Gila elegans - Baird and Girard, 1853
Bonytail
Taxonomic Status: Accepted
Related ITIS Name(s): Gila elegans Baird and Girard, 1853 (TSN 163553)
Unique Identifier: ELEMENT_GLOBAL.2.105598
Element Code: AFCJB13100
Informal Taxonomy: Animals, Vertebrates - Fishes - Bony Fishes - Minnows and Carps
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Actinopterygii Cypriniformes Cyprinidae Gila
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.
Concept Reference Code: B91ROB01NAUS
Name Used in Concept Reference: Gila elegans
Taxonomic Comments: In and below Grand Canyon, individuals of Gila elegans, G. cypha, and G. robusta robusta are readily identified by diagnostic morphological and genetic characters (see Gerber et al. 2001). In the upper Colorado River basin, several studies have yielded evidence of hybridization among these taxa in the mainstem Colorado River above Grand Canyon (see Gerber et al. 2001).

Gerber et al. (2001) found that lower Colorado River basin populations of G. cypha exhibit distinct mtDNAs, with only limited introgression of G. elegans into G. cypha, but most sampled upper basin fishes exhibited only G. cypha haplotypes, with some individuals exhibiting mtDNA from G. elegans. The complete absence of G. robusta mtDNA, even in populations of morphologically pure G. robusta, indicates extensive introgression that predates human influence (Gerber et al. 2001).

Hybridization may be a result of a breakdown in reproductive isolating mechanisms caused by habitat and streamflow changes in the basin (Valdez and Clemmer 1982), but it also can be viewed as playing a significant role in generating the great morphological diversity in the genus Gila and enhancing genetic variability and adaptability to the rigorous physical habitats present in the Colorado River Basin (Dowling and DeMarais 1993).
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 08Feb2012
Global Status Last Changed: 25Sep1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G1 - Critically Imperiled
Reasons: Formerly widespread and common in much of the Colorado River basin; now widely extirpated and very rare, with no known self-sustaining populations; decline apparently has been caused mainly by the effects of dams and exotic fishes, and these continue to threaten the species with extinction.
Nation: United States
National Status: N1 (05Dec1996)

U.S. & Canada State/Province Status
United States Arizona (S1), California (SH), Colorado (SX), Navajo Nation (SX), Nevada (S1), New Mexico (SX), Utah (S1), Wyoming (SX)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (23Apr1980)
U.S. Fish & Wildlife Service Lead Region: R6 - Rocky Mountain
IUCN Red List Category: CR - Critically endangered
American Fisheries Society Status: Endangered (01Aug2008)

NatureServe Global Conservation Status Factors

Range Extent Comments: Bonytails were formerly abundant throughout the Colorado River and its larger tributaries, including the Green River north to the reach now inundated by Flaming Gorge Reservoir in Wyoming and Utah, the Yampa and Gunnison rivers in Colorado, and the Colorado River in Arizona, Colorado, Nevada, and California), and likely also the San Juan River in New Mexico and the Gila and Salt rivers in Arizona (Lee et al. 1980, USFWS 1990, Muth et al. 2000). Documented records exist for Lake Havasu, Lake Mohave, and Grand Canyon in the Lower Colorado River Basin; and Lake Powell, the Colorado River (Cataract Canyon, Green River confluence, Utah; Black Rocks, Colorado), Gunnison River near Delta, Colorado, Green River (Gray Canyon, Utah; Dinosaur National Monument, Colorado and Utah; Hideout Canyon, Utah), and lower Yampa River, Dinosaur National Monument, Colorado), in the Upper Colorado River Basin (USFWS 2002).

An unknown but small number of wild adults exist in Lake Mohave on the mainstem Colorado River of the Lower Colorado River Basin (i.e., downstream of Glen Canyon Dam, Arizona), and there are small numbers of wild individuals in the Green River and upper Colorado River subbasins of the Upper Colorado River Basin (USFWS 2002). USFWS (2002) listed only two locations (Lake Mohave on the Arizona-Nevada border and Lake Havasu along the Arizona-California border) where wild bonytails have been documented since 1990.

