Orientation of rainbow trout (Salmo gairdneri) in normal and null magnetic fields

Abstract

In the absence of distinct visual or olfactory cues, adult and juvenile rainbow trout (Salmo gairdneri) showed preferred orientation in the presence of a normal magnetic field. In contrast, fish tested in a null magnetic field showed no directed orientation. These results were obtained in both the presence and absence of a slight (12-cm/s) circular water current. These findings indicate that nonanadromous salmonids, like anadromous forms, are capable of sensing magnetic cues during certain types of spatial activity.