Our new Biological Assessment is out - Klamath Basin Crisis

Klamath Project Operations Biological Assessment
Coho Salmon: Coho Salmon Life History, Abundance, and Trends
populations, while the Klamath River populations appears to be more stable or
slightly decreasing. However, the correlations are not significant (p > 0.05).
Adult Observations
Within the Klamath River Basin, most observations of adult coho salmon occur at
weir, hatchery, and tribal fishery locations. Once the counting of fall Chinook
salmon is terminated, the weirs are removed prior to the high winter flows.
salmon spawning is known to extend later into the season than the Chinook
salmon spawning. Therefore, counting efforts may not include the later portion of
the coho salmon migration. Although, spawning and carcass surveys directed at
coho salmon have been conducted both in tributaries and in the main stem of the
Klamath River, these surveys have generally been conducted on an inconsistent
basis due to the constraints of funding as well as working in high flows.
Current information suggests little main stem spawning is occurring within the
lower and middle portion of the Klamath River. From 2003 to 2005, USFWS
extended it main stem Klamath River adult salmon surveys into December, as
conditions allowed. Although there were logistical and observational challenges,
low numbers of adult coho salmon redds were observed in the Klamath River
from IGD (river mile 190) to Indian Creek (river mile 107) (Table 3-2). In
contrast, Quigley (2005) counted 273 coho salmon redds within four tributaries of
the Scott River Basin in 2004. The results indicated to NMFS that “the
proportion of main stem spawners may be a relatively small percentage of the
annual adult coho salmon spawning population” (see p. 8, NMFS 2007).
Table 3-2. Main stem Klamath River coho salmon redds observed during fall/winter
surveys from the IGD (river mile 190) to Indian Creek (river mile 107), 2001 to 2005.
Year of Survey
Number of Coho
Salmon Redds
Observed
2001 21
2002 6
2003 7
2004 6
2005 6
Source: USFWS 2007 as cited on p. 8, NMFS 2007.
Another source of observations within the Klamath River Basin is the annual
counts of adult coho salmon returns to the Iron Gate and Trinity River Hatcheries.
These annual counts provide information on the abundance of fish returning to
these locations (Table 3-3 and depicted graphically in Figure 3-2).
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