The humpback chub is a native species of the Colorado River that evolved around 3.5 million years ago and is only found in warm-water canyons of the Colorado River basin. The humpback chub was first described from a fish caught in 1933 near Bright Angel Creek, a tributary of the Colorado River in Grand Canyon, making it one of the last large fish species to be described in North America. The species was protected under the Endangered Species Act in 1973 because large dams and human water use changed the river flow. Actions to conserve the humpback chub include managing river flows, providing passage around dams, and removing non-native predators. Monitoring of humpback chub populations indicates that management actions are benefiting the species. In fact, the Little Colorado River population in Grand Canyon is now estimated at more than 11,000 fish, and the Westwater Canyon population in Utah is estimated to exceed 3,300 fish.
Humpback chub live in rocky canyons where swift, turbulent water makes it difficult for other fish to live. Humpback chub are resilient to a variety of physical and chemical habitat conditions and tolerate a wide range of river flows at all life stages.
A natural body of running water.
Humpback chub eat a variety of foods, including insects, crustaceans, plants, seeds, and occasionally small fish and reptiles.
Typically, humpback chub stay in the same local area for their entire lives, rarely leaving a 10- to 20-mile (16-32 kilometers) stretch of river.
The species is a member of the minnow family and attains a total length of 1.5 feet (about 480 millimeters). Adults have enlarged nuchal humps that rise abruptly behind the head and laterally compressed bodies that are fusiform and tapered toward slender tails.
Adults may attain a weight of 2.6 pounds (about 1.2 kilograms).
Juveniles have greenish backs, silvery sides, and whitish bellies. Adults are similar in coloration with grayish-green backs and sides, fading to whitish bellies.
Individuals generally can reproduce at three-to-five years of age. Young fish live along sheltered shorelines, and adults live in deep pools near rapids and boulders.
The humpback chub can live 20-to-40 years.
Adults spawn in the spring, broadcasting eggs on rocky areas when water temperatures are between 59 and 68 degrees Fahrenheit (15-20 degrees Celsius).
The humpback chub is a member of the genus Gila and is closely related to the bonytail (Gila elegans) and roundtail chub (Gila robusta). The species co-occur in habitats in the Colorado River basin and have substantial evidence of hybridization but maintain species-specific characteristics and populations.
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