It has been my experience salmon dont feed when they come in the river. Salmon actually start changing do to increased hormones in the lake They spend the first day or so in the lower part of the river aclimating . They will strike out of habit.When they move up stream they are motivated to get to their spot. Not much is going to stop them. Once they get to their spot they get cranky.. Then its about agrevating them to strike . They will chase and slash at anything in their space. They aren't eating they are pushing males away and removing egg eating critters from the redd. Fish them low in the river early for reactionary strikes . Once they are on the redd I repeatedly put a bait... fly... in their face until they bite. I personally belive most salmon are flossed or snagged whether intentionally or not. Just my observstions.