Sonora Sucker are Endemic to the upper Gila River and Bill Williams River systems of Arizona, New Mexico and in the Mexican State of Sonora meaning these are the only places on Earth where this species can be found. In the Gila River drainage, they can be found in the Gila, Salt, San Francisco, San Pedro, Santa Cruz, and Verde Rivers.
Sonora Sucker have a thick body. Their head and snout are large and rounded dorsally or above and flattened ventrally or below. Sonora Sucker have a squared dorsal fin. They have large scales with typically more than 60 on the lateral line. The body many times, is bicolored brown above and yellow below. The anal and pelvic fins are usually yellow to white. Fish biologists usually can identify fish at first glance, but if they look markedly similar, we use what is called meristics to identify fish. This is the process of identifying fish by counting dorsal & anal fin spine and rays and lateral line scales to identify species. In the case of Sonora Sucker, we would look at the ray count of their dorsal fin which contains 11 rays and at their lateral line scales which should count more than 60. The maximum SL for Sonora sucker is 61 cm which is two feet long.
Sonora Sucker tolerate both warm water rivers and higher elevation cold-water streams. They are found at elevations of 1000 to 6500 feet. Adults usually seek deeper water and shade in pools along cliff faces, in log piles, root systems, etc. They move into riffles and the margins of pools at night to feed. Their feeding habits varies by system. In some systems, they are almost exclusively insectivorous, meaning they feed on insect larvae and macroinvertebrates. In other systems, they are omnivorous and feed both on plant debris, algae, and macroinvertebrates.
Sonora Sucker reproduce in late winter, spring and early summer from February through early July and occasionally during late summer rains. Some populations do not recruit for years then produce strong year classes two or more years in a row. Spawning occurs between two males and one female. They will spawn on shallow riffles where the bottom is often disturbed. Eggs are adhesive and are buried in the gravel and after hatching the larvae exit this area and drift downstream before settling in backwaters to feed and grow. They have been known to hybridize with Razorback & Desert Sucker
They are quite similar to desert sucker, and since they many times inhabit the same habitats, they can be confused for the other, especially when juveniles. But, Sonora Sucker do not have a scraping plate as desert sucker, Sonora Sucker also have larger scales that are outlined in black many times.
Listed as endangered in Mexico and a species of greatest conservation need in Arizona. Currently not federally listed as endangered or threatened. It has disappeared from most of the mainstems of the River systems in which it is found.
Sonora Sucker are one of the few Big native fish species left in the Lower Colorado River Basin, but is their populations have become fragmented and are declining. Threats to the species include habitat Modification like dams, diversions, and groundwater extraction. Dams change River systems to large reservoirs, Sonora sucker need fast moving water and do not do well in reserviors. Groundwater extraction and surface water diversions for agriculture, municipal, and mining use cause rivers and streams to lose water and potentially dry out which destroys Sonora Sucker habitat. Invasive and non-native species. Species like Yellow bullhead, Flathead Catfish, white bass, & largemouth bass all eat Sonora Sucker and decrease the likelihood of recovery for this species.
The largest and most abundant assemblage of Sonora Sucker that I have seen personally is in the Lower Salt River above granite reef dam. This area is a popular recreation area where very large Sonora Sucker can be seen by floaters in the hundreds and where flyfisherman can catch them. Sonora Sucker were an important food source for American Indians and were often the most found fish bones in arechealogical sites in central and southern Arizona.