came across this few days ago, it actually make sense.
River Stage:
Once the salmon go up samll streams, they stop feeding. In a bigger river like the Nipigon River ro the Niagara River, The salmon will still feed for the first few days in the river. 99% of salmon that are caught in a small stream are snagged. People fish like they are fishing for Rainbows and just wait for the hook and line to cross the salmon's mouth which again, gives the illusion that the salmon was caught legally. But not all salmon are snagged. Salmon have nothing on their minds beside spawning. At this time, they are very aggressive and territorial and will defend their spawning ground from Rainbow and Brown Trout which tent to follow salmon up stream to feed on their eggs. If you throw a Rapala or spinner that has Rainbow or Brown Trout colours, the salmon will hit the lure. They do not hit to feed, they hit to defend. Sometimes they will also hit loud colours such as bright red or bright yellow.