endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (5000-200,000 square km (about 2000-80,000 square miles)) Range is confined to the Gila River basin, Arizona and New Mexico (Minckley and DeMarais 2000, Page and Burr 2011). Voeltz (2002) determined that this species likely occurred in a number of tributaries of the Verde River, most of the Tonto Creek drainage, much of the San Carlos River drainage, and parts of the upper Gila River in New Mexico. Currently, the species occupies the East, Middle, and West forks of the Gila River, and may occupy lower Turkey Creek below a barrier in that stream and the Gila River below the forks area in New Mexico, although these fish have not been definitively identified. In Arizona, headwater chubs are believed to currently occupy: tributaries of the Verde River including Fossil Creek, East Verde River (including tributaries The Gorge, Pine Creek, and Webber Creek), Wet Bottom Creek, and Deadman Creek; and Tonto Creek and several of its tributaries (Buzzard Roost, Dinner, Gordon, Gun, Haigler, Marsh, Rock, Spring, Turkey creeks). The present status of this species in Deadman Creek and Turkey Creek is unclear; fires in the watersheds may have eliminated headwater chub in these waters. Other waters connected to Turkey Creek still contain headwater chubs, so there is opportunity for repopulation of this creek. Headwater chubs may still occur in parts of the San Carlos River basin, although recent survey information for these streams is unavailable because San Carlos Tribal survey information is proprietary and confidential. The taxonomic status of the Gila population in upper West Clear Creek has not been definitively resolved; currently that population is not included in the range of Gila nigra. Source: USFWS (2011), which see for further specific documentation.
Bestgen and Propst (1989) reported headwater chubs in the upper Gila River basin of New Mexico at elevations of 1,325-2,000 meters (4,347-6,562 feet). Unpublished elevational records from the Arizona's Heritage Data Management System range from about 1,200 meters (4,200 feet) in Fossil Creek to nearly 1,520 meters (5,000 feet) in Marsh Creek (Arizona Game and Fish Department 2003).
Catalog Number: USNM 16987
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Fishes
Collector(s): H. Yarrow
Year Collected: 1874
Locality: Ash Creek, Arizona, Arizona, United States, North America
Catalog Number: USNM 16972
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Fishes
Collector(s): H. Henshaw
Year Collected: 1874
Locality: San Carlos, Arizona, Arizona, United States, North America
Habitat Type: Freshwater
Comments: Habitat encompasses middle to headwater reaches of headwaters, creeks, and small rivers (Minckley and DeMarais 2000, Page and Burr 2011). Headwater chubs usually are in pools and runs near cover such as rocks, rootwads, undercuts, or deep water (Bestgen and Propst 1989). Minckley (1973) and Bestgen and Propst (1989) commented that chubs congregate near or in certain pools and are absent in other, similar-type pools. In Fossil Creek, Arizona, headwater chubs were found over sand substrates and appeared to select depths between 0.9-1.5 meters and velocities of 0.15 meters per second (Voeltz 2002). In the Gila River Basin, Bestgen and Propst (1989) found headwater chub in water temperatures of up to 26.5° C and water velocities less than 20 cm/sec.
Spawning occurs in pool, run, and riffle habitat. Eggs are scattered randomly over substrate (Arizona Game and Fish Department 2003).
Neve (1976) observed spawning in Fossil Creek. Males were not territorial, and the female probably chose the spawning site. Several males attended a female, in pool-riffle areas. Neve noted close contact of males to a female, 6 to 10 cm above the sandy-rocky substrate, and males were observed releasing milt. Neve made no mention of finding eggs in the substrate beneath locations of apparent spawning.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Little is known about seasonal movements (Carman 2006).
Comments: In Fossil Creek, Arizona, the headwater chub is omnivorous, consuming mainly aquatic and terrestrial invertebrates, supplemented with plant material, detritus, and fishes (Neve 1976, Bestgen 1985, Rinne and Minckley 1991).
In the mainstem Gila River, Bestgen (1985) found algae, trichopterans, and miscellaneous insect parts to be predominant in the stomachs of chubs <100 mm; algae, ephemeropterans, trichopterans, and unidentified insects were dominant in chubs between 100-170 mm. Fishes longer than 170 mm contained algae, trichopterans, and ephemoeropterans, in addition to fishes and crayfish.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 6 - 20
Comments: Known present range of the headwater chub includes 13 streams in Arizona (USFWS data) and a few in New Mexico.
Minckley and DeMarais (2000) mapped 17 collection sites in Arizona and 4 in New Mexico. There are 7 "populations" in Arizona (S. Schuetze, pers. comm., 2006) and up to 17 range wide (S. Stefferud).
