Montana's Redband Trout
This story is featured in Montana Outdoors May–June 2011 issue
Rainbow trout are common throughout much of Montana, but almost all are nonnatives. They are descendents of coastal rainbow trout originally brought here from California hatcheries starting as far back as the 1880s. The only rainbow trout native to Montana is the Columbia River interior redband trout, a subspecies commonly known as redband trout, found here only in the northwestern corner of the state.
For years coastal rainbows were stocked in Montana streams containing native redbands. As a result, the two rainbow subspecies hybridized, making genetically pure redbands increasingly rare. According to Mike Hensler, Montana Fish, Wildlife & Parks fisheries biologist in Libby, genetically pure redbands today exist primarily in widely disconnected remnant stocks. These redbands are confined to the upper reaches of streams where drainage culverts, small waterfalls, or other barriers prevent hatchery rainbows from moving upstream.
Redbands historically have coexisted with native westslope cutthroat trout. Though the two species sometimes hybridize, the crosses are considered naturally occurring.
“Because they happen at such a low rate—less than 1 percent—they don’t threaten the existence of redband trout, unlike hybridization with hatchery rainbows,” Hensler says.
Montana’s redbands are native to the Kootenai River and its tributaries up to the Fisher River, a few miles downstream of Libby Dam.
The steelhead that move from the Pacific Ocean up the Columbia River into the Snake River basin in Idaho and British Columbia’s Fraser River are a variation of the redband trout.
Each spring a large, lake-dwelling strain of the redband trout known as the Gerard rainbow swims upstream (north) from Kootenay Lake in British Columbia to the Lardeau River to spawn. Hensler suspects that thousands of years ago some Gerards also migrated south through the Idaho Panhandle into Montana to spawn in the Kootenai River and its tributaries. Over time, some of these fish remained and formed the resident redband trout populations here.
Tom Dickson is editor of Montana Outdoors.
[ BACK TO TOP ]