Freshwater fish, especially trout, captivate many. The cutthroat trout is a prized species, recognized for its beauty and angling challenge. Accurate identification is valuable for anglers, conservationists, and nature enthusiasts. Understanding its unique physical attributes ensures proper management and appreciation.
Defining Physical Characteristics
The most distinctive feature of the cutthroat trout is the vivid red, orange, or pink mark in the fold beneath its lower jaw, often called the “cutthroat slash.” This marking, which gives the fish its common name, varies in intensity and may only become fully visible when the fish opens its mouth. While its presence is a primary identifier, the vibrancy of this mark can depend on the specific subspecies, habitat, and the fish’s spawning stage.
Cutthroat trout typically display small, evenly distributed black spots across their body, often denser and more concentrated towards the tail. The size, shape, and overall distribution of these spots vary considerably among individual fish and different populations. Some may have spots spread across the entire body, while others show a clear gradient with fewer spots near the head.
The general body coloration of a cutthroat trout is highly adaptable, ranging from olive green to yellowish-brown or even silvery, influenced by its environment and life stage. Many individuals exhibit a pinkish or red lateral stripe, particularly during spawning periods, which can sometimes be confused with other trout species. The fins generally match the body color, sometimes with an orange hue, especially in lake-dwelling populations.
The cutthroat trout typically has a relatively small mouth where the maxillary, or upper jawbone, extends to or slightly past the posterior edge of the eye. An internal feature is the presence of small basibranchial teeth at the base of the tongue. Unlike some other trout, cutthroat trout typically have solid-colored fins, lacking the distinct white tips seen on some other species.
Differentiating from Similar Species
Distinguishing cutthroat trout from other common trout species requires attention to comparative features. Rainbow trout, a common look-alike, generally lack the prominent red “cutthroat slash” under the jaw, though some coastal populations might exhibit faint reddish markings. Rainbows typically have more uniform spotting that extends onto their head and fins, in contrast to the cutthroat’s often tail-concentrated spots. Rainbow trout are also characterized by a distinct, often iridescent, pink or red stripe along their lateral line, usually more pronounced than any similar coloration on a cutthroat. Interbreeding can produce fertile hybrids known as “cutbows,” which present a challenging identification scenario due to their mixed physical traits.
Brown trout, originating from Eurasia and belonging to a different genus (Salmo), possess distinct dark spots that often have lighter halos, along with scattered reddish-orange spots, patterns not typically found on cutthroat trout. Their overall body coloration tends to be more brown or yellowish-brown, distinguishing them from the varied hues of cutthroat trout.
Brook trout, members of the char genus (Salvelinus) rather than true trout, are easily identified by their distinctive vermiculations, which are worm-like markings, across their backs and dorsal fins. Brook trout also have unique red spots surrounded by blue halos on their sides and possess white-tipped fins, all of which are absent in cutthroat trout.
Geographic Location as an Identification Clue
The native distribution of cutthroat trout spans western North America, providing a significant clue for identification. Their historical and current range extends from coastal Pacific Ocean tributaries, through the Rocky Mountains, and into the Great Basin. This vast area includes regions from Alaska down to northern California, and inland across various states.
Cutthroat trout prefer cold, clear, and well-oxygenated aquatic environments. They commonly inhabit mountain streams, rivers, and high-altitude lakes, often thriving in waters with gravel bottoms suitable for spawning. While many populations are resident in freshwater, some coastal forms are semi-anadromous, migrating between freshwater and saltwater.
However, the presence of cutthroat trout in a particular location is not always a definitive identification factor. These fish have been widely introduced into waters outside of their native range, which can complicate identification based solely on geographic location. Therefore, while location offers strong supporting evidence, it should always be considered alongside detailed physical characteristics.
Variations Among Cutthroat Subspecies
Cutthroat trout encompass a remarkable genetic diversity, with multiple recognized subspecies, such as the Yellowstone, Coastal, Lahontan, Westslope, and Colorado River cutthroat. While all these subspecies share the fundamental identifying features, particularly the red or orange slash under the jaw, they can exhibit subtle differences. These variations often manifest in their specific coloration, the patterns and density of their spots, and their average adult size.
Environmental factors, including water clarity, substrate, and diet, significantly influence the appearance of individual fish within a subspecies. For example, some subspecies may appear more silvery in large lakes, while others in river systems might have darker, more olive tones. While visual cues are helpful for general identification, distinguishing between specific cutthroat subspecies often requires more detailed analysis, such as genetic testing, due to overlapping characteristics and the potential for hybridization.