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.<\/p>\n
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 nonnative species have dramatically reduced the survival chances of native fish, said Northern Arizona University researcher\u00a0Alice Gibb<\/strong>.<\/p>\n A biology professor, Gibb is the corresponding author of a new paper, \u201cPrey Capture Behavior of Native vs. Nonnative Fishes: A Case Study from the Colorado River Drainage Basin (USA),\u201d that will be published in the\u00a0Journal of Experimental Zoology A<\/em>.<\/p>\n That native fish in the Southwest are on the decline is not in dispute, but the research provides more evidence as to why.<\/p>\n \u201cWe altered the habitat native fish evolved for and put in fish that are better-adapted to the new conditions,\u201d Gibb said, calling the changes a \u201cone-two punch\u201d for native fish.<\/p>\n 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\u2014species that occupy the same \u201cecological niche.\u201d<\/p>\n 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.<\/p>\n \u201cI would interpret the native feeding as opportunistic behavior,\u201d Gibb said. But it\u2019s 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\u2014just like those created by the introduction of dams.<\/p>\n Gibb also noted that the nonnatives have bigger mouths. \u201cThat\u2019s going to provide an advantage, especially when it comes to eating other fish,\u201d she said. Smallmouth bass, for example, can eat chub\u2014but not the other way around\u2014and they have a better chance of doing so in clear water.<\/p>\n \u201cThe research results suggest that it\u2019s the conditions that favor the nonnatives,\u201d Gibb said.<\/p>\n Considering that those conditions are human caused, the findings have implications for wildlife management.<\/p>\n \u201cYou can try to extirpate the nonnatives,\u201d Gibb said, noting an environmental restoration of Fossil Creek that has created a reservoir habitat for native fish. \u201cBut people want their sport fish, which are good predators in clear conditions.\u201d<\/p>\n Such dynamics are not the case only in the Southwest. Gibb said there is growing worldwide interest in a field known as \u201cinvasion ecology.\u201d<\/p>\n \u201cIt\u2019s an area that\u2019s recently been recognized as a tool to understand why some species go extinct and others take over.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"