Native Trout Fly Fishing: Hatchery Strain Rainbow Trout

Hatchery Strain Rainbow Trout

Oncorhynchus mykiss

A large hatchery stocked Rainbow Trout from a desert lake in Eastern Washington.

Introduction

While hatchery Rainbow Trout are not an actual subspecies, but instead a mixture of many different strains of Rainbow Trout (and cutthroat for that matter) I have decided to included it on this page due to how common it is across the world and because of the impacts that it has had on native fish. Rainbow Trout have been extremely popular with fisherman since the late 1800's, due to their size, appearance, taste and fighting ability. These traits brought about their spread around the world and today Rainbows are found on every continent (except Antarctica), and are extremely widespread across the United States.

It is often thought that all hatchery trout came from the McClould River Redband Trout, however the original broodstock was also mixed with Coastal Rainbow Trout, and today it is probably mixed with many other forms of Rainbow Trout as well. Through raising trout in hatcheries, Rainbow Trout have been domesticated and artificially selected for a number of traits, such as growth, willingness to come to humans for feeding, and reproduction. Rainbow Trout have also been genetically modified to create different colored fish, such as palomino Rainbow Trout. Triploids are a form of hatchery Rainbows which do not spawn but instead use all of their resources for growth and are grown in hatcheries by exposing eggs to certain stresses. These triploids often grow to very large sizes making them extremely popular with fisherman.

As a rule of thumb, Rainbow Trout spawn in the spring beginning in January till about June depending on the climate of the area. However, through selective breeding in hatcheries, there are some fall spawning Rainbow Trout as well. This trait has also been known to occur when Rainbow Trout are stocked outside of their native range and one example of a place that this has occurred is the Firehole River in Yellowstone, which receives a spawning run of Rainbow Trout from Hebgen Lake each fall.

Due to the fact that these fish were often stocked in waters where other native fish already occurred, they have had some devastating impacts on native trout. Cutthroat and other Rainbow Trout or Redband often hybridize with hatchery Rainbows, leading to a loss their genetic identity. Beyond this, Rainbow Trout compete for food with native fish, which can lead to the depression or extinction of native trout populations. The introduction of non-native Rainbow Trout has already resulted in the extinction of two subspecies of Cutthroat, the Alvord and the Yellowfin, not to mention the loss of countless populations of other native trout throughout the native ranges of these fish. Today stocking practices have luckily been revised to protect native trout, although plenty of damage was done during the last century due to ill-advised practices.

Description

These fish vary greatly in their appearance, due to their mixed lineage, but they do have some general traits. Rainbows have a red or rosy color along their lateral line and on their gill plates. They also usually will have spots spread across their bodies both above and below their lateral line. Their coloration is tends to be a greenish-yellow but they gain a bronze tint during spawning season.