Wildlife-based ecotourism has rapidly increased in popularity, especially when featuring large mammals in their natural environment. Researchers have questioned the sustainability of wildlife-based ecotourism because it may compromise the survival and reproduction of focal animals. I investigated the potential spatio-temporal effects of bear viewers on grizzly bears at a proposed bear viewing site along the Fishing Branch River, Yukon. Spatial river use of grizzly bears was largely explained by habituation status. Bears consumed 24% less salmon when viewers were present, posing serious energetic consequences if spatio-temporal compensation does not occur. Dominance status had no measurable effect on bears' fishing behaviour presumably [...]