Influence of geomagnetism and salinity on the directional choice of eels

Abstract

1. A modified arrangement has been used for the photographic recording of the directional choice of silver eels (Anguilla anguilla and A. rostrata) in a circular tank and under the magnetic action of a Helmholtz coil. 2. The movement of the eels in the experimental tank was very restricted as obvious by photographs taken every 6 seconds. 3. Nine male specimens from the Elbe River near Hamburg, 11 male specimens from the Elbe estuary and 3 to 5 female specimes from Rhode Island (USA) were examined for 17 to 22 hours, either in sea water or in fresh water, and yielded 225 to 946 photographs for each examination. 4. In sea water, eels of all three samples changed their preferred direction from north or south to east, when the normal horizontal north (X) component of the geomagnetic field was compensated to zero. The east component (Y) remained (