Trout Species of Wyoming — A Fly Angler's Field Guide

Most Western states stocked their rivers with rainbows and browns decades ago and never looked back. Wyoming did some of that too — the Bighorn, Grey Reef, and Miracle Mile are tailwater brown trout factories — but it also kept large, intact populations of native Cutthroat in their original drainages. The Snake River Finespotted is found nowhere on Earth outside the upper Snake. The Yellowstone Cutthroat once filled an entire ecosystem before lake trout nearly erased it. The Colorado River Cutthroat is hanging on in the Green River headwaters because biologists chose to fight for it.

For a fly angler this means three things: the fish in your net might be genetically rare, your spot selection has conservation consequences, and an honest day on Wyoming water can put four different species through your hands. Here's how to tell which is which.

Native — Snake River drainage, Teton County

The flagship. The Snake River Finespotted is what most visiting anglers come to Jackson Hole hoping to catch, and what most locals quietly consider the best dry-fly trout in the lower 48. It's a subspecies of Cutthroat unique to the upper Snake River drainage — you cannot catch a wild one anywhere else.

Native — Yellowstone River drainage and Yellowstone Lake

The Yellowstone Cutthroat is the larger, bolder cousin. It once dominated the entire Yellowstone Lake ecosystem — feeding bears, eagles, and otters — until illegally introduced lake trout crashed the population in the 1990s. Restoration is one of the largest native-fish recovery efforts in the West, and it's working.

Native — upper Green River basin, Sublette County

The third native Cutthroat. Colorado River Cutthroat exist in the upper Green River drainage on the west side of the Wind Rivers — New Fork country and the Green's headwater tributaries. They are the rarest of the three to encounter in Wyoming, in part because their range is smaller and in part because many populations are actively being restored.

Non-native — dominant on Wyoming's tailwaters

Brown trout were introduced from Europe more than a century ago and are now the apex trout in most of Wyoming's blue-ribbon tailwaters. They are not native, they do compete with cutthroat where ranges overlap, and they are also the reason rivers like Grey Reef and the Bighorn produce 20-inch fish on a regular basket of Tuesdays.

Stocked statewide, with some wild populations

Rainbows are present in nearly every fishable Wyoming river, mostly through stocking programs that supplement angling pressure. A handful of tailwater reaches — the Bighorn most notably — hold meaningful wild populations that reproduce on their own.

Non-native — high-elevation streams and lakes

Brook trout are native to the eastern United States and were stocked across the Mountain West a century ago. In Wyoming they've taken firm hold in high-elevation tributaries, mountain ponds, and backcountry headwaters where they're often the dominant species. They're beautiful, they're aggressive, and they're a problem where they overlap with native Cutthroat — see the conservation note below.

All three Cutthroat subspecies in Wyoming face the same set of pressures: hybridization with introduced rainbows (the offspring, called "cuttbows," dilute the native genetics), competition from brown trout in shared mainstem rivers, and direct displacement by brook trout in headwater streams. The high country was the last refuge — and brookies followed them there.

You can fish a lot of Western states without ever holding a native fish. Wyoming is the opposite — show up with a fly rod and pay attention, and you'll meet trout that have been here since before Europeans named anything. Learn to tell them apart. Treat the natives like the rare thing they are. The state has done a lot to keep them around. The least we can do is recognize them when they come to hand.