Clear Creek gambusia Gambusia heterochir

Gambusia heterochir

Clear Creek gambusia

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Type Locality

Head spring of Clear Creek (16.8 km west of Menard), Menard County, Texas (Hubbs 1957; Edwards 2001).

Etymology/Derivation of Scientific Name

Gambusia – provential Cuban term, Gambusinos, which signifies “nothing”; according to Poey (original describer of the genus), when one catches nothing, he should say he was “fishing for Gambusinos” (Edwards 1999); heterochir – derived from the Greek heteros (= different) and cheir (=hand) for the distinctive shape of the pectoral fin (Hubbs 1957).

Synonymy

Characters

Maximum size: 54 mm TL (Page and Burr 1991). Rohde (1980) listed adult sizes as 25 mm SL (males) and 45 mm SL (females).

Coloration: Dusky lateral stripe indistinct; anal spot of females not restricted to area immediately around anus; predorsal stripe thin or absent (Hubbs et al. 2008). Page and Burr (1991) described coloration: dark anal spot on female. Dusky teardrop. Olive above; iridescent blue and yellow on silver side. Dusky to clear fins; row of faint spots on middle of dorsal fin (Page and Burr 1991). Edwards (2001) noted that Gambusia heterochir has a metallic sheen, and scattered terminal dark marks present on many lateral or dorsal scales form distinctive concentric marks.

Counts: Dorsal fin rays 7-8 (Hubbs et al. 2008).

Mouth position:

Body shape: Deep and rounded (Hubbs 1957). Dorsal fin origin well behind anal fin origin (Hubbs et al. 2008).

External morphology: Pectoral fin of males with indentation, much deeper than widest pectoral fin ray; distal segments of anterior branch of 4^th fin ray of gonopodium not coalesced to elbow; spines at tip of 3^rd anal fin ray of male gonopodium 4-10 times longer than wide (Hubbs et al. 2008).

Internal morphology: Intestinal canal short with few convolutions (Hubbs et al. 2008).

Distribution (Native and Introduced)

U.S. distribution:

Texas distribution: Restricted to impounded headwater springs of Clear Creek, a tributary to the San Saba River (Menard County; Rohde 1980; Hubbs et al. 2008).

Abundance/Conservation status (Federal, State, NGO)

State Endangered (Texas); Federally Endangered (Edwards et al. 2004; Hubbs et al. 1991, 2008). Listed as Endangered by the American Fisheries Society; status has declined since 1989; categories of threats: natural or anthropogenic factors that affect the existence of this species, including impacts of nonidigenous organisms, hybridization, competition, and/or predation; and a narrowly restricted range (Jelks et al. 2008). G. heterochir very abundant in the head pool (Clear Creek; Johnson and Hubbs 1989; Edwards 2001), yet faces potential threat of diminished spring flows from water withdrawals from the Edwards-Trinity Aquifer (Edwards 2001). G. heterochir listed as Endangered (Warren et al. 2000). Rare; headwater springs of Clear Creek are now impounded, and Gambusia heterochir is threatened with extinction; recognized as Endangered species (Page and Burr 1991). Endangered due to restricted range; hybridizes with G. affinis (Minckley et al. 1991). Species listed as Threatened by the American Fisheries Society (Williams et al. 1989). U.S. Fish and Wildlife Service and the Rio Grande Fishes Recovery Team developed a recovery plan for this species (U.S. Fish and Wildlife Service 1980; Edwards 2001; Edwards et al. 2004). Gambusia heterochir recognized as endangered in the nation’s original endangered species legislation (U.S. Fish and Wildlife Service 1967; Edwards et al. 2004).

Habitat Associations

Macrohabitat: Springs (Page and Burr 1991; Hubbs 1957,1995).

Mesohabitat: Populations apparently correlated with factors associated with Ceratophyllum beds (Rohde 1980); submerged and emergent vegetation was prolific in all parts of Clear Creek (Hubbs 1957); inhabits stenothermal (20°C), low pH waters (6.1-6.5) waters (Edwards 1999).

Biology

Spawning season: Reproductive season of female fish is from February to September (Hubbs 1971; Yan 1986).