USFWS (2011) concluded that headwater chubs now occurs in 23 of 26 streams in which the species has been documented. The extant populations are in four drainages (San Carlos River (2), Tonto Creek (10),
Upper Gila (4), and Verde River (7)). Three of the Upper Gila populations are connected (the Forks
populations), the two San Carlos populations are probably connected, the Tonto Creek populations are in two
clusters; Gordon, Haigler, Marsh and Tonto Creeks in the upper drainage and the five Spring Creek basin and
Gunn Creek populations in the middle portion of the drainage, and the Verde populations have one cluster of
four on the East Verde River and the remainder are isolated from each other (USFWS 2011).
Comments: Total adult population size is unknown.
Life History and Behavior
Spawning occurs in spring and early summer at the end of spring runoff, at water temperatures of 14-24°C. Eggs hatch in 4-7 days at a water temperature of 19-20°C. Larval stage lasts up to 53 days.
In the Gila River basin, Bestgen and Propst (1989) observed ripe females and males in pools in late spring to summer. Afternoon water temperatures for spawning in the East Fork of the Gila River were 22 °C (Bestgen 1985). Headwater chubs probably grow rapidly in their first and second years, until reaching maturity at 2-5 years of age (Carman 2006). Life span ranges up to 8-10 years (Arizona Game and Fish Department 2003).
In Fossil Creek, Arizona (Neve 1976), young-of-year first appeared in May and by June measured 12 to 28 mm SL. Average sizes at year classes 0, 1, 2, 3, and 5 were 68, 127, 174, 217, and 321 mm (one fish) TL, respectively.
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G2 - Imperiled
Reasons: Small range in Gila River basin, Arizona and New Mexico; declining as a result of habitat loss and degradation and effects of non-native fishes; recently recognized as a distinct species, but some molecular evidence indicates that this taxon should be lumped with Gila robusta.
Lead Region: Southwest Region (Region 2)
For most current information and documents related to the conservation status and management of Gila nigra, see its USFWS Species Profile
Global Short Term Trend: Decline of 10-30%
Comments: Of the 23 extant populations, one is stable-secure, seven are stable-threatened, seven are unstable-threatened, and eight have unknown status (USFWS 2011). USFWS (2011) reviewed available information and concluded that the headwater chub is "probably in worse condition than assumed in 2006, and with the decline of the Upper Gila Forks populations, is in worse condition now than in 2006."
Global Long Term Trend: Decline of 50-70%
Comments: Historical distribution of the headwater chub is uncertain, so long-term trend cannot be precisely quantified. However, area of occupancy, number of subpopulations, and population size are believed to have declined over the long term. USFWS (2011) estimated that the species now occurs in 40-50 percent of the historical range.
Degree of Threat: High
Comments: USFWS (2011) summarized threats as follows: Remaining populations are fragmented and isolated, and threatened by a combination of factors. Headwater chubs are threatened by introductions of nonnative fishes (predators, competitors); these nonnative fishes are difficult to eliminate and thus pose an on-going threat. Habitat destruction and modification have occurred and continue to occur; examples include dewatering, impoundment, channelization, and channel changes caused by alteration of riparian vegetation, and watershed degradation from mining, grazing, roads, water pollution, urban and suburban development, groundwater pumping, and other human actions. Existing regulatory mechanisms do not appear to be adequate for addressing the impact of nonnative fishes and also have not removed or eliminated the threats that continue to be posed in relation to habitat destruction or modification. The fragmented nature and rarity of existing populations makes them vulnerable to other natural or manmade factors, such as drought and wildfire. The two most significant threats facing headwater chubs across the range are the presence of nonnative aquatic species in their habitats and wildfire.
Threats includes habitat loss and degradation resulting from dams, diversions, groundwater pumping, mining, recreation, and livestock grazing, as well as predation by and competition with nonnative fishes (Arizona Game and Fish Department 2003).
The decline of chubs in the Gila River basin in New Mexico has been attributed mainly to the introduction of nonnative species such as catfish and bass (Bestgen and Propst 1989, Carman 2006). Additionally, habitat has been lost as a result of drought (Carman 2006).
In New Mexico, ash flows associated with wildfires have negatively impacted much of the drainage occupied by headwater and Gila chub, primarily in West Middle, and East forks Gila River and Turkey Creek (Carman 2006).
Relevance to Humans and Ecosystems
Stewardship Overview: Primary management needs: watershed and stream flow protection; research to determine mechanisms of disappearance; amelioration of deleterious effects of nonnative fishes (Arizona Game and Fish Department 2003); reestablishment of headwater chub in formerly occupied waters.
A recovery plan is available for New Mexico (Carman 2006).
The body of the Headwater Chub is thick and chunky to streamlined but not markedly attenuate. The maximum size of the male fish is about 50 cm females are about 10–18 cm total length. The coloration of the fish is dark olive-gray or brown above, with a silver side, and white below. The longitudinal stripes are often diffuse, and are rarely with dark dorsal-lateral blotches. The caudal peduncle is not pencil-like, its length is less than its head length; the fins are small to moderate in size, sometimes convex, and are rarely curved, with inter-radial membranes of fins variously pigmented. Scales are developed and cover the entire body, with the basal radii variable. There are 73-83 lateral scales, with usually 8 dorsal and anal fin rays, and rarely 7 or 9 fin rays.
