Field Identification of Yellowstone Cutthroat Trout, Rainbow Trout, and Their Hybrids.

Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri)

Characteristic features

- Red/Orange slash under jaw

- Round spots concentrated on the dorsal and caudal region

- Solid orange/red fins (No white tip)


Rainbow trout (Oncorhynchus mykiss)

Characteristic features

- Irregular shaped spots located across the body.

- White tips on pectoral, pelvic, and anal fin

- Red/pink streak along lateral line


Cutthroat trout / Rainbow trout Hybrid

Characteristic features

- Combination of cutthroat and rainbow trout features

- Rainbow features Spots across the body

- Pink streak along lateral line

- Cutthroat features (No white on fins)

Across levels of hybridization, the combination of cutthroat trout and rainbow trout characteristics becomes very complex. Even some trout that appear to be pure cutthroat trout or rainbow trout may be advanced hybrids that are ‘hiding’ genes of the other species.