| Summary: | The fitness of female Pacific salmon (Oncorhynchus spp.) with respect to breeding behavior can be partitioned into at least four components: survival to reproduction, competition for breeding sites, success of egg incubation, and suitability of the local environment near breeding sites for early rearing of juveniles. Accordingly, breeding sites should exhibit predictable habitat features linked to these components. In this study, I evaluated the relative influences of habitat features linked to fitness components on selection of breeding sites by coho salmon (Oncorhynchus kisutch). I also evaluated associations between breeding site selection and additions of large wood, as the latter were introduced into the study system as a means of restoring habitat conditions to benefit coho salmon. I used a model selection approach to organize specific habitat features into groupings reflecting fitness components and influences of large wood. The relative likelihood of each of these models was then evaluated based on how coho salmon were observed to select breeding sites. Specific variables examined within these models included depth at the redd, width to depth ratio, stream network location, proximity to other redds, maximum depth, proximity to a pool tail, and the count of naturally occurring and artificially placed large wood. Results of this work suggest that female coho salmon most likely select breeding sites based on habitat features linked to all four hypothesized fitness components. Linkages between large wood and breeding site selection were less clear, likely due to mismatches between the scale at which availability was quantified relative to the geomorphic influences of wood, insufficient time for wood to have geomorphic influences on habitat, or the directionality in which geomorphic effects are currently manifested (i.e., upstream, downstream, or bi-directional influences). Future work focused on geomorphic processes in this system could reveal stronger linkages between instream wood and the habitat features that coho salmon select for breeding. === Graduation date: 2013
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