Brain Food: Experimental High-Flows May Benefit Bonytail Chub Of Colorado River

Apr 22, 2016

New knowledge about the endangered Bonytail Chub is helping biologists understand more about the native Colorado River fish: how it maneuvered through pre-dam floods and is surviving current experimental high-flow releases. 

The lower backbone of the Bonytail Chub
Credit KNAU/Bonnie Stevens


Alice Gibb of Northern Arizona University studies the chub's narrow lower backbone. She says, "The reason the Bonytail has that bony tail is that the muscle is concentrated in the anterior portion of the fish, and the force is transmitted down the tail. It can then swing from side to side, cutting through undisturbed water and producing water voteses, and that's what generates the force to push the fish forward."

Researchers measured the Bonytail's performance in a flow tank - sort of a treadmill for fish - where they could change the velocity of the water. Gibb says the fish were able to maintain their positions, swim against and even through strong currents.

NAU biologist Alice Gibb in her lab
Credit KNAU/Bonnie Stevens

"The new finding from the study," Gibb says, "is that the role of flow is probably very important to the ecology of the native fish of the Colorado River. And we believe that this is support for the idea of using floods recreate normal or natural conditions for the Colorado River."

Gibb says non-native fish, like Brown Trout and Striped Bass that have been introduced into the river system, do not have the same tail structure and power as the Bonytail, yet they're out-competing them for food, even eating their young. She believes periodic flooding of the river would wash some of the game fish downstream and give native fish, like the Bonytail, a better chance at survival.

Brain Food is produced by KNAU, Arizona Public Radio.