‘Spawning Urger’, ‘Homing Instinct’, and ‘Waiting’ in Salmon Return

Abstract

NOT infrequently we misinterpret the mental processes of our closest friends—why they do certain things—and have to be corrected by them. If we misinterpret the mental processes of salmon, we can have no hope that they will correct us. From certain facts we may infer that salmon under the impelling force of a ‘spawning urge’ travel to their natal rivers by virtue of a ‘homing instinct’, and ‘wait’ at the mouths of the rivers until the conditions are right for their ascent, but we can have no hope of knowing these things, which are unverifiable assumptions. It is true that these conceptions are of very distinct value in presenting a readily appreciated picture of salmon behaviour, but are they the best for the scientific investigator? There can be no objection to them if, known for what they are, they are in quite full agreement with the facts. I do not wish to be an iconoclast, since ‘images’ have value, but, if they make us blind to realities, it seems desirable that we should see them as they are, even if we do not get rid of them. What are the realities?