Hybridization of the Cutthroat Trout

This post was last updated on April 8th, 2014 at 05:41 pm

What is Hybridization of the Cutthroat Trout?

Hybrid Cutthroat TroutThe cutthroat evolved in areas of mountainous seclusion. As they evolved they faced limited exposure to other trout and fish species. As people began to populate the western United states, they brought with them thoughts of bringing more fish for them to enjoy. Unfortunately, the trout they brought from the far west such as the rainbow trout have had dire consequences. The cutthroat trout in its natural habitat will breed with these rainbow trout and create what is known as a hybrid or “cutbow”. Although these hybrids tend to fight really hard when they are hooked, they are really bad for the cutthroat trout overall. After multiple generations of the hybrids start to breed, it becomes clear that eventually the pure strain of cutthroat will be gone. It will make nearly all cutthroats a variation of at least part rainbow trout. While immediately most people just like to have fish to hook; so it doesn’t seem to pose a huge problem, but what happens when the whole species becomes slowly extinct? This is a real threat to these fish and there are clear examples of this taking place all over the west.

The Hybridization is a Problem Almost Everywhere the Cutthroat Exists

There are multiple ways that fisheries are trying to deal with the hybrid cutthroats and non native trout

  • Poisons: They are actually poisoning whole sections of river to rid them of non native trout species. After the poison becomes inert they will then proceed to plant pure strains of cutthroat trout. Most states have secured genetically pure cutthroat trout in hatcheries to use as breeding stock. They will extract a small amount of fish from known areas of wild populations. Within a few generations of trout they can have a large amount of pure strain cutt’s to use for stocking efforts. 
  • Killing off the non native trout using sportsman: Often times the fishery professionals will enlist fisherman to kill off the trout that are hurting the cutthroats. For example:
Tags placed in rainbow trout in the south fork of the snake river.
Here are a few tags I have extracted from Various rainbows and cutthroat hybrids. These are all from the south fork of the snake in Idaho placed by Idaho Fish and Game.

In the South Fork of the Snake, Idaho They are aggressively trying to kill the rainbows. They have implanted tags in the fish that are often times worth money. If you catch a rainbow trout you can place its head in drop boxes located at a couple different locations at boat launches. The Idaho fish and game will then decipher whether your trout has a tag, if it does they will potentially send you a check. At one time they planted large visible red tags on fish. The fish and game officials found that people would remove the tags (for possible cash) and release the rainbows. There are still many of these trout in the river system even though this technique hasn’t been used in a couple years. I caught 2 last year on various fishing trips. Now they plant small invisible tags or “chips” in the heads of fish, trying to increase the likely hood that fisherman will kill the rainbows to turn them in for a possible reward.

The non native trout are a huge threat to all of the Cutthroat trout, there are more tactics than ever before to try to rid the native streams of these species. The cutthroats might just breed themselves out of existence if drastic measures aren’t continually taken. Nearly every species of cutthroat are either on the endangered list, or under threatened status because of this problem.