Spawning habitat:

Spawning behavior: Viviparous (bears live young); once female is inseminated females store sperm for several months so that males need not be present during much of the reproductive season (Hubbs 1971; USFWS 1980; Edwards 1999). Brood production affected by light intensity (Hubbs 1999); species had significantly fewer broods at lower light. Males place their gonopodia on their unique pectoral fins during copulation (Warburton et al. 1957; Peden 1970; Edwards 2001).

Fecundity: Fecundity of female varies from 1-28 with an average of 9.02 embryos per brood; interbrood interval varies from 48-60 days with an average of 60.7 days under 20°C, 14 hours light/10 hours dark condition (Yan 1986).

Age/size at maturation: Size at sexual maturity for female is 24.50 mm SL; minimum maturation size of male fish is 17 mm SL. (Yan 1986). Females begin reproducing at 16 mm SL (Edwards 2001). Females may be mature at 3 months (Edwards 2001).

Migration:

Growth and Population structure:

Longevity: Females seldom live more than 1 year (Edwards 2001).

Food habits:

Phylogeny and morphologically similar fishes

Gambusia heterochir is a member of the G. nobilis species group (Rivas 1963; Rauchenberger 1989).

Edwards (1999) listed the western mosquitofish (Gambusia affinis) and the Pecos gambusia (G. nobilis) as similar species to G. heterochir: G. affinis differs from G. heterochir in that the spines on ray 3 of its gonopodium are short, and an elongated terminal hook is present on ray 4p; sides with only scattered melanophores, not approaching a distinctive crescent shape; often with spots on caudal fin; females with only a small anal spot; and usually having 6 dorsal fin rays. G. nobilis differs from G. heterochir in that the lateral stripe on sides of body is thin and threadlike; the caudal fin has a dark margin; sides with small spots, but not in crescent shapes; and having a strong predorsal streak (Edwards 1999). Unlike Gambusia heterochir, other species of Gambusia lack deep notch in pectoral fin; have dark or dusky stripe along back, shorter elbow on gonopodium (Page and Burr 1991).

Gambusia heterochir hybridizes in nature with the western mosquitofish (G. affinis; Hubbs 1957, 1959, 1971).

Host Records

Commercial or Environmental Importance

A series of old dams located at the extreme headwaters of Clear Creek contributed to a competitive advantage by G. affinis (western mosquitofish) at this location and also resulted in a long established hybrid swarm (Hubbs 1971) between G. heterochir and G. affinis (Hubbs et al. 2008); a major dam reconstruction during the late 1970s has had the effect of reducing the incidence of hybridization above the dam (Edwards and Hubbs 1985; Edwards 1999, 2001; Edwards et al. 2004; Hubbs et al. 2008). Edwards (2001) recommended full implementation of all recovery objectives listed in the Clear Creek Gambusia Recovery Plan.

[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Peden (1973, 1975); Yan (1987); Echelle et al. (1989).]

References

Echelle, A.A., D.M. Wildrick, and A.F. Echelle. 1989. Allozyme studies of genetic variation on Poeciliid fishes, Chapter 12. pp 217-234 In: G.K. Meffe and F.F. Snelson, Jr. (eds). Ecology and Evolution of Livebearing Fishes (Poeciliidae). Prentice Hall, Englewood Cliffs. 453 pp.

Edwards, R.J. 1999. Ecological profiles for selected stream-dwelling Texas freshwater fishes II. Report to the Texas Water Development Board. 69 pp.

Edwards, R.J. 2001. Ecological profiles for selected stream-dwelling Texas freshwater fishes III. Report to the Texas Water Development Board. 59 pp.

Edwards, R.J., and C. Hubbs. 1985. Temporal changes in the Gambusia heterochir x G. affinis hybrid swarm following dam reconstruction. Endangered Species Report No. 13. U.S. Fish and Wildlife Service, Albuquerque, New Mexico.

Edwards, R.J., G.P. Garrett, and N.L. Allan. 2004. Aquifer dependent fishes of the Edwards Plateau region, Chapter 13. pp. 253-268 in: Mace, R.E., E.S. Angle, and W.F. Mulligan, III (Eds.). Aquifers of the Edwards Plateau. Texas Water Development Board. 360 pp.

Hubbs, C. 1957. Gambusia heterochir, a new poeciliid fish from Texas with an account of its hybridization with G. affinis. Tulane Stud. Zool. 5:3-16.

