Western Lake Trout – Just Say Whoa!

Scientific Disciplines
Biological Sciences - Aquatic
bull trout
Fish and Wildlife Service
lake trout
mysis relicta
lake trout management
lake trout populations
Volume 16, No. 4

Western lake trout – Just say whoa!
Wade Fredenberg,  USDI Fish and Wildlife Service, 780 Creston Hatchery Road, Kalispell, 
Montana 59901 wade_fredenberg@fws.gov
In Montana lake trout (Salvelinus namaycush) are a self-sustaining introduced species 
in approximately 20 lakes west of the Continental Divide. Less than half those lakes 
were intentionally stocked and lake trout naturally invaded the others through connected 

waterways. Lake trout populations are a detriment to native fish recovery in the majority of 
waters where they occur, including large lakes in Glacier National Park as well as Flathead, 
Swan, Whitefish, and others. In lakes with threatened native bull trout (S. confluentus), lake 
trout management runs headlong into the Endangered Species Act. In addition, ongoing 
lake trout expansion ranks high amongst future threats to bull trout in the Clearwater lakes 
(Salmon, Seeley, Alva, Inez, etc.), Lindbergh Lake, Holland Lake, Lake Koocanusa, and 
others. In oligotrophic lakes of the Columbia Basin, introduced lake trout are well adapted 
and reproduce liberally, preying upon and competing with other native and sport fishes. Lake 
trout preference for deepwater habitat and in-lake spawning limits their exposure to land-
based and avian predators. Lake trout are long-lived, hardy and resistant to starvation. In 
systems where Mysis relicta are added to the mix, a tipping point has often been exceeded for 
maintaining a diverse native ecosystem. Historically, lake trout management strategies were 
often designed to produce both maximum yield and trophy specimens. A recent review of 
seven western states revealed agencies are increasingly implementing strategies to reduce lake 
trout populations in attempts to minimize their impacts. However, management action to deter 
proliferation of lake trout has often been too little, with too few viable options, too costly, and 
sometimes too late. In addition, marginal support for lake trout suppression from an unhappy 
and divided angling public is also an issue.