Before a salmon enters the river, it feeds quite heavily and relies on stored body fat to survive the perils of spawning. In goes off the bite, or stops eating. But it still possesses natural feeding instincts even though spawning is its primary mission. The sense of feeding is the primary attractant. Although I haven't yet seen a lure that imitates spawning salmon, that doesn't mean that there isn't one.
Food means nothing to a salmon in a river.
If a salmon decides to put its mouth on your bait or lure, it's from instinct, not because it is hungry. To begin with, you need lots of patience. But patience will usually prevail if you take the time to figure out what they would like to bite on. Sometimes, it's not you favorite lure. So you have to make a change.