Study of feeding behaviors points to challenges for native fish

February 3, 2012
Populations of the roundtail chub have greatly declined in recent decades, and the results of a recent NAU study suggest that human-caused conditions favor nonnative species of fish found in the Colorado River.

( -- A study detailing the feeding behaviors of four species of fish found in the Colorado River and its tributaries uncovered a few surprises and opened new insights to the challenges faced by native fish species in the Southwest.

Some of the biggest challenges are relatively recent ones. In a diverse region known for its markers of geologic time, a combination of dam building and the introduction of have dramatically reduced the survival chances of native fish, said Northern Arizona University researcher Alice Gibb.

A biology professor, Gibb is the corresponding author of a new paper, “Prey Capture Behavior of Native vs. Nonnative Fishes: A Case Study from the Drainage Basin (USA),” that appears in the Journal of Experimental Zoology A.

That native fish in the Southwest are on the decline is not in dispute, but the research provides more evidence as to why.

“We altered the habitat native fish evolved for and put in fish that are better-adapted to the new conditions,” Gibb said, calling the changes a “one-two punch” for native fish.

For the study, Gibb and her colleagues compared the native roundtail chub with the nonnative smallmouth bass, and the native Sonora sucker with the nonnative common carp—species that occupy the same “ecological niche.”

While Gibb expected the nonnatives to consume everything offered to them, the study found that it was the native fish that had a broad diet in the lab. The nonnatives were choosier.

“I would interpret the native feeding as opportunistic behavior,” Gibb said. But it’s a behavior that evolved in the constantly changing habitat of the Southwest in warm, turbid water. The nonnatives, Gibb said, are from more stable and clear conditions—just like those created by the introduction of dams.

Gibb also noted that the nonnatives have bigger mouths. “That’s going to provide an advantage, especially when it comes to eating other fish,” she said. Smallmouth bass, for example, can eat chub—but not the other way around—and they have a better chance of doing so in clear water.

“The research results suggest that it’s the conditions that favor the nonnatives,” Gibb said.

Considering that those conditions are human caused, the findings have implications for wildlife management.

“You can try to extirpate the nonnatives,” Gibb said, noting an environmental restoration of Fossil Creek that has created a reservoir habitat for . “But people want their sport fish, which are good predators in clear conditions.”  

Such dynamics are not the case only in the Southwest. Gibb said there is growing worldwide interest in a field known as “invasion ecology.”

“It’s an area that’s recently been recognized as a tool to understand why some species go extinct and others take over.”

Explore further: River damming leads to dramatic decline in native fish numbers

Related Stories

Weeds and the Murray

February 15, 2011

( -- A new study has revealed that human-induced changes in the flow of the Murray River has led to mass weed invasion and reduced biodiversity in wetlands along the riverbank, highlighting the need for a review ...

How fish swim: Imaging device shows contribution of fins

April 22, 2011

There are fish tales and then there are fish tails. And a report from Harvard researchers in the current issue of the journal Biology Letters seems to demonstrate that previous theories about how bony fish move through the ...

Can we bring the grayling back to Michigan?

August 16, 2011

( -- Overfishing and destruction of its habitat have driven the Arctic grayling from its native Upper Michigan waters. But Michigan Technological University biologists Nancy Auer and Casey Huckins are looking ...

Fish jump into picture of evolutionary land invasion

October 6, 2011

( -- Research sometimes means looking for one thing and finding another. Such was the case when biology professor Alice Gibb and her research team at Northern Arizona University witnessed a small amphibious fish, ...

Native species proposed as viable long-term sequesters

January 26, 2012

( -- New research into the carbon sequestration abilities of native tree species was undertaken by Greening Australia, and will hopefully make native species more attractive and viable option for carbon farming.

Recommended for you

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

A huge chunk of a tardigrade's genome comes from foreign DNA

November 23, 2015

Researchers from the University of North Carolina at Chapel Hill have sequenced the genome of the nearly indestructible tardigrade, the only animal known to survive the extreme environment of outer space, and found something ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.