As of the early 1990s, populations were being established in urban lakes in Tempe, on the Buenos Aires NWR, and at TNC's Hassayampa Reserve, all in Arizona; plans called for stocking of experimental populations into Arizona streams (Minckley and Deacon 1991).

Number of Occurrences:  
Number of Occurrences Comments: Currently no self-sustaining populations of bonytail exist in the wild (USFWS 2002).

Population Size: 1 - 1000 individuals
Population Size Comments: Total adult population size is unknown but apparently is very small.

Number of Occurrences with Good Viability/Integrity: None (zero)
Viability/Integrity Comments: Releases of hatchery-reared bonytails have not resulted in definite reproduction in the wild or population recruitment. Approximately 130,000 hatchery-produced F1 and F2 fishes were released into Lake Mohave between 1981 and 1987 as part of an effort by the USFWS to prevent extinction and promote eventual recovery of the species. Younger bonytail of adult size and spawning ability were collected from the reservoir in the 1990s along with the old adults of the founder population. It is unknown whether these younger adults are from the original stockings or a result of natural reproduction (USFWS 2002). Releases of hatchery-reared adults into riverine reaches in the upper basin have resulted in low survival (Chart and Cranney 1991), with no evidence of reproduction or recruitment (USFWS 2002).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Threats to the species include habitat modifications resulting from streamflow regulation, dams that function as movement barriers on main-stem rivers, competition with and predation by nonnative fish species, hybridization (possibly), and pesticides and pollutants (USFWS 2002). The significance of, and factors leading to, hybridization with other Gila species are unclear, and this factor is not regarded as an important threat at the present time (USFWS 2002). However, hybridization should be evaluated as bonytails are released into the wild and populations become established (USFWS 2002). Low population size and lack of recruitment are major obstacles to recovery.

Short-term Trend: Unknown
Short-term Trend Comments: Recent trend is unknown because so few bonytails have been captured. Wild population likely is declining.

Long-term Trend: Decline of >90%
Long-term Trend Comments: This species formerly was widespread and abundant; today it occurs in the wild as only a few scattered individuals and is regarded as functionally extinct (USFWS 1990, Muth et al. 2000). In the Green River basin, this species has been virtually nonexistent in recent collections (Muth et al. 2000). The last observed large concentration of bonytail occurred 1954 when about 500 adults were observed spawning over a gravel shelf in Lake Mohave, Arizona-Nevada (Jonez and Sumner 1954). Collections of bonytail in Lake Mohave yielded at least 50 specimens in the 1970s and 1980s, but USFWS (2002) reported that only one bonytail subsequently was captured there. Significant numbers of bonytail were last captured in the Upper Colorado River Basin (lower Yampa River and Green River below the Yampa) in the 1960s and early 1970s, shortly after the closure of Flaming Gorge Dam. Since then, only a few single captures were recorded (all in the 1980s) in the entire Upper Colorado River Basin (USFWS 2002).

Other NatureServe Conservation Status Information

Protection Needs: Information on bonytail habitat requirements is limited, but the flow and temperature recommendations made for the other endangered native fishes in the Green River basin would presumably benefit any bonytails that may remain in the system and would not limit their future recovery potential (Muth et al. 2000).

Distribution
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Global Range: Bonytails were formerly abundant throughout the Colorado River and its larger tributaries, including the Green River north to the reach now inundated by Flaming Gorge Reservoir in Wyoming and Utah, the Yampa and Gunnison rivers in Colorado, and the Colorado River in Arizona, Colorado, Nevada, and California), and likely also the San Juan River in New Mexico and the Gila and Salt rivers in Arizona (Lee et al. 1980, USFWS 1990, Muth et al. 2000). Documented records exist for Lake Havasu, Lake Mohave, and Grand Canyon in the Lower Colorado River Basin; and Lake Powell, the Colorado River (Cataract Canyon, Green River confluence, Utah; Black Rocks, Colorado), Gunnison River near Delta, Colorado, Green River (Gray Canyon, Utah; Dinosaur National Monument, Colorado and Utah; Hideout Canyon, Utah), and lower Yampa River, Dinosaur National Monument, Colorado), in the Upper Colorado River Basin (USFWS 2002).

