There have been 1000's of threads on here and other Forums about the why's and what for's regarding Salmon fishing and to be honest the answers are all hot air because no one knows anything about what goes on in a Salmons head.It's all guess work and anyone who says otherwise is a very brave man indeed.No one has the secret of how to catch Salmon. Are they like in training for the rivers?? Again, this explanation is only my opinion, but I believe it has some merit. 13, 2018 , 4:00 PM. Most salmon spawn in small streams and they must navigate shallow water, rapids, and sometimes even waterfalls. So why do the jump? Thanks If they couldn’t jump, many salmon would never make it to their spawning grounds. As mentioned previously, salmon do not feed when they enter fresh water and lies are not based on access to food but relate more to comfort, safety and shelter requirements. I live in Alaska and I am sitting here watching salmon jump out of the water. The correct answer to the question, “Why do salmon jump?” is: no one knows. Look for breaks in water flow, depressions in the river bottom, large rocks where salmon can hold without expending much energy. Moving upstream Salmon may jump to clear obstacles. Wiki User October 12, 2010 3:50PM. By Joshua Rapp Learn Jul. Answer. It is not a river, it is wide open water. Why are these salmon jumping? why do salmon jump in open waters. I don't know , so please someone tell me. Why do salmon jump?