Russel B. Kiefer
Thursday, February 23, 2006
Can the Victoria Index be used to forecast Columbia River Spring Chinook adult return rates?
This is a simple exploratory analysis initiated after I saw a presentation by Nate Mantua at the Climate Impacts Group that included Victoria Index values which appeared to trend with smolt to adult return rate data I was working with. I obtained Victoria Index values from Nate and conducted simple linear regressions with several Columbia River spring Chinook salmon adult return rate data sets. There appears to be a relationship between the Victoria Index and the three adult return rate data sets I had access to. This relationship provided a potential explanation for the relatively high adult return rate for Snake River wild/natural spring Chinook salmon in smolt migration year 2001 even though that was a low flow year with no spillway passage provided. If the Victoria Index or another index can be used to forecast ocean conditions Columbia River spring Chinook salmon smolts will encounter, it would provide a potentially powerful management tool. Potential management uses are: adjusting mainstem smolt migration mitigation efforts to match needs, improvements to adult return forecast, and providing a better match between lower Columbia River harvest rates and actual adult returns.
Russel Kiefer is a biologist with Idaho's Department of Fish and Game.