Lake trout are a coldwater species found throughout Canada.
Because this species does not tolerate warm water, lake trout from southerly populations are forced to retreat to the deep cold waters of the lake's hypolimnion during the summer months. Luckily for lake trout, many lakes contain species of pelagic prey fish like cisco that are found in deep waters, so lake trout can find food throughout the year. In lakes that do not contain any species of pelagic prey fish, lake trout are separated from the inshore fish by a thermal barrier, and are forced to subsist on zooplankton and invertebrates during the summer months. These invertebrate feeding lake trout grow more slowly and reproduce earlier than lake trout that are piscivorous year-round.