You are here:
VARIATION IN JUVENILE COHO SALMON END-OF-SUMMER SIZE: HIERARACHICAL ANALYSIS OF HABITAT EFFECTS
Citation:
EBERSOLE, J. L., M. COLVIN, P. J. WIGINGTON JR, M. CHURCH, J. E. COMPTON, J. P. BAKER, M. A. CAIRNS, S. G. LEIBOWITZ, AND D. WHITE. VARIATION IN JUVENILE COHO SALMON END-OF-SUMMER SIZE: HIERARACHICAL ANALYSIS OF HABITAT EFFECTS. Presented at Oregon Chapter, American Fisheries Society, Eugene, OR, February 28, 2007.
Description:
The size of coho salmon juveniles entering the winter has been shown to influence overwinter survival, and hence may be a useful indicator of linkages between summer habitat conditions and subsequent smolt production. We are investigating habitat-specific demographics of juvenile salmonids in the West Fork Smith River, a 6800 ha watershed in coastal Oregon, to evaluate the relationship of habitat conditions to summer abundance and growth. We are using hierarchical linear mixed effects models to evaluate habitat attributes at multiple spatial scales (habitat unit, reach, and stream levels) that are associated with variation in end-of-summer condition of juvenile coho salmon (Oncorhynchus kisutch). From 2002 through 2005, end-of-summer size and condition of juvenile coho salmon varied by watershed location, and was associated with juvenile density and degree of infestation by a parasitic Neascus-type trematode at the habitat unit level, and with nitrate at the stream level. Year to year variation in size was also evident, likely reflecting annual differences in both overall abundance and habitat conditions. These results complement analyses of patterns of juvenile abundance presented in a companion paper (Colvin et al.; this session). We conclude by discussing the implications of these results for stream management; specifically modifications to physical habitat or trophic/nutrient status (e.g., spawner carcass planting).