Pictures by Chad Thomas, Texas State University-San Marcos
Rio Grande chub
Sangre de Cristo Pass, Rio Grande Basin, New Mexico (Cope 1872).
Etymology/Derivation of Scientific Name
Gila – name of New Mexico river where thought to have first been collected, which was actually the Zuni River; pandora – etymology unknown; Cope was unsure of the “truer affinities” of the species and mentioned several genera to which it may have belonged. Perhaps the taxonomic ambiguity was, for Cope and future taxonomists, a source of troubles much like Pandora’s box (Scharpf 2005)
Clinostomus pandora Cope 1872:475.
Gila nigrescens (Girard); Knapp 1953:61 (misidentification; Sublette et al. 1990); Hubbs 1954:279; Koster 1957:61 (misidentification, in part; Sublette et al. 1990).
Gila pandora Miller and Hubbs (1962); Sublette et al. 1990:123; Hubbs et al. 1991:18.
Maximum size: 250 mm (9.84 in) TL (Rees et al. 2005).
Coloration: Back and sides dusky; sides with two darker stripes (Sublette et al. 1990); dusky to black caudal spot (Page and Burr 1991); abdomen silvery; peritoneum tan to light brown with occasional black spots; insertions of anal, pelvic, and pectoral fins yellowish orange; young silvery (Sublette et al. 1990). Breeding individual with red-orange anal, dorsal, and paired fin bases and side of head; orange lower side (Page and Burr 1991); males commonly had brighter and more intense breeding coloration than females (Rinne 1995).
Counts: Pharyngeal teeth 2,5-4,2 (1,5-4,2; 2,5-4,1; 1,5-4,1) (Miller and Hubbs 1962). 51-67 lateral scales; 6-10 rakers on first gill arch (Miller and Hubbs 1962). Rio Grande populations of G. pandora usually with 9 pelvic fin soft rays and Pecos River populations usually with 8 pelvic fin soft rays (Miller and Hubbs 1962; Suttkus and Cashner 1981). Sublette et al (1990) listed the following counts: 8 (8-9) dorsal fin soft rays; 16 (12-20) pectoral fin soft rays; 8-9 (8-10) pelvic fin soft rays; 8 (7-9) anal fin soft rays; 18-19 caudal fin soft rays.
Mouth position: Slightly subterminal mouth (Page and Burr 1991); mouth obliquely extending to a point under anterior edge of the pupil (Sublette et al. 1990); rounded, fairly blunt snout (Page and Burr 1991).
Body shape: Fairly deep, compressed body; deep caudal peduncle (Page and Burr 1991). Distance from origin of anal fin to end of caudal peduncle contained two and one-half or fewer times in distance from tip of snout to origin of anal fin (Hubbs et al. 1991, 2008). Dorsal fin inserted behind the front of the pelvic fins (Koster 1957).
External morphology: Lower lip thin, without a fleshy lobe; lateral line usually not decurved, either straight or with a broad arch; premaxillaries protractile; upper lip separated form skin of snout by a deep groove continuous across the midline (Hubbs et al. 1991, 2008). Adult males have more pronounced tubercles on caudal peduncle, anal fins, and caudal fins than do females (Rinne 1995; Rees et al. 2005).
Distribution (Native and Introduced)
U.S. distribution: Inhabits limited areas of the Rio Grande and Pecos basins in New Mexico and southern Colorado (Probst 1987; Hubbs et al. 1991; Hubbs et al. 2008). Found in the Canadian River, New Mexico (Calamusso and Rinne 1995; Probst 1999; Scharpf 2005); possibly native to the drainage (Sublette et al. 1990).
Texas distribution: Isolated population found in Little Aguja Creek (Nations Canyon) in the Davis Mountains of Trans-Pecos Texas (Miller and Hubbs 1962; Hubbs et al. 1991, 2008).
