Our new Biological Assessment is out - Klamath Basin Crisis

Klamath Project Operations Biological Assessment
Coho Salmon: Factors Affecting Species Environment
Life Stage Temperature Consideration Unit and Temperature 1
Juvenile
Rearing
Adult
Migration
Lethal temperature with one
week exposure.
Optimal Growth with unlimited
food,
Optimal Growth with limited food,
Impairment to smoltification.
High disease risk in lab. Studies.
Elevated disease risk in lab.
Studies.
Minimized disease risk in lab.
Studies.
Lethal temperature with one
week exposure.
High disease risk in lab. Studies.
Elevated disease risk in lab.
Studies.
Minimized disease risk in lab.
Studies.
Migrations blockage and
migration delay.
Reduced adult swimming
performance.
Optimal adult swimming
performance.
Constant: 23 to 26 °C
Constant: 13 to 20 °C
Constant: 10 to 26 °C
Constant: 12 to 15 °C
Constant: 18 to 20 °C
Constant: 14 to 17 °C
Constant: 12 to 13 °C
Constant: 21 to 22 °C
Constant: 18 to 20 °C
Constant: 14 to 17 °C
Constant: 12 to 13 °C
Average: 21 to 22 °C
Constant: > 20 °C
Constant: 15 to 19 °C
Prolong Exposure: > 17 to 18
°C
Overall reduction in migration
fitness due to cumulative
stresses.
1 All temperatures in ºC, for a reference: 15 ºC = 59 ºF, 20 ºC = 68 ºF, 23 ºC = 73.4 ºF.
High water temperatures during the late spring and summer months can be an important
factor affecting the distribution, growth, and survival of juvenile coho salmon.
Figure 3-15 is a longitudinal view of daily mean water temperatures from IGD to Turwar,
on June 1 in a typical year. Water temperatures above 60.8 ºF (16 ºC) can trigger
movement of juvenile coho salmon during these months. Movement occurs as fish seek
refuge from high temperatures. The National Academy of Science concluded that any
juvenile coho salmon living in the main stem of the Klamath River probably tolerate the
temperature only by staying in pockets of cool water created by ground-water seepage or
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