Selected Aspects of the Natural History of Gila Chub (Gila intermedia)
BLM, AZGFD, USFWS, BOR, USGS
September 2002 to December 2009
Little is known about the natural history of Gila chub Gila intermedia, a moderate-sized cyprinid endemic to the Gila River Basin of Arizona, New Mexico, and Mexico, recently listed as endangered. We studied the habitat preferences, reproductive ecology, and movement patterns of Gila chub in Bonita Creek and Cienega Creek, Arizona. Overall catch density of Gila chub was almost three times greater in Bonita Creek than Cienega Creek, and six times greater for adult chub. Gila chub in Bonita Creek, frequently occurred in a broader range of habitat types and conditions than Gila chub in Cienega Creek. Gila chub in Cienega Creek were highly pool oriented. In contrast, Gila chub in Bonita Creek generally preferred, or used in proportion, swifter shallower habitat types. Segregation between size classes in relation to habitat variables was noted, but was less than expected. Reproduction appears to commence in February and peaks at the beginning of spring, dropping off as summer begins. Spawning in the fall is suggested by the presence of small YOY and gonad development. Adult and juvenile Gila chub showed little movement. The student is finalized his Ph.D. dissertation and writing up results for publication.