An unknown but small number of wild adults exist in Lake Mohave on the mainstem Colorado River of the Lower Colorado River Basin (i.e., downstream of Glen Canyon Dam, Arizona), and there are small numbers of wild individuals in the Green River and upper Colorado River subbasins of the Upper Colorado River Basin (USFWS 2002). USFWS (2002) listed only two locations (Lake Mohave on the Arizona-Nevada border and Lake Havasu along the Arizona-California border) where wild bonytails have been documented since 1990.

As of the early 1990s, populations were being established in urban lakes in Tempe, on the Buenos Aires NWR, and at TNC's Hassayampa Reserve, all in Arizona; plans called for stocking of experimental populations into Arizona streams (Minckley and Deacon 1991).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZ, CA, COextirpated, NMextirpated, NNextirpated, NV, UT, WYextirpated

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ La Paz (04012), Maricopa (04013), Mohave (04015), Yuma (04027)
CA Imperial (06025)*, San Bernardino (06071)*
CO Mesa (08077)*
NM Rio Arriba (35039)*, San Juan (35045)*
NV Clark (32003), White Pine (32033)*
UT Carbon (49007), Emery (49015), Garfield (49017), Grand (49019), Kane (49025)*, San Juan (49037), Uintah (49047), Wayne (49055)
WY Sweetwater (56037)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
14 Colorado headwaters-Plateau (14010005)+*, Lower Gunnison (14020005)*, Westwater Canyon (14030001)+, Lower Dolores (14030004)*, Upper Colorado-Kane Springs (14030005)+, Upper Green-Flaming Gorge Reservoir (14040106)+*, Blacks Fork (14040107)+*, Lower Yampa (14050002)*, Upper White (14050005)*, Lower White (14050007)*, Lower Green-Diamond (14060001)+, Ashley-Brush (14060002)+, Lower Green-Desolation Canyon (14060005)+, Price (14060007)+*, Lower Green (14060008)+, Upper Lake Powell (14070001)+, Lower Lake Powell (14070006)+*, Upper San Juan (14080101)+*, Piedra (14080102)*, Middle San Juan (14080105)*, Lower San Juan-Four Corners (14080201)*
15 Lower Colorado-Marble Canyon (15010001)*, Grand Canyon (15010002)*, Lake Mead (15010005)*, Lower Little Colorado (15020016)*, Havasu-Mohave Lakes (15030101)+, Imperial Reservoir (15030104)+, Lower Colorado (15030107)*, Bill Williams (15030204)+, Upper Gila-San Carlos Reservoir (15040005)*, Middle Gila (15050100)*, Lower San Pedro (15050203)*, Upper Salt (15060103)*, Lower Salt (15060106)*, Lower Verde (15060203)*, Lower Gila-Painted Rock Reservoir (15070101)*, Hassayampa (15070103)+, Lower Gila (15070201)*
16 Spring-Steptoe Valleys (16060008)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
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Basic Description: A large minnow (to 62 cm) with a long, slender caudal peduncle.
Reproduction Comments: Natural reproduction of bonytail was last documented in the Green River in Dinosaur National Monument in the 1960s (Vanicek and Kramer 1969). Bonytails in reproductive condition were captured from mid-June to early July at a water temperature of 18°C. Spawning in Lake Mohave was observed in May (Jonez and Sumner 1954). Hamman (1985) found that hatchery-reared bonytails began to sexually mature at age 2. Bonytails can mature within one year in artificial ponds (Minckley and Marsh 2009). Examination of otoliths from four bonytails from Lake Mohave indicated ages of 34, 40, 42, and 49 years (Rinne et al. 1986).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): BIG RIVER, Low gradient, MEDIUM RIVER, Moderate gradient, Pool
Lacustrine Habitat(s): Deep water, Shallow water
Habitat Comments: Gila elegans is a warm-water species that appears to favor main-stem rivers regardless of turbidity, usually in or near deep swift water, in flowing pools and eddies just outside the main current. It also has been found in reservoirs. Available data suggest that habitats required for conservation include river channels and flooded, ponded, or inundated riverine habitats, especially those where competition from non-native fishes is absent or reduced (USFWS, Federal Register, 21 March 1994).

