How to Identify Rio Grande Cutthroat Trout

To identify Rio Grande Cutthroat Trout (Oncorhynchus virginalis), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Overall yellowish-green to brassy, darker olive/brown on back, lighter belly. Distinctive red or orange 'cutthroat' markings on the underside of the lower jaw. Black spots are typically concentrated posteriorly, especially on the caudal peduncle and caudal fin, and less numerous or absent anteriorly.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Red or orange 'cutthroat' mark on the underside of the lower jaw., Small, irregular black spots, often concentrated towards the tail., Absence of basibranchial teeth (a key diagnostic feature for distinguishing from some other trout species)., Typically 17-20 dorsal fin rays., Adipose fin present.

Dorsal fin

Single, relatively tall dorsal fin, typically with 17-20 rays.

Tail fin

Slightly emarginate to truncate caudal fin.

Pectoral fin

Paired pectoral fins, moderately sized.

Distinctive fins

Adipose fin present between the dorsal and caudal fins, characteristic of salmonids.

Identification Tips

1. 1

   Cutthroat Markings

   Look for the prominent red, orange, or sometimes yellow-orange streaks on the underside of the lower jaw, resembling a 'cut throat'.

2. 2

   Spotting Pattern

   Observe the black spots. They are generally small, irregular, and more numerous and concentrated towards the tail and caudal fin, becoming sparse or absent towards the head. This contrasts with other trout like Rainbow Trout which often have more uniform spotting.

3. 3

   Coloration

   Note the overall body color, which is typically yellowish-green to brassy on the sides, with a darker back and lighter belly.

4. 4

   Absence of Basibranchial Teeth

   While requiring careful examination, the absence of teeth on the basibranchial plate (on the floor of the mouth) is a key diagnostic feature for pure Rio Grande Cutthroat Trout, distinguishing them from Rainbow Trout and many hybrids.

Explore Rio Grande Cutthroat Trout