Activity Levels of Trout (Salmo trutta) in Airthrey Loch, Stirling, and Loch Leven, Kinross

Abstract
Brown trout were tagged with sonic tags in Airthrey Loch, Stirling, and Loch Leven, Kinross. The results were expressed as mean hourly and maximum specific swimming speeds, centres of activity and home ranges. The results indicated that tagging effects lasted for up to 48 hours after release. There were seasonal changes in the levels of activity with a peak in March. Home ranges tended to be widest at dusk and dawn. Mean hourly specific swimming speeds were very low (0·14 BL/sec). The trout did not move randomly throughout either loch, and in Loch Leven remained within 1·4 km of the release point.