Spawning occurs probably in spring over rocky substrates; spawning in reservoirs has been observed over rocky shoals and shorelines (USFWS 2002). Flooded bottomland habitats appear to be important growth and
conditioning areas, particularly as nursery habitats for young (USFWS 2002).

Adult Food Habits: Herbivore, Invertivore
Immature Food Habits: Herbivore, Invertivore
Food Comments: Diet and feeding habits are poorly known. Probably the diet includes insects, fishes, and plant matter.
Length: 52 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Needed management actions include the following (USFWS (2002): 1. Reestablish populations with hatchery-produced fish. 2. Identify genetic variability of bonytail and maintain a genetic refuge in a suitable location in the lower basin. 3. Provide and legally protect habitat (including flow regimes necessary to restore and maintain required environmental conditions) necessary to provide adequate habitat and sufficient range for all life stages to support recovered populations. 4. Provide passage over barriers within occupied habitat to allow unimpeded movement and, potentially, range expansion. 5. Investigate options for providing appropriate water temperatures in the Gunnison River. 6. Minimize entrainment of subadults and adults at diversion/out-take structures. 7. Investigate habitat requirements for all life stages and provide those habitats. 8. Ensure adequate protection from overutilization. 9. Ensure adequate protection from diseases and parasites. 10. Regulate nonnative fish releases and escapement into the main river, floodplain, and tributaries. 11. Control problematic nonnative fishes as needed. 12. Minimize the risk of increased hybridization among Gila spp. 13. Minimize the risk of hazardous-materials spills in critical habitat. 14. Remediate water-quality problems. 15. Provide for the long-term management and protection of populations and their habitats beyond delisting (i.e., conservation plans).
Management Requirements: Hatchery culture and reintroduction to suitable habitat may be the only feasible method of recovery, but this approach is not without possible detrimental effects (Valdez and Clemmer 1982). Hatchery rearing and release into the Colorado River was discontinued (as of 1990) until clear management and recovery objectives are established by USFWS (California Department of Fish and Game 1990). See Minckley and Deacon (1991) for information on hatchery culture of bonytail.

Large populations of crayfish in ponds used for rearing razorback suckers negatively affect razorback survival through predation and competition for food (Lenon et al. 2002). Because juvenile bonytail may reduce numbers of small crayfish, integration of rearing programs for these two endangered fishes could benefit both species (Lenon et al. 2002).

Draft recovery goals for Gila cypha, Gila elegans, Ptychocheilus lucius, and Xyrauchen texanus were available in September 2001 (http://www.r6.fws.gov/crrip/rg.htm).

Population/Occurrence Delineation
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Group Name: Large Cyprinids

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs and larvae) in appropriate habitat.
Separation Barriers: Dam lacking a suitable fishway; high waterfall; upland habitat.
Separation Distance for Unsuitable Habitat: 20 km
Separation Distance for Suitable Habitat: 20 km
Separation Justification: Data on dispersal and other movements generally are not available. In some species, individuals may migrate variable distances between spawning areas and nonspawning habitats.

Separation distances (in aquatic kilometers) for cyprinids are arbitrary but reflect the presumption that movements and appropriate separation distances generally should increase with fish size. Hence small, medium, and large cyprinids, respectively, have increasingly large separation distances. Separation distance reflects the likely low probability that two occupied locations separated by less than many kilometers of aquatic habitat would represent truly independent populations over the long term.

Because of the difficulty in defining suitable versus unsuitable habitat, especially with respect to dispersal, and to simplify the delineation of occurrences, a single separation distance is used regardless of habitat quality.

