klamath River during summer months.
Little is known about the genetic and life history diversity of the upper Klamath River
Population Unit. However, the population is believed to be highly influenced by IGH (Garza
2012 in CDFG 2012) and has likely experienced a loss of life history diversity due to
environmental conditions and loss of habitat. Currently, genetic work is continuing to be
performed to determine the genetic makeup of wild and hatchery fish from the Upper Klamath
Population Unit. The Upper Klamath River coho salmon population is at a high risk of
extinction because its abundance, spatial structure and diversity are substantially limited
compared to historical conditions.
12.3.2.2 Middle Klamath River Population
The Middle Klamath River Population covers the area from the Trinity River confluence
upstream to Portuguese Creek (inclusive) and Seiad and Grider Creeks. Little data on adult coho
are available for this stretch of river (Ackerman et al. 2006). Adult spawning surveys and
snorkel surveys have been conducted by the US Forest Service and Karuk Tribe, but data from
those efforts are insufficient to draw definitive conclusions on run sizes (Ackerman et al. 2006).
Ackerman et al. (2006) relied on professional judgment of local biologists to determine what run
sizes would be in high, moderate, and low return years to these tributaries; therefore, the run size
approximations are judgment based estimates. In each of the three most recent years, the run
size estimates fall below the low risk annual abundance threshold, but are above the high risk
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