Effect of Olfactory Occlusion on Migrating Silver Salmon (O. kisutch)

Abstract

Silver salmon were captured in traps in Issaquah Creek and its East Fork. The olfactory pits of approximately one-half of the fish were occluded before all of them were displaced to the Issaquah about one mile below the junction of the two streams. The control salmon, unlike those with occluded olfactory pits, showed an excellent ability to repeat their original choice at the stream juncture. This is interpreted to mean that the operated fish were not able to differentiate between the two streams but were distributing themselves in a random fashion. The results, therefore, are in accord with those which would be expected if the fish were relying on their sense of smell in making this choice.