Abundance/Conservation status (Federal, State, Non-governmental organizations)
Vulnerable (National Heritage Program global rank; Rees et al. 2005; Scharpf 2005); threatened status in Texas (Hubbs et al. 1991, 2008; Scharpf 2005); species of concern status in Colorado (Rees et al. 2005; Scharpf 2005); status of populations in New Mexico is stable (Sublette et al. 1990), but Rees et al. (2005) noted that the species is considered sensitive in the state. Abundance and distribution of G. pandora has decreased over the past 100 years due to human activities; threatened by habitat degradation and interactions with non-native species (Bestgen et al. 2003; Rees et al. 2005).
Macrohabitat: Headwaters, creeks, and small rivers (Page and Burr 1991).
Mesohabitat: Part of a guild preferring clear, cool, fast-flowing water over rubble or gravel substratum (Platania 1991; Rinne 1995). Found in pools with overhanging banks and brush (Page and Burr 1991; Rinne 1995; Rees et al. 2005). Collected at sites where most common substrate types were cobble, gravel, sand and silt; found most often over sand substrate and least often over cobble substrate (Bestgen et al. 2003; Rees et al. 2005).
Spawning season: Occurs mid June-mid August, in the Rio Bonito, New Mexico (Caldwell et al. 2004). Based on the condition of females from the Rio de las Vacas, New Mexico, spawning could occur from March-June (Rinne 1995; Rees et al. 2005). Autumn spawning documented in Hot Creek, Colorado and a brief autumnal spawning event occurred one year in the Rio de las Vacas, New Mexico, suggesting that autumn spawning may occasionally occur when environmental conditions are suitable (Rinne 1995; Bestgen et al. 2003).
Spawning habitat: Riffle habitat in streams (Koster 1957); reported to reproduce in lakes, but this activity has not been observed (Zuckerman and Langlois 1990; Rees et al. 2005).
Spawning behavior: Nest construction and parental care not observed (Koster 1957).
Fecundity: 1,366 to 6,322 ova average 3,362 ± 366 (SE) ova (Rinne 1995).
Age/size at maturation: Mature females were about 90 mm (3.54 in) TL (Rinne 1995); age 3 (Rees et al. 2005).
Migration: In spring and early summer, G. pandora apparently moves from pools into riffles to spawn (Koster 1957; Rees et al. 2005).
Growth and Population structure: Adult females averaged significantly greater in both length and volume than males (Rinne 1995). In Hot Creek, Colorado, species appeared represented by age-0 (27-54 mm, 1.06-2.13 in, TL), age-1 (63-115 mm, 2.48-4.53 in, TL), age-2 (140-153 mm, 5.51-6.02 in, TL), and age-3 or older (180-186 mm, 7.09-7.32 in, TL) fish (Bestgen et al. 2003).
Longevity: No information at this time.
Food habits: Mid-water carnivore; diet includes zooplankton, aquatic and terrestrial insects, crustaceans, juvenile fish, and a limited amount of detritus (Sublette et al. 1990; Zuckerman and Langlois 1990; Bestgen et al. 2003).
Phylogeny and morphologically similar fishes
Suttkus and Cashner (1981) reported G. pandora X Rhinichthys cataractae (longnose dace) hybrids from the upper Rio Grande system and the Pecos River system; Hubbs (1955) and Cross and Minckley (1960) also reported hybrids between these two species. Drought conditions or reduction in water quantity due to irrigation results in crowding of individuals during the spawning season which may lead to hybridization (Cross and Minckley 1960; Suttkus and Cashner 1981).
No information at this time.
Commercial or Environmental Importance
Predation by brown trout (Salmo trutta) reported (Zuckerman and Bergerson 1986; Zuckerman and Langlois 1990; Rees et al. 2005).
Bestgen, K.R., R.I. Compton, K.A. Zelasko, and J.E. Alves. 2003. Distribution and status of Rio Grande chub in Colorado. Larval Fish Laboratory Contribution 135, Larval Fish Laboratory, Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, Colorado 80523. 61 pp.
Calamusso, B., and J.R. Rinne. 1995. Distribution of Rio Grande cutthroat trout and its co-occurrence with the Rio Grande sucker and Rio Grande chub on the Carson and Santa Fe National Forests. Rocky Mountain Forest and Range Experiment Station, U.S. Dept. of Agriculture. Fort Collins, Colo. (USA). pp. 157-167.
