Upper Missouri Missing Big Rainbows

December 20, 2004 By: Marshall Cutchin

Lots of factors, including generational changes, are causing big rainbows in the Missouri below Holter Dam to become increasingly scarce. But Whirling Disease and drought are taking their toll in recent years. “Montana’s rainbow trout numbers peaked in 1999, when all fish thrived from several years of high water, but began to fall last year when symptoms of drought surfaced and anglers reported finding whirling disease in many trout. The disease infects young trout and destroys their nerves and cartilage. The trout whirl in circles and are either consumed by predators or starve. The parasite leaves the dead fish to invade others.” From the Associated Press.