Trout

Westslope Cutthroat

Oncorhynchus clarkii lewisi

3.9

At a Glance

Avg Length

15"

Avg Weight

1.8 lbs

World Record

10 lbs

Habitat

Rocky Mountain Streams

About the Westslope Cutthroat

Westslope Cutthroat (Oncorhynchus clarkii lewisi). Found in Rocky Mountain Streams. Average length 15 in, weight 1.8 lbs. World record: 10.0 lbs (Montana).

The Westslope Cutthroat is one of the most recognizable freshwater species in North American waters, classified scientifically as <em>Oncorhynchus clarkii lewisi</em>. It belongs to the Trout group, most commonly found in rocky mountain streams environments. Anglers target this species for both sport and table fare, and it appears across a broad range of water bodies throughout the United States.

A typical Westslope Cutthroat runs 15 inches in length and weighs around 1.8 pounds, though fish in prime habitat regularly exceed these averages. The all-tackle world record stands at 10 lbs, set at Montana, making it a legitimate target for anglers chasing personal bests. Conservation status varies by region — check local regulations before keeping fish, as some waters have slot limits or catch-and-release requirements in place.

Habitat & Range

Primary habitat: Rocky Mountain Streams.

The Westslope Cutthroat thrives across a wide range of freshwater environments throughout North America. Seasonal movements are driven by water temperature — fish tend to move into shallower water during spring and fall feeding periods, and push deeper or seek cover during the heat of summer and cold of winter. Understanding these patterns is critical to locating fish consistently across the season.

How to Fish for Westslope Cutthroat

Best bait: Nymphs.

Technique: Fly Fishing.

Match your presentation to the season and conditions. In clear water, downsize your bait and slow your retrieve. In stained or muddy water, switch to high-contrast colors and add vibration. Early morning and evening are the most productive windows during summer months. During spawning season, fish become highly territorial and will strike out of aggression as well as hunger.

World Record

The all-tackle world record Westslope Cutthroat weighed 10 lbs, caught at Montana. This record represents the upper end of what this species achieves under ideal conditions. Most anglers targeting personal bests focus on proven trophy waters with the right combination of habitat, forage base, and light fishing pressure.

State Regulations

Regulations vary by state and water body. Before fishing for Westslope Cutthroat, verify current size limits, bag limits, and open seasons with your state fish and wildlife agency. Check your state's fishing license requirements and season dates at the FishLog Fishing License guide.