Caldwell, C.A., S.A. Fuller, W.R. Gould, P.R. Turner, and D.M. Hallford. 2004. Seasonal changes in 17-ß estradiol of the Rio Grande chub (Gila pandora) in south-central New Mexico. The Southwestern Naturalist 49(3):311-315.
Cope, E.D. 1872. Report on the recent reptiles and fishes of the survey collected by Campbell, Carrington, and C.B. Dawes. Preliminary Report of the U.S. Geological Survey of Territories. U.S. Geological Survey, Washington, D.C.
Cross, F.B., and W.L. Minckley. 1960. Five natural hybrid combinations in minnows (cyprinidae). Univ. Kansas Publ. Mus. Nat. Hist. 13(1):1-18.
Hubbs, C. 1954. Corrected distributional records for Texas fresh-water fishes. Texas Journal of Science 1954(3):277-291.
Hubbs, C., R. J. Edwards, and G. P. Garrett. 1991. An annotated checklist of the freshwater fishes of Texas, with keys to the identification of species. Texas Journal of Science, Supplement 43(4):1-56.
Hubbs, C., R.J. Edwards, and G.P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement, 2nd edition 43(4):1-87.
Hubbs, C.L. 1955. Hybridization between fishes in nature. Systematic Zoology 4(1):1-20.
Knapp, F.T. 1953. Fishes Found in the Freshwaters of Texas. Ragland Studio and Litho Printing Co., Brunswick, Georgia. 166 pp.
Koster, W.J. 1957. Guide to the Fishes of New Mexico. University of New Mexico Press, Albuquerque. 116 pp.
Miller, R.R. and C. Hubbs. 1962. Gila pandora, a cyprinid new to the Texas fish fauna. Texas Journal of Science 14(1):111-113.
Page, L. M. and B. M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.
Platania, S.P. 1991. Fishes of the Rio Chama and upper Rio Grande, New Mexico, with preliminary comments on their longitudinal distribution. The Southwestern Naturalist 36(2):186-193.
Probst, D.L. 1999. Threatened and endangered fishes of New Mexico. Tech. Report No. 1. New Mexico Dept. of Game and Fish, Sante Fe, New Mexico. 84 pp.
Probst, D.L., G.L. Burton, and B.H. Pridgeon. 1987. Fishes of the Rio Grande between Elephant Butte and Caballo reservoirs, New Mexico. Southwestern Naturalist 32(3):408-411.
Rees, D.E., R.J. Carr, and W.J. Miller. 2005, May 11. Rio Grande Chub (Gila pandora): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/riograndechub.pdf [17 June 2008].
Rinne, J.N. 1995. Reproductive biology of the Rio Grande chub, Gila pandora (Teleostomi: Cypriniformes), in a montane stream, New Mexico. Southwest. Nat. 40:107-10.
Scharpf, C. 2005. Annotated checklist of North American freshwater fishes including subspecies and undescribed forms, Part 1: Petromyzontidae through Cyprinidae. American Currents, Special Publication 31(4):1-44.
Sublette, J.E., M.D. Hatch, and M. Sublette. 1990. The Fishes of New Mexico. University of New Mexico Press, Albuquerque. 393 pp.
Suttkus, R.D., and R.C. Cashner. 1981. The intergeneric hybrid combination, Gila pandora X Rhinichthys cataractae (Cyprinidae), and comparisons with parental species. Southwestern Naturalist 26(1):78-81.
Zuckerman, L.D. and E.P. Bergerson. 1986. Aquatic Ecology and Management of Wilderness Streams in the Great Sand Dunes National Monument, Colorado. U.S. Forest Service General Technical Report INT No. 212:221-231.
Zuckerman, L.D. and D. Langlois. 1990. Status of the Rio Grande sucker and Rio Grande chub in Colorado. Colorado Division of Wildlife, Montrose, CO. 44 pp.