|Document Type:||Chapter or Section|
|Type of Book:||Technical|
|Section or Chapter Title:||Importance of water temperature in the main stems of the Columbia and Snake Rivers in relation to the survival of salmon. Report No. 59|
|Book Title:||Fish-Passage Research Program review of progress 1964, Volume V|
|Author:||Anthony J. Novotny|
|Editor:||Gerald B. Collins, Carl H. Elling (Eds.)|
|Publisher:||Report of the Accelerated Fish-Passage Research Program to the U.S. Bureau of Commercial Fisheries. Seattle, Washington|
The relation between the distribution of separate species of poikilothermal fish and environmental temperature is very strong. Permanent shifts in the temperature regime can eventually cause changes in the species composition within the geographical area affected. The tilefish (Lopholatilus chamaeleonticeps) appeared off of the New England coast in large enough quantities to support a commercial fishery in the late l800s. In 1882, a sharp cooling trend set in, causing mass mortalities of the species. The tilefish disappeared completely from this region. Nikolsky (1963) states, "The cooling caused by the spread of the ice sheet at the end of the Tertiary and the beginning of the Quaternary periods enabled the representatives of the salmon family, which were adapted to cold water, to spread considerably southward as far as the Mediterranean Sea basin, including the rivers of Asia Minor and North Africa." The Pacific salmon, which has evolved as a cold–water species, is able to adapt to temporary shifts of the temperature regime it inhabits, although not without loss. A permanent temperature shift to higher levels during the freshwater life history could result in minimal survival conditions.
The taxing demands of heavy fishing pressure, obstructions to upstream and downstream migrations, and the gradual loss of adequate spawning grounds have placed the upper Columbia River and the Snake River salmon runs in jeopardy. Instead of accepting rising temperatures in the river with resultant fish losses as a way of life, fishery agencies might well take an aggressive stand and seek the means to create beneficial rather than harmful temperature changes.
The purpose of this report is to point out the importance of water temperature as an environmental condition and the advantages to be gained by control.