Movements of ultrasonically tagged brown trout (Sulmo trutta L.) in Lake Constance

Abstract

In Lake Constance from September 1986 to May 1988 13 adult lake dwelling brown trout (Sulmo trutta L.) were tagged with ultrasonic transmitters and tracked almost continuously for up to 13 days. Two behaviour types were observed: (a) random movement in locally restricted areas and (b) excursions of up to 40 km distance. Swimming activity during the day was significantly higher than at night in most experiments. In summer swimming depth ranged between 8 and 16 m, and in winter between 0 and 3m. The preferred water temperature was about 14°C in the thermally stratified waterbody. During the experiments mean swimming speed ranged between 0.3 km h−1 (0.1 bodylengths s−1) and 0.9 km h−1 (0.6 bodylengths s−1).