Electroencephalographic Olfactory Responses in Adult Salmon to Waters Traversed in the Homing Migration

Abstract

By infusing various natural waters into noses of homing salmon (Oncorhynchus tshawytscha and O. kisutch) and recording electroencephalographic (EEG) patterns from the olfactory bulb, data were collected showing responsiveness to waters along the freshwater migratory route. The largest responses always were evoked by the home water for each of the three spawning groups. Generally, the responses to various waters along the migrating route were equivalent, or did not vary in any recognizable progression. Accordingly, it does not seem that homing salmon are following a single olfactory clue in increasing concentration. Instead, they appear to be responding olfactorily to individual loci along the route.