Lake Trout Mountain FSI

The Fish Sustainability Index (FSI) uses scientific and local knowledge to assess health of lake trout in Alberta's mountains and foothills.

Artist rendering of a lake trout

The Fish Sustainability Index (FSI) combines scientific, and local knowledge to assess the health of lake trout in the mountains and foothills of Alberta.

Lake Trout: Mountain FSI Maps

Adult Density (Current and Historic)

Stocked lake populations are denoted with a circle. Please note that data reliability is not currently displayed in these figures.

Habitat and Overharvest Protection Needs

Please note that data reliability is not currently displayed in these figures.

Lake trout FSI spatial layers can be viewed on our interactive web mapping platform.

Lake Trout: Mountain Population Status

In summary, mountain lake trout in Alberta were found to be, generally, in improving condition, with man-made reservoirs adding to the historical habitat.

  • Historically, lake trout were found in the mountains and foothills of Alberta (outside of National Parks) in two lakes; Rock Lake and Swan Lake. Other populations in three river systems (North Saskatchewan, Bow, and Waterton rivers) were likely occasional strays from lakes upstream in Banff and Waterton Lakes National Parks.
  • Constructions of dams and reservoirs downstream of existing lake trout populations in the National Parks (primarily Glacier Lake, Minnewanka Lake, and Waterton Lake) allowed emigrant lake trout to form new populations. These new populations are at low to moderate densities. Of the two original provincially-managed lake trout lakes, Rock Lake fish remain abundant, but fish in Swan Lake have declined to a low density.

Threats to Sustainability

The main threats to sustainability of lake trout in the mountains and foothills appear to be:

  • Reservoirs are managed primarily for water storage, and lake trout habitat is consequently very limited (e.g., winter water draw-down exposes spawning shoals). Populations likely cannot increase unless water management priorities change.
  • Both native lake trout lakes are small, accessible, and easily overfished. Strict regulations on harvest will remain necessary.
  • Increasing summer temperatures will continue to limit lake trout habitat within both natural lakes, and extreme events (e.g., summer heat periods) may result in summerkills.

Next Steps

  • If lake trout are deemed a priority to manage in the reservoirs, water use plans must be adjusted to allow for consistent spawning and recruitment.
  • Cooperation with the management and conservation of lake trout in the upstream National Parks is critical, as these populations are likely the source of replenishment for Alberta's fish. These populations (and those in Jasper) may also provide genetically-similar lake trout should extreme climate events cause the two lake populations to be lost.