An Experimental Approach to Fish Compass and Map Orientation

Abstract

A review of field studies indicates that the homeward migrations of maturing Pacific salmon from the open ocean are well timed and oriented. It is hypothesized that salmon can determine their location realtive to home and that this map sense is based on the inclination and declination of the earth's magnetic field. In order to test this hypothesis experimental techniques which successfully documented compass orientation in small fishes may be modified to allow adult salmon to display directional orientation. The existence of a map sense could be evaluated by testing salmon after displacement. Subtle, systematic changes in the magnetic field around the area simulating displacement could provide data with which to evaluate the role of the magnetic field in the map sense.