Monitoring Multiple Life Stages of Coho Salmon to Analyze Freshwater Production and Marine Survival

The Oregon Department of Fish and Wildlife Life Cycle Monitoring (LCM) Program monitors adult and juvenile salmonids at multiple sites on the Oregon coast.  We have 13 years of corresponding adult return and juvenile out-migrant data at seven sites which allows us to estimate marine and freshwater components of survival for wild coho salmon (Oncorhynchus kisutch).  We also collect age-structure data at the LCM sites to estimate survival components for steelhead (O. mykiss).  These data can be used to verify habitat capacity models such as the Habitat Limiting Factors Model (HLFM, Nickelson et al. 1998).  The HLFM appears to set an upper limit on expected smolt production, however observed production does not reach this limit in all years.  We are investigating how variation in non-habitat factors such as parental spawner abundance and environmental conditions influence observed smolt production.  We are also exploring how year-to-year changes in habitat quality, particularly annual changes in highly productive areas like beaver dam pools, may explain some of this variation.  Finally, we have developed new analysis of LCM data for potential use in coho harvest management.  Analysis of LCM data to estimate wild coho production for the Coastal Oregon Coho ESU is a more accurate approach than past models based on hatchery jack returns.  ODFW is developing proposed changes to Amendment 13 coho harvest management based on this analysis.