Why Idaho's State Fish Is the Cutthroat Trout — and Why Protecting It Matters

How to recognize a cutthroat trout

The name comes from the red or orange markings beneath the fish's lower jaw. These slash-like markings are among its most recognizable features.

Its body color can vary considerably. The Idaho Secretary of State describes cutthroat trout as having backs that range from steel gray to olive green, with sides that may be yellow-brown and reddish or pink coloring along the belly.

The scientific name, Oncorhynchus clarkii, honors William Clark of the Lewis and Clark expedition. Clark documented cutthroat trout encountered in the Columbia River region, while Meriwether Lewis had encountered cutthroat trout farther east in 1805.

Color alone is not always enough for a definitive identification. Fish can vary by population, and cutthroat trout can hybridize with rainbow trout.

Where Idaho's native cutthroat trout live

The state fish is not limited to a single Idaho river or one form of cutthroat trout.

Westslope cutthroat trout are native to waters in northern and central Idaho, including portions of the Clearwater, Salmon and other river systems. Idaho Fish and Game documents populations in both rivers and lakes.

Yellowstone cutthroat trout are native to southeastern Idaho's upper Snake River watershed, including the South Fork Snake River. This population is a major focus of conservation work.

Bonneville cutthroat trout are native to the Bear Lake watershed in southeastern Idaho and neighboring Utah. Restoration efforts have helped conserve this population and support fishing opportunities.

The Secretary of State's short state-symbol description highlights the westslope and Yellowstone forms. Idaho Fish and Game also recognizes the Bonneville cutthroat as a native subspecies, including in its fisheries management plans.

Why the South Fork Snake River matters

The South Fork Snake River is one of Idaho's most important remaining strongholds for native Yellowstone cutthroat trout.

Idaho Fish and Game describes the river as supporting a significant native cutthroat population, but one facing competition and hybridization from rainbow trout introduced outside their native range in that watershed.

Cutthroat trout and rainbow trout can reproduce together. Their hybrid offspring can also reproduce, allowing rainbow trout genes to spread through a cutthroat population over successive generations.

That makes the challenge different from simply having two species sharing a river. Over time, hybridization can reduce the number of genetically intact native Yellowstone cutthroat trout.

Why Idaho sometimes encourages anglers to keep rainbow trout

Normally, anglers might assume releasing every trout is the most conservation-minded decision. On the South Fork Snake River, the situation is more complicated.

Idaho Fish and Game operates a Rainbow Trout Harvest Incentive Program intended to reduce the number of rainbow trout and hybrids competing and interbreeding with native Yellowstone cutthroat trout.

Under the program, tagged rainbow trout and hybrids may qualify anglers for monetary rewards. The program describes tags worth $50 to $1,000, along with other prizes, subject to its current conditions.

The objective is not to eliminate rainbow trout throughout Idaho. Rainbow trout are themselves native to other Idaho watersheds. Management depends on which species belong naturally in a particular river system.

Anglers should always check current fishing regulations, identification guidance and incentive-program requirements before harvesting fish.

Conservation also happens in smaller tributaries

Idaho's work extends beyond the South Fork.

In September 2025, Idaho Fish and Game announced a project in Teton Canyon intended to protect Yellowstone cutthroat trout by reducing nonnative rainbow trout in Badger Creek.

The agency described the Teton River Canyon between Felt Dam and the former Teton Dam site as the last section of the river where Yellowstone cutthroat remained the dominant trout.

The project illustrates how conservation sometimes focuses on tributaries where fish spawn and where introduced species can enter important native habitat.

Other efforts include habitat restoration, fish population monitoring, genetics research and fish-passage improvements. Idaho's 2025–2030 Fisheries Management Plan provides the broader statewide framework.

What Idaho anglers and residents can do

Protecting native cutthroat trout does not require everyone to become a fisheries biologist.

Anglers can learn the differences between native cutthroat and other trout, follow water-specific regulations, avoid illegally moving live fish between waterways and support habitat conservation. The correct harvest or release decision depends on the location and applicable rules.

For fishing locations and regulations, consult Idaho Fish and Game's official fishing resources and the South Fork incentive-program page in the references below.

Readers interested in other Idaho wildlife can also explore Idaho's state bird, the mountain bluebird, or browse more Idaho stories.

More than a state symbol

The cutthroat trout represents more than a colorful fish with a distinctive marking beneath its jaw.

It is part of Idaho's natural heritage, with populations adapted to different river systems across the state. Keeping those native populations healthy requires understanding their habitat, protecting genetic diversity and making management decisions that fit each watershed.

The same fish chosen as Idaho's official symbol in 1990 remains a living measure of how the state cares for its rivers.