Whirling disease now infects about 150 streams across Montana, but researchers say they are still optimistic about the future of trout fishing in the state.

One of the most promising developments, they say, is the discovery of wild rainbow trout that are naturally resistant to whirling disease. Another is the mysterious rebound of rainbow trout in the Madison River, the first Montana river where whirling disease was discovered.

The biggest surprise is that the rainbow trout population has started to rebound in the Madison River, Vincent said. He first noticed around 1991 that young rainbow trout populations were showing large declines in the upper Madison River. By 1994, they had fallen by 90 percent. Now, despite a high rate of infection and significant inbreeding, the rainbow trout population in the upper Madison is 60 to 70 percent of what it was before it started to crash.
MSU News Service - Whirling disease researchers optimistic about Montana's trout

Current location of Whirling Disease


I am posting this here because it looks like quite a few out of staters are planning trips to Montana, you need to be aware that there is whirling disease, so that you do not transfer it back to your home waters.