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INFLUENCE OF SUMMER TEMPERATURE SPATIAL VARIABILITY ON DISTRIBUTION AND CONDITION OF JUVENILE COHO SALMON
Citation:
COLVIN, M. E., J. L. EBERSOLE, P. J. WIGINGTON JR, AND K. RODNICK. INFLUENCE OF SUMMER TEMPERATURE SPATIAL VARIABILITY ON DISTRIBUTION AND CONDITION OF JUVENILE COHO SALMON. Presented at American Fisheries Society Annual Meeting, Lake Placid, NY, September 10 - 14, 2006.
Description:
abstract
Temperature during the summer months can influence the distribution, abundance and physiology of stream salmonids such as coho salmon (Oncorhynchus kisutch). Effects can be direct, via physiological responses, as well as indirect, via limited food resources, altered competitive ability, and increased parasite and disease prevalence. Understanding how temperature directly and indirectly affects the physical condition of juvenile coho salmon over the summer is important, as the physical condition of coho parr in the fall has been linked to overwinter survival. We examined the spatial distribution, abundance, condition, and external parasite load of juvenile coho salmon in an Oregon coast range basin from 2002 through 2005 to understand the influence of summer temperature. Distribution was not influenced by temperature, despite temperatures exceeding 22°C in some locations. Temperature was negatively associated with coho density and positively associated with parasite load over all study years. In addition we found a negative association of maximum temperature and condition factor in the warmest year of the study. These results illustrate that juvenile coho salmon distribution in relation to temperature may be a poor indicator of the true effects of temperature on fish fitness.