For fly anglers, there are moments that carve themselves into your memory forever. One of them is watching a native Yellowstone cutthroat rise—slow, confident, deliberate—to sip a dry fly off the surface of the South Fork Snake. It’s not just beautiful. It’s sacred.
And it’s in danger.
These native trout now occupy less than half their historical range. Less than a quarter are genetically pure. Their hold on the West is fragile. But in one rare stretch of Idaho’s Swan Valley, on the South Fork of the Snake River, they’re still hanging on.
Not by luck. By grit.
For nearly 30 years, Trout Unlimited has made this river a battleground for native trout conservation. In partnership with Idaho Fish and Game, TU has worked the long game: rebuilding habitat, replanting willows, opening up blocked tributaries, and battling an invasive rival—rainbow trout.
Rainbows are fighters. Flashy, photogenic, and aggressive. But they don’t belong here. Introduced in the 1950s, they began hybridizing with native cutthroat, creating cutbows and slowly replacing the genetic identity of the river. Scientists saw the shift. TU responded.
The strategy? Remove 30% of rainbows annually. That meant lifting daily bag limits. Tagging rainbows and offering cash rewards. Encouraging guides and anglers to keep what they catch. It meant building weirs to block rainbow spawners and even using electrofishing equipment to thin the population.
It wasn’t always popular.
Catch-and-release is religion to many fly fishers. The idea of killing fish—even for a good cause—runs counter to their instincts. But Matt Woodard, who led TU’s South Fork project for two decades, knew this wasn’t about preference. It was about survival. He and the Snake River Cutthroats chapter worked tirelessly to show why.
The message began to land. Data backed it up. In stretches where rainbow suppression took hold, Yellowstone cutthroat numbers stabilized. Catch rates held steady. The wild fish were reclaiming their river.
For readers of The Call of the Creek, this should hit deep. The book isn’t just about trout—it’s about honoring wild things, wild places, and the quiet responsibility of those who love them. To love a native fish is to defend it. Sometimes, that means doing the hard thing.
Andy Bosworth, conservation VP of the Snake River Cutthroats, says it best: “We all want to catch fish. But beyond being anglers, we’re also conservationists. If we don’t protect Yellowstone cutthroat here, we could lose them.”
This isn’t a one-season campaign. It’s a generational one. Data must be tracked. Goals adjusted. Management adapted. But if you stand beside this river and watch a cutthroat rise through the morning calm, you’ll understand why it matters.
This isn’t just a fish. It’s a living emblem of what still runs wild. And the effort to save it is one of the clearest calls we’ll ever hear.