Gila cypha, (Miller, 1946)
The humpback chub is an Endangered, native species of the Colorado River that evolved around 3.5 million years ago.
SIZE: The common length for the Humpback chub is 25 cm (9.8 in) with the maximum reported length being 38 cm (15 in).
RANGE: Humpback chub are found in the Little Colorado River. The humpback chub historically occupied portions of the main stem of the Colorado River in Arizona and Colorado, and the Green and Yampa Rivers (Northern rivers of Utah and Colorado).
HABITAT: Currently, the humpback chub is found in the Little Colorado River, adjacent portions of the Colorado River and in the White River.
DIET: The diet of the humpback chub is not well known. The stomach contents of humpback chubs have consisted of algae, plant debris, ﬁsh remains, Mormon crickets and other terrestrial insects.
The humpback chub reaches sexual maturity between two to three years. Spawning season for this species is from May through July, when water temperature are between 14 - 24 degrees Celsius (57.2 ‐ 75.2 degrees Fahrenheit).
Humpback chub spawning normally takes place over boulder, sand, and possibly gravel substrates at depths of 1.8 m to 3 m (5 ft. 11 in to 12.5 ft.)and water velocities of 0.15 to 0.3 m/sec (5.9 to 11.8 in/sec). The hatching success of humpback chub eggs are temperature dependent. Greatest hatching success for humpback chub eggs occurs at 20 degrees Celsius (68 degrees Fahrenheit).
Currently, six self‐sustaining populations of humpback chub exist in the Upper Colorado River Basin. The humpback chub was listed as Endangered by the U.S. Fish and Wildlife Service in 1967. This species was then given full protection under the Endangered Species Act in 1973. Subsequently, it was protected under Utah Law in 1973 and listed as Endangered under Colorado law in 1976.
Present day management actions to conserve, restore and protect the humpback chub include water management to provide adequate in-stream flows within their existing range, the construction of ﬁsh passages and screens at major diversion dams to provide them with access to hundreds of miles to critical habitat, the monitoring of ﬁsh population numbers and the managing of non‐native ﬁshes and invasive species.