Similar species include the Humpback Chub (Gila cypha) and Bonytail Chub (G. elegans), however, these fish have extremely slender caudal peduncles, smaller eyes, angle along anal fin base continuing above the caudal fin. Large individuals have a hump on their nape, and a depressed head which is absent on the Headwater Chub. Gila Nigra are somewhat trout-like in appearance, except they lack an adipose fin. Not surprisingly, they are morphologically intermediate between the Roundtail chub (Gila robusta) and the Gila chub (Gila intermedia).
Headwater Chubs are endemic to the Gila River basin of Arizona and New Mexico where they occupy the middle and headwater reaches of middle-sized streams. Populations have been recognized from the mainstream Gila River (above confluence with Mangus Creek) in New Mexico, this includes West, Middle and East forks of the Gila River, along with the San Carlos River (a tributary to the Gila). They are also identified from Ash Creek (tributary to San Carlos River), Tonto Creek (tributary to the Salt River), and Spring Creek, (tributary of Tonto Creek). In the Verde River system, they inhabit Upper Fossil Creek (above the diversion dam), East Verde River and Deadman Creek.
Adult Headwater Chub occupy cool to warm water in mid- to headwater stretches of mid-sized streams of the Gila River basin. They are associated with deep, near shore pools adjacent to swift riffles and runs, and near obstructions. Cover consists of root wads, boulders, undercut banks, submerged organic debris, or deep water. In Fossil Creek, they were found in water more than 1.8 m deep with velocities under 0.10 meters per second. Substrates they are associated with include gravel, small boulders, and large in-stream objects. Preferred water temperature ranges of 20-27°C with a minimum temperature around 7°C. Juveniles are associated with shallow, low velocity habitat with overhead cover. In Fossil Creek, Headwater Chub seem to select depths between 0.9-1.5 m and velocities of 0.15 meters per second and are found over sand substrate.
The Headwater Chub are associated with substrates including gravel, small boulders, and large in-stream objects. The preferred water temperature ranges of the Headwater Chub are 20-27°C with a minimum temperature around 7°C. Juvenile Headwater Chub are associated with shallow, low velocity habitat with overhead cover. In Fossil Creek, they seem to select depths between 0.9-1.5 m and velocities of 0.15 mps and are found over sand substrate.
The Headwater Chub life span is 8–10 years. The Headwater Chub grow rapidly but growth is dependent on water temperature. The maximum size of the fish is about 50 cm.
As with many native fish, reductions in range and numbers are likely the result of habitat loss, as well as competition with, and predation by, non-native fish species.
Activities that are known to be detrimental to Headwater Chub populations should be avoided, including dewatering of habitats through re-routing stream water, stream impoundment, channelization, domestic livestock grazing, timber harvesting, mining, road construction, polluting, and stocking non-native fish.
- Threats: aquifer pumping; stream diversion; reduction in stream flows; predation by and competition with nonnative fishes.
- Management needs: watershed and stream flow protection; research to determine mechanisms of disappearance; ameliorate effects of deleterious nonnative fishes.
Protective measures taken
This species is currently being considered for T & E listing by the US Fish and Wildlife Service.
- Minckley, W.L. and B.D. DeMarais, 2000. Taxonomy of Chubs (Teleostei, Cyprinidae, Genus Gila) in the American Southwest with comments on conservation. Copeia, 2000(1), pp. 251-256.
- Bestgen, K.R. and D.L. Probst. 1989. Distribution, status and notes on the ecology of Gila robusta in the Gila River drainage, New Mexico. The Southwestern Naturalist 34(3): pp 402-412.
- Animal Abstract:Gila nigra. Compiled by the Heritage Data Management System, Arizona Game and Fish Department, 2003.
- Voeltz, J.B. 2002. Roundtail Chub (“Gila robusta”) status survey of the Lower Colorado River Basin. AGFD Nongame and Endangered Wildlife Program Technical Report #186, Arizona Game and Fish Department. Phoenix, Arizona. pp. 221.
Names and Taxonomy
Comments: Minckley and DeMarais (2000) proposed that "Gila nigra," an assemblage that possibly arose through more than one hybridization event between Gila robusta and Gila intermedia, be recognized as a distinct species ("headwater chub"). However, Gerber et al. (2001) cited several studies of allozymic and mtDNA characters that failed to identify any diagnostic characters among Gila intermedia, Gila nigra, and Gila robusta robusta; they referred to these taxa as "G. robusta." Nevertheless, the most recent AFS checklist (Nelson et al. 2004) listed Gila robusta and Gila nigra as distinct species.
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