Wildlife and Anthropogenic Changes in the Arid Southwest - Design with the Desert: Conservation and Sustainable Development - page 177

(a) (b)

FIGURE 9.10
Humpback chub (a) from the Little Colorado River and razorback sucker (b) from Lake Mohave. (Courtesy of
U.S. Fish and Wildlife Service, Washington, DC.)

three of eight native fish species have become extinct in Grand Canyon since the comple-
tion of Glen Canyon Dam, including the Colorado pikeminnow, bonytail, and roundtail
chub. A fourth, the razorback sucker, may also be extirpated in Grand Canyon. 61 Currently,
the humpback chub occupies habitat along an estimated 310 river miles in the Colorado,
Green, and Yampa rivers. 68 The largest remaining population of humpback chub occurs in
the Grand Canyon, primarily inhabiting the lower 8.4 miles of the Little Colorado River,
and the Colorado River in close proximity to the Little Colorado River. 69
Of all the native endangered fishes of the Colorado River, the Little Colorado River
population of humpback chub appears to be faring the best. Despite significant decline
documented during the 1990s, the Little Colorado River humpback chub population has
recently been documented as increasing (Figure 9.11). 70 This is thought to be the result of a

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FIGURE 9.11
Estimated abundance of the Little Colorado River population of adult humpback chub. (From Coggins, L.G. Jr.
and Walters, C.J., Abundance trends and status of the Little Colorado River population of humpback chub: An
update considering data from 1989-2008, U.S. Geological Survey Open-File Report 2009-1075, 18 pp., 2009.)