Simulation analysis of salmon life history diversity and population productivity and abundance

Results from modeling salmon (Oncorhynchus sp.) life history diversity provide insight into the effects on population productivity and abundance. Productivity and capacity for a particular life history pathway is affected by the quantity of key habitat encountered, its quality, and the amount of exposure to these factors. Juvenile Chinook salmon express multiple life history pathways from emergence to ocean entry and each pathway is a unique history of exposure to habitat conditions in time and place. The Ecosystem Diagnosis and Treatment model was used to predict the Beverton-Holt productivity and capacity parameters across a variety of life histories. The model was used to explore the consequence of life history diversity and habitat conditions on performance of fall Chinook originating from streams in the lower Columbia River and Puget Sound. Priorities for habitat restoration can differ considerably among life histories. A comparison of modeled historic and current life history performance informs the potential for life history diversity in a population. A diverse combination of life history pathways is shown to help stabilize brood year ocean recruitment of Nisqually Chinook.