Rainbow trout are native to Pacific coastal streams of North America, but have been introduced to the Truckee River and other cool-temperature rivers, lakes and streams across the country and around the world (Sigler & Sigler 1987; Moyle 2002;). They are adaptable and may evolve into different strains when populations become isolated (Moyle 2002). Young trout feed mostly on invertebrates like insects and crustaceans. As adults, they feed on smaller fish and insects drifting at the water surface, which is where they encounter fly-fishermen. In the wild, the typical maximum age is about 5 years (Sigler & Sigler 1987). Predators include birds such as Kingfishers, Mergansers and Herons (Moyle 2002).
Rainbow trout sometimes interbreed with Lahontan cutthroat trout (Rivers 1994). The offspring are called “cutbows”. I am not sure whether this is common in the Truckee River. If you know the answer to this question, please comment below!
Moyle, P. B. (2002). Inland fishes of California. Berkeley: University of California Press.
Rivers, I. L. (1994). Fishes and fisheries of Nevada. Reno: University of Nevada Press.
Sigler, W. F., & Sigler, J. W. (1987). Fishes of the Great Basin: A natural history. Reno: University of Nevada Press.