This species appears to inhabit only the larger streams, primarily the Missouri and Yellowstone rivers. The largest weight for this species in Montana is slightly over 10 pounds. It was once taken commercially from the Mississippi River but is now too rare. Very little is known about the habits and abundance of this species in Montana. Bull trout are a sensitive species that do not tolerate high sediment levels in their spawning streams.
Sediment can suffocate the developing embryos before they hatch.
In Flathead Lake, where they achieve trophy sizes of up to 25 pounds, the bull trout life cycle has been studied extensively. They spawn in the fall and the adults return to the lake. Young fish may spend up to three years in the tributaries before returning to mature in Flathead lake. In other river systems, bull trout may be a resident stream fish. Often, native bull trout have been displaced through competitive interaction with introduced brook trout.