Hubbs, C. 1959. Population analysis of a hybrid swarm between Gambusia affinis and G. heterochir. Evolution 13(2):236-246.

Hubbs, C. 1971. Competition and isolation mechanisms in the Gambusia affinis X G. heterochir. Bulletin of the Texas Memorial Museum 19:1-46.

Hubbs, C. 1995. Springs and spring runs as unique aquatic systems. Copeia 1995(4):989-991.

Hubbs, C. 1999. Effect of light intensity on brood production of livebearers Gambusia spp. Transactions of the American Fisheries Society 128(4):747-750.

Hubbs, C., R.J. Edwards, and G.P. Garrett. 1991. An annotated checklist of the freshwater fishes of Texas, with keys to 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, 2^nd edition 43(4):1-87.

Jelks, H.L., S.J. Walsh, N.M. Burkhead, S. Contreras-Balderas, E. Diaz-Pardo, D.A. Hendrickson, J. Lyons, N.E. Mandrak, F. McCormick, J.S. Nelson, S.P. Platania, B.A. Porter, C.B. Renaud, J.J. 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.

Johnson, J.E., and C. Hubbs. 1989. Status and conservation of Poeciliid fishes, Chapter 16. pp 301-317 In: G.K. Meffe and F.F. Snelson, Jr. (eds). Ecology and Evolution of Livebearing Fishes (Poeciliidae). Prentice Hall, Englewood Cliffs. 453 pp.

Minckley, W.L., G.K. Meffe, and D.L. Soltz. 1991. Conservation and management of short-lives fishes: the Cyprinodontoids, Chapter 15. pp. 247-282 in: Minckley, W.L., and J.E. Deacon (Eds.). Battle Against Extinction: Native Fish Management in the American West. University of Arizona Press, Tucson, Arizona. 517 pp.

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

Peden, A.E. 1970. Courtship behavior of Gambusia (Poecilidae) with emphasis on isolating mechanisms. Ph.D. dissertation, University of Texas at Austin. 273 pp.

Peden, A.E. 1973. Variation in anal spot expression of gambusiin females and its effect on male courtship. Copeia 1973(2):250-263.

Peden, A.E. 1975. Differences in copulatory behavior as partial isolating mechanisms in the poeciliid fish Gambusia. Canadian Journal of Zoology 53:1290-1296.

Rauchenberger, M. 1989. Systematics and biogeography of the genus Gambusia (Cyprinodontiformes: Poeciliidae). American Museum Novitates 2951:1-74.

Rivas, L.R. 1963. Subgenera and species groups in the poeciliid fish genus Gambusia Poey. Copeia 1963(2):331-347.

Rohde, F.C. 1980. Gambusia heterochir (Hubbs), Clear Creek gambusia. pp. 543 in D. S. Lee et al., Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

U.S. Fish and Wildlife Service. 1967. Endangered Species List-1967: Federal Register v.32, p. 4001.

U.S. Fish and Wildlife Service. 1980. Clear Creak Gambusia Recovery Plan: U.S. Fish and Wildlife Service, Albuquerque, New Mexico. 29 pp.

Warburton,B., C. Hubbs, and D.W. Hagen. 1957. Reproductive behavior of Gambusia heterochir. Copeia 1957(4):299-300.

Warren, M.L., Jr., B.M. Burr, S.J. Walsh, H.L. Bart, Jr., R.C. Cashner, D.A. Etnier, B.J. Freeman, B.R. Kuhajda, R.L. Mayden, H.W. Robison, S.T. Ross, and W.C. Starnes. 2000. Diversity, Distribution, and Conservation status of the native freshwater fishes of the southern United States. Fisheries 25(10):7-29.

Williams, J.E., J.E. Johnson, D.A. Hendrickson, S. Contreras-Balderas, J.D. Williams, M. Navarro-Mendoza, D.E. McAllister, and J.E. Deacon. 1989. Fishes of North America endangered, threatened, or of special concern: 1989. Fisheries 14(6):2-20.

Yan, H. 1986. Reproductive strategies of the Clear Creek gambusia, Gambusia heterochir (Reproduction, endangered species, ecology). Ph.D. dissertation, University of Texas at Austin. 188 pp.

Yan, H.Y. 1987. Size at maturity in male Gambusia heterochir. Journal of Fish Biology 30(6):731-741.