A review and synthesis of effects of alteration to the water temperature regime on freshwater life stages of salmonids, with special reference to Chinook salmon

Despite the great significance of the Columbia River Thermal Effects Study (a jointpublication of the USEPA, NMFS, and AEC) and a compilation of temperature criteria andmethods by the National Academy of Sciences in the 1970s that has been key EPA guidance onwater temperature, too little attention has been placed on the key role of thermal pollution of riversystems in reducing fish survival and production. The current review and synthesis of effects ofwater temperature on salmonids is an attempt to update important aspects of these earlier worksin light of current ecological understanding. This revision is in terms of numeric criteria by species and life stage but, more importantly, is an explanation of the concepts that must be considered tofully protect salmonids from thermal effects under the Endangered Species Act.Regulation of water temperature in salmon-bearing streams of the Pacific Northwest involvesselection of appropriate biologically-based temperature standards and then creation ofimplementation procedures that insure that the biological intent is effected on necessary spatialand temporal scales. Selection of standards involves a thorough review of the effects oftemperature on key life stages of species, variation in response among species and stocks, andan ability to estimate immediate and delayed biological responses from temperature statistics.Implementation involves consideration of problems such as where, when, and how to monitorwater temperature in a watershed and developing a process for responding to violations ofstandards. This report deals primarily with a review of biological aspects of temperature in theenvironment, but the best understanding of the influence of temperature will not be effectiveunless implementation procedures are also meaningful. The tight interconnection between thesetwo elements necessitated a broader review that incorporated a wide variety of spatial andtemporal issues in fish ecology. In this context, full protection was viewed in terms of entire lifecycle effects, single and multiple species, variation among stocks of a species, multipleenvironmental gradients, watershed to reach scales, and multiple biological responses (survival,growth, preference, fitness, reproduction, migration, swimming, feeding, etc.). Full report at
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