Occupied locations that are separated by a gap of 10 km or more of any aquatic habitat that is not known to be occupied represent different occurrences. However, it is important to evaluate seasonal changes in habitat to ensure that an occupied habitat occurrence for a particular population does not artificially separate spawning areas and nonspawning areas as different occurrences simply because there have been no collections/observations in an intervening area that may exceed the separation distance.

Date: 21Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 08Feb2012
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 08Feb2012
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • California Department of Fish and Game (CDF&G). 1990. 1989 annual report on the status of California's state listed threatened and endangered plants and animals. 188 pp.

  • Chart, T. E., and J. S. Cranney. 1991. Radio-telemetered monitoring of stocked bonytail chubs (Gila elegans) in the Green River, Utah, 1988-1989. Draft Final Report, Utah Division of Wildlife Resources, Salt Lake City.

  • Dowling, T. E., and B. D. DeMarais. 1993. Evolutionary significance of introgressive hybridization in cyprinid fishes. Nature 362:444-446.

  • Gerber, A. S., C. A. Tibbets, and T. E. Dowling. 2001. The role of introgressive hybridization in the evolution of the Gila robusta complex (Teleostei: Cyprinidae). Evolution 55:2028-2039.

  • Hamman, R. L. 1985. Induced spawning of hatchery-reared bonytail. Progressive Fish-Culturist 47:239-241.

  • Jelks, H. L., S. J. Walsh, N. M. Burkhead, S. Contreras-Balderas, E. Díaz-Pardo, D. A. Hendrickson, J. Lyons, N. E. Mandrak, F. McCormick, J. S. Nelson, S. P. Platania, B. A. Porter, C. B. Renaud, J. Jacobo Schmitter-Soto, E. B. Taylor, and M.L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33(8):372-407.

  • Jonez, A., and R. C. Sumner. 1954. Lakes Mead and Mohave investigations: a comparative study of an established reservoir as related to a newly created impoundment. Final Report. Federal Aid Wildlife Restoration (Dingell-Johnson) Project F-l-R, Nevada Game and Fish Commission, Carson City.

  • Kaeding, L. R., B. D. Burdick, P. A. Schrader and W. R. Noonan. 1986. Recent capture of a bonytail (Gila elegans) and observations on this nearly extinct cyprinid from the Colorado River. Copeia 1986(4):1021-1023.

  • Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, North Carolina. i-x + 854 pp.

  • Lenon, N., K. Stave, T. Burke, and J. E. Deacon. 2002. Bonytail (Gila elegans) may enhance survival of razorback suckers (Xyrauchen texanus) in rearing ponds by preying on exotic crayfish. Journal of the Arizona-Nevada Academy of Science 34(1):46-52.

  • Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.

  • Miller, R. R. (with the collaboration of W. L. Minckley and S. M. Norris). 2005 [actually published in 2006]. Freshwater fishes of Mexico. University of Chicago Press, Chicago, Illinois. 490 pp.

  • Miller, W. H., H. M. Tyus, and C. A. Carlson. 1982. Fishes of the upper Colorado system: present and future. American Fisheries Society, Bethesda, Maryland. 131 pp.

  • Minckley, W. L. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenix, Arizona. 293 pp.

  • Minckley, W. L., and J. E. Deacon. 1991. Battle Against Extinction: Native Fish Management in the American West. University of Arizona Press, Tucson. xviii + 517 pp.

  • Minckley, W. L., and P. C. Marsh. 2009. Inland fishes of the greater Southwest: chronicle of a vanishing biota. University of Arizona Press, Tucson, Arizona, 426 pp.

  • Moyle, P. B. 2002. Inland fishes of California. Revised and expanded. University of California Press, Berkeley. xv + 502 pp.

  • Muth, R. T., L. W. Crist, K. E. LaGory, J. W. Hayse, K. R. Bestgen, T. P. Ryan, J. K. Lyons, and R. A. Valdez. 2000. Flow and temperature recommendations for endangered fishes in the Green River downstream of Flaming Gorge Dam. Final Report. Upper Colorado River Endangered Fish Recovery Program Project FG-53.

