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Warm waters are a threat to cold water fish like salmon and trout. But a study led by researchers at University of California, Davis suggests that habitats with abundant food sources may help buffer the effects of increasing water temperature.
The study, published in the Canadian Journal of Fisheries and Aquatic Sciences today, Dec. 10, shows that the availability of food in a natural system—not just stream temperature and flows—is an essential component of fish habitat.
Future - Climate - Change - Ecosystems - Rivers
"In the future under climate change, productive ecosystems like spring-fed rivers, floodplains, estuaries and seasonal lagoons will be key links that give cold-water fish like salmon and trout a leg up," said lead author Robert Lusardi, a research ecologist and adjunct faculty at UC Davis and the California Trout Coldwater Fish Scientist.
For the experiment, researchers reared juvenile Coho salmon in a series of enclosures within the Shasta River basin, which is a tributary to the Klamath River. They examined how natural gradients in temperature and prey availability affected summer growth rates and survival.
Southern - Oregon/Northern - California - Coast - Coho
Southern Oregon/Northern California Coast Coho salmon, like those used in the experiment, are a threatened species and are among the most temperature intolerant of Pacific salmonids. They can experience stress under water temperatures as low as 60.8 degrees Fahrenheit in many ecosystems. Previous studies put their optimal stream temperatures between 53-57 F.
For this study, the researchers were surprised to find that Coho salmon growth rates peaked at average water temperatures of 61.8 F (16.6 degrees Celsius) and an "unheard of" maximum...
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