By Sam R. Johnson
Today, if the word “trout” is mentioned, it’s probably the “rainbow” trout that comes to mind. Perhaps that’s because rainbows, or “bows” as they’re commonly called, are the ones most often seen on restaurant menus. To that point, when’s the last time you saw brook trout or brown trout on a menu? The rainbow trout (salmo gairdneri) is also the species most likely to be seen or caught in many of the cold-water rivers and streams of the eastern US. They have earned a spot in America’s trout fishing mindset - and appetite!
Between rainbows, browns and brookies, the rainbows are best known for several reasons. First, is their undisputed superiority in terms of sheer numbers for reasons we’ll discuss later. Second, is their agility, acrobatics and endurance during the fight that endear them most to anglers. Many times, I’ve seen seven-inch rainbows behave like Flipper the dolphin and jump a full four feet out of the water repeatedly before eventually coming to net. As a fly fisher, it’s enough to make your heart jump for joy! For their sheer numbers and ability to fight, the rainbow is fun to pursue and catch.
Most people are surprised to learn that rainbows are not native to Appalachia, or any eastern waters for that matter. Only the brook trout is native. Both bows and brown trout were originally transported to the region as a result of an effort by the government, timber companies, and other concerned groups to re-establish healthy cold water fish habitats after logging destroyed many of the watersheds in the eastern half of the country in the early 1900’s. Along with browns, they are considered to be “exotics” here in the eastern waters by fishery biologists – documented / green card toting Pisces immigrants so to speak. Just a hundred or so years after being introduced to the region, as proof of their ability to adapt, the majority of the primary trout streams along the Appalachian Range that once were dominated by brook trout, now support reproducing wild populations of these colorful interlopers. In the evolutionary scale of time, rainbows have done an amazing job of becoming the dominate trout in terms of populations and range of habitat.
Records indicate the first rainbows were transported to the Appalachians from the Sierra Mountains of California – although some argue they first came from a bit further north and west up the coastal regions of western Canada. Both seem probable since bows enjoy a natural range that extends from California, through Canada, and all the way up to Alaska. Some reportedly came as eggs, some as fry, and still others as adults. Many were transported across the country by refrigerated or iced rail car. Upon arriving in the east, they were released in carefully selected waters throughout the affected Appalachian watersheds where their prospects of survival would be greatest. As a result, with the exception of those waters being protected for brook trout, rainbows inhabit practically every other river, stream and creek along the Appalachian Range.
The success of the rainbow is attributed to its hardy nature and a keen ability to adjust to its environment. This is in stark contrast to the browns and infinitely more than the delicate brook trout. One of the Rainbows unique survival traits is their ability to tolerate warmer water temperatures than either the brook trout they were replacing or the brown trout. They can tolerate water temps in the low to mid 80°s with low oxygen saturation levels for short periods of time, although they best thrive in 50° to 60° water. Another factor contributing to their success is their ability to live in waters with wider turbidity ranges than the other two trout. They may prefer clean and clear water, but they can live in water that’s less than clear as long as it’s cool and reasonably well oxygenated. This alone greatly extends their habitat range and survival rates.
A lifespan of seven to eleven years is not uncommon for a rainbow, as compared to a brook trout’s four to seven. Age alone allows rainbows the opportunity to attain larger sizes, and the larger size allows them to push their weight around and be more aggressive and competitive for the available food supply in a given body of water. This ability to grow old and bigger is also aided by the bow’s preference for moving water – especially with rapids, runs and riffles. These habitat features create a broken surface that’s more difficult for predators to see through from above. The moving surface serves as a safety feature for the rainbow – a feature that’s lacking in the still waters preferred by brook trout, or even the bigger and calmer waters lower down a watershed that browns prefer. Opaque water ultimately makes rainbows harder to prey upon and consequently, allows them to live longer and get bigger.
Depending on the quality of the bow’s habitat, they will take a variety of insects common to the waters they inhabit including caddisflies, mayflies, stoneflies as well as most of the other usual subsurface entomology suspects and terrestrial insects. Having the advantage of being able to survive in small creeks and streams to large rivers allows the rainbow to encounter a larger variety and quantity of insects with more frequent and larger hatches - and more elbow room to go after them.
Rainbows, especially wild ones, are particularly beautiful fish. An Appalachian rainbow’s color scheme ranges from light to dark green / dark blue on a back that is heavily covered with black spots and specs, with a gray to off-white belly. An irregular or “blurry” reddish stripe runs along the lateral line of each side – which is the bow’s signature identifier. This stripe on a wild bow can run from the gill plate to its tail and is often stunningly bright blood red in appearance. In some watersheds, the area in front of the gill plate will also have a patch of bright red coloration. Stock rainbows on the other hand often show little or no sign of red hues on any portion of their bodies and are predominantly silver. The side stripes of stockers, if visible at all, will be a light pink hue with possibly some shades of blue bordering it. The reason for this variance in colors might in part be from variances in genetics, and part from the food sources the trout is snacking on while in the wild or in the hatchery. In short, wild bugs in a natural habitat, opposed to food pellets in a hatchery, have some effect on coloration of the bow.
In most of the wild trout waters I fish, I see rainbows in the 7” to 10” range with a few over 12”. Occasionally, it’s possible to take a 12” to 17” wild bow from a larger pool or run that’s off the beaten path. A wild bow over 17” from most wild eastern waters is considered a wall hanger. In the waters that are hatchery supported, rainbows will average in the 7” to 12” range. Occasionally a brood fish will be released that will be in the 16” – 18” range. Those bows fortunate enough to be fed in private and protected trophy waters can easily attain 20” – 25” and even larger. As a rule, as you move north on the map the water becomes more productive for bug production because of the effects of more nutrients leaching from the soil into the water. As a result, trout can get larger than they can in southern waters because there’s simply more to eat.
Rainbows might not have been in the eastern waters from the start, but they have certainly carved out an important place in today’s eastern waters. They have become a popular and sustainable farmed food source, and a prized sport fish for anglers. They’re everyone’s trout!
ABOUT SAM JOHNSON
Sam Johnson is a Partner in Wild Bearings, LLC, and the author of “Fly Fishing the Blue Ridge Parkway – NC Section.” His next book about fly-fishing the VA Section of the Parkway is due to be released sometime in 2023. He is a lifelong freshwater fly fisherman, freelance contributor to several fly-fishing magazines, maker of bamboo fly rods, member of Mojo Sportswear Co.’s Pro Staff Team., and a general outdoors do-gooder.