How to Identify Bonneville Cutthroat Trout

To identify Bonneville Cutthroat Trout (Oncorhynchus clarkii utah), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Variable, typically olive-green to yellowish-brown on the back, fading to silvery or yellowish on the sides and white on the belly. Distinctive black spots are scattered over the body, often concentrated towards the tail. The most defining feature is the presence of red to orange 'cutthroat' markings on the underside of the lower jaw, which can range from faint to vivid.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Red to orange 'cutthroat' markings on the underside of the lower jaw., Numerous small, irregularly shaped black spots, often concentrated posteriorly., Absence of basibranchial teeth (a key diagnostic feature for distinguishing from some other trout species)., Relatively large mouth extending beyond the posterior margin of the eye.

Dorsal fin

Single, moderately sized, typically with 10-12 rays. Often spotted.

Tail fin

Slightly forked to emarginate (nearly square), heavily spotted.

Pectoral fin

Paired, relatively small, clear to slightly dusky.

Distinctive fins

Adipose fin present, typical of salmonids.

Identification Tips

1. 1

   Cutthroat Markings

   Look for the characteristic red, orange, or sometimes yellow-orange slash marks on the underside of the lower jaw. These can vary in intensity.

2. 2

   Spotting Pattern

   Observe the black spots. Bonneville Cutthroat Trout typically have numerous, relatively small, irregularly shaped spots that are often more concentrated towards the tail and on the dorsal and caudal fins. Spots are generally absent or sparse on the head and anterior body.

3. 3

   Mouth Size

   The mouth is relatively large, with the maxilla (upper jaw bone) extending noticeably beyond the posterior margin of the eye.

4. 4

   Basibranchial Teeth

   A definitive, but often difficult to observe without dissection, feature is the absence of basibranchial teeth (teeth on the tongue). This distinguishes them from Yellowstone Cutthroat Trout (O. c. bouvieri) which possess these teeth.

5. 5

   Coloration

   General body coloration can vary, but the olive-green to yellowish-brown back and silvery/yellowish sides are common. Spawning males may develop more intense red or orange hues on their flanks.

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