I hesitate to insert myself into this conversation for two reasons:
1. I'm not a biologist and therefore probably don't even know the questions to ask.
2. I have no dog in this particular hunt.

The study (or Bill's synopsis) is interesting for sure. It reinforces one of my beliefs that habitat is a very critical part of the equation. As long as there is enough spawning beds and feed for the newly hatched fish, there should not be a problem with summers and winters spawning in the same stretch of river. Now, a wild run of summers or a hatchery run of winters in this stretch of water may yield different results.