Nevada Fish & Wildlife Office
Pacific Southwest Region

Humpback chub
(Gila cypha)

 
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Gila
Species: cypha
Length: approx 15 in
Lifespan: up to 30 years
Feed: aquatic and terrestrial arthropods, small fishes, diatoms, planktonic crustaceans and algae
Habitat: variety of habitats ranging from pools with turbulent to little or no current; substrates of silt, sand, boulder, or bedrock; and depth ranging from 1 meter to as deep as 15 meters.
 

Official Status:

Endangered
 

Life History:

The humpback chub is a member of the Cyprinidae family, and is distinguishable from other chubs by a pronounced hump that arises above the gills and extends to the origin of the dorsal fin. It has a flattened, concave head; small eyes; subterminal, beak-like mouth; a long snout that protrudes over the lower jaw; and large fins. The humpback chub is grey or olive colored on its back, with silver sides and a white belly. During the spawning season, adults will develop rosy-red fins and gill coverings.

Some areas of the Colorado River are turbulent. Consequently, it is believed that the hump causes the humpback chub to be pushed to the bottom where water velocities are lower and where the chub can hold its position without exerting excess energy. Grooves associated with the hump may aid in directing water to the fish's gills (Minckley 1973). The long snout and beak-like mouth may allow the fish to feed without the mouth becoming filled with rushing water.

This species reaches sexual maturity between 2-3 years of age, but can live up to up to 30 years. Spawning season is from May to July when water temperatures are between 14 ° and -24 ° C. Laboratory studies have show that hatching success is dependent upon temperature, with the greatest hatching success occurring at 20 ° C. Spawning occurs at depths ranging 1.8 to 3.8 meters, and water velocities of 0.15 to 0.3 meters per second, over boulder, sand, and possibly gravel substrates.

 

Distribution and Habitat:

  The known historic distribution of the humpback chub includes portions of the mainstem Colorado River and four of its tributaries: the Green, Yampa, White, and Little Colorado rivers.

However, its original distribution throughout the Colorado River basin is not known with certainty. Before the 1940's there was considerable manmade alteration occurring along the Colorado River, and there is some speculation that prior to this there may have been humpback chub populations in some river reaches of the Lower Colorado River Basin, although no documentation exists. Presently, the humpback chub is found only in the Little Colorado River and adjacent portions of the Colorado River.

Humpback chub habitat preferences are not well understood. The humpback chub have been associated with a variety of habitats ranging from pools with turbulent to little or no current; substrates of silt, sand, boulder, or bedrock; and depth ranging from 1 meter to as deep as 15 meters.
 

Threats:

  The construction and operation of Flaming Gorge, Glen Canyon, and Hoover dams have eliminated, or altered portions of this species habitat blocking migration routes. Competition, predation, and possible hybridization by introduced species have also been a factor in the decline of the humpback chub. Humpback chub living in habitats with high pollution/pesticide levels have been found to have spinal deformities, although there is no data showing a direct correlation between the pollution/pesticide levels and the species deformities.
 

Actions / Current Information:

 

  Date Title   Plan Action Status
  • 09/19/1990 Humpback Chub - 1990 2nd Revised Final Plan (8MB PDF)   View Implementation Progress
             
    Last updated: April 16, 2014