• Siluriformes;
  • home range;
  • core area;
  • biotelemetry;
  • energy consumption

Abstract –  Electromyogram (EMG) biotelemetry allows a description of the spatial distribution of fish together with a simultaneous measurement of individual energy consumption. Using this technique, we observed behaviour of the largest European freshwater predator, Silurus glanis, in the Elbe River, Central Europe. In total, 52 diurnal cycles and 1248 individual fish positions were recorded with 12,480 EMG records during the period from March to May 2006; 1013 fish positions with 10,130 EMG records were further used for statistical analyses. Energy consumption increased with decreasing mutual distance between specimens, an effect that occurred predominantly when both of them were simultaneously in overlapping preferred areas [core areas (CAs)] appointed within their home ranges (HRs). Furthermore, with increasing energy consumption individual’s movement range in longitudinal and lateral profiles decreased; i.e., the fish were positioned within a small area. When the CAs of tested individuals did not overlap, no relationship between EMG signals and mutual distance of conspecifics was found. Our results indicate that movement activity and also social behaviour can be determined with physiological sensors.