  • Nelson, J. S., E. J. Crossman, H. Espinosa-Perez, L. T. Findley, C. R. Gilbert, R. N. Lea, and J. D. Williams. 2004. Common and scientific names of fishes from the United States, Canada, and Mexico. American Fisheries Society, Special Publication 29, Bethesda, Maryland. 386 pp.

  • Page, L. M., H. Espinosa-Pérez, L. T. Findley, C. R. Gilbert, R. N. Lea, N. E. Mandrak, R. L. Mayden, and J. S. Nelson. 2013. Common and scientific names of fishes from the United States, Canada, and Mexico. Seventh edition. American Fisheries Society, Special Publication 34, Bethesda, Maryland.

  • Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes: North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.

  • Page, L. M., and B. M. Burr. 2011. Peterson field guide to freshwater fishes of North America north of Mexico. Second edition. Houghton Mifflin Harcourt, Boston. xix + 663 pp.

  • Rinne, J. N., J. E. Johnson, B. L. Jensen, A. W. Ruger, and R. Sorenson. 1986. The role of hatcheries in the management and recovery of threatened and endangered fishes. Pages 271-285 in R.H. Stroud (editor.). Fish culture in fisheries management. American Fisheries Society, Bethesda, Maryland.

  • Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.

  • Rosenfeld, M. J., and J. A. Wilkinson. 1989. Biochemical genetics of the Colorado River Gila complex (Pisces: Cyprinidae). Southwestern Naturalist 34(2):232-244.

  • Smith, G. R., R. R. Miller, and W. D. Sable. 1979. Species relationships among fishes of the genus Gila in the Upper Colorado River drainage. Pages 613-623 In R.M Linn, ed. Proceedings of the First Conference on Scientific Research in the National Parks, 9-12 November 1976, New Orleans, Louisiana. USDI National Park Service Transactions and Proceedings Series No. 5.

  • U.S. Fish and Wildlife Service (USFWS). 1990. Bonytail chub recovery plan. U.S. Fish and Wildlife Service, Denver, Colorado.

  • U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened species recovery program: report to Congress. 406 pp.

  • U.S. Fish and Wildlife Service (USFWS). 1993. Notice of availability of draft agreement regarding Section 7 consultation, sufficient progress and historic projects, recovery implementation program for the endangered fish species in the upper Colorado River basin, and the draft recovery implementation program recovery action plan. Federal Register 58(159):44188-44189. 19 August 1993.

  • U.S. Fish and Wildlife Service (USFWS). 2002. Bonytail (Gila elegans) recovery goals: amendment and supplement to the bonytail chub recovery plan. U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, Colorado.

  • Valdez, R. A., and G. H. Clemmer. 1982. Life history and prospects for recovery of the humpback and bonytail chub. Pages 109-119 in Miller, W. H., ed. Fishes of the Upper Colorado River System: present and future. American Fisheries Society, Bethesda, Maryland.

  • Vanicek, C. D. 1967. Ecological studies of native Green River fishes below Flaming Gorge Dam, 1964-1966. Doctoral Dissertation. Utah State University, Logan, Utah.

  • Vanicek, C. D., and R. H. Kramer. 1969. Life history of the Colorado squawfish, Ptychocheilus lucius, and the Colorado chub, Gila robusta, in the Green River in Dinosaur National Monument, 1964-1966. Transactions of the American Fisheries Society. 98(2):193-208

References for Watershed Distribution Map
  • State Natural Heritage Data Centers. 1996a. Aggregated element occurrence data from all U.S. state natural heritage programs, including the Tennessee Valley Authority, Navajo Nation and the District of Columbia. Science Division, The Nature Conservancy.

  • State Natural Heritage Data Centers. 1996b. Aggregated element occurrence data from all U.S. state natural heritage programs, including the Tennessee Valley Authority, Navajo Nation and the District of Columbia: Export of freshwater fish and mussel records west of the Mississippi River in 1997. Science Division, The Nature Conservancy.

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