About two years ago, I wrote an article on the importance of food for foraging salmon, particularly during their early life history stages.  In that article, I suggested that food rich habitats such as spring-fed rivers, floodplains, estuaries, and lagoons would become disproportionally important for coldwater fishes under a rapidly changing climate.  

The argument largely relies on bioenergetic theory: as water temperatures increase with the onset of global change, the metabolic activity of coldwater fishes will also increase.  If those increases in metabolic activity are not compensated for by either moving to cold water or increasing food consumption, salmon may experience reductions in growth, increases in stress, and higher rates of disease prevalence.  

Increasing water temperatures, as a result of climate change, are already reducing thermal habitat for coldwater fishes throughout California and elsewhere.  For instance, Wenger et al. (2011) projected nearly a 50% decline in thermal habitat for all trout species by 2080. Ultimately, this suggests that salmonids find themselves in an increasingly precarious predicament, particularly those species at the southern end of their range where the impacts of global warming may be greater.  

While conserving and enhancing coldwater habitat has received ample attention in the literature and is likely the single best strategy to mitigate the effects of climate change, few have focused on food rich habitats as possible refuges for coldwater fishes.

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