Our new Biological Assessment is out - Klamath Basin Crisis

Klamath Project Operations Biological Assessment
Coho Salmon: Coho Salmon Life History, Abundance, and Trends
Figure 3-5. Natural-origin coho salmon smolt captured in downstream migrant traps in
the main stem Klamath River and various tributaries by year 1998 to 2006. Although the
traps have had inconsistent periods of operation (days trapped), the data collected do
indicate a possible increasing trend in relative abundance, especially for the Scott River.
Coho Salmon Smolt Captured
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
Scott River
Non- Scott River
For tributary origin juvenile coho salmon, the main stem provides a migratory
corridor between ocean and tributaries and provides rearing habitat for fry and
juveniles. As mentioned earlier, current information suggests that relatively few
coho salmon spawn within the main stem of the Klamath River. However,
limitations in juvenile trapping data do not allow conclusions of spawning
abundance based on this data.
The USFWS described the life history periodicities 9 for anadromous salmonids,
including coho salmon, in the Lower Klamath River Basin (USFWS 1997). The
USFWS used data from the juvenile out-migrant traps and reviewed relevant
literature to conclude that coho salmon fry are present in the main stem Klamath
River below IGD from at least April through late July and coho salmon yearlings
are present from mid-March through late July.
9 Periodicities may be defined as recurrence at regular intervals. For example, the outmigration
of coho salmon typically occurs in March through June in each year.
157