Biological Opinions - Bureau of Reclamation

some coho salmon smolts may stop migrating entirely for short periods of time if factors such as
water temperature inhibit migration. Within the Klamath River, at least 11 percent of wild coho
salmon smolts exhibited rearing-type behavior during their downstream migration (Stutzer et al.
2006). Salmonid smolts may further delay their downstream migration by residing in the lower
river and/or estuary (Voight 2008). Sampling indicates coho salmon smolts are largely absent
from the Klamath River estuary by July (NRC 2004).
Location and
Life stage Feb Mar Apr May Jun Jul
Bogus Cr.
Shasta R. 0+
Shasta R. 1+
Kinsman Cr.
Scott R. 0+
Scott R. 1+
Big Bar
Figure 12.14. Juvenile coho salmon general emigration timing within the Klamath River and tributaries.
Black areas represent peak migration periods, those shaded gray indicate non-peak periods (Pinnix et al.
2007, Daniels et al. 2011).
Peak emigration timing varies throughout the basin from April until July, depending on the
watershed and the age class of fish moving (Pinnix et al. 2007). Many coho salmon parr migrate
downstream from the Shasta River and into the mainstem Klamath River during the spring
months after emergence and a brief (