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Humpback chub (Gila cypha)The pronounced hump behind its head gives the humpback chub a striking, unusual appearance. Like the Colorado pikeminnow and bonytail, the humpback chub is a member of the minnow family. It has an olive-colored back, silver sides, a white belly, small eyes and a long snout that overhangs its jaw. These fish spawn as young as 2-3 years and at lengths as small as 5 inches. Their spawning season is between March and July. |
This fish can grow to nearly 20 inches and may survive more than 30 years in the wild. It is thought to have evolved around 3-5 million years ago. The humpback chub does not have the swimming speed or strength of species such as the Colorado pikeminnow. Instead, it uses its large fins to "glide" through slow-moving areas, feeding on insects that become trapped in water pockets. (Also see: Historical perspective.)
Status and distribution:
The humpback chub lives primarily in canyons with swift currents and white water. Historically, it inhabited canyons of the Colorado River and four of its tributaries: the Green, Yampa, White and Little Colorado rivers. Now, there are two populations near the Colorado/Utah border - one at Westwater Canyon in Utah and one in an area called Black Rocks, in Colorado. Though now smaller in number than they were historically, the two populations seem to be fairly stable in these two areas. Smaller numbers have been found in the Yampa and Green rivers in Dinosaur National Monument, Desolation and Gray canyons on the Green River in Utah, Cataract Canyon on the Colorado River in Utah and the Colorado River in Arizona The largest known population is in the Little Colorado River in the Grand Canyon, where there may be up to 10,000 fish. There are no population estimates available for the rest of the upper Colorado River basin.
Recovery strategies:
Actions being taken to recover humpback chub include boosting and protecting river flows in the spring, monitoring fish population numbers and managing stocking of non-native fish to avoid conflict with endangered fish recovery.
Recovery goals:
Humpback chub will be considered for "down-listing" to threatened when five viable, self-sustaining populations have been located or restored. The species will be eligible for removal from the endangered species list when the five populations have been restored and when the fish's habitat has been protected.
More specific recovery goals are under development and will be published in draft in the Federal Register in early 2001. The recovery goals consist of both demographic criteria and criteria to minimize or remove threats. The objective, measurable criteria are presented for both downlisting and delisting for each of the four endangered fishes throughout their range.