How to Identify Colorado River Cutthroat Trout

To identify Colorado River Cutthroat Trout (Oncorhynchus clarkii pleuriticus), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Body coloration varies from yellowish-green to olive, often with bronze or copper hues, especially along the flanks. The belly is typically white to yellowish. Spawning males can exhibit more intense red or orange coloration, particularly on the lower flanks and opercula. The most distinguishing feature is the prominent red to orange 'cutthroat' mark on the underside of the lower jaw in the folds of the branchiostegal membranes. Numerous small, irregularly shaped black spots are distributed over the entire body, including the head, dorsal fin, adipose fin, and caudal fin. Spotting is generally denser posteriorly.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Prominent red to orange 'cutthroat' mark on the underside of the lower jaw., Numerous small, evenly distributed black spots over the entire body, including head and fins., Generally yellowish-green to olive body coloration., Absence of parr marks in adults (though present in juveniles)., Relatively large mouth extending beyond the posterior margin of the eye.

Dorsal fin

Single dorsal fin, typically with 8-11 rays. Often spotted.

Tail fin

Slightly forked to emarginate caudal fin, often heavily spotted.

Pectoral fin

Paired pectoral fins, typically clear or lightly pigmented.

Distinctive fins

Adipose fin present, often spotted. Pelvic fins are paired and located abdominally.

Identification Tips

1. 1

   Cutthroat Mark

   Look for the distinctive red, orange, or sometimes yellow-orange slash on the underside of the lower jaw, in the folds of the branchiostegal membranes. This is the most reliable field mark.

2. 2

   Spotting Pattern

   Observe the spotting. CRCT typically has numerous small, evenly distributed black spots over the entire body, including the head, dorsal fin, adipose fin, and caudal fin. The spots are often concentrated towards the tail.

3. 3

   Body Coloration

   Note the overall body color, which is usually yellowish-green to olive, sometimes with bronze or copper tones. This can vary with habitat and age.

4. 4

   Mouth Size

   The mouth is relatively large, extending past the posterior margin of the eye.

5. 5

   Absence of White Fin Tips

   Unlike some other trout species (e.g., Brook Trout), CRCT typically lacks white leading edges on its fins.

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