Rainbow Trout

Description

The following was paraphrased from the incredible book Trout and Salmon of North America by Robert Behnke, which any self-respecting angler should own and study regularly. Rainbow trout are frequently easily distinguished by the faint pink rose-colored stripe that runs along their lateral line. The back is typically a blue-green color and covered with small black spots, including on the dorsal and tail fins. The belly of the rainbow trout can often be more silver-colored than the back, but not always. Juvenile rainbow trout often have vertically-oriented fainted blotches (called “parr” marks) within the pink along the lateral line, but don’t let that confuse you.

Distribution

Rainbow trout are native to the Pacific Coast of North American, ranging from Alaska to southern California. As a result of systematic stocking over, rainbow trout are now a ubiquitous introduced sport fish throughout the United States. In Colorado, a majority of the state’s rainbow trout populations are maintained by stocking, as CPW annually stocks millions of catchable (>8 inches) rainbow trout.

Biology

Rainbow trout are spring spawners, and they will initiate spawning in response to warming water temperatures and increasing daylight hours. As noted above, many of the rainbow trout in Colorado are the product of a robust State stocking program, however some natural reproduction does occur. The feeding habits of cutthroat trout are similar to other trout species in similar habitats, in that they largely rely on eating insects for much of their lives, but may become piscivorous as they get larger. In the right habitat conditions, rainbow trout can get quite large, and will jump and fight when hooked.

Conservation

In recent years, a parasite called whirling disease has severely impacted natural reproduction of rainbow trout in Colorado streams, and Colorado Parks and Wildlife has responded by stocking the more whirling disease resistant Hofer rainbow trout. Due to the timing of their reproduction (spring spawners), rainbow trout can readily spawn with native cutthroat trout sub-species, resulting in a viable hybrid offspring called the “cutbow”. Because these cutbow offspring can reproduce, over time, if rainbow trout are present within a cutthroat trout fishery, they can dilute the genetics of the cutthroat fishery. As such, for a cutthroat trout fishery to be viable long term, it must be isolated from rainbow trout and other competing non-native species (e.g. brown trout and brook trout).