Pretty sure the biologist you're referring to is Steve Pettit. Slender guy, maybe 5-10 with curly brown hair and beard. He works for Idaho Fish and Game out of Lewiston and is generally regarded as the region's most knowledgeable source on steelhead and salmon, and in many circles the area's finest fly fisherman. I'm not familiar with the study you're referring to, but I have heard this from him personally: Steelhead are a very resilient species, much more so than salmon. That is probably the primarly factor contributing to the decline of wild salmon runs on the Snake. They just don't negotiate the dams very well.