Sunday, October 29, 2006

Hybridization - Why it Can Be a Bad Thing

As mentioned yesterday, hybridization is the interbreeding of trout species. Many fish (especially trout) interbreed with other species. Over time, this can lead to a species' survival being threatened.

Arizona is home to the Apache and Gila trout. With the exception of the Gila trout (which can also be found in New Mexico), these twp species don’t exist anywhere else in the world. Due to hybridization, their survival has been threatened and they’ve been on the Endangered list since 1967.

But thanks to the Arizona Fish and Game Department teaming up with other organizations, these two species not only survive today, but are making a comeback!

These agencies have been sterilizing certain rivers and lakes to kill off unwanted fish and plant Apache and Gila trout into these waters. In doing so, these trout species have an opportunity to survive and repopulate the waters.

In 2006 the Arizona Fish and Game Department sterilized the West Fork of the Little Colorado River to remove Rainbow and Brook trout which were threatening Apache trout. Once it's been confirmed that Rainbow and Brook trout have been successfully removed, the river will be restocked with Apache trout.

The process of sterilization is very safe and interesting. A very small concentration of an EPA approved chemical (Antimycin) is introduced into the river. Antimycin is actually an antibiotic developed for human use. In this case, it interferes with the fish's ability to exchange oxygen within its cells; thereby removing unwanted fish from the stream. At specific doses, it can remove some fish without affecting others.

Antimycin is neutralized by applying potassium permanganate, which oxidizes the Antimycin. After a couple days, fish can be restocked.

One of the biologists involved in the project told me that they hope to take Apache trout off the Engendered list by next January.


If you'd like to read more about the Apache trout recovery project, click here.

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