The cutthroat trout, a fish species recognized for its striking appearance, is a popular sight across western North America. This iconic trout holds a special place for anglers and nature enthusiasts alike, often inhabiting clear, cold waters in mountainous regions.
The Signature Mark
The cutthroat trout’s common name originates from the red, pink, or orange linear marks found on the underside of its lower jaw. These vibrant slashes are located in the lower folds of the gill plates. The intensity and visibility of these markings can vary significantly, sometimes appearing as vivid, bright red, while at other times they might be faint or yellowish, depending on the individual fish, its subspecies, habitat, and even its age or spawning condition. While this throat mark is a primary identifier, it is important to note that similar reddish or pink throat markings can occasionally appear on some populations of coastal rainbow trout or redband trout. However, for most cutthroat trout, this “cutthroat” slash remains the most reliable visual cue.
Body, Color, and Spots
Beyond its signature throat mark, the cutthroat trout possesses a streamlined, elongated body shape. The size of mature cutthroat trout varies widely, ranging from approximately 6 to 40 inches in length, with weight dependent on its environment and food availability. Stream-resident fish tend to be smaller, while those in larger lakes can grow considerably larger, with some reaching over 12 pounds.
The overall body coloration of a cutthroat trout is highly variable, influenced by its genetics, specific habitat, and life stage. Colors can range from golden to gray, green, or olive on the back, often transitioning to lighter shades on the sides, and a white or silvery belly. During spawning periods, some cutthroat subspecies, like the Colorado River cutthroat, can display intensified colors, including darker tones or brilliant red hues.
Cutthroat trout exhibit distinctive, irregular black spots. These spots are generally sparse near the head and become more concentrated and larger towards the tail. The spotting pattern often extends onto the dorsal, adipose, and caudal fins. Fins usually match the body color or may have an orange tint, particularly in lake-dwelling varieties. Pure cutthroat trout do not have white-tipped fins.
Identifying Differences
Distinguishing cutthroat trout from other species, particularly rainbow trout and their hybrids, involves several key features. Rainbow trout typically lack the prominent red or orange slashes under the jaw, or these marks are very faint. Pure cutthroat trout also possess small basibranchial teeth at the base of their tongue, a feature generally absent in rainbow trout. Additionally, the upper jaw of a cutthroat trout extends beyond the posterior edge of its eye.
Differences in spotting patterns are also helpful. Rainbow trout often have a more even distribution of spots across their entire body, sometimes with finer speckles, whereas cutthroat trout usually show spots that are sparse on the head and become denser and larger towards the tail. Rainbow trout are also known for a distinct pink or red stripe along their lateral line, a feature that can be present in cutthroat trout, especially during spawning, but is generally less pronounced.
Hybrid forms, known as “cutbows,” result from interbreeding between cutthroat and rainbow trout. These hybrids can exhibit a mix of features from both parent species, making visual identification challenging. A cutbow might display a fainter jaw slash or combine a slash with white-tipped fins. Definitive identification often requires genetic analysis due to their variable appearance.