Seasonal shifts in habitat use of lake trout in Lake Champlain

Behavioral responses of cold-water fishes to seasonal changes in temperate lakes may be analogous to the response of these species to changing climate conditions. In temperate systems, increased water temperature caused by seasonal warming may force cold-water species to thermal refugia. Lake Champlain is a temperate lake that is separated into three basins by causeways that have narrow, shallow (\u3c 6 m) openings. Therefore, cold-water species have access to these openings only during cold-water periods. In addition, two basins are relatively shallow compared to a third, deeper basin, suggesting they are less optimal for cold-water species during warmer periods. In the present study, acoustic transmitters were implanted in 93 adult lake trout to study their movement throughout Lake Champlain for up to four years. Of these 93 individuals, 18 were tracked moving between basins. Most of these individuals only moved between basins during winter or isothermal conditions. In addition, some individuals demonstrated repeated behaviors across years. These results suggest that lake trout evaluate seasonal habitat limitations and either avoid or move to more optimal habitat before changing temperatures cause thermal stress