Saving the Salmon
Memories of a Columbia with vigorous wild salmon runs don’t seem so far fetched when looking at a 121 pound salmon.
Why don’t they get this big anymore? The 4 "H's" are commonly blamed for the decline of what once was the largest salmon fishery in the world: over-Harvest, Hydro-power, mismanaged Hatcheries, and the loss of Habitat, including poor water quality.
Poor water quality is of major concern for the two endangered and five threatened salmon runs, as well as five endangered steelhead runs on the Columbia. Salmon are highly sensitive to pollution and are an indicator species, the river’s version of the canary in the coal mine.
While toxic pollutants receive more attention, salmon are also facing a more insidious pollutant: hot water. Salmon are a coolwater species that suffer in waters above 60° F. Yet CRK and state data show the Columbia regularly exceeds 70° F, near the lethal limit for salmon. A major goal of CRK’s monitoring program is to identify and protect the salmon’s cool-water refugia,
which include input from cool-water tributaries and groundwater. CRK also pushes for changes in policy and lifestyle that increase flow in the river.
A plan to reduce temperature, or a Total Maximum Daily Load (TMDL) is being
developed by the EPA, Idaho, Oregon, and Washington state agencies for the
Columbia River, but the process has been delayed since 2003.
|
Temperature |
Effects |
| 12-13°C (53.6 – 60.8°F) | Upper limit of optimal range 13°C (55.4°F) Smolting inhibited |
| 15°C (59°F) | Ability to migrate reduced; Fish stay in freshwater |
| 16-17°C (60.8-62.6°F) | Disease starts to be a concern: Aeromonas liquefaciens, Salmonicida, Flexibacter columnaris |
| 19-20°C (68°F) |
Growth rate declines |
| 20-21°C (68-69.8°F) | Predation- optimum range for northern pikeminnow, walleye, smallmouth bass, channel catfish |
| 23°C (73.4°F) | Lethal range |
EPA identified dam reservoirs as the major cause of hot water, in addition to
climate change, municipal and industrial dischargers, and the loss of many alluvial flood plains as well as riparian shade along tributaries.
CRK volunteers have placed underwater, continuous temperature loggers at key sites this summer to help identify trends, and push the state agencies to further investigate sources and solutions. We’ve discovered that shoreline temperatures are two to three degrees warmer than temperatures typically measured mid-river by state and federal agencies.
CRK’S data continues to demonstrate the Columbia is simply too hot for salmon.
