Todd:

"All the fish that went beyond that waterfall were weighed, measured, named and numbered, DNA sampled, and released."

I had to figure that all the technology available would be brought into use. By using the DNA markers no doubt they could tell exactly whose kid was whose!

If the fish, genetically, are the same, then clearly there are other factors (like attitude?) that enter into the equation of the w/h crosses that survive the smolt stage but show such a poor (if any) return as adult fish, where the w/w fish do so much better. Sounds like Darwin might have been right about some things.

You explanation makes perfect sense, Todd. Many thanks for the most understandable info.

Mike