California golden trout and climate change: Is their stream habitat vulnerable to climate warming?

Abstract

The California golden trout (CGT) Oncorhynchus mykiss aguabonita is one of the few native high-elevation fish in the Sierra Nevada. They are already in trouble because of exotic trout, genetic introgression, and degraded habitat, and now face further stress from climate warming. Their native habitat on the Kern Plateau meadows mostly in the Golden Trout Wilderness (GTW) currently includes stream areas impacted by cattle grazing. As a result, some areas have reduced streamside vegetation (willows or sedge) and widened channels with shallow stream depths that often lead to warmer water temperatures. Climate change will further compromise CGT and their habitat in stream areas still being grazed, because the warmer water temperatures predicted under most warming scenarios could increase water temperatures to lethal levels. One important management response to climate warming will be to ensure that habitats are more resilient to predicted changes in water temperature, flow, and snow pack. I have initiated a study to determine the climate change resiliency of golden trout habitat by conducting a spatially explicit analysis of stream temperatures in restored and degraded sections of meadows in the GTW. Preliminary data from 2008 to 2010 indicate that stream temperatures are already 24oC in degraded areas. The detailed temperature profiles will also be used to estimate what proportion of the habitat will be resilient to climate change and what proportion should undergo increased restoration. Because water temperatures are already approaching stressful limits, management action to restore CGT habitat is imperative.

Citation

Matthews, Kathleen R. 2010. California golden trout and climate change: Is their stream habitat vulnerable to climate warming? In: Carline, R.F. ed. 2010. Conserving Wild trout: Proceedings of Wild Trout X symposium; 2010 September 28-30; West Yellowstone, Montana. pp. 81-87