Did you know that many of the trout that we find in the clear streams and lakes of the Rocky Mountains are not from the area?  Many of the trout that we find now were originally brought from elsewhere, but why?

It seems hard to believe that people would have introduced an animal that was not native to the Rocky Mountains, and encouraged it to spread and live in the wild.  Yet that is exactly what people did.  It is a story that is common in many parts of the world.

What Does It Mean To Be Introduced?

To be introduced is pretty simple to explain – it means that people brought an animal to an area that is not originally from.  In other words, people introduced a new animal to an area.  In this case, I would say that people introduced several types of non-native trout to the Rocky Mountains.

Which Trout Were Introduced?

There are currently many common fish in the Rocky Mountains.  These include several species of trout as well as others.

Some of the non-native trout that were introduced include Brook Trout, Brown Trout, and Rainbow Trout.

What Does It Mean To Be a Non-Native?

Any animal, including people, that is not from an area is called a non-native.  For example, I am a native of California.  Now I live in Utah, which makes me a non-native since I am originally native of California.

Why Were The Non-Native Trout Introduced?

The reason that people brought trout to the United States is fairly simple – they did it for the thrill of the hunt or for recreational fishing.  The non-native trout were first introduced to the Rocky Mountains from Europe (Brown Trout), the west coast (rainbow trout), or elsewhere in order to create a place where people could come and go fishing.

Brown Trout can grow very big, are hard to catch because they are sneaky, and put up a big fight when you catch them.  Likewise Rainbow Trout also put up a big fight if you catch them.  This made both of these fish great to put into rivers everywhere as fishermen would enjoy trying to catch them.

Example of Rocky Mountain National Park

I just want to give one example of how the non-native trout were introduced by talking about Rocky Mountain National Park.  It is hard to know for certain, but before the fish were introduced in the late 1800s there were only 4 native fish to the area.  The National Park Service suggests that many of the waters in the Park had no fish in them either because fish couldn’t get to them due to waterfalls or because the water temperature was too low.

According to the National Park Service, between 1886 and 1968 nearly 20 million non-native fish (mostly trout) had been stocked or introduced into the waters of Rocky Mountain National Park.  These non-native fish were stocked for recreational fishing.  By the time that fish were no longer being stocked or placed into the waters of the park the non-native trout were living in almost all of the lakes and streams of the park and continue to live and thrive there today.  Unfortunately, the massive introduction of these non-native trout led to many of the native fish being kicked out of those areas and changed the aquatic landscape.

What Does This Mean?

Everything in the natural world is connected in ways that we have a hard time understanding or seeing.  This means that anytime we, people, make changes to the natural world we don’t actually know what may happen.  We can make a pretty good guess, but it is just impossible for us to know every possible outcome.  There may alway be some unintended consequence of our actions.  This is known as the Law of Unintended Consequences.

So, what does it mean for us that we introduced millions of fish into the waters of the Rocky Mountains just so that we could go out and do some fishing?  The good news is that now we can go fishing and enjoy the outdoors.  But, the bad news is that we have forever changed the natural waters of the Rocky Mountains and we don’t know what that may mean in the future.